// File: contracts/MerkleDistributor.sol



import "./MerkleProof.sol";
import "./IERC20.sol";

contract MerkleDistributor {

    address public immutable token;
    address public immutable sweeper;
    bytes32 public immutable merkleRoot;

    /// @notice Mapping of addresses who have claimed tokens
    mapping(address => bool) public hasClaimed;

     /// @notice Thrown if address has already claimed
    error AlreadyClaimed();

    /// @notice Thrown if address/amount are not part of Merkle tree
    error NotInMerkle();

    /// @notice Emitted after a successful token claim
    /// @param to recipient of claim
    /// @param amount of tokens claimed
    event Claim(address indexed to, uint256 amount);

    /// @notice Emitted after all the tokens in the contract have been sweeped
    /// @param to recipient of claim
    /// @param amount of tokens claimed
    event Sweeped(address indexed to, uint256 amount);

    constructor(
        address token_, 
        bytes32 merkleRoot_,
        address sweeper_
    ) public {
        token = token_;
        merkleRoot = merkleRoot_;
        sweeper = sweeper_;
    }

    /// @notice Allows claiming tokens if address is part of merkle tree
    /// @param to address of claimee
    /// @param amount of tokens owed to claimee
    /// @param proof merkle proof to prove address and amount are in tree
    function claim(address to, uint256 amount, bytes32[] calldata proof) external {
        // Throw if address has already claimed tokens
        if (hasClaimed[to]) revert AlreadyClaimed();

        // Verify merkle proof, or revert if not in tree
        bytes32 leaf = keccak256(abi.encodePacked(to, amount));
        bool isValidLeaf = MerkleProof.verify(proof, merkleRoot, leaf);
        if (!isValidLeaf) revert NotInMerkle();

        // Set address to claimed
        hasClaimed[to] = true;

        require(IERC20(token).transfer(to, amount), 'MerkleDistributor: Transfer failed.');

        // Emit claim event
        emit Claim(to, amount);
    }

    /// @notice Allows all the tokens in the contrac to be sweeped for unclaimed tokens
    function sweep() external {
        // Ensure that only the sweeper can call the contract!
        require(
            msg.sender == sweeper,
            "Sweep can only be called by the sweeper"
        );

        IERC20 tokenContract = IERC20(token);
        uint256 balance = tokenContract.balanceOf(address(this));
        tokenContract.transfer(sweeper, balance);

        // Emit the sweep event
        emit Sweeped(sweeper, balance);
    }
}
// File: contracts/MerkleProof.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.0;

/**
 * @dev These functions deal with verification of Merkle Trees proofs.
 *
 * The proofs can be generated using the JavaScript library
 * https://github.com/miguelmota/merkletreejs[merkletreejs].
 * Note: the hashing algorithm should be keccak256 and pair sorting should be enabled.
 *
 * See `test/utils/cryptography/MerkleProof.test.js` for some examples.
 *
 * WARNING: You should avoid using leaf values that are 64 bytes long prior to
 * hashing, or use a hash function other than keccak256 for hashing leaves.
 * This is because the concatenation of a sorted pair of internal nodes in
 * the merkle tree could be reinterpreted as a leaf value.
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(
        bytes32[] memory proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }

    /**
     * @dev Returns the rebuilt hash obtained by traversing a Merkle tree up
     * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
     * hash matches the root of the tree. When processing the proof, the pairs
     * of leafs & pre-images are assumed to be sorted.
     *
     * _Available since v4.4._
     */
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];
            if (computedHash <= proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = _efficientHash(computedHash, proofElement);
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = _efficientHash(proofElement, computedHash);
            }
        }
        return computedHash;
    }

    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}
// File: contracts/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        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);
}