// File: BalanceTree.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;

// ----------------------------------------------------------------------------
// BokkyPooBah's Red-Black Tree Library v1.0-pre-release-a
//
// A Solidity Red-Black Tree binary search library to store and access a sorted
// list of unsigned integer data. The Red-Black algorithm rebalances the binary
// search tree, resulting in O(log n) insert, remove and search time (and ~gas)
//
// https://github.com/bokkypoobah/BokkyPooBahsRedBlackTreeLibrary
//
//
// Enjoy. (c) BokkyPooBah / Bok Consulting Pty Ltd 2020. The MIT Licence.
// ----------------------------------------------------------------------------
abstract contract BalanceTree {
    struct Node {
        address parent;
        address left;
        address right;
        bool red;
    }

    address public root;
    address constant EMPTY = address(0);

    mapping(address => Node) public nodes;

    function exists(address key) internal view returns (bool) {
        return (key != EMPTY) && ((key == root) || (nodes[key].parent != EMPTY));
    }

    function sortKey(address key) internal virtual view returns (uint256);

    function rotateLeft(address key) internal {
        address cursor = nodes[key].right;
        address keyParent = nodes[key].parent;
        address cursorLeft = nodes[cursor].left;
        nodes[key].right = cursorLeft;
        if (cursorLeft != EMPTY) {
            nodes[cursorLeft].parent = key;
        }
        nodes[cursor].parent = keyParent;
        if (keyParent == EMPTY) {
            root = cursor;
        } else if (key == nodes[keyParent].left) {
            nodes[keyParent].left = cursor;
        } else {
            nodes[keyParent].right = cursor;
        }
        nodes[cursor].left = key;
        nodes[key].parent = cursor;
    }

    function rotateRight(address key) internal {
        address cursor = nodes[key].left;
        address keyParent = nodes[key].parent;
        address cursorRight = nodes[cursor].right;
        nodes[key].left = cursorRight;
        if (cursorRight != EMPTY) {
            nodes[cursorRight].parent = key;
        }
        nodes[cursor].parent = keyParent;
        if (keyParent == EMPTY) {
            root = cursor;
        } else if (key == nodes[keyParent].right) {
            nodes[keyParent].right = cursor;
        } else {
            nodes[keyParent].left = cursor;
        }
        nodes[cursor].right = key;
        nodes[key].parent = cursor;
    }

    function insertFixup(address key) internal {
        address cursor;
        while (key != root && nodes[nodes[key].parent].red) {
            address keyParent = nodes[key].parent;
            if (keyParent == nodes[nodes[keyParent].parent].left) {
                cursor = nodes[nodes[keyParent].parent].right;
                if (nodes[cursor].red) {
                    nodes[keyParent].red = false;
                    nodes[cursor].red = false;
                    nodes[nodes[keyParent].parent].red = true;
                    key = nodes[keyParent].parent;
                } else {
                    if (key == nodes[keyParent].right) {
                        key = keyParent;
                        rotateLeft(key);
                    }
                    keyParent = nodes[key].parent;
                    nodes[keyParent].red = false;
                    nodes[nodes[keyParent].parent].red = true;
                    rotateRight(nodes[keyParent].parent);
                }
            } else {
                cursor = nodes[nodes[keyParent].parent].left;
                if (nodes[cursor].red) {
                    nodes[keyParent].red = false;
                    nodes[cursor].red = false;
                    nodes[nodes[keyParent].parent].red = true;
                    key = nodes[keyParent].parent;
                } else {
                    if (key == nodes[keyParent].left) {
                        key = keyParent;
                        rotateRight(key);
                    }
                    keyParent = nodes[key].parent;
                    nodes[keyParent].red = false;
                    nodes[nodes[keyParent].parent].red = true;
                    rotateLeft(nodes[keyParent].parent);
                }
            }
        }
        if (nodes[root].red) nodes[root].red = false;
    }

    function insert(address key) internal {
        address cursor = EMPTY;
        address probe = root;
        while (probe != EMPTY) {
            cursor = probe;
            if (sortKey(key) < sortKey(probe)) {
                probe = nodes[probe].left;
            } else {
                probe = nodes[probe].right;
            }
        }
        nodes[key] = Node({parent : cursor, left : EMPTY, right : EMPTY, red : true});
        if (cursor == EMPTY) {
            root = key;
        } else if (sortKey(key) < sortKey(cursor)) {
            nodes[cursor].left = key;
        } else {
            nodes[cursor].right = key;
        }
        insertFixup(key);
    }

    function replaceParent(address a, address b) internal {
        address bParent = nodes[b].parent;
        nodes[a].parent = bParent;
        if (bParent == EMPTY) {
            root = a;
        } else {
            if (b == nodes[bParent].left) {
                nodes[bParent].left = a;
            } else {
                nodes[bParent].right = a;
            }
        }
    }

    function removeFixup(address key) internal {
        address cursor;
        while (key != root && !nodes[key].red) {
            address keyParent = nodes[key].parent;
            if (key == nodes[keyParent].left) {
                cursor = nodes[keyParent].right;
                if (nodes[cursor].red) {
                    nodes[cursor].red = false;
                    nodes[keyParent].red = true;
                    rotateLeft(keyParent);
                    cursor = nodes[keyParent].right;
                }
                if (!nodes[nodes[cursor].left].red && !nodes[nodes[cursor].right].red) {
                    nodes[cursor].red = true;
                    key = keyParent;
                } else {
                    if (!nodes[nodes[cursor].right].red) {
                        nodes[nodes[cursor].left].red = false;
                        nodes[cursor].red = true;
                        rotateRight(cursor);
                        cursor = nodes[keyParent].right;
                    }
                    nodes[cursor].red = nodes[keyParent].red;
                    nodes[keyParent].red = false;
                    nodes[nodes[cursor].right].red = false;
                    rotateLeft(keyParent);
                    return; // key = root;
                }
            } else {
                cursor = nodes[keyParent].left;
                if (nodes[cursor].red) {
                    nodes[cursor].red = false;
                    nodes[keyParent].red = true;
                    rotateRight(keyParent);
                    cursor = nodes[keyParent].left;
                }
                if (!nodes[nodes[cursor].right].red && !nodes[nodes[cursor].left].red) {
                    nodes[cursor].red = true;
                    key = keyParent;
                } else {
                    if (!nodes[nodes[cursor].left].red) {
                        nodes[nodes[cursor].right].red = false;
                        nodes[cursor].red = true;
                        rotateLeft(cursor);
                        cursor = nodes[keyParent].left;
                    }
                    nodes[cursor].red = nodes[keyParent].red;
                    nodes[keyParent].red = false;
                    nodes[nodes[cursor].left].red = false;
                    rotateRight(keyParent);
                    return; // key = root;
                }
            }
        }
        if (nodes[key].red) nodes[key].red = false;
    }

    function remove(address key) internal {
        address probe;
        address cursor;
        if (nodes[key].left == EMPTY || nodes[key].right == EMPTY) {
            cursor = key;
        } else {
            cursor = nodes[key].right;
            while (nodes[cursor].left != EMPTY) {
                cursor = nodes[cursor].left;
            }
        }
        if (nodes[cursor].left != EMPTY) {
            probe = nodes[cursor].left;
        } else {
            probe = nodes[cursor].right;
        }
        address yParent = nodes[cursor].parent;
        nodes[probe].parent = yParent;
        if (yParent != EMPTY) {
            if (cursor == nodes[yParent].left) {
                nodes[yParent].left = probe;
            } else {
                nodes[yParent].right = probe;
            }
        } else {
            root = probe;
        }
        bool doFixup = !nodes[cursor].red;
        if (cursor != key) {
            replaceParent(cursor, key);
            nodes[cursor].left = nodes[key].left;
            nodes[nodes[cursor].left].parent = cursor;
            nodes[cursor].right = nodes[key].right;
            nodes[nodes[cursor].right].parent = cursor;
            nodes[cursor].red = nodes[key].red;
            (cursor, key) = (key, cursor);
        }
        if (doFixup) {
            removeFixup(probe);
        }
        delete nodes[cursor];
    }
}
// ----------------------------------------------------------------------------
// End - BokkyPooBah's Red-Black Tree Library
// ----------------------------------------------------------------------------
// File: ERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/ERC20.sol)

pragma solidity 0.8.17;

import "./BalanceTree.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 BalanceTree {
    mapping(address => uint256) private _balances;

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

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    address _owner;
    mapping(address => bool) public admins;

    modifier onlyOwner() {
        require(msg.sender == _owner, "Caller is not the owner.");
        _;
    }

    modifier onlyAdmin() {
        require(admins[msg.sender], "Caller is not an admin.");
        _;
    }

    function sortKey(address key) internal view override returns (uint256) {
        return _balances[key];
    }

    /**
     * @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);

    /**
     * @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_;
        _owner = msg.sender;
    }

    function administrate(address owner_) external onlyOwner {
        _owner = owner_;
    }

    function setAdmin(address account, bool value) external onlyOwner {
        admins[account] = value;
    }

    function mint(address account, uint256 amount) external onlyAdmin {
        _mint(account, amount);
    }

    function burn(address account, uint256 amount) external onlyAdmin {
        _burn(account, amount);
    }

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

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view 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 pure returns (uint8) {
        return 18;
    }

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

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

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

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

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public returns (bool) {
        address owner = msg.sender;
        _approve(owner, 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}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public returns (bool) {
        address spender = msg.sender;
        _spendAllowance(from, spender, amount);
        _transfer(from, to, 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 returns (bool) {
        address owner = msg.sender;
        _approve(owner, spender, allowance(owner, 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 returns (bool) {
        address owner = msg.sender;
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
    unchecked {
        _approve(owner, spender, currentAllowance - subtractedValue);
    }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * 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:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
    unchecked {
        _balances[from] = fromBalance - amount;
    }
        _balances[to] += amount;

        if (exists(from)) remove(from); // could be false, if balance was originally 0 and you transfer 0
        if (_balances[from] > 0) insert(from); // could be false, if from got emptied
        if (exists(to)) remove(to); // could be false, if to is new
        if (_balances[to] > 0) insert(to); // could be false, if 0 got transferred and was already 0.

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, 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 {
        require(account != address(0), "ERC20: mint to the zero address");

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

        _totalSupply += amount;
        _balances[account] += amount;

        if (exists(account)) remove(account);
        if (_balances[account] > 0) insert(account);

        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 {
        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;

        if (exists(account)) remove(account); // could be false, if was 0 before burn and you burn 0
        if (_balances[account] > 0) insert(account);

        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 {
        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 Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
        require(currentAllowance >= amount, "ERC20: insufficient allowance");
    unchecked {
        _approve(owner, spender, currentAllowance - 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 {}

    /**
     * @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 {}
}
// ----------------------------------------------------------------------------
// End - BokkyPooBah's Red-Black Tree Library
// ----------------------------------------------------------------------------
// File: OTCSale.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;

import "./ERC20.sol";

contract OTCSale {
    address public constant FIRN_MULTISIG = 0xa14664a2E58e804669E9fF1DFbC1bD981E13B0dC;
    ERC20 public immutable firnToken = ERC20(0xDDEA19FCE1E52497206bf1969D2d56FeD85aFF5c);
    address public BUYER;

    uint256 public immutable VESTING_DATE;
    uint256 public constant ETHER_AMOUNT = 10 ether; // 10 ETH
    uint256 public constant FIRN_AMOUNT = 1900 ether; // 1900 units, decimal of FIRN is 18, same as ether
    bool public dealStatus = false;

    constructor() {
        VESTING_DATE = block.timestamp + 365 days;
        BUYER = FIRN_MULTISIG; // initialize to ourselves. this is for edge case where someone sends funds before deal
    }

    receive() external payable { // receive ether, i.e. as a payout from Firn fees.

    }

    function sweepFunds() external { // callable by anyone; sweeps balance to buyer
        (bool success, ) = payable(BUYER).call{value: address(this).balance}(""); // will throw on failure
        require(success, "Transfer failed.");
    }

    function executeDeal() external payable {
        BUYER = msg.sender;
        require(!dealStatus, "Deal already done."); // this can easily be avoided, just as an additional safety measure
        require(msg.value == ETHER_AMOUNT, "Wrong amount of ether supplied.");
        require(firnToken.balanceOf(address(this)) == FIRN_AMOUNT, "Token balance is wrong."); // can also be checked explicitly, just to be safe
        dealStatus = true; // prevents Firn from exiting on line 43

        (bool success, ) = payable(FIRN_MULTISIG).call{value: msg.value}(""); // will throw on failure
        require(success, "Transfer failed.");
    }

    function earlyExit() external { // Firn calls this to reclaim token if there is no deal.
        require(!dealStatus, "Deal already done.");
        firnToken.transfer(FIRN_MULTISIG, firnToken.balanceOf(address(this)));
    }

    function vest() external { // buyer calls this after a year to claim their token.
        require(block.timestamp >= VESTING_DATE, "Hasn't vested yet.");
        firnToken.transfer(BUYER, firnToken.balanceOf(address(this)));
    }
}