// File: contracts/PowerTONSwapper.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.8.0;
pragma experimental ABIEncoderV2;

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { ITOS } from "./ITOS.sol";
import "@uniswap/v3-periphery/contracts/interfaces/ISwapRouter.sol";

contract PowerTONSwapper {
    IERC20 wton;
    ITOS tos;
    ISwapRouter uniswapRouter;

    event Swapped(
        uint256 amount
    );

    constructor(
        address _wton,
        address _tos,
        address _uniswapRouter
    )
    {
        wton = IERC20(_wton);
        tos = ITOS(_tos);
        uniswapRouter = ISwapRouter(_uniswapRouter);
    }

    function approveToUniswap() external {
        wton.approve(
            address(uniswapRouter),
            type(uint256).max
        );
    }

    function swap(
        uint24 _fee,
        uint256 _deadline,
        uint256 _amountOutMinimum,
        uint160 _sqrtPriceLimitX96
    )
        external
    {
        uint256 wtonBalance = getWTONBalance();

        ISwapRouter.ExactInputSingleParams memory params =
            ISwapRouter.ExactInputSingleParams({
                tokenIn: address(wton),
                tokenOut: address(tos),
                fee: _fee,
                recipient: address(this),
                deadline: block.timestamp + _deadline,
                amountIn: wtonBalance,
                amountOutMinimum: _amountOutMinimum,
                sqrtPriceLimitX96: _sqrtPriceLimitX96
            });
        ISwapRouter(uniswapRouter).exactInputSingle(params);

        uint256 burnAmount = tos.balanceOf(address(this));
        tos.burn(address(this), burnAmount);

        emit Swapped(burnAmount);
    }

    function getWTONBalance() public view returns(uint256) {
        return wton.balanceOf(address(this));
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, 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 `sender` to `recipient` 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 sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: contracts/ITOS.sol



//SPDX-License-Identifier: Unlicense
pragma solidity >0.7.0;

interface ITOS {
    function balanceOf(address account) external view returns (uint256);

    /// @dev Issue a token.
    /// @param to  who takes the issue
    /// @param amount the amount to issue
    function mint(address to, uint256 amount) external returns (bool);

    // @dev burn a token.
    /// @param from Whose tokens are burned
    /// @param amount the amount to burn
    function burn(address from, uint256 amount) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function nonces(address owner) external view returns (uint256);

    /// @dev Authorizes the owner's token to be used by the spender as much as the value.
    /// @dev The signature must have the owner's signature.
    /// @param owner the token's owner
    /// @param spender the account that spend owner's token
    /// @param value the amount to be approve to spend
    /// @param deadline the deadline that valid the owner's signature
    /// @param v the owner's signature - v
    /// @param r the owner's signature - r
    /// @param s the owner's signature - s
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /// @dev verify the signature
    /// @param owner the token's owner
    /// @param spender the account that spend owner's token
    /// @param value the amount to be approve to spend
    /// @param deadline the deadline that valid the owner's signature
    /// @param _nounce the _nounce
    /// @param sigR the owner's signature - r
    /// @param sigS the owner's signature - s
    /// @param sigV the owner's signature - v
    function verify(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint256 _nounce,
        bytes32 sigR,
        bytes32 sigS,
        uint8 sigV
    ) external view returns (bool);

    /// @dev the hash of Permit
    /// @param owner the token's owner
    /// @param spender the account that spend owner's token
    /// @param value the amount to be approve to spend
    /// @param deadline the deadline that valid the owner's signature
    /// @param _nounce the _nounce
    function hashPermit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint256 _nounce
    ) external view returns (bytes32);
}


// File: @uniswap/v3-periphery/contracts/interfaces/ISwapRouter.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.7.5;
pragma abicoder v2;

import '@uniswap/v3-core/contracts/interfaces/callback/IUniswapV3SwapCallback.sol';

/// @title Router token swapping functionality
/// @notice Functions for swapping tokens via Uniswap V3
interface ISwapRouter is IUniswapV3SwapCallback {
    struct ExactInputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
        uint160 sqrtPriceLimitX96;
    }

    /// @notice Swaps `amountIn` of one token for as much as possible of another token
    /// @param params The parameters necessary for the swap, encoded as `ExactInputSingleParams` in calldata
    /// @return amountOut The amount of the received token
    function exactInputSingle(ExactInputSingleParams calldata params) external payable returns (uint256 amountOut);

    struct ExactInputParams {
        bytes path;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
    }

    /// @notice Swaps `amountIn` of one token for as much as possible of another along the specified path
    /// @param params The parameters necessary for the multi-hop swap, encoded as `ExactInputParams` in calldata
    /// @return amountOut The amount of the received token
    function exactInput(ExactInputParams calldata params) external payable returns (uint256 amountOut);

    struct ExactOutputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountOut;
        uint256 amountInMaximum;
        uint160 sqrtPriceLimitX96;
    }

    /// @notice Swaps as little as possible of one token for `amountOut` of another token
    /// @param params The parameters necessary for the swap, encoded as `ExactOutputSingleParams` in calldata
    /// @return amountIn The amount of the input token
    function exactOutputSingle(ExactOutputSingleParams calldata params) external payable returns (uint256 amountIn);

    struct ExactOutputParams {
        bytes path;
        address recipient;
        uint256 deadline;
        uint256 amountOut;
        uint256 amountInMaximum;
    }

    /// @notice Swaps as little as possible of one token for `amountOut` of another along the specified path (reversed)
    /// @param params The parameters necessary for the multi-hop swap, encoded as `ExactOutputParams` in calldata
    /// @return amountIn The amount of the input token
    function exactOutput(ExactOutputParams calldata params) external payable returns (uint256 amountIn);
}

// File: @uniswap/v3-core/contracts/interfaces/callback/IUniswapV3SwapCallback.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title Callback for IUniswapV3PoolActions#swap
/// @notice Any contract that calls IUniswapV3PoolActions#swap must implement this interface
interface IUniswapV3SwapCallback {
    /// @notice Called to `msg.sender` after executing a swap via IUniswapV3Pool#swap.
    /// @dev In the implementation you must pay the pool tokens owed for the swap.
    /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
    /// amount0Delta and amount1Delta can both be 0 if no tokens were swapped.
    /// @param amount0Delta The amount of token0 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token0 to the pool.
    /// @param amount1Delta The amount of token1 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token1 to the pool.
    /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#swap call
    function uniswapV3SwapCallback(
        int256 amount0Delta,
        int256 amount1Delta,
        bytes calldata data
    ) external;
}