// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

library SafeMath {
    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);
        }
    }

    function trySub(
        uint256 a,
        uint256 b
    ) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    function tryMul(
        uint256 a,
        uint256 b
    ) internal pure returns (bool, uint256) {
        unchecked {
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    function tryDiv(
        uint256 a,
        uint256 b
    ) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    function tryMod(
        uint256 a,
        uint256 b
    ) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

pragma solidity ^0.8.0;

interface IERC20 {
    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(
        address recipient,
        uint256 amount
    ) external returns (bool);

    function allowance(
        address owner,
        address spender
    ) external view returns (uint256);

    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
}

pragma solidity ^0.8.0;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

pragma solidity ^0.8.0;

abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    constructor() {
        _transferOwnership(_msgSender());
    }

    function owner() public view virtual returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        _transferOwnership(newOwner);
    }

    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

pragma solidity ^0.8.0;

contract OwnerWithdrawable is Ownable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    receive() external payable {}

    fallback() external payable {}

    function withdraw(address token, uint256 amt) public onlyOwner {
        IERC20(token).safeTransfer(msg.sender, amt);
    }

    function withdrawAll(address token) public onlyOwner {
        uint256 amt = IERC20(token).balanceOf(address(this));
        withdraw(token, amt);
    }

    function withdrawCurrency(uint256 amt) public onlyOwner {
        payable(msg.sender).transfer(amt);
    }

    // function deposit(address token, uint256 amt) public onlyOwner {
    //     uint256 allowance = IERC20(token).allowance(msg.sender, address(this));
    //     require(allowance >= amt, "Check the token allowance");
    //     IERC20(token).transferFrom(owner(), address(this), amt);
    // }
}

pragma solidity ^0.8.0;

library Address {
    function isContract(address account) internal view returns (bool) {
        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    function sendValue(address payable recipient, uint256 amount) internal {
        require(
            address(this).balance >= amount,
            "Address: insufficient balance"
        );

        (bool success, ) = recipient.call{value: amount}("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }

    function functionCall(
        address target,
        bytes memory data
    ) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return
            functionCallWithValue(
                target,
                data,
                value,
                "Address: low-level call with value failed"
            );
    }

    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(
            address(this).balance >= value,
            "Address: insufficient balance for call"
        );
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(
            data
        );
        return verifyCallResult(success, returndata, errorMessage);
    }

    function functionStaticCall(
        address target,
        bytes memory data
    ) internal view returns (bytes memory) {
        return
            functionStaticCall(
                target,
                data,
                "Address: low-level static call failed"
            );
    }

    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    function functionDelegateCall(
        address target,
        bytes memory data
    ) internal returns (bytes memory) {
        return
            functionDelegateCall(
                target,
                data,
                "Address: low-level delegate call failed"
            );
    }

    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            if (returndata.length > 0) {
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

pragma solidity ^0.8.0;

library SafeERC20 {
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(token.transfer.selector, to, value)
        );
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(token.transferFrom.selector, from, to, value)
        );
    }

    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(token.approve.selector, spender, value)
        );
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                spender,
                newAllowance
            )
        );
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(
                oldAllowance >= value,
                "SafeERC20: decreased allowance below zero"
            );
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(
                token,
                abi.encodeWithSelector(
                    token.approve.selector,
                    spender,
                    newAllowance
                )
            );
        }
    }

    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        bytes memory returndata = address(token).functionCall(
            data,
            "SafeERC20: low-level call failed"
        );
        if (returndata.length > 0) {
            require(
                abi.decode(returndata, (bool)),
                "SafeERC20: ERC20 operation did not succeed"
            );
        }
    }
}

pragma solidity ^0.8.0;

interface IERC20Metadata is IERC20 {
    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}

pragma solidity ^0.8.0;

contract Presale is OwnerWithdrawable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;
    using SafeERC20 for IERC20Metadata;

    uint256 public rate;

    address public saleToken;

    uint public saleTokenDec;

    uint256 public totalTokensforSale;

    mapping(address => bool) public payableTokens;

    mapping(address => uint256) public tokenPrices;

    bool public saleStatus;

    address[] public buyers;
    mapping(address => BuyerDetails) public buyersDetails;

    uint256 public totalBuyers;
    uint256 public totalTokensSold;

    struct BuyerDetails {
        uint amount;
        bool exists;
    }

    struct BuyerAmount {
        uint amount;
        address buyer;
    }

    constructor() {
        saleStatus = false;
    }

    modifier saleEnabled() {
        require(saleStatus == true, "Presale: is not enabled");
        _;
    }

    modifier saleStoped() {
        require(saleStatus == false, "Presale: is not stopped");
        _;
    }

    function setSaleToken(
        uint256 _decimals,
        uint256 _totalTokensforSale,
        uint256 _rate,
        bool _saleStatus
    ) external onlyOwner {
        require(_rate != 0);
        rate = _rate;
        saleStatus = _saleStatus;
        saleTokenDec = _decimals;
        totalTokensforSale = _totalTokensforSale;
    }

    function stopSale() external onlyOwner saleEnabled {
        saleStatus = false;
    }

    function resumeSale() external onlyOwner saleStoped {
        saleStatus = true;
    }

    function addPayableTokens(
        address[] memory _tokens,
        uint256[] memory _prices
    ) external onlyOwner {
        require(
            _tokens.length == _prices.length,
            "Presale: tokens & prices arrays length mismatch"
        );

        for (uint256 i = 0; i < _tokens.length; i++) {
            require(_prices[i] != 0);
            payableTokens[_tokens[i]] = true;
            tokenPrices[_tokens[i]] = _prices[i];
        }
    }

    function payableTokenStatus(
        address _token,
        bool _status
    ) external onlyOwner {
        require(payableTokens[_token] != _status);

        payableTokens[_token] = _status;
    }

    function updateTokenRate(
        address[] memory _tokens,
        uint256[] memory _prices,
        uint256 _rate
    ) external onlyOwner {
        require(
            _tokens.length == _prices.length,
            "Presale: tokens & prices arrays length mismatch"
        );

        if (_rate != 0) {
            rate = _rate;
        }

        for (uint256 i = 0; i < _tokens.length; i += 1) {
            require(payableTokens[_tokens[i]] == true);
            require(_prices[i] != 0);
            tokenPrices[_tokens[i]] = _prices[i];
        }
    }

    function getTokenAmount(
        address token,
        uint256 amount
    ) public view returns (uint256) {
        uint256 amtOut;
        if (token != address(0)) {
            require(payableTokens[token] == true, "Presale: Token not allowed");
            uint256 price = tokenPrices[token];
            amtOut = amount.mul(10 ** saleTokenDec).div(price);
        } else {
            amtOut = amount.mul(10 ** saleTokenDec).div(rate);
        }
        return amtOut;
    }

    function transferETH() private {
        payable(owner()).transfer(msg.value);
    }

    function transferToken(address _token, uint256 _amount) private {
        IERC20(_token).safeTransferFrom(
            msg.sender,
            owner(),
            _amount
        );
    }

    function buyToken(
        address _token,
        uint256 _amount
    ) external payable saleEnabled {
        uint256 saleTokenAmt = _token != address(0)
            ? getTokenAmount(_token, _amount)
            : getTokenAmount(address(0), msg.value);

        require(saleTokenAmt != 0, "Presale: Amount is 0");
        require(
            (totalTokensSold + saleTokenAmt) < totalTokensforSale,
            "Presale: Not enough tokens to be sale"
        );

        if (_token != address(0)) {
            transferToken(_token, _amount);
        } else {
            transferETH();
        }

        totalTokensSold += saleTokenAmt;

        if (!buyersDetails[msg.sender].exists) {
            buyers.push(msg.sender);
            buyersDetails[msg.sender].exists = true;
            totalBuyers += 1;
        }

        buyersDetails[msg.sender].amount += saleTokenAmt;
    }

    function buyersAmountList(
        uint _from,
        uint _to
    ) external view returns (BuyerAmount[] memory) {
        require(_from < _to, "Presale: _from should be less than _to");

        uint to = _to > totalBuyers ? totalBuyers : _to;
        uint from = _from > totalBuyers ? totalBuyers : _from;

        BuyerAmount[] memory buyersAmt = new BuyerAmount[](to - from);

        for (uint i = from; i < to; i += 1) {
            buyersAmt[i].amount = buyersDetails[buyers[i]].amount;
            buyersAmt[i].buyer = buyers[i];
        }

        return buyersAmt;
    }
}