//SPDX-License-Identifier: MIT

pragma solidity ^0.8.15;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view 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);
}
interface IDEXRouter01 {
    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 factory() external pure returns (address);
    function WETH() external pure returns (address);
    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);
}

interface IDEXRouter02 is IDEXRouter01 {
    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;
}
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = valueIndex; // Replace lastvalue's index to valueIndex

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}
abstract contract Ownable {
    address private _owner;

    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        address msgSender = msg.sender;
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == msg.sender, "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 onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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 onlyOwner {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}
contract Presale is  Ownable{
    using EnumerableSet for EnumerableSet.AddressSet;
    uint public maxContribution;
    uint public minContribution;

    address public recipient; 
    IDEXRouter02 router=IDEXRouter02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
    //mainnet
    address public USDC=0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
    uint8 decimalCorrection=12;//token has 12 decimals more than USDC
    //testnet
    //address public USDC=0x07865c6E87B9F70255377e024ace6630C1Eaa37F;
    //uint8 decimalCorrection=12;//token has 12 decimals more than USDC


    address public Token;

    uint public PresaleStartTimestamp=type(uint).max;
    uint public PresaleEndTimestamp=type(uint).max;

    EnumerableSet.AddressSet private _allContributors;
    function allContributorsLength() external view returns(uint){
        return _allContributors.length();
    }
    function allContributors(uint at) external view returns(address){
        return _allContributors.at(at);
    }
    function presaleOpen() public view returns (bool){
        uint timestamp=block.timestamp;
        return(timestamp>=PresaleStartTimestamp)&&(timestamp<=PresaleEndTimestamp);
    }
    function claimOpen() public view returns (bool){
        return(block.timestamp>PresaleEndTimestamp);
    }

    mapping(address=>uint) public tokensPurchased;
    uint public totalTokensSold;
    uint public totalUSDRaised;
    uint public currentStage;

    Stage[] public stages;
    function stagesLength() external view returns (uint){
        return stages.length;
    } 



    constructor(){
        recipient=msg.sender;
    }
    struct Stage{
        uint soldTokens;
        uint maxTokens;
        uint tokenPerUSDC;//in 1/1,000,000
    }
    function startPresale() external{
        setStart(block.timestamp);
    }
    function endPresale() external{
        setEnd(block.timestamp);
    }
    function setStart(uint presaleStart) public onlyOwner{
        PresaleStartTimestamp=presaleStart;
    }
    function setEnd(uint presaleEnd) public onlyOwner{
        PresaleEndTimestamp=presaleEnd;
    }
    function changeRecipient(address newRecipient) external onlyOwner{
        recipient=newRecipient;
    }
    function changeToken(address token) external onlyOwner{
        Token=token;
    }
    function addStage(uint maxTokens, uint tokenPerUSDC) external onlyOwner{
        stages.push(Stage(0,maxTokens,tokenPerUSDC));
    }
    function setMinMaxTokens(uint min, uint max) external onlyOwner{
        minContribution=min;
        maxContribution=max;
    }

    function changeStage(uint id, uint maxTokens, uint tokenPerUSDC) external onlyOwner{
        Stage storage stage=stages[id];
        stage.maxTokens=maxTokens;
        stage.tokenPerUSDC=tokenPerUSDC;
    }


    function contributeETH(uint minAmount, address referer) external payable{

        address[] memory path = new address[](2);
        path[0] = router.WETH();
        path[1] = USDC;
        uint balanceBefore=IERC20(USDC).balanceOf(recipient);
        router.swapExactETHForTokens{value:msg.value}(minAmount, path, recipient, block.timestamp);
        uint received=IERC20(USDC).balanceOf(recipient)-balanceBefore;
        _contribute(received);
    }
    function contributeUSDC(uint amount,address referer) external {
        IERC20(USDC).transferFrom(msg.sender,address(recipient),amount);
        _contribute(amount);
    }
    event OnContribute(address contributor, uint amountContributed, uint amountReceived);
    function _contribute(uint amount) private{
        require(presaleOpen(),"not yet open");
        address msgSender=msg.sender;
        _allContributors.add(msgSender);
        require(currentStage<stages.length,"presale over");

        Stage storage stage=stages[currentStage];
        uint amountReceived=amount*10**(decimalCorrection)*stage.tokenPerUSDC/1_000_000;

        uint tokensLeftToSell=stage.maxTokens-stage.soldTokens;
        uint finalContribution;
        if(amountReceived>=tokensLeftToSell)
        {        
            finalContribution=tokensPurchased[msgSender]+tokensLeftToSell;
            require(finalContribution<=maxContribution,"over maxContribution");
            require(finalContribution>=minContribution,"less than minContribution");
            tokensPurchased[msgSender]=finalContribution;
            stage.soldTokens+=tokensLeftToSell;
            totalTokensSold+=tokensLeftToSell;
            uint nextStageContribution=(amountReceived-tokensLeftToSell)*1_000_000/(stage.tokenPerUSDC*10**decimalCorrection);
            uint contributionThisStage=amount-nextStageContribution;
            totalUSDRaised+=contributionThisStage;
            currentStage++;
            emit OnContribute(msgSender,contributionThisStage,tokensLeftToSell);
            if(nextStageContribution>0)
                _contribute(nextStageContribution);
            return;
        }
        totalUSDRaised+=amount;
        finalContribution=tokensPurchased[msgSender]+amountReceived;
        require(finalContribution<=maxContribution,"over maxContribution");
        require(finalContribution>=minContribution,"less than minContribution");
        tokensPurchased[msgSender]=finalContribution;
        stage.soldTokens+=amountReceived;
        totalTokensSold+=amountReceived;
            emit OnContribute(msgSender,amount,amountReceived);
    }
    event OnClaim(address recipient, uint amountReceived);
    function claim() public{ 
        require(claimOpen(),"Presale not yet concluded");
        address msgSender=msg.sender;
        require(block.timestamp>PresaleEndTimestamp);
        uint contributed=tokensPurchased[msgSender];
        tokensPurchased[msgSender]=0;
        IERC20(Token).transfer(msgSender,contributed);
        emit OnClaim(msgSender,contributed);
    }



}