// File: /Users/davidroon/projects/tribute-contracts/contracts/core/DaoConstants.sol



pragma solidity ^0.8.0;

// SPDX-License-Identifier: MIT

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */

abstract contract DaoConstants {
    // Adapters
    bytes32 internal constant VOTING = keccak256("voting");
    bytes32 internal constant ONBOARDING = keccak256("onboarding");
    bytes32 internal constant NONVOTING_ONBOARDING =
        keccak256("nonvoting-onboarding");
    bytes32 internal constant TRIBUTE = keccak256("tribute");
    bytes32 internal constant FINANCING = keccak256("financing");
    bytes32 internal constant MANAGING = keccak256("managing");
    bytes32 internal constant RAGEQUIT = keccak256("ragequit");
    bytes32 internal constant GUILDKICK = keccak256("guildkick");
    bytes32 internal constant EXECUTION = keccak256("execution");
    bytes32 internal constant CONFIGURATION = keccak256("configuration");
    bytes32 internal constant DISTRIBUTE = keccak256("distribute");
    bytes32 internal constant TRIBUTE_NFT = keccak256("tribute-nft");

    // Extensions
    bytes32 internal constant BANK = keccak256("bank");
    bytes32 internal constant NFT = keccak256("nft");
    bytes32 internal constant ERC20_EXT = keccak256("erc20-ext");

    // Reserved Addresses
    address internal constant GUILD = address(0xdead);
    address internal constant TOTAL = address(0xbabe);
    address internal constant ESCROW = address(0x4bec);
    address internal constant UNITS = address(0xFF1CE);
    address internal constant LOOT = address(0xB105F00D);
    address internal constant ETH_TOKEN = address(0x0);
    address internal constant MEMBER_COUNT = address(0xDECAFBAD);

    uint8 internal constant MAX_TOKENS_GUILD_BANK = 200;

    //helper
    function getFlag(uint256 flags, uint256 flag) public pure returns (bool) {
        return (flags >> uint8(flag)) % 2 == 1;
    }

    function setFlag(
        uint256 flags,
        uint256 flag,
        bool value
    ) public pure returns (uint256) {
        if (getFlag(flags, flag) != value) {
            if (value) {
                return flags + 2**flag;
            } else {
                return flags - 2**flag;
            }
        } else {
            return flags;
        }
    }

    /**
     * @notice Checks if a given address is reserved.
     */
    function isNotReservedAddress(address addr) public pure returns (bool) {
        return addr != GUILD && addr != TOTAL && addr != ESCROW;
    }

    /**
     * @notice Checks if a given address is zeroed.
     */
    function isNotZeroAddress(address addr) public pure returns (bool) {
        return addr != address(0x0);
    }
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/core/DaoRegistry.sol



pragma solidity ^0.8.0;

// SPDX-License-Identifier: MIT

import "./DaoConstants.sol";
import "../guards/AdapterGuard.sol";
import "../guards/MemberGuard.sol";
import "../extensions/IExtension.sol";

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */

contract DaoRegistry is MemberGuard, AdapterGuard {
    bool public initialized = false; // internally tracks deployment under eip-1167 proxy pattern

    enum DaoState {CREATION, READY}

    /*
     * EVENTS
     */
    /// @dev - Events for Proposals
    event SubmittedProposal(bytes32 proposalId, uint256 flags);
    event SponsoredProposal(
        bytes32 proposalId,
        uint256 flags,
        address votingAdapter
    );
    event ProcessedProposal(bytes32 proposalId, uint256 flags);
    event AdapterAdded(
        bytes32 adapterId,
        address adapterAddress,
        uint256 flags
    );
    event AdapterRemoved(bytes32 adapterId);

    event ExtensionAdded(bytes32 extensionId, address extensionAddress);
    event ExtensionRemoved(bytes32 extensionId);

    /// @dev - Events for Members
    event UpdateDelegateKey(address memberAddress, address newDelegateKey);
    event ConfigurationUpdated(bytes32 key, uint256 value);
    event AddressConfigurationUpdated(bytes32 key, address value);

    enum MemberFlag {EXISTS}

    enum ProposalFlag {EXISTS, SPONSORED, PROCESSED}

    enum AclFlag {
        REPLACE_ADAPTER,
        SUBMIT_PROPOSAL,
        UPDATE_DELEGATE_KEY,
        SET_CONFIGURATION,
        ADD_EXTENSION,
        REMOVE_EXTENSION,
        NEW_MEMBER
    }

    /*
     * STRUCTURES
     */
    struct Proposal {
        // the structure to track all the proposals in the DAO
        address adapterAddress; // the adapter address that called the functions to change the DAO state
        uint256 flags; // flags to track the state of the proposal: exist, sponsored, processed, canceled, etc.
    }

    struct Member {
        // the structure to track all the members in the DAO
        uint256 flags; // flags to track the state of the member: exists, etc
    }

    struct Checkpoint {
        // A checkpoint for marking number of votes from a given block
        uint96 fromBlock;
        uint160 amount;
    }

    struct DelegateCheckpoint {
        // A checkpoint for marking number of votes from a given block
        uint96 fromBlock;
        address delegateKey;
    }

    struct AdapterEntry {
        bytes32 id;
        uint256 acl;
    }

    struct ExtensionEntry {
        bytes32 id;
        mapping(address => uint256) acl;
    }

    /*
     * PUBLIC VARIABLES
     */
    mapping(address => Member) public members; // the map to track all members of the DAO
    address[] private _members;

    // delegate key => member address mapping
    mapping(address => address) public memberAddressesByDelegatedKey;

    // memberAddress => checkpointNum => DelegateCheckpoint
    mapping(address => mapping(uint32 => DelegateCheckpoint)) checkpoints;
    // memberAddress => numDelegateCheckpoints
    mapping(address => uint32) numCheckpoints;

    DaoState public state;

    /// @notice The map that keeps track of all proposasls submitted to the DAO
    mapping(bytes32 => Proposal) public proposals;
    /// @notice The map that tracks the voting adapter address per proposalId
    mapping(bytes32 => address) public votingAdapter;
    /// @notice The map that keeps track of all adapters registered in the DAO
    mapping(bytes32 => address) public adapters;
    /// @notice The inverse map to get the adapter id based on its address
    mapping(address => AdapterEntry) public inverseAdapters;
    /// @notice The map that keeps track of all extensions registered in the DAO
    mapping(bytes32 => address) public extensions;
    /// @notice The inverse map to get the extension id based on its address
    mapping(address => ExtensionEntry) public inverseExtensions;
    /// @notice The map that keeps track of configuration parameters for the DAO and adapters
    mapping(bytes32 => uint256) public mainConfiguration;
    mapping(bytes32 => address) public addressConfiguration;

    uint256 public lockedAt;

    /// @notice Clonable contract must have an empty constructor
    // constructor() {
    // }

    /**
     * @notice Initialises the DAO
     * @dev Involves initialising available tokens, checkpoints, and membership of creator
     * @dev Can only be called once
     * @param creator The DAO's creator, who will be an initial member
     * @param payer The account which paid for the transaction to create the DAO, who will be an initial member
     */
    function initialize(address creator, address payer) external {
        require(!initialized, "dao already initialized");
        potentialNewMember(msg.sender);
        potentialNewMember(payer);
        potentialNewMember(creator);

        initialized = true;
    }

    /**
     * @notice default fallback function to prevent from sending ether to the contract
     */
    receive() external payable {
        revert("you cannot send money back directly");
    }

    /**
     * @dev Sets the state of the dao to READY
     */
    function finalizeDao() external {
        state = DaoState.READY;
    }

    function lockSession() external {
        if (isAdapter(msg.sender) || isExtension(msg.sender)) {
            lockedAt = block.number;
        }
    }

    function unlockSession() external {
        if (isAdapter(msg.sender) || isExtension(msg.sender)) {
            lockedAt = 0;
        }
    }

    /**
     * @notice Sets a configuration value
     * @dev Changes the value of a key in the configuration mapping
     * @param key The configuration key for which the value will be set
     * @param value The value to set the key
     */
    function setConfiguration(bytes32 key, uint256 value)
        external
        hasAccess(this, AclFlag.SET_CONFIGURATION)
    {
        mainConfiguration[key] = value;

        emit ConfigurationUpdated(key, value);
    }

    function potentialNewMember(address memberAddress)
        public
        hasAccess(this, AclFlag.NEW_MEMBER)
    {
        require(memberAddress != address(0x0), "invalid member address");

        Member storage member = members[memberAddress];
        if (!getFlag(member.flags, uint8(MemberFlag.EXISTS))) {
            require(
                memberAddressesByDelegatedKey[memberAddress] == address(0x0),
                "member address already taken as delegated key"
            );
            member.flags = setFlag(
                member.flags,
                uint8(MemberFlag.EXISTS),
                true
            );
            memberAddressesByDelegatedKey[memberAddress] = memberAddress;
            _members.push(memberAddress);
        }

        address bankAddress = extensions[BANK];
        if (bankAddress != address(0x0)) {
            BankExtension bank = BankExtension(bankAddress);
            if (bank.balanceOf(memberAddress, MEMBER_COUNT) == 0) {
                bank.addToBalance(memberAddress, MEMBER_COUNT, 1);
            }
        }
    }

    /**
     * @notice Sets an configuration value
     * @dev Changes the value of a key in the configuration mapping
     * @param key The configuration key for which the value will be set
     * @param value The value to set the key
     */
    function setAddressConfiguration(bytes32 key, address value)
        external
        hasAccess(this, AclFlag.SET_CONFIGURATION)
    {
        addressConfiguration[key] = value;

        emit AddressConfigurationUpdated(key, value);
    }

    /**
     * @return The configuration value of a particular key
     * @param key The key to look up in the configuration mapping
     */
    function getConfiguration(bytes32 key) external view returns (uint256) {
        return mainConfiguration[key];
    }

    /**
     * @return The configuration value of a particular key
     * @param key The key to look up in the configuration mapping
     */
    function getAddressConfiguration(bytes32 key)
        external
        view
        returns (address)
    {
        return addressConfiguration[key];
    }

    /**
     * @notice Adds a new extension to the registry
     * @param extensionId The unique identifier of the new extension
     * @param extension The address of the extension
     * @param creator The DAO's creator, who will be an initial member
     */
    function addExtension(
        bytes32 extensionId,
        IExtension extension,
        address creator
    ) external hasAccess(this, AclFlag.ADD_EXTENSION) {
        require(extensionId != bytes32(0), "extension id must not be empty");
        require(
            extensions[extensionId] == address(0x0),
            "extension Id already in use"
        );
        extensions[extensionId] = address(extension);
        inverseExtensions[address(extension)].id = extensionId;
        extension.initialize(this, creator);
        emit ExtensionAdded(extensionId, address(extension));
    }

    function setAclToExtensionForAdapter(
        address extensionAddress,
        address adapterAddress,
        uint256 acl
    ) external hasAccess(this, AclFlag.ADD_EXTENSION) {
        require(isAdapter(adapterAddress), "not an adapter");
        require(isExtension(extensionAddress), "not an extension");
        inverseExtensions[extensionAddress].acl[adapterAddress] = acl;
    }

    /**
     * @notice Replaces an adapter in the registry in a single step.
     * @notice It handles addition and removal of adapters as special cases.
     * @dev It removes the current adapter if the adapterId maps to an existing adapter address.
     * @dev It adds an adapter if the adapterAddress parameter is not zeroed.
     * @param adapterId The unique identifier of the adapter
     * @param adapterAddress The address of the new adapter or zero if it is a removal operation
     * @param acl The flags indicating the access control layer or permissions of the new adapter
     * @param keys The keys indicating the adapter configuration names.
     * @param values The values indicating the adapter configuration values.
     */
    function replaceAdapter(
        bytes32 adapterId,
        address adapterAddress,
        uint128 acl,
        bytes32[] calldata keys,
        uint256[] calldata values
    ) external hasAccess(this, AclFlag.REPLACE_ADAPTER) {
        require(adapterId != bytes32(0), "adapterId must not be empty");

        address currentAdapterAddr = adapters[adapterId];
        if (currentAdapterAddr != address(0x0)) {
            delete inverseAdapters[currentAdapterAddr];
            delete adapters[adapterId];
            emit AdapterRemoved(adapterId);
        }

        for (uint256 i = 0; i < keys.length; i++) {
            bytes32 key = keys[i];
            uint256 value = values[i];
            mainConfiguration[key] = value;
            emit ConfigurationUpdated(key, value);
        }

        if (adapterAddress != address(0x0)) {
            require(
                inverseAdapters[adapterAddress].id == bytes32(0),
                "adapterAddress already in use"
            );
            adapters[adapterId] = adapterAddress;
            inverseAdapters[adapterAddress].id = adapterId;
            inverseAdapters[adapterAddress].acl = acl;
            emit AdapterAdded(adapterId, adapterAddress, acl);
        }
    }

    /**
     * @notice Removes an adapter from the registry
     * @param extensionId The unique identifier of the extension
     */
    function removeExtension(bytes32 extensionId)
        external
        hasAccess(this, AclFlag.REMOVE_EXTENSION)
    {
        require(extensionId != bytes32(0), "extensionId must not be empty");
        require(
            extensions[extensionId] != address(0x0),
            "extensionId not registered"
        );
        delete inverseExtensions[extensions[extensionId]];
        delete extensions[extensionId];
        emit ExtensionRemoved(extensionId);
    }

    /**
     * @notice Looks up if there is an extension of a given address
     * @return Whether or not the address is an extension
     * @param extensionAddr The address to look up
     */
    function isExtension(address extensionAddr) public view returns (bool) {
        return inverseExtensions[extensionAddr].id != bytes32(0);
    }

    /**
     * @notice Looks up if there is an adapter of a given address
     * @return Whether or not the address is an adapter
     * @param adapterAddress The address to look up
     */
    function isAdapter(address adapterAddress) public view returns (bool) {
        return inverseAdapters[adapterAddress].id != bytes32(0);
    }

    /**
     * @notice Checks if an adapter has a given ACL flag
     * @return Whether or not the given adapter has the given flag set
     * @param adapterAddress The address to look up
     * @param flag The ACL flag to check against the given address
     */
    function hasAdapterAccess(address adapterAddress, AclFlag flag)
        public
        view
        returns (bool)
    {
        return getFlag(inverseAdapters[adapterAddress].acl, uint8(flag));
    }

    /**
     * @notice Checks if an adapter has a given ACL flag
     * @return Whether or not the given adapter has the given flag set
     * @param adapterAddress The address to look up
     * @param flag The ACL flag to check against the given address
     */
    function hasAdapterAccessToExtension(
        address adapterAddress,
        address extensionAddress,
        uint8 flag
    ) public view returns (bool) {
        return
            isAdapter(adapterAddress) &&
            getFlag(
                inverseExtensions[extensionAddress].acl[adapterAddress],
                uint8(flag)
            );
    }

    /**
     * @return The address of a given adapter ID
     * @param adapterId The ID to look up
     */
    function getAdapterAddress(bytes32 adapterId)
        external
        view
        returns (address)
    {
        require(adapters[adapterId] != address(0), "adapter not found");
        return adapters[adapterId];
    }

    /**
     * @return The address of a given extension Id
     * @param extensionId The ID to look up
     */
    function getExtensionAddress(bytes32 extensionId)
        external
        view
        returns (address)
    {
        require(extensions[extensionId] != address(0), "extension not found");
        return extensions[extensionId];
    }

    /**
     * PROPOSALS
     */
    /**
     * @notice Submit proposals to the DAO registry
     */
    function submitProposal(bytes32 proposalId)
        public
        hasAccess(this, AclFlag.SUBMIT_PROPOSAL)
    {
        require(proposalId != bytes32(0), "invalid proposalId");
        require(
            !getProposalFlag(proposalId, ProposalFlag.EXISTS),
            "proposalId must be unique"
        );
        proposals[proposalId] = Proposal(msg.sender, 1); // 1 means that only the first flag is being set i.e. EXISTS
        emit SubmittedProposal(proposalId, 1);
    }

    /**
     * @notice Sponsor proposals that were submitted to the DAO registry
     * @dev adds SPONSORED to the proposal flag
     * @param proposalId The ID of the proposal to sponsor
     * @param sponsoringMember The member who is sponsoring the proposal
     */
    function sponsorProposal(
        bytes32 proposalId,
        address sponsoringMember,
        address votingAdapterAddr
    ) external onlyMember2(this, sponsoringMember) {
        // also checks if the flag was already set
        Proposal storage proposal =
            _setProposalFlag(proposalId, ProposalFlag.SPONSORED);

        uint256 flags = proposal.flags;

        require(
            proposal.adapterAddress == msg.sender,
            "only the adapter that submitted the proposal can process it"
        );

        require(
            !getFlag(flags, uint8(ProposalFlag.PROCESSED)),
            "proposal already processed"
        );
        votingAdapter[proposalId] = votingAdapterAddr;
        emit SponsoredProposal(proposalId, flags, votingAdapterAddr);
    }

    /**
     * @notice Mark a proposal as processed in the DAO registry
     * @param proposalId The ID of the proposal that is being processed
     */
    function processProposal(bytes32 proposalId) external {
        Proposal storage proposal =
            _setProposalFlag(proposalId, ProposalFlag.PROCESSED);

        require(proposal.adapterAddress == msg.sender, "err::adapter mismatch");
        uint256 flags = proposal.flags;

        emit ProcessedProposal(proposalId, flags);
    }

    /**
     * @notice Sets a flag of a proposal
     * @dev Reverts if the proposal is already processed
     * @param proposalId The ID of the proposal to be changed
     * @param flag The flag that will be set on the proposal
     */
    function _setProposalFlag(bytes32 proposalId, ProposalFlag flag)
        internal
        returns (Proposal storage)
    {
        Proposal storage proposal = proposals[proposalId];

        uint256 flags = proposal.flags;
        require(
            getFlag(flags, uint8(ProposalFlag.EXISTS)),
            "proposal does not exist for this dao"
        );

        require(
            proposal.adapterAddress == msg.sender,
            "only the adapter that submitted the proposal can set its flag"
        );

        require(!getFlag(flags, uint8(flag)), "flag already set");

        flags = setFlag(flags, uint8(flag), true);
        proposals[proposalId].flags = flags;

        return proposals[proposalId];
    }

    /*
     * MEMBERS
     */

    /**
     * @return Whether or not a given address is a member of the DAO.
     * @dev it will resolve by delegate key, not member address.
     * @param addr The address to look up
     */
    function isMember(address addr) public view returns (bool) {
        address memberAddress = memberAddressesByDelegatedKey[addr];
        return getMemberFlag(memberAddress, MemberFlag.EXISTS);
    }

    /**
     * @return Whether or not a flag is set for a given proposal
     * @param proposalId The proposal to check against flag
     * @param flag The flag to check in the proposal
     */
    function getProposalFlag(bytes32 proposalId, ProposalFlag flag)
        public
        view
        returns (bool)
    {
        return getFlag(proposals[proposalId].flags, uint8(flag));
    }

    /**
     * @return Whether or not a flag is set for a given member
     * @param memberAddress The member to check against flag
     * @param flag The flag to check in the member
     */
    function getMemberFlag(address memberAddress, MemberFlag flag)
        public
        view
        returns (bool)
    {
        return getFlag(members[memberAddress].flags, uint8(flag));
    }

    function getNbMembers() public view returns (uint256) {
        return _members.length;
    }

    function getMemberAddress(uint256 index) public view returns (address) {
        return _members[index];
    }

    /**
     * @notice Updates the delegate key of a member
     * @param memberAddr The member doing the delegation
     * @param newDelegateKey The member who is being delegated to
     */
    function updateDelegateKey(address memberAddr, address newDelegateKey)
        external
        hasAccess(this, AclFlag.UPDATE_DELEGATE_KEY)
    {
        require(newDelegateKey != address(0x0), "newDelegateKey cannot be 0");

        // skip checks if member is setting the delegate key to their member address
        if (newDelegateKey != memberAddr) {
            require(
                // newDelegate must not be delegated to
                memberAddressesByDelegatedKey[newDelegateKey] == address(0x0),
                "cannot overwrite existing delegated keys"
            );
        } else {
            require(
                memberAddressesByDelegatedKey[memberAddr] == address(0x0),
                "address already taken as delegated key"
            );
        }

        Member storage member = members[memberAddr];
        require(
            getFlag(member.flags, uint8(MemberFlag.EXISTS)),
            "member does not exist"
        );

        // Reset the delegation of the previous delegate
        memberAddressesByDelegatedKey[
            getCurrentDelegateKey(memberAddr)
        ] = address(0x0);

        memberAddressesByDelegatedKey[newDelegateKey] = memberAddr;

        _createNewDelegateCheckpoint(memberAddr, newDelegateKey);
        emit UpdateDelegateKey(memberAddr, newDelegateKey);
    }

    /**
     * Public read-only functions
     */

    /**
     * @param checkAddr The address to check for a delegate
     * @return the delegated address or the checked address if it is not a delegate
     */
    function getAddressIfDelegated(address checkAddr)
        public
        view
        returns (address)
    {
        address delegatedKey = memberAddressesByDelegatedKey[checkAddr];
        return delegatedKey == address(0x0) ? checkAddr : delegatedKey;
    }

    /**
     * @param memberAddr The member whose delegate will be returned
     * @return the delegate key at the current time for a member
     */
    function getCurrentDelegateKey(address memberAddr)
        public
        view
        returns (address)
    {
        uint32 nCheckpoints = numCheckpoints[memberAddr];
        return
            nCheckpoints > 0
                ? checkpoints[memberAddr][nCheckpoints - 1].delegateKey
                : memberAddr;
    }

    /**
     * @param memberAddr The member address to look up
     * @return The delegate key address for memberAddr at the second last checkpoint number
     */
    function getPreviousDelegateKey(address memberAddr)
        public
        view
        returns (address)
    {
        uint32 nCheckpoints = numCheckpoints[memberAddr];
        return
            nCheckpoints > 1
                ? checkpoints[memberAddr][nCheckpoints - 2].delegateKey
                : memberAddr;
    }

    /**
     * @notice Determine the prior number of votes for an account as of a block number
     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
     * @param memberAddr The address of the account to check
     * @param blockNumber The block number to get the vote balance at
     * @return The number of votes the account had as of the given block
     */
    function getPriorDelegateKey(address memberAddr, uint256 blockNumber)
        external
        view
        returns (address)
    {
        require(
            blockNumber < block.number,
            "Uni::getPriorDelegateKey: not yet determined"
        );

        uint32 nCheckpoints = numCheckpoints[memberAddr];
        if (nCheckpoints == 0) {
            return memberAddr;
        }

        // First check most recent balance
        if (
            checkpoints[memberAddr][nCheckpoints - 1].fromBlock <= blockNumber
        ) {
            return checkpoints[memberAddr][nCheckpoints - 1].delegateKey;
        }

        // Next check implicit zero balance
        if (checkpoints[memberAddr][0].fromBlock > blockNumber) {
            return memberAddr;
        }

        uint32 lower = 0;
        uint32 upper = nCheckpoints - 1;
        while (upper > lower) {
            uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
            DelegateCheckpoint memory cp = checkpoints[memberAddr][center];
            if (cp.fromBlock == blockNumber) {
                return cp.delegateKey;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return checkpoints[memberAddr][lower].delegateKey;
    }

    /**
     * @notice Creates a new delegate checkpoint of a certain member
     * @param member The member whose delegate checkpoints will be added to
     * @param newDelegateKey The delegate key that will be written into the new checkpoint
     */
    function _createNewDelegateCheckpoint(
        address member,
        address newDelegateKey
    ) internal {
        uint32 nCheckpoints = numCheckpoints[member];
        if (
            nCheckpoints > 0 &&
            checkpoints[member][nCheckpoints - 1].fromBlock == block.number
        ) {
            checkpoints[member][nCheckpoints - 1].delegateKey = newDelegateKey;
        } else {
            checkpoints[member][nCheckpoints] = DelegateCheckpoint(
                uint96(block.number),
                newDelegateKey
            );
            numCheckpoints[member] = nCheckpoints + 1;
        }
    }
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/extensions/IExtension.sol



pragma solidity ^0.8.0;
import "../core/DaoRegistry.sol";

// SPDX-License-Identifier: MIT

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */

interface IExtension {
    function initialize(DaoRegistry dao, address creator) external;
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/extensions/bank/Bank.sol



pragma solidity ^0.8.0;

// SPDX-License-Identifier: MIT

import "../../core/DaoConstants.sol";
import "../../core/DaoRegistry.sol";
import "../IExtension.sol";
import "../../guards/AdapterGuard.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */

contract BankExtension is DaoConstants, AdapterGuard, IExtension {
    using Address for address payable;
    using SafeERC20 for IERC20;

    uint8 public maxExternalTokens; // the maximum number of external tokens that can be stored in the bank

    bool public initialized = false; // internally tracks deployment under eip-1167 proxy pattern
    DaoRegistry public dao;

    enum AclFlag {
        ADD_TO_BALANCE,
        SUB_FROM_BALANCE,
        INTERNAL_TRANSFER,
        WITHDRAW,
        EXECUTE,
        REGISTER_NEW_TOKEN,
        REGISTER_NEW_INTERNAL_TOKEN,
        UPDATE_TOKEN
    }

    modifier noProposal {
        require(dao.lockedAt() < block.number, "proposal lock");
        _;
    }

    /// @dev - Events for Bank
    event NewBalance(address member, address tokenAddr, uint160 amount);

    event Withdraw(address account, address tokenAddr, uint160 amount);

    /*
     * STRUCTURES
     */

    struct Checkpoint {
        // A checkpoint for marking number of votes from a given block
        uint96 fromBlock;
        uint160 amount;
    }

    address[] public tokens;
    address[] public internalTokens;
    // tokenAddress => availability
    mapping(address => bool) public availableTokens;
    mapping(address => bool) public availableInternalTokens;
    // tokenAddress => memberAddress => checkpointNum => Checkpoint
    mapping(address => mapping(address => mapping(uint32 => Checkpoint)))
        public checkpoints;
    // tokenAddress => memberAddress => numCheckpoints
    mapping(address => mapping(address => uint32)) public numCheckpoints;

    /// @notice Clonable contract must have an empty constructor
    // constructor() {
    // }

    modifier hasExtensionAccess(AclFlag flag) {
        require(
            address(this) == msg.sender ||
                address(dao) == msg.sender ||
                dao.state() == DaoRegistry.DaoState.CREATION ||
                dao.hasAdapterAccessToExtension(
                    msg.sender,
                    address(this),
                    uint8(flag)
                ),
            "bank::accessDenied"
        );
        _;
    }

    /**
     * @notice Initialises the DAO
     * @dev Involves initialising available tokens, checkpoints, and membership of creator
     * @dev Can only be called once
     * @param creator The DAO's creator, who will be an initial member
     */
    function initialize(DaoRegistry _dao, address creator) external override {
        require(!initialized, "bank already initialized");
        require(_dao.isMember(creator), "bank::not member");
        dao = _dao;
        initialized = true;

        availableInternalTokens[UNITS] = true;
        internalTokens.push(UNITS);

        availableInternalTokens[MEMBER_COUNT] = true;
        internalTokens.push(MEMBER_COUNT);
        uint256 nbMembers = _dao.getNbMembers();
        for (uint256 i = 0; i < nbMembers; i++) {
            addToBalance(_dao.getMemberAddress(i), MEMBER_COUNT, 1);
        }

        _createNewAmountCheckpoint(creator, UNITS, 1);
        _createNewAmountCheckpoint(TOTAL, UNITS, 1);
    }

    function withdraw(
        address payable member,
        address tokenAddr,
        uint256 amount
    ) external hasExtensionAccess(AclFlag.WITHDRAW) {
        require(
            balanceOf(member, tokenAddr) >= amount,
            "bank::withdraw::not enough funds"
        );
        subtractFromBalance(member, tokenAddr, amount);
        if (tokenAddr == ETH_TOKEN) {
            member.sendValue(amount);
        } else {
            IERC20 erc20 = IERC20(tokenAddr);
            erc20.safeTransfer(member, amount);
        }

        emit Withdraw(member, tokenAddr, uint160(amount));
    }

    /**
     * @return Whether or not the given token is an available internal token in the bank
     * @param token The address of the token to look up
     */
    function isInternalToken(address token) external view returns (bool) {
        return availableInternalTokens[token];
    }

    /**
     * @return Whether or not the given token is an available token in the bank
     * @param token The address of the token to look up
     */
    function isTokenAllowed(address token) public view returns (bool) {
        return availableTokens[token];
    }

    /**
     * @notice Sets the maximum amount of external tokens allowed in the bank
     * @param maxTokens The maximum amount of token allowed
     */
    function setMaxExternalTokens(uint8 maxTokens) external {
        require(!initialized, "bank already initialized");
        require(
            maxTokens > 0 && maxTokens <= MAX_TOKENS_GUILD_BANK,
            "max number of external tokens should be (0,200)"
        );
        maxExternalTokens = maxTokens;
    }

    /*
     * BANK
     */

    /**
     * @notice Registers a potential new token in the bank
     * @dev Can not be a reserved token or an available internal token
     * @param token The address of the token
     */
    function registerPotentialNewToken(address token)
        external
        hasExtensionAccess(AclFlag.REGISTER_NEW_TOKEN)
    {
        require(isNotReservedAddress(token), "reservedToken");
        require(!availableInternalTokens[token], "internalToken");
        require(
            tokens.length <= maxExternalTokens,
            "exceeds the maximum tokens allowed"
        );

        if (!availableTokens[token]) {
            availableTokens[token] = true;
            tokens.push(token);
        }
    }

    /**
     * @notice Registers a potential new internal token in the bank
     * @dev Can not be a reserved token or an available token
     * @param token The address of the token
     */
    function registerPotentialNewInternalToken(address token)
        external
        hasExtensionAccess(AclFlag.REGISTER_NEW_INTERNAL_TOKEN)
    {
        require(isNotReservedAddress(token), "reservedToken");
        require(!availableTokens[token], "availableToken");

        if (!availableInternalTokens[token]) {
            availableInternalTokens[token] = true;
            internalTokens.push(token);
        }
    }

    function updateToken(address tokenAddr)
        external
        hasExtensionAccess(AclFlag.UPDATE_TOKEN)
    {
        require(isTokenAllowed(tokenAddr), "token not allowed");
        uint256 totalBalance = balanceOf(TOTAL, tokenAddr);

        uint256 realBalance;

        if (tokenAddr == ETH_TOKEN) {
            realBalance = address(this).balance;
        } else {
            IERC20 erc20 = IERC20(tokenAddr);
            realBalance = erc20.balanceOf(address(this));
        }

        if (totalBalance < realBalance) {
            addToBalance(GUILD, tokenAddr, realBalance - totalBalance);
        } else if (totalBalance > realBalance) {
            uint256 tokensToRemove = totalBalance - realBalance;
            uint256 guildBalance = balanceOf(GUILD, tokenAddr);
            if (guildBalance > tokensToRemove) {
                subtractFromBalance(GUILD, tokenAddr, tokensToRemove);
            } else {
                subtractFromBalance(GUILD, tokenAddr, guildBalance);
            }
        }
    }

    /**
     * Public read-only functions
     */

    /**
     * Internal bookkeeping
     */

    /**
     * @return The token from the bank of a given index
     * @param index The index to look up in the bank's tokens
     */
    function getToken(uint256 index) external view returns (address) {
        return tokens[index];
    }

    /**
     * @return The amount of token addresses in the bank
     */
    function nbTokens() external view returns (uint256) {
        return tokens.length;
    }

    /**
     * @return All the tokens registered in the bank.
     */
    function getTokens() external view returns (address[] memory) {
        return tokens;
    }

    /**
     * @return The internal token at a given index
     * @param index The index to look up in the bank's array of internal tokens
     */
    function getInternalToken(uint256 index) external view returns (address) {
        return internalTokens[index];
    }

    /**
     * @return The amount of internal token addresses in the bank
     */
    function nbInternalTokens() external view returns (uint256) {
        return internalTokens.length;
    }

    /**
     * @notice Adds to a member's balance of a given token
     * @param member The member whose balance will be updated
     * @param token The token to update
     * @param amount The new balance
     */
    function addToBalance(
        address member,
        address token,
        uint256 amount
    ) public payable hasExtensionAccess(AclFlag.ADD_TO_BALANCE) {
        require(
            availableTokens[token] || availableInternalTokens[token],
            "unknown token address"
        );
        uint256 newAmount = balanceOf(member, token) + amount;
        uint256 newTotalAmount = balanceOf(TOTAL, token) + amount;

        _createNewAmountCheckpoint(member, token, newAmount);
        _createNewAmountCheckpoint(TOTAL, token, newTotalAmount);
    }

    /**
     * @notice Remove from a member's balance of a given token
     * @param member The member whose balance will be updated
     * @param token The token to update
     * @param amount The new balance
     */
    function subtractFromBalance(
        address member,
        address token,
        uint256 amount
    ) public hasExtensionAccess(AclFlag.SUB_FROM_BALANCE) {
        uint256 newAmount = balanceOf(member, token) - amount;
        uint256 newTotalAmount = balanceOf(TOTAL, token) - amount;

        _createNewAmountCheckpoint(member, token, newAmount);
        _createNewAmountCheckpoint(TOTAL, token, newTotalAmount);
    }

    /**
     * @notice Make an internal token transfer
     * @param from The member who is sending tokens
     * @param to The member who is receiving tokens
     * @param amount The new amount to transfer
     */
    function internalTransfer(
        address from,
        address to,
        address token,
        uint256 amount
    ) public hasExtensionAccess(AclFlag.INTERNAL_TRANSFER) {
        uint256 newAmount = balanceOf(from, token) - amount;
        uint256 newAmount2 = balanceOf(to, token) + amount;

        _createNewAmountCheckpoint(from, token, newAmount);
        _createNewAmountCheckpoint(to, token, newAmount2);
    }

    /**
     * @notice Returns an member's balance of a given token
     * @param member The address to look up
     * @param tokenAddr The token where the member's balance of which will be returned
     * @return The amount in account's tokenAddr balance
     */
    function balanceOf(address member, address tokenAddr)
        public
        view
        returns (uint160)
    {
        uint32 nCheckpoints = numCheckpoints[tokenAddr][member];
        return
            nCheckpoints > 0
                ? checkpoints[tokenAddr][member][nCheckpoints - 1].amount
                : 0;
    }

    /**
     * @notice Determine the prior number of votes for an account as of a block number
     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
     * @param account The address of the account to check
     * @param blockNumber The block number to get the vote balance at
     * @return The number of votes the account had as of the given block
     */
    function getPriorAmount(
        address account,
        address tokenAddr,
        uint256 blockNumber
    ) external view returns (uint256) {
        require(
            blockNumber < block.number,
            "Uni::getPriorAmount: not yet determined"
        );

        uint32 nCheckpoints = numCheckpoints[tokenAddr][account];
        if (nCheckpoints == 0) {
            return 0;
        }

        // First check most recent balance
        if (
            checkpoints[tokenAddr][account][nCheckpoints - 1].fromBlock <=
            blockNumber
        ) {
            return checkpoints[tokenAddr][account][nCheckpoints - 1].amount;
        }

        // Next check implicit zero balance
        if (checkpoints[tokenAddr][account][0].fromBlock > blockNumber) {
            return 0;
        }

        uint32 lower = 0;
        uint32 upper = nCheckpoints - 1;
        while (upper > lower) {
            uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
            Checkpoint memory cp = checkpoints[tokenAddr][account][center];
            if (cp.fromBlock == blockNumber) {
                return cp.amount;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return checkpoints[tokenAddr][account][lower].amount;
    }

    /**
     * @notice Creates a new amount checkpoint for a token of a certain member
     * @dev Reverts if the amount is greater than 2**64-1
     * @param member The member whose checkpoints will be added to
     * @param token The token of which the balance will be changed
     * @param amount The amount to be written into the new checkpoint
     */
    function _createNewAmountCheckpoint(
        address member,
        address token,
        uint256 amount
    ) internal {
        bool isValidToken = false;
        if (availableInternalTokens[token]) {
            require(
                amount < type(uint88).max,
                "token amount exceeds the maximum limit for internal tokens"
            );
            isValidToken = true;
        } else if (availableTokens[token]) {
            require(
                amount < type(uint160).max,
                "token amount exceeds the maximum limit for external tokens"
            );
            isValidToken = true;
        }
        uint160 newAmount = uint160(amount);

        require(isValidToken, "token not registered");

        uint32 nCheckpoints = numCheckpoints[token][member];
        if (
            nCheckpoints > 0 &&
            checkpoints[token][member][nCheckpoints - 1].fromBlock ==
            block.number
        ) {
            checkpoints[token][member][nCheckpoints - 1].amount = newAmount;
        } else {
            checkpoints[token][member][nCheckpoints] = Checkpoint(
                uint96(block.number),
                newAmount
            );
            numCheckpoints[token][member] = nCheckpoints + 1;
        }
        emit NewBalance(member, token, newAmount);
    }
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/extensions/token/erc20/ERC20TokenExtension.sol



pragma solidity ^0.8.0;

// SPDX-License-Identifier: MIT
import "../../../core/DaoRegistry.sol";
import "../../../core/DaoConstants.sol";
import "../../../guards/AdapterGuard.sol";
import "../../../utils/PotentialNewMember.sol";
import "../../IExtension.sol";
import "../../bank/Bank.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/access/AccessControlEnumerable.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Pausable.sol";

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */

/**
 *
 * The ERC20Extension is a contract to give erc20 functionality
 * to the internal token units held by DAO members inside the DAO itself.
 */
contract ERC20Extension is
    DaoConstants,
    AdapterGuard,
    PotentialNewMember,
    IExtension,
    IERC20
{
    // The DAO address that this extension belongs to
    DaoRegistry public dao;

    // The custom configuration to set the transfer type, e.g:
    // (0: transfers are enabled only between dao members)
    // (1: transfers are enabled between dao members and external accounts)
    // (2: all transfers are paused)
    bytes32 public constant ERC20_EXT_TRANSFER_TYPE =
        keccak256("erc20ExtTransferType");

    // Internally tracks deployment under eip-1167 proxy pattern
    bool public initialized = false;

    // The token address managed by the DAO that tracks the internal transfers
    address public tokenAddress;

    // The name of the token managed by the DAO
    string public tokenName;

    // The symbol of the token managed by the DAO
    string public tokenSymbol;

    // The number of decimals of the token managed by the DAO
    uint8 public tokenDecimals;

    // Tracks all the token allowances: owner => spender => amount
    mapping(address => mapping(address => uint256)) private _allowances;

    /// @notice Clonable contract must have an empty constructor
    // constructor() {}

    /**
     * @notice Initializes the extension with the DAO that it belongs to,
     * and checks if the parameters were set.
     * @param _dao The address of the DAO that owns the extension.
     * @param creator The owner of the DAO and Extension that is also a member of the DAO.
     */
    function initialize(DaoRegistry _dao, address creator) external override {
        require(!initialized, "already initialized");
        require(_dao.isMember(creator), "not a member");
        require(tokenAddress != address(0x0), "missing token address");
        require(bytes(tokenName).length != 0, "missing token name");
        require(bytes(tokenSymbol).length != 0, "missing token symbol");
        initialized = true;
        dao = _dao;
    }

    /**
     * @dev Returns the token address managed by the DAO that tracks the
     * internal transfers.
     */
    function token() public view virtual returns (address) {
        return tokenAddress;
    }

    /**
     * @dev Sets the token address if the extension is not initialized,
     * not reserved and not zero.
     */
    function setToken(address _tokenAddress) external {
        require(!initialized, "already initialized");
        require(_tokenAddress != address(0x0), "invalid token address");
        require(
            isNotReservedAddress(_tokenAddress),
            "token address already in use"
        );

        tokenAddress = _tokenAddress;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return tokenName;
    }

    /**
     * @dev Sets the name of the token if the extension is not initialized.
     */
    function setName(string memory _name) external {
        require(!initialized, "already initialized");
        tokenName = _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return tokenSymbol;
    }

    /**
     * @dev Sets the token symbol if the extension is not initialized.
     */
    function setSymbol(string memory _symbol) external {
        require(!initialized, "already initialized");
        tokenSymbol = _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     */
    function decimals() public view virtual returns (uint8) {
        return tokenDecimals;
    }

    /**
     * @dev Sets the token decimals if the extension is not initialized.
     */
    function setDecimals(uint8 _decimals) external {
        require(!initialized, "already initialized");
        tokenDecimals = _decimals;
    }

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() public view override returns (uint256) {
        BankExtension bank = BankExtension(dao.getExtensionAddress(BANK));
        return bank.balanceOf(TOTAL, tokenAddress);
    }

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) public view override returns (uint256) {
        BankExtension bank = BankExtension(dao.getExtensionAddress(BANK));
        return bank.balanceOf(account, tokenAddress);
    }

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender)
        public
        view
        override
        returns (uint256)
    {
        return _allowances[owner][spender];
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     * @param spender The address account that will have the units decremented.
     * @param amount The amount to decrement from the spender account.
     * @return a boolean value indicating whether the operation succeeded.
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount)
        public
        override
        reentrancyGuard(dao)
        returns (bool)
    {
        address senderAddr = dao.getAddressIfDelegated(msg.sender);
        require(
            isNotZeroAddress(senderAddr),
            "ERC20: approve from the zero address"
        );
        require(
            isNotZeroAddress(spender),
            "ERC20: approve to the zero address"
        );
        require(dao.isMember(senderAddr), "sender is not a member");
        require(
            isNotReservedAddress(spender),
            "spender can not be a reserved address"
        );

        _allowances[senderAddr][spender] = amount;
        emit Approval(senderAddr, spender, amount);
        return true;
    }

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     * @dev The transfer operation follows the DAO configuration specified
     * by the ERC20_EXT_TRANSFER_TYPE property.
     * @param recipient The address account that will have the units incremented.
     * @param amount The amount to increment in the recipient account.
     * @return a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount)
        public
        override
        reentrancyGuard(dao)
        returns (bool)
    {
        address senderAddr = dao.getAddressIfDelegated(msg.sender);
        require(
            isNotZeroAddress(recipient),
            "ERC20: transfer to the zero address"
        );

        BankExtension bank = BankExtension(dao.getExtensionAddress(BANK));
        require(
            bank.balanceOf(senderAddr, tokenAddress) >= amount && amount > 0,
            "sender does not have units to transfer"
        );

        uint256 transferType = dao.getConfiguration(ERC20_EXT_TRANSFER_TYPE);
        if (transferType == 0) {
            // members only transfer
            require(dao.isMember(recipient), "recipient is not a member");
            bank.internalTransfer(senderAddr, recipient, tokenAddress, amount);
            emit Transfer(senderAddr, recipient, amount);
            return true;
        } else if (transferType == 1) {
            // external transfer
            require(
                isNotReservedAddress(recipient),
                "recipient address can not be reserved"
            );
            bank.internalTransfer(senderAddr, recipient, tokenAddress, amount);
            potentialNewMember(recipient, dao, bank);
            emit Transfer(senderAddr, recipient, amount);
            return true;
        } else if (transferType == 2) {
            // closed/paused transfers
            return false;
        }
        return false;
    }

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     * @dev The transfer operation follows the DAO configuration specified
     * by the ERC20_EXT_TRANSFER_TYPE property.
     * @param sender The address account that will have the units decremented.
     * @param recipient The address account that will have the units incremented.
     * @param amount The amount to decrement from the sender account.
     * @return a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public override reentrancyGuard(dao) returns (bool) {
        require(
            isNotZeroAddress(recipient),
            "ERC20: transferFrom recipient can not be zero address"
        );

        address senderAddr = dao.getAddressIfDelegated(sender);
        uint256 currentAllowance = _allowances[senderAddr][msg.sender];
        //check if sender has approved msg.sender to spend amount
        require(
            currentAllowance >= amount,
            "ERC20: transfer amount exceeds allowance"
        );

        BankExtension bank = BankExtension(dao.getExtensionAddress(BANK));
        require(
            bank.balanceOf(senderAddr, tokenAddress) >= amount && amount > 0,
            "bank does not have enough units to transfer"
        );

        uint256 transferType = dao.getConfiguration(ERC20_EXT_TRANSFER_TYPE);
        if (transferType == 0) {
            // members only transfer
            require(dao.isMember(recipient), "recipient is not a member");

            _allowances[senderAddr][msg.sender] = currentAllowance - amount;

            bank.internalTransfer(senderAddr, recipient, tokenAddress, amount);
            emit Transfer(senderAddr, recipient, amount);

            return true;
        } else if (transferType == 1) {
            // external transfer
            _allowances[senderAddr][msg.sender] = currentAllowance - amount;
            require(
                isNotReservedAddress(recipient),
                "recipient address can not be reserved"
            );
            bank.internalTransfer(senderAddr, recipient, tokenAddress, amount);
            potentialNewMember(recipient, dao, bank);
            emit Transfer(senderAddr, recipient, amount);
            return true;
        } else if (transferType == 2) {
            // closed/paused transfers
            return false;
        }

        return false;
    }
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/guards/AdapterGuard.sol



pragma solidity ^0.8.0;

// SPDX-License-Identifier: MIT

import "../core/DaoRegistry.sol";
import "../extensions/IExtension.sol";

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */
abstract contract AdapterGuard {
    /**
     * @dev Only registered adapters are allowed to execute the function call.
     */
    modifier onlyAdapter(DaoRegistry dao) {
        require(
            (dao.state() == DaoRegistry.DaoState.CREATION &&
                creationModeCheck(dao)) || dao.isAdapter(msg.sender),
            "onlyAdapter"
        );
        _;
    }

    modifier reentrancyGuard(DaoRegistry dao) {
        require(dao.lockedAt() != block.number, "reentrancy guard");
        dao.lockSession();
        _;
        dao.unlockSession();
    }

    modifier hasAccess(DaoRegistry dao, DaoRegistry.AclFlag flag) {
        require(
            (dao.state() == DaoRegistry.DaoState.CREATION &&
                creationModeCheck(dao)) ||
                dao.hasAdapterAccess(msg.sender, flag),
            "accessDenied"
        );
        _;
    }

    function creationModeCheck(DaoRegistry dao) internal view returns (bool) {
        return
            dao.getNbMembers() == 0 ||
            dao.isMember(msg.sender) ||
            dao.isAdapter(msg.sender);
    }
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/guards/MemberGuard.sol



pragma solidity ^0.8.0;

// SPDX-License-Identifier: MIT

import "../core/DaoRegistry.sol";
import "../extensions/bank/Bank.sol";

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */
abstract contract MemberGuard is DaoConstants {
    /**
     * @dev Only members of the DAO are allowed to execute the function call.
     */
    modifier onlyMember(DaoRegistry dao) {
        _onlyMember(dao, msg.sender);
        _;
    }

    modifier onlyMember2(DaoRegistry dao, address _addr) {
        _onlyMember(dao, _addr);
        _;
    }

    function _onlyMember(DaoRegistry dao, address _addr) internal view {
        require(isActiveMember(dao, _addr), "onlyMember");
    }

    function isActiveMember(DaoRegistry dao, address _addr)
        public
        view
        returns (bool)
    {
        address bankAddress = dao.extensions(BANK);
        if (bankAddress != address(0x0)) {
            address memberAddr = dao.getAddressIfDelegated(_addr);
            return BankExtension(bankAddress).balanceOf(memberAddr, UNITS) > 0;
        }

        return dao.isMember(_addr);
    }
}

// File: /Users/davidroon/projects/tribute-contracts/contracts/utils/PotentialNewMember.sol



pragma solidity ^0.8.0;
import "../extensions/bank/Bank.sol";

// SPDX-License-Identifier: MIT

/**
MIT License

Copyright (c) 2020 Openlaw

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
 */

abstract contract PotentialNewMember {
    address internal constant _MEMBER_COUNT = address(0xDECAFBAD);

    function potentialNewMember(
        address memberAddress,
        DaoRegistry dao,
        BankExtension bank
    ) public {
        dao.potentialNewMember(memberAddress);
        require(memberAddress != address(0x0), "invalid member address");
        if (address(bank) != address(0x0)) {
            if (bank.balanceOf(memberAddress, _MEMBER_COUNT) == 0) {
                bank.addToBalance(memberAddress, _MEMBER_COUNT, 1);
            }
        }
    }
}

// File: @openzeppelin/contracts/access/AccessControl.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    function hasRole(bytes32 role, address account) external view returns (bool);
    function getRoleAdmin(bytes32 role) external view returns (bytes32);
    function grantRole(bytes32 role, address account) external;
    function revokeRole(bytes32 role, address account) external;
    function renounceRole(bytes32 role, address account) external;
}

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping (address => bool) members;
        bytes32 adminRole;
    }

    mapping (bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId
            || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual override {
        require(hasRole(getRoleAdmin(role), _msgSender()), "AccessControl: sender must be an admin to grant");

        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual override {
        require(hasRole(getRoleAdmin(role), _msgSender()), "AccessControl: sender must be an admin to revoke");

        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        emit RoleAdminChanged(role, getRoleAdmin(role), adminRole);
        _roles[role].adminRole = adminRole;
    }

    function _grantRole(bytes32 role, address account) private {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) private {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// File: @openzeppelin/contracts/access/AccessControlEnumerable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./AccessControl.sol";
import "../utils/structs/EnumerableSet.sol";

/**
 * @dev External interface of AccessControlEnumerable declared to support ERC165 detection.
 */
interface IAccessControlEnumerable {
    function getRoleMember(bytes32 role, uint256 index) external view returns (address);
    function getRoleMemberCount(bytes32 role) external view returns (uint256);
}

/**
 * @dev Extension of {AccessControl} that allows enumerating the members of each role.
 */
abstract contract AccessControlEnumerable is IAccessControlEnumerable, AccessControl {
    using EnumerableSet for EnumerableSet.AddressSet;

    mapping (bytes32 => EnumerableSet.AddressSet) private _roleMembers;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControlEnumerable).interfaceId
            || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns one of the accounts that have `role`. `index` must be a
     * value between 0 and {getRoleMemberCount}, non-inclusive.
     *
     * Role bearers are not sorted in any particular way, and their ordering may
     * change at any point.
     *
     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
     * you perform all queries on the same block. See the following
     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
     * for more information.
     */
    function getRoleMember(bytes32 role, uint256 index) public view override returns (address) {
        return _roleMembers[role].at(index);
    }

    /**
     * @dev Returns the number of accounts that have `role`. Can be used
     * together with {getRoleMember} to enumerate all bearers of a role.
     */
    function getRoleMemberCount(bytes32 role) public view override returns (uint256) {
        return _roleMembers[role].length();
    }

    /**
     * @dev Overload {grantRole} to track enumerable memberships
     */
    function grantRole(bytes32 role, address account) public virtual override {
        super.grantRole(role, account);
        _roleMembers[role].add(account);
    }

    /**
     * @dev Overload {revokeRole} to track enumerable memberships
     */
    function revokeRole(bytes32 role, address account) public virtual override {
        super.revokeRole(role, account);
        _roleMembers[role].remove(account);
    }

    /**
     * @dev Overload {renounceRole} to track enumerable memberships
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        super.renounceRole(role, account);
        _roleMembers[role].remove(account);
    }

    /**
     * @dev Overload {_setupRole} to track enumerable memberships
     */
    function _setupRole(bytes32 role, address account) internal virtual override {
        super._setupRole(role, account);
        _roleMembers[role].add(account);
    }
}

// File: @openzeppelin/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor () {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "../../utils/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The defaut value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overloaded;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        _approve(sender, _msgSender(), currentAllowance - amount);

        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        _approve(_msgSender(), spender, currentAllowance - subtractedValue);

        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        _balances[sender] = senderBalance - amount;
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        _balances[account] = accountBalance - amount;
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/token/ERC20/extensions/ERC20Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../ERC20.sol";
import "../../../security/Pausable.sol";

/**
 * @dev ERC20 token with pausable token transfers, minting and burning.
 *
 * Useful for scenarios such as preventing trades until the end of an evaluation
 * period, or having an emergency switch for freezing all token transfers in the
 * event of a large bug.
 */
abstract contract ERC20Pausable is ERC20, Pausable {
    /**
     * @dev See {ERC20-_beforeTokenTransfer}.
     *
     * Requirements:
     *
     * - the contract must not be paused.
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
        super._beforeTokenTransfer(from, to, amount);

        require(!paused(), "ERC20Pausable: token transfer while paused");
    }
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/structs/EnumerableSet.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}