// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;

// File: @openzeppelin/contracts/math/SafeMath.sol

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

/*
 * @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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/access/Ownable.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.
 */
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 () internal {
        address msgSender = _msgSender();
        _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 == _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 {
        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 virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

/**
 * @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/strategies/IStrategy.sol

// Assume the strategy generates `TOKEN`.
interface IStrategy {

    function approve(IERC20 _token) external;

    function getValuePerShare(address _vault) external view returns(uint256);
    function pendingValuePerShare(address _vault) external view returns (uint256);

    // Deposit tokens to a farm to yield more tokens.
    function deposit(address _vault, uint256 _amount) external;

    // Claim the profit from a farm.
    function claim(address _vault) external;

    // Withdraw the principal from a farm.
    function withdraw(address _vault, uint256 _amount) external;

    // Target farming token of this strategy.
    function getTargetToken() external view returns(address);
}

// File: contracts/SodaMaster.sol

/*

Here we have a list of constants. In order to get access to an address
managed by SodaMaster, the calling contract should copy and define
some of these constants and use them as keys.

Keys themselves are immutable. Addresses can be immutable or mutable.

a) Vault addresses are immutable once set, and the list may grow:

K_VAULT_WETH = 0;
K_VAULT_USDT_ETH_SUSHI_LP = 1;
K_VAULT_SOETH_ETH_UNI_V2_LP = 2;
K_VAULT_SODA_ETH_UNI_V2_LP = 3;
K_VAULT_GT = 4;
K_VAULT_GT_ETH_UNI_V2_LP = 5;


b) SodaMade token addresses are immutable once set, and the list may grow:

K_MADE_SOETH = 0;


c) Strategy addresses are mutable:

K_STRATEGY_CREATE_SODA = 0;
K_STRATEGY_EAT_SUSHI = 1;
K_STRATEGY_SHARE_REVENUE = 2;


d) Calculator addresses are mutable:

K_CALCULATOR_WETH = 0;

Solidity doesn't allow me to define global constants, so please
always make sure the key name and key value are copied as the same
in different contracts.

*/


// SodaMaster manages the addresses all the other contracts of the system.
// This contract is owned by Timelock.
contract SodaMaster is Ownable {

    address public pool;
    address public bank;
    address public revenue;
    address public dev;

    address public soda;
    address public wETH;
    address public usdt;

    address public uniswapV2Factory;

    mapping(address => bool) public isVault;
    mapping(uint256 => address) public vaultByKey;

    mapping(address => bool) public isSodaMade;
    mapping(uint256 => address) public sodaMadeByKey;

    mapping(address => bool) public isStrategy;
    mapping(uint256 => address) public strategyByKey;

    mapping(address => bool) public isCalculator;
    mapping(uint256 => address) public calculatorByKey;

    // Immutable once set.
    function setPool(address _pool) external onlyOwner {
        require(pool == address(0));
        pool = _pool;
    }

    // Immutable once set.
    // Bank owns all the SodaMade tokens.
    function setBank(address _bank) external onlyOwner {
        require(bank == address(0));
        bank = _bank;
    }

    // Mutable in case we want to upgrade this module.
    function setRevenue(address _revenue) external onlyOwner {
        revenue = _revenue;
    }

    // Mutable in case we want to upgrade this module.
    function setDev(address _dev) external onlyOwner {
        dev = _dev;
    }

    // Mutable, in case Uniswap has changed or we want to switch to sushi.
    // The core systems, Pool and Bank, don't rely on Uniswap, so there is no risk.
    function setUniswapV2Factory(address _uniswapV2Factory) external onlyOwner {
        uniswapV2Factory = _uniswapV2Factory;
    }

    // Immutable once set.
    function setWETH(address _wETH) external onlyOwner {
       require(wETH == address(0));
       wETH = _wETH;
    }

    // Immutable once set. Hopefully Tether is reliable.
    // Even if it fails, not a big deal, we only used USDT to estimate APY.
    function setUSDT(address _usdt) external onlyOwner {
        require(usdt == address(0));
        usdt = _usdt;
    }
 
    // Immutable once set.
    function setSoda(address _soda) external onlyOwner {
        require(soda == address(0));
        soda = _soda;
    }

    // Immutable once added, and you can always add more.
    function addVault(uint256 _key, address _vault) external onlyOwner {
        require(vaultByKey[_key] == address(0), "vault: key is taken");

        isVault[_vault] = true;
        vaultByKey[_key] = _vault;
    }

    // Immutable once added, and you can always add more.
    function addSodaMade(uint256 _key, address _sodaMade) external onlyOwner {
        require(sodaMadeByKey[_key] == address(0), "sodaMade: key is taken");

        isSodaMade[_sodaMade] = true;
        sodaMadeByKey[_key] = _sodaMade;
    }

    // Mutable and removable.
    function addStrategy(uint256 _key, address _strategy) external onlyOwner {
        isStrategy[_strategy] = true;
        strategyByKey[_key] = _strategy;
    }

    function removeStrategy(uint256 _key) external onlyOwner {
        isStrategy[strategyByKey[_key]] = false;
        delete strategyByKey[_key];
    }

    // Mutable and removable.
    function addCalculator(uint256 _key, address _calculator) external onlyOwner {
        isCalculator[_calculator] = true;
        calculatorByKey[_key] = _calculator;
    }

    function removeCalculator(uint256 _key) external onlyOwner {
        isCalculator[calculatorByKey[_key]] = false;
        delete calculatorByKey[_key];
    }
}

interface IMasterChef {
    // Deposit LP tokens to MasterChef for SUSHI allocation.
    function deposit(uint256 _pid, uint256 _amount) external;
    // Withdraw LP tokens from MasterChef.
    function withdraw(uint256 _pid, uint256 _amount) external;

    function pendingSushi(uint256 _pid, address _user) external view returns (uint256);
}

// This contract is owned by Timelock.
// What it does is simple: deposit USDT-ETH UNI-V2 LP to sushiswap, and wait for SodaPool's command.
contract EatSushi is IStrategy, Ownable {
    using SafeMath for uint256;

    uint256 constant PER_SHARE_SIZE = 1e12;

    IMasterChef public masterChef;

    SodaMaster public sodaMaster;
    IERC20 public sushiToken;

    struct PoolInfo {
        IERC20 lpToken;
        uint256 poolId;  // poolId in sushi pool.
    }

    mapping(address => PoolInfo) public poolMap;  // By vault.
    mapping(address => uint256) private valuePerShare;  // By vault.

    // usdtETHSLPToken = "0x06da0fd433C1A5d7a4faa01111c044910A184553"
    // sushiToken = "0x6b3595068778dd592e39a122f4f5a5cf09c90fe2"
    // masterChef = "0xc2EdaD668740f1aA35E4D8f227fB8E17dcA888Cd"
    // usdtETHLPId = 0
    constructor(SodaMaster _sodaMaster,
                IERC20 _sushiToken,
                IMasterChef _masterChef) public {
        sodaMaster = _sodaMaster;
        sushiToken = _sushiToken;
        masterChef = _masterChef;
        // Approve all.
        sushiToken.approve(sodaMaster.pool(), type(uint256).max);
    }

    function approve(IERC20 _token) external override onlyOwner {
        _token.approve(sodaMaster.pool(), type(uint256).max);
        _token.approve(address(masterChef), type(uint256).max);
    }

    function setPoolInfo(
        address _vault,
        IERC20 _lpToken,
        uint256 _sushiPoolId
    ) external onlyOwner {
        poolMap[_vault].lpToken = _lpToken;
        poolMap[_vault].poolId = _sushiPoolId;
        _lpToken.approve(sodaMaster.pool(), type(uint256).max);
        _lpToken.approve(address(masterChef), type(uint256).max);
    }

    function getValuePerShare(address _vault) external view override returns(uint256) {
        return valuePerShare[_vault];
    }

    function pendingValuePerShare(address _vault) external view override returns (uint256) {
        uint256 shareAmount = IERC20(_vault).totalSupply();
        if (shareAmount == 0) {
            return 0;
        }

        uint256 amount = masterChef.pendingSushi(poolMap[_vault].poolId, address(this));
        return amount.mul(PER_SHARE_SIZE).div(shareAmount);
    }

    function _update(address _vault, uint256 _tokenAmountDelta) internal {
        uint256 shareAmount = IERC20(_vault).totalSupply();
        if (shareAmount > 0) {
            valuePerShare[_vault] = valuePerShare[_vault].add(
                _tokenAmountDelta.mul(PER_SHARE_SIZE).div(shareAmount));
        }
    }

    /**
     * @dev See {IStrategy-deposit}.
     */
    function deposit(address _vault, uint256 _amount) public override {
        require(sodaMaster.isVault(msg.sender), "sender not vault");

        uint256 tokenAmountBefore = sushiToken.balanceOf(address(this));
        masterChef.deposit(poolMap[_vault].poolId, _amount);
        uint256 tokenAmountAfter = sushiToken.balanceOf(address(this));

        _update(_vault, tokenAmountAfter.sub(tokenAmountBefore));
    }

    /**
     * @dev See {IStrategy-claim}.
     */
    function claim(address _vault) external override {
        require(sodaMaster.isVault(msg.sender), "sender not vault");

        // Sushi is strage that it uses deposit to claim.
        deposit(_vault, 0);
    }

    /**
     * @dev See {IStrategy-withdraw}.
     */
    function withdraw(address _vault, uint256 _amount) external override {
        require(sodaMaster.isVault(msg.sender), "sender not vault");

        uint256 tokenAmountBefore = sushiToken.balanceOf(address(this));
        masterChef.withdraw(poolMap[_vault].poolId, _amount);
        uint256 tokenAmountAfter = sushiToken.balanceOf(address(this));

        _update(_vault, tokenAmountAfter.sub(tokenAmountBefore));
    }

    /**
     * @dev See {IStrategy-getTargetToken}.
     */
    function getTargetToken() external view override returns(address) {
        return address(sushiToken);
    }
}