// File: /Users/jacob/Developer/DeFiWorkspace/punk.protocol/contracts/FairLaunch.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0 <0.9.0;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/proxy/utils/Initializable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "./interfaces/ForgeInterface.sol";
import "./Ownable.sol";
import "./Referral.sol";

contract FairLaunch is Initializable, Ownable{
    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    event Deposit( uint256 blockNumber, uint256 blockTime, address account, uint256 amount, uint256 accAmount,uint256 totalAmount, uint256 cap, bytes12 referralCode);
    event Withdraw( uint256 blockNumber, uint256 blockTime, address account, uint256 amount, uint256 accAmount,uint256 totalAmount, uint256 cap, bytes12 referralCode);
    
    uint256 constant private OPEN_TIMESTAMP = 1628553600;
    uint256 constant private CLOSED_TIMESTAMP = 1630022400;

    Referral private _referral;
    IERC20 private _token;
    ForgeInterface private _forge;
    
    uint256 private  _count;
    uint256 private _decimals;
    uint256 private _cap;
    uint256 private _totalAmount;
    uint256 private _rewardCap;
    string private _name;

    mapping( address=>bool ) _entered;
    mapping( address=>uint256 ) _indexes;
    
    uint256 [] private _caps;
    uint256 [] private _capUpdateTimestamps;

    function initializeForge( 
            address storage_, 
            address forge_,
            address token_,
            address referral_,
            uint8 decimals_,
            string memory name_
        ) public initializer {

        Ownable.initialize( storage_ );

        _forge          = ForgeInterface(forge_);
        _token          = IERC20(token_);
        _referral       = Referral(referral_);
        _decimals       = decimals_;
        _totalAmount    = 0;
        _count          = 0;
        _rewardCap      = 70000 * 10**18;
        _name           = name_;

        _token.safeApprove(forge_,  2**256 - 1);
    }

    function enter( uint256 amount ) public returns(bool){
        return enter(amount, 0x0);
    }

    function enter( uint256 amount, bytes12 ref ) public returns(bool) {
        require( block.timestamp > OPEN_TIMESTAMP, "FL : Not Opened yet");
        require( _totalAmount + amount <= _cap, "FL : Amount Overflow" );
        require( _token.allowance(msg.sender, address(this)) >= amount, "FL : Allowance Error");
        
        ( bool entered, uint index ) = isEntered( msg.sender );

        _token.safeTransferFrom(msg.sender, address(this), amount);
        address issuer = _referral.validate( ref );

        if( entered ){
            _forge.addDeposit(index, amount);
        }else{
            _indexes[msg.sender] = _forge.countByAccount(address(this));
            _entered[msg.sender] = true;
            if( ref == 0x0 ){
                _forge.craftingSaver(amount, CLOSED_TIMESTAMP, 1, 1);
                _count += 1;
            }else{
                require( issuer != address(0x0), "FL : Not Registry Ref Code");
                _forge.craftingSaver(amount, CLOSED_TIMESTAMP, 1, 1, ref);
                _count += 1;
            }
        }
        _totalAmount = _totalAmount.add(amount);
        ( entered, index ) = isEntered( msg.sender );
        emit Deposit(block.number, block.timestamp, msg.sender, amount, _forge.saver(address(this), index).accAmount, _totalAmount, _cap, _forge.saver(address(this), index).ref);
        return true;
    }

    function exit() public returns(bool) {
        require(_entered[msg.sender], "FL : Not Entering");
        
        uint beforeBalanceOf = _token.balanceOf(address(this));
        uint index = _indexes[msg.sender];
        _forge.terminateSaver(index);
        uint afterBalanceOf = _token.balanceOf(address(this));
        uint repayable = afterBalanceOf.sub(beforeBalanceOf);
        
        _entered[msg.sender] = false;
        _token.safeTransfer(msg.sender, repayable);
        _totalAmount = _totalAmount.sub(_forge.saver(address(this), index).accAmount);
        _count -= 1;

        emit Withdraw(block.number, block.timestamp, msg.sender, repayable, 0, _totalAmount, _cap, _forge.saver(address(this), index).ref);
        return true;
    }

    function isEntered( address account ) public view returns(bool, uint256){
        return ( _entered[account], _indexes[account] );
    }

    function setCap( uint256 cap_ ) public OnlyAdmin returns(bool){
        _cap = cap_;
        _caps.push(cap_);
        _capUpdateTimestamps.push(block.timestamp);
        return true;
    }

    function cap() public view returns(uint256){
        return _cap;
    }

    function rewardCap() public view returns(uint256){
        return _rewardCap;
    }

    function count() public view returns(uint256){
        return _count;
    }

    function totalAmount() public view returns(uint256){
        return _totalAmount;
    }

    function decimals() public view returns(uint256){
        return _decimals;
    }

    function name() public view returns(string memory){
        return _name;
    }

    function caps() public view returns(uint256 [] memory, uint256 [] memory){
        return ( _caps, _capUpdateTimestamps );
    }

}
// File: /Users/jacob/Developer/DeFiWorkspace/punk.protocol/contracts/Ownable.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0 <0.9.0;

import "./OwnableStorage.sol";

contract Ownable{

    OwnableStorage _storage;

    function initialize( address storage_ ) public {
        _storage = OwnableStorage(storage_);
    }

    modifier OnlyAdmin(){
        require( _storage.isAdmin(msg.sender) );
        _;
    }

    modifier OnlyGovernance(){
        require( _storage.isGovernance( msg.sender ) );
        _;
    }

    modifier OnlyAdminOrGovernance(){
        require( _storage.isAdmin(msg.sender) || _storage.isGovernance( msg.sender ) );
        _;
    }

    function updateAdmin( address admin_ ) public OnlyAdmin {
        _storage.setAdmin(admin_);
    }

    function updateGovenance( address gov_ ) public OnlyAdminOrGovernance {
        _storage.setGovernance(gov_);
    }

}
// File: /Users/jacob/Developer/DeFiWorkspace/punk.protocol/contracts/OwnableStorage.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0 <0.9.0;

contract OwnableStorage {

    address public _admin;
    address public _governance;

    constructor() payable {
        _admin = msg.sender;
        _governance = msg.sender;
    }

    function setAdmin( address account ) public {
        require( isAdmin( msg.sender ));
        _admin = account;
    }

    function setGovernance( address account ) public {
        require( isAdmin( msg.sender ) || isGovernance( msg.sender ));
        _admin = account;
    }

    function isAdmin( address account ) public view returns( bool ) {
        return account == _admin;
    }

    function isGovernance( address account ) public view returns( bool ) {
        return account == _admin;
    }

}
// File: /Users/jacob/Developer/DeFiWorkspace/punk.protocol/contracts/Referral.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0 <0.9.0;

contract Referral {

    mapping( address=>bytes12 ) private _registers;
    mapping( bytes12=>address ) private _referrals;
    uint private _count;
    
    function issue(address account) public returns(bool){
        require( account != address(0x0), "REF : Account is Zero address" );
        require( _registers[account] == 0, "REF : Already Registry" );
        
        uint salt = 0;
        while( true ){
            bytes12 code = _issueReferralCode(account, salt);
            if( _referrals[code] == address(0x0) ){
                _referrals[code] = account;
                _registers[account] = code;    
                break;
            }
            salt++;
        }
        _count++;
        return true;
    }

    function _issueReferralCode( address sender, uint salt ) private pure returns( bytes12 ){
        return bytes12(bytes32(uint(keccak256(abi.encodePacked(sender, salt)))));
    }
    
    function validate( bytes12 code ) public view returns( address ){
        return _referrals[code];
    }
    
    function referralCode( address account ) public view returns( bytes12 ){
        return _registers[account];
    }

}
// File: /Users/jacob/Developer/DeFiWorkspace/punk.protocol/contracts/Saver.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0 <0.9.0;

struct Saver{
    uint256 createTimestamp;
    uint256 startTimestamp;
    uint count;
    uint interval;
    uint256 mint;
    uint256 released;
    uint256 accAmount;
    uint256 relAmount;
    uint score;
    uint status;
    uint updatedTimestamp;
    bytes12 ref;
}

struct Transaction{
    bool pos;
    uint timestamp;
    uint amount;
}
// File: /Users/jacob/Developer/DeFiWorkspace/punk.protocol/contracts/interfaces/ForgeInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0 <0.9.0;
pragma experimental ABIEncoderV2;

import "../Saver.sol";

interface ForgeInterface{

    event CraftingSaver ( address owner, uint index, uint deposit );
    event AddDeposit ( address owner, uint index, uint deposit );
    event Withdraw ( address owner, uint index, uint amount );
    event Terminate ( address owner, uint index, uint amount );
    event Bonus ( address owner, uint index, uint amount );
    event SetModel ( address from, address to );

    function modelAddress() external view returns (address);

    function withdrawable( address account, uint index ) external view returns(uint);
    function countByAccount( address account ) external view returns (uint);
    
    function craftingSaver( uint amount, uint startTimestamp, uint count, uint interval ) external returns(bool);
    function craftingSaver( uint amount, uint startTimestamp, uint count, uint interval, bytes12 referral ) external returns(bool);
    function addDeposit( uint index, uint amount ) external returns(bool);
    function withdraw( uint index, uint amount ) external returns(bool);
    function terminateSaver( uint index ) external returns(bool);

    function countAll() external view returns(uint);
    function saver( address account, uint index ) external view returns( Saver memory );
    function transactions( address account, uint index ) external view returns ( Transaction [] memory );

    function totalScore() external view returns(uint256);
    function getExchangeRate() external view returns( uint );
    function getBonus() external view returns( uint );
    function getTotalVolume( ) external view returns( uint );

}
// File: @openzeppelin/contracts/proxy/utils/Initializable.sol



// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity ^0.8.0;

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

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }
}

// 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/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/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
 * now has built in overflow checking.
 */
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) {
        unchecked {
            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) {
        unchecked {
            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) {
        unchecked {
            // 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) {
        unchecked {
            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) {
        unchecked {
            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) {
        return a + b;
    }

    /**
     * @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) {
        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) {
        return a * b;
    }

    /**
     * @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.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        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) {
        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) {
        unchecked {
            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.
     *
     * 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).
     *
     * 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) {
        unchecked {
            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) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}