// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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;
    }
}

/**
 * ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡀⠀⠀⠀⣰⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
 * ⠀⠀⠀⠀⠀⠀⠀⡀⠀⢀⠒⠑⣴⣦⣾⣧⣤⢀⡤⠀⠀⠀⡀⠀⠀⠀
 * ⠀⠀⠀⠀⢀⠀⢀⡘⠉⠁⣰⣾⣿⣿⣿⣿⣿⣿⣷⢀⡤⠊⠀⠀⠀⠀
 * ⠀⠀⠀⠀⠀⢱⠊⡄⠒⠾⣿⣿⣿⣿⣿⣿⠿⠛⢹⣿⣯⣤⠤⠄⠀⠀
 * ⠀⠀⠀⠒⢦⠂⠀⣇⠀⠸⠟⢈⣿⣿⡁⠺⠗⠀⣸⣿⣿⣃⠀⠀⠀⠀
 * ⠀⠀⠀⠀⢘⢀⣼⠻⢷⣶⣶⣿⣿⣿⣿⣶⣶⣾⠟⣻⣿⡯⠁⠀⠀⠀
 * ⠀⠀⠀⠉⠱⢾⣿⡀⠀⠈⠉⠙⠛⠛⠛⠉⠉⠀⢀⣿⣿⠿⠛⠒⠀⠀
 * ⠀⠀⠀⠀⠔⢛⣿⣷⡈⠒⠀⠀⠀⠔⠁⠊⠒⢈⣾⣿⡏⠀⠀⠀⠀⠀
 * ⠀⠀⠀⠀⠀⠜⠛⠿⣿⣶⣤⣀⣀⣀⣀⣤⣶⣿⠿⣿⠉⠀⠀⠀⠀⠀
 * ⠀⠀⠀⠀⠀⠀⠀⡸⠛⢉⡿⠻⠟⣿⢿⡟⣏⠁⠀⠘⠄⠀⠀⠀⠀⠀
 * ⠀⠀⠀⠀⠀⠀⠀⠀⠀⡜⠀⠀⠀⠁⠀⠃⠘⡀⠀⠀⠀⠀⠀
 *
 * COVID GAMBIT: A REVOLUTIONARY ERC-20 DIGITAL GAME INSPIRED BY REAL-WORLD PANDEMICS
 *
 * This document provides a comprehensive guide to understanding and navigating Covid Gambit,
 * an innovative ERC-20 digital game that is based on real-world epidemiological events.
 *
 * Gameplay Guidelines:
 *
 * Participants can acquire $COVID tokens via Uniswap. Upon every transaction, there exists a 10% probability
 * that the participant will become an index case, or in gaming terms, "infected".
 *
 * Once a player is designated as infected, they are faced with a decision: to potentially infect others
 * by utilizing the "sneeze" function or to self-isolate in the quarantine module. It is crucial to
 * note that infected players have a time constraint of 48 hours to make this decision, failure to which
 * results in game "death" due to disease progression, thereby disabling the ability to transfer tokens.
 *
 * The "sneeze" function carries a dual probability: a 30% chance of the infected player gaining immunity
 * and a 100% probability of the target player becoming infected. Therefore, on average, an infected player
 * must "sneeze" on three non-infected wallets to gain immunity and continue the spread of infection.
 * Immunity provides a one-week protection from being "sneezed on" by other players. This function is only
 * applicable to non-infected players.
 *
 * Alternatively, an infected player may choose to enter the quarantine module, which requires a one-week
 * commitment during which the player cannot transfer tokens. Upon completion of the quarantine period, the
 * player will be considered "healthy". Access to the quarantine module is restricted to infected players only.
 *
 * Non-infected or "healthy" players can maintain their status by executing the washHands() function, granting
 * them immunity for an 24-hour period, during which they are unaffected by the "sneeze" function of other
 * players. Regular execution of the washHands() function is advised to maintain player health.
 *
 * Game Dynamics:
 *
 * As per the game's mechanics, only 33% of players can achieve long-term immunity. Given the restriction
 * against "sneezing" on other infected players, a player's options are limited to either entering the
 * week-long quarantine module (locking tokens), or exiting the game by selling their tokens.
 *
 * Strategic Considerations:
 *
 * The goal of this game is twofold: to maintain individual health for the longest possible duration and to
 * collectively combat the pandemic. Players are faced with a moral dilemma: do they infect others to gain
 * immunity, or do they choose to quarantine, promoting collective efforts to end the pandemic?
 * The choice is in the hands of each player.
 *
 * Website: covidgambit.com
 * Twitter: twitter.com/CovidGambitGame
 * Telegram: t.me/CovidGambit
 */

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

import "lib/openzeppelin-contracts/contracts/token/ERC20/ERC20.sol";
import "lib/openzeppelin-contracts/contracts/access/Ownable.sol";
import "interfaces/IUniswapV2Router02.sol";
import "interfaces/IUniswapV2Pair.sol";
import "interfaces/IUniswapV2Factory.sol";

contract CovidGambit is ERC20, Ownable {
    mapping(address => bool) public isVaxxed;
    mapping(address => uint256) public firstInfectedTime;
    mapping(address => uint256) public immunityEndTime;
    mapping(address => uint256) public quarantineEndTime;

    bool plandemicStarted;

    event Sneezed(address indexed patient, address indexed target, bool indexed gotImmunity);
    event GotCovid(address indexed patient, address indexed from);
    event WashedHands(address indexed patient, uint256 immunityEndTime);
    event EnteredQuarantine(address indexed patient, uint256 quarantineEndTime);

    IUniswapV2Pair public pair;
    IUniswapV2Router02 public router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
    uint256 maxWallet;

    constructor() ERC20("Covid Gambit", "COVID") {
        getVaxxed(address(this));
        getVaxxed(address(router));
        getVaxxed(address(pair));
        getVaxxed(msg.sender);
        getVaxxed(0xEf1c6E67703c7BD7107eed8303Fbe6EC2554BF6B); // Universal router

        _mint(msg.sender, 19_000_000e18);
        pair = IUniswapV2Pair(IUniswapV2Factory(router.factory()).createPair(address(this), router.WETH()));
        maxWallet = totalSupply() / 200; // 0.5% max wallet at launch
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
        // Launch stuff
        if (from == address(pair) && !isVaxxed[to]) {
            require(amount + balanceOf(to) <= maxWallet, "You can't buy that much right now");
        }

        if (plandemicStarted) {
            // Infected dies in 48 hrs
            if (!isHealthy(from)) {
                require(!isDead(from), "You got covid and died");
            }
            // Can only buy and sell
            require(from == address(pair) || to == address(pair) || isVaxxed[from], "You can't escape covid");
            // Can't sell if in quarantine
            require(!isQuarantined(from), "You are in quarantine");
            // If you buy there's a 10% chance of contracting covid (if you dont have immunity)
            if (from == address(pair) && !isImmune(to) && !isVaxxed[to]) {
                if (isPatientZero(10, to) && !isInfected(to)) {
                    firstInfectedTime[to] = block.timestamp;
                    emit GotCovid(to, from);
                }
            }
        }

        super._beforeTokenTransfer(from, to, amount);
    }

    function sneeze(address target) public {
        require(isInfected(msg.sender), "Not infected or already dead");
        require(!isImmune(msg.sender), "Already has immunity");
        require(!isQuarantined(msg.sender), "Already in quarantine");
        require(balanceOf(msg.sender) > 0, "Covid denier");
        require(!isImmune(target), "Target has immunity");
        require(!isVaxxed[target], "Target is vaxxed");
        require(!isQuarantined(target), "Target in quarantine");
        require(isHealthy(target), "Target already infected or dead");
        require(balanceOf(target) > 0, "Target is covid denier");
        firstInfectedTime[target] = block.timestamp;
        bool gotImmunity;
        if (isPatientZero(30, target)) {
            firstInfectedTime[msg.sender] = 0;
            immunityEndTime[msg.sender] = block.timestamp + 7 days;
            gotImmunity = true;
        }
        emit Sneezed(msg.sender, target, gotImmunity);
        emit GotCovid(target, msg.sender);
    }

    function washHands() public {
        require(isHealthy(msg.sender), "Already infected");
        require(!isQuarantined(msg.sender), "Already in quarantine");
        require(balanceOf(msg.sender) > 0, "Covid denier");
        immunityEndTime[msg.sender] = block.timestamp + 24 hours;
        emit WashedHands(msg.sender, immunityEndTime[msg.sender]);
    }

    function enterQuarantine() public {
        require(isInfected(msg.sender), "Not infected or already dead");
        require(!isQuarantined(msg.sender), "Already in quarantine");
        require(!isImmune(msg.sender), "Already has immunity");
        require(balanceOf(msg.sender) > 0, "Covid denier");
        firstInfectedTime[msg.sender] = 0;
        quarantineEndTime[msg.sender] = block.timestamp + 7 days;
        emit EnteredQuarantine(msg.sender, quarantineEndTime[msg.sender]);
    }

    function plandemicStats(address[] memory patients)
        public
        view
        returns (uint256, uint256, uint256, uint256, uint256)
    {
        uint256 healthyCount;
        uint256 infectedCount;
        uint256 quarantinedCount;
        uint256 immuneCount;
        uint256 deadCount;

        for (uint256 i = 0; i < patients.length; i++) {
            uint256 status = patientStatus(patients[i]);

            if (status == 0) {
                healthyCount++;
            } else if (status == 1) {
                infectedCount++;
            } else if (status == 2) {
                quarantinedCount++;
            } else if (status == 3) {
                immuneCount++;
            } else if (status == 4) {
                deadCount++;
            }
        }

        return (healthyCount, infectedCount, quarantinedCount, immuneCount, deadCount);
    }

    function patientStatus(address patient) public view returns (uint256 status) {
        if (isHealthy(patient) && !isQuarantined(patient) && !isImmune(patient) || isVaxxed[patient]) {
            return 0;
        } else if (isInfected(patient)) {
            return 1;
        } else if (isQuarantined(patient)) {
            return 2;
        } else if (isImmune(patient)) {
            return 3;
        } else if (isDead(patient)) {
            return 4;
        }
    }

    function startPlandemic(bool isStarted) public onlyOwner {
        plandemicStarted = isStarted;
    }

    function getVaxxed(address patient) public onlyOwner {
        isVaxxed[patient] = true;
    }

    function getUnvaxxed(address patient) public onlyOwner {
        isVaxxed[patient] = false;
    }

    function setMaxWallet(uint256 _maxWallet) public onlyOwner {
        maxWallet = _maxWallet;
    }
    
    function isPatientZero(uint256 chance, address patient) private returns (bool isIndeed) {
        uint256 dna = uint256(keccak256(abi.encodePacked(patient, block.timestamp, balanceOf(patient)))) % 101;
        return dna <= chance;
    }

    function isHealthy(address patient) private view returns (bool isIndeed) {
        return firstInfectedTime[patient] == 0;
    }

    function isInfected(address patient) private view returns (bool isIndeed) {
        return firstInfectedTime[patient] + 48 hours > block.timestamp;
    }

    function isQuarantined(address patient) private view returns (bool isIndeed) {
        return quarantineEndTime[patient] > block.timestamp;
    }

    function isImmune(address patient) private view returns (bool isIndeed) {
        return immunityEndTime[patient] > block.timestamp;
    }

    function isDead(address patient) private view returns (bool isIndeed) {
        return firstInfectedTime[patient] + 48 hours < block.timestamp;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/ERC20.sol)

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.openzeppelin.com/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:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, 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}.
     *
     * 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 virtual override returns (bool) {
        address owner = _msgSender();
        _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 virtual override returns (bool) {
        address spender = _msgSender();
        _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 virtual returns (bool) {
        address owner = _msgSender();
        _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 virtual returns (bool) {
        address owner = _msgSender();
        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 virtual {
        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;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

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

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

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _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;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _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 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 virtual {
        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 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 {}
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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 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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

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);
}

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

pragma solidity >=0.6.2;

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

pragma solidity >=0.6.2;

import './IUniswapV2Router01.sol';

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

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() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

{
  "compilationTarget": {
    "src/CovidGambit.sol": "CovidGambit"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": [
    ":ds-test/=lib/forge-std/lib/ds-test/src/",
    ":forge-std/=lib/forge-std/src/",
    ":openzeppelin-contracts/=lib/openzeppelin-contracts/"
  ]
}