// File: contracts/rUMB2.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "./interfaces/rUMBV2.sol";
import "./interfaces/Blacklisted.sol";
import "./interfaces/OnDemandTokenBridgable.sol";

contract rUMB2 is Blacklisted, rUMBV2, OnDemandTokenBridgable {
     constructor (
        address _owner,
        uint256 _maxAllowedTotalSupply,
        uint32 _swapStartsOn,
        uint32 _dailyCup,
        string memory _name,
        string memory _symbol,
        address _umb
    ) rUMBV2(_owner, _maxAllowedTotalSupply, _swapStartsOn, _dailyCup, _name, _symbol, _umb) {}

    function mint(address _holder, uint256 _amount)
        external
        override(MintableToken, OnDemandToken)
        onlyOwnerOrMinter()
        assertMaxSupply(_amount)
    {
        require(_amount != 0, "zero amount");

        _mint(_holder, _amount);
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount)
        internal
        override(Blacklisted, OnDemandTokenBridgable, ERC20)
    {
        Blacklisted._beforeTokenTransfer(from, to, amount);
        OnDemandTokenBridgable._beforeTokenTransfer(from, to, amount);
    }
}

// File: contracts/interfaces/rUMBV2.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

// Inheritance
import "./SwappableTokenV2.sol";
import "./MintableToken.sol";


/// @title   Umbrella Rewards contract
/// @author  umb.network
/// @notice  This is reward UMB token (rUMB)
/// @dev     Rewards tokens are used for farming and other rewards distributions.
abstract contract rUMBV2 is MintableToken, SwappableTokenV2 {
    // ========== STATE VARIABLES ========== //

    // ========== CONSTRUCTOR ========== //

    constructor (
        address _owner,
        uint256 _maxAllowedTotalSupply,
        uint32 _swapStartsOn,
        uint32 _dailyCup,
        string memory _name,
        string memory _symbol,
        address _umb
    )
        Owned(_owner)
        ERC20(_name, _symbol)
        MintableToken(_maxAllowedTotalSupply)
        SwappableTokenV2(_umb, _swapStartsOn, _dailyCup) {}
}

// File: contracts/interfaces/Blacklisted.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "@openzeppelin/contracts/access/Ownable.sol";

abstract contract Blacklisted is Ownable {
    mapping (address => bool) public blacklist;

    event BlacklistedWallet(address wallet, bool status);

    function setupBlacklist(address[] calldata _addresses, bool[] calldata _statuses) external onlyOwner {
        uint256 n = _addresses.length;

        for (uint256 i; i < n; i++) {
            blacklist[_addresses[i]] = _statuses[i];
            emit BlacklistedWallet(_addresses[i], _statuses[i]);
        }
    }

    function _beforeTokenTransfer(address _from, address _to, uint256) internal virtual {
        if (blacklist[_to] || blacklist[_from]) {
            revert("address blacklisted");
        }
    }
}

// File: contracts/interfaces/OnDemandTokenBridgable.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "./OnDemandToken.sol";

abstract contract OnDemandTokenBridgable is OnDemandToken {
    mapping (address => bool) public bridges;

    event SetupBridge(address bridge, bool active);

    function setupBridge(address _bridge, bool _active) external onlyOwner() {
        bridges[_bridge] = _active;
        emit SetupBridge(_bridge, _active);
    }

    function _beforeTokenTransfer(address _from, address _to, uint256 _amount) internal virtual override {
        if (_from != address(0) && _to != address(0) && bridges[msg.sender]) {
            uint256 balance = balanceOf(msg.sender);

            if (balance < _amount) {
                uint256 amountToMint = _amount - balance;
                _assertMaxSupply(amountToMint);
                _mint(msg.sender, amountToMint);
            }
        }
    }
}

// File: contracts/interfaces/SwappableTokenV2.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

// Inheritance
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

import "../interfaces/Owned.sol";
import "../interfaces/ISwapReceiver.sol";


/// @title   Umbrella Rewards contract V2
/// @author  umb.network
/// @notice  This contract serves Swap functionality for rewards tokens
/// @dev     It allows to swap itself for other token (main UMB token).
abstract contract SwappableTokenV2 is Owned, ERC20 {
    struct SwapData {
        // number of tokens swapped so far (no decimals)
        uint32 swappedSoFar;
        // used limit since last swap (no decimals)
        uint32 usedLimit;
        // daily cup (no decimals)
        uint32 dailyCup;
        uint32 dailyCupTimestamp;
        uint32 swapEnabledAt;
    }

    uint256 public constant ONE = 1e18;

    uint256 public immutable swapStartsOn;
    ISwapReceiver public immutable umb;

    SwapData public swapData;

    event LogStartEarlySwapNow(uint time);
    event LogSwap(address indexed swappedTo, uint amount);
    event LogDailyCup(uint newCup);

    constructor(address _umb, uint32 _swapStartsOn, uint32 _dailyCup) {
        require(_dailyCup != 0, "invalid dailyCup");
        require(_swapStartsOn > block.timestamp, "invalid swapStartsOn");
        require(ERC20(_umb).decimals() == 18, "invalid UMB token");

        swapStartsOn = _swapStartsOn;
        umb = ISwapReceiver(_umb);
        swapData.dailyCup = _dailyCup;
    }

    function swapForUMB() external {
        SwapData memory data = swapData;

        (uint256 limit, bool fullLimit) = _currentLimit(data);
        require(limit != 0, "swapping period not started OR limit");

        uint256 amountToSwap = balanceOf(msg.sender);
        require(amountToSwap != 0, "you dont have tokens to swap");

        uint32 amountWoDecimals = uint32(amountToSwap / ONE);
        require(amountWoDecimals <= limit, "daily CUP limit");

        swapData.usedLimit = uint32(fullLimit ? amountWoDecimals : data.usedLimit + amountWoDecimals);
        swapData.swappedSoFar += amountWoDecimals;
        if (fullLimit) swapData.dailyCupTimestamp = uint32(block.timestamp);

        _burn(msg.sender, amountToSwap);
        umb.swapMint(msg.sender, amountToSwap);

        emit LogSwap(msg.sender, amountToSwap);
    }

    function startEarlySwap() external onlyOwner {
        require(block.timestamp < swapStartsOn, "swap is already allowed");
        require(swapData.swapEnabledAt == 0, "swap was already enabled");

        swapData.swapEnabledAt = uint32(block.timestamp);
        emit LogStartEarlySwapNow(block.timestamp);
    }

    /// @param _cup daily cup limit (no decimals), eg. if cup=5 means it is 5 * 10^18 tokens
    function setDailyCup(uint32 _cup) external onlyOwner {
        swapData.dailyCup = _cup;
        emit LogDailyCup(_cup);
    }

    function isSwapStarted() external view returns (bool) {
        // will it save gas if I do 2x if??
        return block.timestamp >= swapStartsOn || swapData.swapEnabledAt != 0;
    }

    function canSwapTokens(address _address) external view returns (bool) {
        uint256 balance = balanceOf(_address);
        if (balance == 0) return false;

        (uint256 limit,) = _currentLimit(swapData);
        return balance / ONE <= limit;
    }

    function currentLimit() external view returns (uint256 limit) {
        (limit,) = _currentLimit(swapData);
        limit *= ONE;
    }

    function _currentLimit(SwapData memory data) internal view returns (uint256 limit, bool fullLimit) {
        if (block.timestamp < swapStartsOn && data.swapEnabledAt == 0) return (0, false);

        fullLimit = block.timestamp - data.dailyCupTimestamp >= 24 hours;
        limit = fullLimit ? data.dailyCup : data.dailyCup - data.usedLimit;
    }
}

// File: contracts/interfaces/MintableToken.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

import "../interfaces/Owned.sol";
import "../interfaces/IBurnableToken.sol";

/// @author  umb.network
abstract contract MintableToken is Owned, ERC20, IBurnableToken {
    uint256 public immutable maxAllowedTotalSupply;
    uint256 public everMinted;

    modifier assertMaxSupply(uint256 _amountToMint) {
        _assertMaxSupply(_amountToMint);
        _;
    }

    // ========== CONSTRUCTOR ========== //

    constructor (uint256 _maxAllowedTotalSupply) {
        require(_maxAllowedTotalSupply != 0, "_maxAllowedTotalSupply is empty");

        maxAllowedTotalSupply = _maxAllowedTotalSupply;
    }

    // ========== MUTATIVE FUNCTIONS ========== //

    function burn(uint256 _amount) override external {
        _burn(msg.sender, _amount);
    }

    // ========== RESTRICTED FUNCTIONS ========== //

    function mint(address _holder, uint256 _amount)
        virtual
        external
        onlyOwner()
        assertMaxSupply(_amount)
    {
        require(_amount != 0, "zero amount");

        _mint(_holder, _amount);
    }

    function _assertMaxSupply(uint256 _amountToMint) internal {
        uint256 everMintedTotal = everMinted + _amountToMint;
        everMinted = everMintedTotal;
        require(everMintedTotal <= maxAllowedTotalSupply, "total supply limit exceeded");
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../../utils/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.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 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

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

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) public {
        _name = name_;
        _symbol = symbol_;
        _decimals = 18;
    }

    /**
     * @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 {_setupDecimals} is
     * called.
     *
     * 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 _decimals;
    }

    /**
     * @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);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        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].add(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) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        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);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(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 = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(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);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(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 Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal virtual {
        _decimals = decimals_;
    }

    /**
     * @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: contracts/interfaces/Owned.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "@openzeppelin/contracts/access/Ownable.sol";

abstract contract Owned is Ownable {
    constructor(address _owner) {
        transferOwnership(_owner);
    }
}

// File: contracts/interfaces/ISwapReceiver.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

interface ISwapReceiver {
    function swapMint(address _holder, uint256 _amount) external;
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 GSN 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 payable) {
        return msg.sender;
    }

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

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../utils/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/interfaces/IBurnableToken.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

interface IBurnableToken {
    function burn(uint256 _amount) external;
}

// File: contracts/interfaces/OnDemandToken.sol



//SPDX-License-Identifier: MIT
pragma solidity 0.7.5;

import "./MintableToken.sol";

abstract contract OnDemandToken is MintableToken {
    bool constant public ON_DEMAND_TOKEN = true;

    mapping (address => bool) public minters;

    event SetupMinter(address minter, bool active);

    modifier onlyOwnerOrMinter() {
        address msgSender = _msgSender();
        require(owner() == msgSender || minters[msgSender], "access denied");

        _;
    }

    function setupMinter(address _minter, bool _active) external onlyOwner() {
        minters[_minter] = _active;
        emit SetupMinter(_minter, _active);
    }

    function setupMinters(address[] calldata _minters, bool[] calldata _actives) external onlyOwner() {
        for (uint256 i; i < _minters.length; i++) {
            minters[_minters[i]] = _actives[i];
            emit SetupMinter(_minters[i], _actives[i]);
        }
    }

    function mint(address _holder, uint256 _amount)
        external
        virtual
        override
        onlyOwnerOrMinter()
        assertMaxSupply(_amount)
    {
        require(_amount != 0, "zero amount");

        _mint(_holder, _amount);
    }
}