// File: contracts/DCHFToken.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.14;
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

import "./Dependencies/CheckContract.sol";
import "./Interfaces/IDCHFToken.sol";

/*
 * DCHFToken contract valid for both V1 and V2:
 *
 * It allows to have 2 or more TroveManagers registered that can mint and burn.
 * It allows to have 2 or more BorrowerOperations registered that can mint and burn.
 *
 * Two public arrays record the TroveManager and BorrowerOps addresses registered.
 *
 * Two events are logged when modifying the array of troveManagers and borrowerOps.
 *
 * The different modifiers are updated and check if either one of the TroveManagers
 * or BorrowerOperations are making the call with mapping(address => bool).
 *
 * functions addTroveManager and addBorrowerOps register new contracts into the array.
 *
 * functions removeTroveManager and removeBorrowerOps enable the removal of a contract
 * from both the mapping and the public array.
 *
 * Additional checks in place in order to ensure that the addresses added are real
 * TroveManager or BorrowerOps contracts.
 */

interface ITroveManager {
	function isContractTroveManager() external pure returns (bool);
}

interface IBorrowerOps {
	function isContractBorrowerOps() external pure returns (bool);
}

contract DCHFToken is CheckContract, IDCHFToken, Ownable {
	using SafeMath for uint256;

	address[] public troveManagers;
	address[] public borrowerOps;

	IStabilityPoolManager public immutable stabilityPoolManager;

	mapping(address => bool) public emergencyStopMintingCollateral;

	mapping(address => bool) public validTroveManagers;
	mapping(address => bool) public validBorrowerOps;

	event EmergencyStopMintingCollateral(address _asset, bool state);
	event UpdateTroveManagers(address[] troveManagers);
	event UpdateBorrowerOps(address[] borrowerOps);

	constructor(address _stabilityPoolManagerAddress) ERC20("Defi Franc", "DCHF") {
		checkContract(_stabilityPoolManagerAddress);

		stabilityPoolManager = IStabilityPoolManager(_stabilityPoolManagerAddress);
		emit StabilityPoolAddressChanged(_stabilityPoolManagerAddress);
	}

	// --- Functions for intra-Dfranc calls ---

	function emergencyStopMinting(address _asset, bool status) external override onlyOwner {
		emergencyStopMintingCollateral[_asset] = status;
		emit EmergencyStopMintingCollateral(_asset, status);
	}

	function mint(
		address _asset,
		address _account,
		uint256 _amount
	) external override {
		_requireCallerIsBorrowerOperations();
		require(!emergencyStopMintingCollateral[_asset], "Mint is blocked on this collateral");
		_mint(_account, _amount);
	}

	function burn(address _account, uint256 _amount) external override {
		_requireCallerIsBOorTroveMorSP();
		_burn(_account, _amount);
	}

	function sendToPool(
		address _sender,
		address _poolAddress,
		uint256 _amount
	) external override {
		_requireCallerIsStabilityPool();
		_transfer(_sender, _poolAddress, _amount);
	}

	function returnFromPool(
		address _poolAddress,
		address _receiver,
		uint256 _amount
	) external override {
		_requireCallerIsTroveMorSP();
		_transfer(_poolAddress, _receiver, _amount);
	}

	// --- External functions ---

	function transfer(address recipient, uint256 amount) public override returns (bool) {
		_requireValidRecipient(recipient);
		return super.transfer(recipient, amount);
	}

	function transferFrom(
		address sender,
		address recipient,
		uint256 amount
	) public override returns (bool) {
		_requireValidRecipient(recipient);
		return super.transferFrom(sender, recipient, amount);
	}

	function addTroveManager(address _troveManager) external override onlyOwner {
		CheckContract(_troveManager);
		assert(ITroveManager(_troveManager).isContractTroveManager());
		require(!validTroveManagers[_troveManager], "TroveManager already exists");
		validTroveManagers[_troveManager] = true;
		troveManagers.push(_troveManager);
		emit UpdateTroveManagers(troveManagers);
	}

	function removeTroveManager(address _troveManager) external override onlyOwner {
		require(validTroveManagers[_troveManager], "TroveManager does not exist");
		delete validTroveManagers[_troveManager];
		_removeElement(troveManagers, _troveManager);
		emit UpdateTroveManagers(troveManagers);
	}

	function addBorrowerOps(address _borrowerOps) external override onlyOwner {
		CheckContract(_borrowerOps);
		assert(IBorrowerOps(_borrowerOps).isContractBorrowerOps());
		require(!validBorrowerOps[_borrowerOps], "BorrowerOps already exists");
		validBorrowerOps[_borrowerOps] = true;
		borrowerOps.push(_borrowerOps);
		emit UpdateBorrowerOps(borrowerOps);
	}

	function removeBorrowerOps(address _borrowerOps) external override onlyOwner {
		require(validBorrowerOps[_borrowerOps], "BorrowerOps does not exist");
		delete validBorrowerOps[_borrowerOps];
		_removeElement(borrowerOps, _borrowerOps);
		emit UpdateBorrowerOps(borrowerOps);
	}

	// --- Internal functions ---

	function _removeElement(address[] storage _array, address _contract) internal {
		for (uint256 i; i < _array.length; i++) {
			if (_array[i] == _contract) {
				_array[i] = _array[_array.length - 1];
				_array.pop();
				break;
			}
		}
	}

	// --- 'require' functions ---

	function _requireValidRecipient(address _recipient) internal view {
		require(
			_recipient != address(0) && _recipient != address(this),
			"DCHF: Cannot transfer tokens directly to the DCHF token contract or the zero address"
		);
		require(
			!stabilityPoolManager.isStabilityPool(_recipient) &&
				!validTroveManagers[_recipient] &&
				!validBorrowerOps[_recipient],
			"DCHF: Cannot transfer tokens directly to the StabilityPool, TroveManager or BorrowerOps"
		);
	}

	function _requireCallerIsBorrowerOperations() internal view {
		require(validBorrowerOps[msg.sender], "DCHFToken: Caller is not BorrowerOperations");
	}

	function _requireCallerIsBOorTroveMorSP() internal view {
		require(
			validBorrowerOps[msg.sender] ||
				validTroveManagers[msg.sender] ||
				stabilityPoolManager.isStabilityPool(msg.sender),
			"DCHF: Caller is neither BorrowerOperations nor TroveManager nor StabilityPool"
		);
	}

	function _requireCallerIsStabilityPool() internal view {
		require(
			stabilityPoolManager.isStabilityPool(msg.sender),
			"DCHF: Caller is not the StabilityPool"
		);
	}

	function _requireCallerIsTroveMorSP() internal view {
		require(
			validTroveManagers[msg.sender] || stabilityPoolManager.isStabilityPool(msg.sender),
			"DCHF: Caller is neither TroveManager nor StabilityPool"
		);
	}
}

// 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. 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;
        }
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^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() {
        _setOwner(_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 {
        _setOwner(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");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: contracts/Dependencies/CheckContract.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.14;

contract CheckContract {
	function checkContract(address _account) internal view {
		require(_account != address(0), "Account cannot be zero address");

		uint256 size;
		assembly {
			size := extcodesize(_account)
		}
		require(size > 0, "Account code size cannot be zero");
	}
}

// File: contracts/Interfaces/IDCHFToken.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.14;
import "../Dependencies/ERC20Permit.sol";
import "../Interfaces/IStabilityPoolManager.sol";

abstract contract IDCHFToken is ERC20Permit {
	// --- Events ---

	event StabilityPoolAddressChanged(address _newStabilityPoolAddress);

	event DCHFTokenBalanceUpdated(address _user, uint256 _amount);

	function emergencyStopMinting(address _asset, bool status) external virtual;

	function addTroveManager(address _troveManager) external virtual;

	function removeTroveManager(address _troveManager) external virtual;

	function addBorrowerOps(address _borrowerOps) external virtual;

	function removeBorrowerOps(address _borrowerOps) external virtual;

	function mint(
		address _asset,
		address _account,
		uint256 _amount
	) external virtual;

	function burn(address _account, uint256 _amount) external virtual;

	function sendToPool(
		address _sender,
		address poolAddress,
		uint256 _amount
	) external virtual;

	function returnFromPool(
		address poolAddress,
		address user,
		uint256 _amount
	) external virtual;
}

// 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) {
        return msg.data;
    }
}

// File: contracts/Dependencies/ERC20Permit.sol



pragma solidity ^0.8.14;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

interface IERC2612Permit {
	/**
	 * @dev Sets `amount` as the allowance of `spender` over `owner`'s tokens,
	 * given `owner`'s signed approval.
	 *
	 * IMPORTANT: The same issues {IERC20-approve} has related to transaction
	 * ordering also apply here.
	 *
	 * Emits an {Approval} event.
	 *
	 * Requirements:
	 *
	 * - `owner` cannot be the zero address.
	 * - `spender` cannot be the zero address.
	 * - `deadline` must be a timestamp in the future.
	 * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
	 * over the EIP712-formatted function arguments.
	 * - the signature must use ``owner``'s current nonce (see {nonces}).
	 *
	 * For more information on the signature format, see the
	 * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
	 * section].
	 */
	function permit(
		address owner,
		address spender,
		uint256 amount,
		uint256 deadline,
		uint8 v,
		bytes32 r,
		bytes32 s
	) external;

	/**
	 * @dev Returns the current ERC2612 nonce for `owner`. This value must be
	 * included whenever a signature is generated for {permit}.
	 *
	 * Every successful call to {permit} increases ``owner``'s nonce by one. This
	 * prevents a signature from being used multiple times.
	 */
	function nonces(address owner) external view returns (uint256);
}

abstract contract ERC20Permit is ERC20, IERC2612Permit {
	using Counters for Counters.Counter;

	mapping(address => Counters.Counter) private _nonces;

	// keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
	bytes32 public constant PERMIT_TYPEHASH =
		0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;

	bytes32 public DOMAIN_SEPARATOR;

	constructor() {
		uint256 chainID;
		assembly {
			chainID := chainid()
		}

		DOMAIN_SEPARATOR = keccak256(
			abi.encode(
				keccak256(
					"EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
				),
				keccak256(bytes(name())),
				keccak256(bytes("1")), // Version
				chainID,
				address(this)
			)
		);
	}

	/**
	 * @dev See {IERC2612Permit-permit}.
	 *
	 */
	function permit(
		address owner,
		address spender,
		uint256 amount,
		uint256 deadline,
		uint8 v,
		bytes32 r,
		bytes32 s
	) external virtual override {
		require(block.timestamp <= deadline, "Permit: expired deadline");

		bytes32 hashStruct = keccak256(
			abi.encode(PERMIT_TYPEHASH, owner, spender, amount, _nonces[owner].current(), deadline)
		);

		bytes32 _hash = keccak256(abi.encodePacked(uint16(0x1901), DOMAIN_SEPARATOR, hashStruct));

		address signer = ecrecover(_hash, v, r, s);
		require(signer != address(0) && signer == owner, "ERC20Permit: Invalid signature");

		_nonces[owner].increment();
		_approve(owner, spender, amount);
	}

	/**
	 * @dev See {IERC2612Permit-nonces}.
	 */
	function nonces(address owner) public view override returns (uint256) {
		return _nonces[owner].current();
	}

	function chainId() public view returns (uint256 chainID) {
		assembly {
			chainID := chainid()
		}
	}
}

// File: contracts/Interfaces/IStabilityPoolManager.sol



pragma solidity ^0.8.14;

import "./IStabilityPool.sol";

interface IStabilityPoolManager {
	event StabilityPoolAdded(address asset, address stabilityPool);
	event StabilityPoolRemoved(address asset, address stabilityPool);

	function isStabilityPool(address stabilityPool) external view returns (bool);

	function addStabilityPool(address asset, address stabilityPool) external;

	function getAssetStabilityPool(address asset) external view returns (IStabilityPool);

	function unsafeGetAssetStabilityPool(address asset) external view returns (address);
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.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 Contracts guidelines: functions revert
 * instead 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, IERC20Metadata {
    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 default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two 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 override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override 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
     * overridden;
     *
     * 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 override 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");
        unchecked {
            _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");
        unchecked {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `sender` to `recipient`.
     *
     * This 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");
        unchecked {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);

        _afterTokenTransfer(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:
     *
     * - `account` 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);

        _afterTokenTransfer(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");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

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

        _afterTokenTransfer(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 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 {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 */
library Counters {
    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }

    function increment(Counter storage counter) internal {
        unchecked {
            counter._value += 1;
        }
    }

    function decrement(Counter storage counter) internal {
        uint256 value = counter._value;
        require(value > 0, "Counter: decrement overflow");
        unchecked {
            counter._value = value - 1;
        }
    }

    function reset(Counter storage counter) internal {
        counter._value = 0;
    }
}

// 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/IERC20Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: contracts/Interfaces/IStabilityPool.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.14;

import "./IDeposit.sol";

interface IStabilityPool is IDeposit {
	// --- Events ---
	event StabilityPoolAssetBalanceUpdated(uint256 _newBalance);
	event StabilityPoolDCHFBalanceUpdated(uint256 _newBalance);

	event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
	event TroveManagerAddressChanged(address _newTroveManagerAddress);
	event DefaultPoolAddressChanged(address _newDefaultPoolAddress);
	event DCHFTokenAddressChanged(address _newDCHFTokenAddress);
	event SortedTrovesAddressChanged(address _newSortedTrovesAddress);
	event CommunityIssuanceAddressChanged(address _newCommunityIssuanceAddress);

	event P_Updated(uint256 _P);
	event S_Updated(uint256 _S, uint128 _epoch, uint128 _scale);
	event G_Updated(uint256 _G, uint128 _epoch, uint128 _scale);
	event EpochUpdated(uint128 _currentEpoch);
	event ScaleUpdated(uint128 _currentScale);

	event DepositSnapshotUpdated(address indexed _depositor, uint256 _P, uint256 _S, uint256 _G);
	event SystemSnapshotUpdated(uint256 _P, uint256 _G);
	event UserDepositChanged(address indexed _depositor, uint256 _newDeposit);
	event StakeChanged(uint256 _newSystemStake, address _depositor);

	event AssetGainWithdrawn(address indexed _depositor, uint256 _Asset, uint256 _DCHFLoss);
	event MONPaidToDepositor(address indexed _depositor, uint256 _MON);
	event AssetSent(address _to, uint256 _amount);

	// --- Functions ---

	function NAME() external view returns (string memory name);

	/*
	 * Called only once on init, to set addresses of other Dfranc contracts
	 * Callable only by owner, renounces ownership at the end
	 */
	function setAddresses(
		address _assetAddress,
		address _borrowerOperationsAddress,
		address _troveManagerAddress,
		address _troveManagerHelperAddress,
		address _dchfTokenAddress,
		address _sortedTrovesAddress,
		address _communityIssuanceAddress,
		address _dfrancParamsAddress
	) external;

	/*
	 * Initial checks:
	 * - Frontend is registered or zero address
	 * - Sender is not a registered frontend
	 * - _amount is not zero
	 * ---
	 * - Triggers a MON issuance, based on time passed since the last issuance. The MON issuance is shared between *all* depositors and front ends
	 * - Tags the deposit with the provided front end tag param, if it's a new deposit
	 * - Sends depositor's accumulated gains (MON, ETH) to depositor
	 * - Sends the tagged front end's accumulated MON gains to the tagged front end
	 * - Increases deposit and tagged front end's stake, and takes new snapshots for each.
	 */
	function provideToSP(uint256 _amount) external;

	/*
	 * Initial checks:
	 * - _amount is zero or there are no under collateralized troves left in the system
	 * - User has a non zero deposit
	 * ---
	 * - Triggers a MON issuance, based on time passed since the last issuance. The MON issuance is shared between *all* depositors and front ends
	 * - Removes the deposit's front end tag if it is a full withdrawal
	 * - Sends all depositor's accumulated gains (MON, ETH) to depositor
	 * - Sends the tagged front end's accumulated MON gains to the tagged front end
	 * - Decreases deposit and tagged front end's stake, and takes new snapshots for each.
	 *
	 * If _amount > userDeposit, the user withdraws all of their compounded deposit.
	 */
	function withdrawFromSP(uint256 _amount) external;

	/*
	 * Initial checks:
	 * - User has a non zero deposit
	 * - User has an open trove
	 * - User has some ETH gain
	 * ---
	 * - Triggers a MON issuance, based on time passed since the last issuance. The MON issuance is shared between *all* depositors and front ends
	 * - Sends all depositor's MON gain to  depositor
	 * - Sends all tagged front end's MON gain to the tagged front end
	 * - Transfers the depositor's entire ETH gain from the Stability Pool to the caller's trove
	 * - Leaves their compounded deposit in the Stability Pool
	 * - Updates snapshots for deposit and tagged front end stake
	 */
	function withdrawAssetGainToTrove(address _upperHint, address _lowerHint) external;

	/*
	 * Initial checks:
	 * - Caller is TroveManager
	 * ---
	 * Cancels out the specified debt against the DCHF contained in the Stability Pool (as far as possible)
	 * and transfers the Trove's ETH collateral from ActivePool to StabilityPool.
	 * Only called by liquidation functions in the TroveManager.
	 */
	function offset(uint256 _debt, uint256 _coll) external;

	/*
	 * Returns the total amount of ETH held by the pool, accounted in an internal variable instead of `balance`,
	 * to exclude edge cases like ETH received from a self-destruct.
	 */
	function getAssetBalance() external view returns (uint256);

	/*
	 * Returns DCHF held in the pool. Changes when users deposit/withdraw, and when Trove debt is offset.
	 */
	function getTotalDCHFDeposits() external view returns (uint256);

	/*
	 * Calculates the ETH gain earned by the deposit since its last snapshots were taken.
	 */
	function getDepositorAssetGain(address _depositor) external view returns (uint256);

	/*
	 * Calculate the MON gain earned by a deposit since its last snapshots were taken.
	 * If not tagged with a front end, the depositor gets a 100% cut of what their deposit earned.
	 * Otherwise, their cut of the deposit's earnings is equal to the kickbackRate, set by the front end through
	 * which they made their deposit.
	 */
	function getDepositorMONGain(address _depositor) external view returns (uint256);

	/*
	 * Return the user's compounded deposit.
	 */
	function getCompoundedDCHFDeposit(address _depositor) external view returns (uint256);

	/*
	 * Return the front end's compounded stake.
	 *
	 * The front end's compounded stake is equal to the sum of its depositors' compounded deposits.
	 */
	function getCompoundedTotalStake() external view returns (uint256);

	function getNameBytes() external view returns (bytes32);

	function getAssetType() external view returns (address);

	/*
	 * Fallback function
	 * Only callable by Active Pool, it just accounts for ETH received
	 * receive() external payable;
	 */
}

// File: contracts/Interfaces/IDeposit.sol



pragma solidity ^0.8.14;

interface IDeposit {
	function receivedERC20(address _asset, uint256 _amount) external;
}