// Contract: ProofSFM
// Target function: function getAccount(address _account, address _rewardToken)
Min,
        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);
}

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;
}

contract DividendPayingToken is DividendPayingTokenInterface, DividendPayingTokenOptionalInterface, Ownable {
  using SafeMath for uint256;
  using SafeMathUint for uint256;
  using SafeMathInt for int256;

  // With `magnitude`, we can properly distribute dividends even if the amount of received usdc is small.
  // For more discussion about choosing the value of `magnitude`,
  uint256 constant internal magnitude = 2**128;

  mapping(address => uint256) internal magnifiedDividendPerShare;
  address[] public rewardTokens;
  address public nextRewardToken;
  uint256 public rewardTokenCounter;
  
  IUniswapV2Router02 public immutable uniswapV2Router;
  
  
  // About dividendCorrection:
  // If the token balance of a `_user` is never changed, the dividend of `_user` can be computed with:
  //   `dividendOf(_user) = dividendPerShare * balanceOf(_user)`.
  // When `balanceOf(_user)` is changed (via minting/burning/transferring tokens),
  //   `dividendOf(_user)` should not be changed,
  //   but the computed value of `dividendPerShare * balanceOf(_user)` is changed.
  // To keep the `dividendOf(_user)` unchanged, we add a correction term:
  //   `dividendOf(_user) = dividendPerShare * balanceOf(_user) + dividendCorrectionOf(_user)`,
  //   where `dividendCorrectionOf(_user)` is updated whenever `balanceOf(_user)` is changed:
  //   `dividendCorrectionOf(_user) = dividendPerShare * (old balanceOf(_user)) - (new balanceOf(_user))`.
  // So now `dividendOf(_user)` returns the same value before and after `balanceOf(_user)` is changed.
  mapping(address => mapping(address => int256)) internal magnifiedDividendCorrections;
  mapping(address => mapping(address => uint256)) internal withdrawnDividends;
  
  mapping (address => uint256) public holderBalance;
  uint256 public totalBalance;

  mapping(address => uint256) public totalDividendsDistributed;
  
  constructor(){
      IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D); // router 
      uniswapV2Router = _uniswapV2Router; 
      
      // Mainnet

      rewardTokens.push(address(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48)); // USDC 
      
      nextRewardToken = rewardTokens[0];
  }

  

  /// @dev Distributes dividends whenever ether is paid to this contract.
  receive() external payable {
    distributeDividends();
  }

  /// @notice Distributes ether to token holders as dividends.
  /// @dev It reverts if the total supply of tokens is 0.
  /// It emits the `DividendsDistributed` event if the amount of received ether is greater than 0.
  /// About undistributed ether:
  ///   In each distribution, there is a small amount of ether not distributed,
  ///     the magnified amount of which is
  ///     `(msg.value * magnitude) % totalSupply()`.
  ///   With a well-chosen `magnitude`, the amount of undistributed ether
  ///     (de-magnified) in a distribution can be less than 1 wei.
  ///   We can actually keep track of the undistributed ether in a distribution
  ///     and try to distribute it in the next distribution,
  ///     but keeping track of such data on-chain costs much more than
  ///     the saved ether, so we don't do that.
    
  function distributeDividends() public override payable { 
    require(totalBalance > 0);
    uint256 initialBalance = IERC20(nextRewardToken).balanceOf(address(this));
    buyTokens(msg.value, nextRewardToken);
    uint256 newBalance = IERC20(nextRewardToken).balanceOf(address(this)).sub(initialBalance);
    if (newBalance > 0) {
      magnifiedDividendPerShare[nextRewardToken] = magnifiedDividendPerShare[nextRewardToken].add(
        (newBalance).mul(magnitude) / totalBalance
      );
      emit DividendsDistributed(msg.sender, newBalance);

      totalDividendsDistributed[nextRewardToken] = totalDividendsDistributed[nextRewardToken].add(newBalance);
    }
    rewardTokenCounter = rewardTokenCounter == rewardTokens.length - 1 ? 0 : rewardTokenCounter + 1;
    nextRewardToken = rewardTokens[rewardTokenCounter];
  }
  
    function buyTokens(uint256 ethAmountInWei, address rewardToken) internal {
        // generate the uniswap pair path of weth -> eth
        address[] memory path = new address[](2);
        path[0] = uniswapV2Router.WETH();
        path[1] = rewardToken;

        // make the swap
        uniswapV2Router.swapExactETHForTokensSupportingFeeOnTransferTokens{value: ethAmountInWei}(
            0, // accept any amount of Ethereum
            path,
            address(this),
            block.timestamp
        );
    }
  
  /// @notice Withdraws the ether distributed to the sender.
  /// @dev It emits a `DividendWithdrawn` event if the amount of withdrawn ether is greater than 0.
  function withdrawDividend(address _rewardToken) external virtual override {
    _withdrawDividendOfUser(payable(msg.sender), _rewardToken);
  }

  /// @notice Withdraws the ether distributed to the sender.
  /// @dev It emits a `DividendWithdrawn` event if the amount of withdrawn ether is greater than 0.
  function _withdrawDividendOfUser(address payable user, address _rewardToken) internal returns (uint256) {
    uint256 _withdrawableDividend = withdrawableDividendOf(user, _rewardToken);
    if (_withdrawableDividend > 0) {
      withdrawnDividends[user][_rewardToken] = withdrawnDividends[user][_rewardToken].add(_withdrawableDividend);
      emit DividendWithdrawn(user, _withdrawableDividend);
      IERC20(_rewardToken).transfer(user, _withdrawableDividend);
      return _withdrawableDividend;
    }

    return 0;
  }


  /// @notice View the amount of dividend in wei that an address can withdraw.
  /// @param _owner The address of a token holder.
  /// @return The amount of dividend in wei that `_owner` can withdraw.
  function dividendOf(address _owner, address _rewardToken) external view override returns(uint256) {
    return withdrawableDividendOf(_owner, _rewardToken);
  }

  /// @notice View the amount of dividend in wei that an address can withdraw.
  /// @param _owner The address of a token holder.
  /// @return The amount of dividend in wei that `_owner` can withdraw.
  function withdrawableDividendOf(address _owner, address _rewardToken) public view override returns(uint256) {
    return accumulativeDividendOf(_owner,_rewardToken).sub(withdrawnDividends[_owner][_rewardToken]);
  }

  /// @notice View the amount of dividend in wei that an address has withdrawn.
  /// @param _owner The address of a token holder.
  /// @return The amount of dividend in wei that `_owner` has withdrawn.
  function withdrawnDividendOf(address _owner, address _rewardToken) external view override returns(uint256) {
    return withdrawnDividends[_owner][_rewardToken];
  }


  /// @notice View the amount of dividend in wei that an address has earned in total.
  /// @dev accumulativeDividendOf(_owner) = withdrawableDividendOf(_owner) + withdrawnDividendOf(_owner)
  /// = (magnifiedDividendPerShare * balanceOf(_owner) + magnifiedDividendCorrections[_owner]) / magnitude
  /// @param _owner The address of a token holder.
  /// @return The amount of dividend in wei that `_owner` has earned in total.
  function accumulativeDividendOf(address _owner, address _rewardToken) public view override returns(uint256) {
    return magnifiedDividendPerShare[_rewardToken].mul(holderBalance[_owner]).toInt256Safe()
      .add(magnifiedDividendCorrections[_rewardToken][_owner]).toUint256Safe() / magnitude;
  }

  /// @dev Internal function that increases tokens to an account.
  /// Update magnifiedDividendCorrections to keep dividends unchanged.
  /// @param account The account that will receive the created tokens.
  /// @param value The amount that will be created.
  function _increase(address account, uint256 value) internal {
    for (uint256 i; i < rewardTokens.length; i++){
        magnifiedDividendCorrections[rewardTokens[i]][account] = magnifiedDividendCorrections[rewardTokens[i]][account]
          .sub((magnifiedDividendPerShare[rewardTokens[i]].mul(value)).toInt256Safe());
    }
  }

  /// @dev Internal function that reduces an amount of the token of a given account.
  /// Update magnifiedDividendCorrections to keep dividends unchanged.
  /// @param account The account whose tokens will be burnt.
  /// @param value The amount that will be burnt.
  function _reduce(address account, uint256 value) internal {
      for (uint256 i; i < rewardTokens.length; i++){
        magnifiedDividendCorrections[rewardTokens[i]][account] = magnifiedDividendCorrections[rewardTokens[i]][account]
          .add( (magnifiedDividendPerShare[rewardTokens[i]].mul(value)).toInt256Safe() );
      }
  }

  function _setBalance(address account, uint256 newBalance) internal {
    uint256 currentBalance = holderBalance[account];
    holderBalance[account] = newBalance;
    if(newBalance > currentBalance) {
      uint256 increaseAmount = newBalance.sub(currentBalance);
      _increase(account, increaseAmount);
      totalBalance += increaseAmount;
    } else if(newBalance < currentBalance) {
      uint256 reduceAmount = currentBalance.sub(newBalance);
      _reduce(account, reduceAmount);
      totalBalance -= reduceAmount;
    }
  }
}

contract DividendTracker is DividendPayingToken {
    using SafeMath for uint256;
    using SafeMathInt for int256;

    struct Map {
        address[] keys;
        mapping(address => uint) values;
        mapping(address => uint) indexOf;
        mapping(address => bool) inserted;
    }

    function get(address key) private view returns (uint) {
        return tokenHoldersMap.values[key];
    }

    function getIndexOfKey(address key) private view returns (int) {
        if(!tokenHoldersMap.inserted[key]) {
            return -1;
        }
        return int(tokenHoldersMap.indexOf[key]);
    }

    function getKeyAtIndex(uint index) private view returns (address) {
        return tokenHoldersMap.keys[index];
    }



    function size() private view returns (uint) {
        return tokenHoldersMap.keys.length;
    }

    function set(address key, uint val) private {
        if (tokenHoldersMap.inserted[key]) {
            tokenHoldersMap.values[key] = val;
        } else {
            tokenHoldersMap.inserted[key] = true;
            tokenHoldersMap.values[key] = val;
            tokenHoldersMap.indexOf[key] = tokenHoldersMap.keys.length;
            tokenHoldersMap.keys.push(key);
        }
    }

    function remove(address key) private {
        if (!tokenHoldersMap.inserted[key]) {
            return;
        }

        delete tokenHoldersMap.inserted[key];
        delete tokenHoldersMap.values[key];

        uint index = tokenHoldersMap.indexOf[key];
        uint lastIndex = tokenHoldersMap.keys.length - 1;
        address lastKey = tokenHoldersMap.keys[lastIndex];

        tokenHoldersMap.indexOf[lastKey] = index;
        delete tokenHoldersMap.indexOf[key];

        tokenHoldersMap.keys[index] = lastKey;
        tokenHoldersMap.keys.pop();
    }

    Map private tokenHoldersMap;
    uint256 public lastProcessedIndex;

    mapping (address => bool) public excludedFromDividends;

    mapping (address => uint256) public lastClaimTimes;

    uint256 public claimWait;
    uint256 public immutable minimumTokenBalanceForDividends;

    event ExcludeFromDividends(address indexed account);
    event IncludeInDividends(address indexed account);
    event ClaimWaitUpdated(uint256 indexed newValue, uint256 indexed oldValue);

    event Claim(address indexed account, uint256 amount, bool indexed automatic);

    constructor() {
    	claimWait = 1200;
        minimumTokenBalanceForDividends = 1000 * (10**18);
    }

    function excludeFromDividends(address account) external onlyOwner {
    	excludedFromDividends[account] = true;

    	_setBalance(account, 0);
    	remove(account);

    	emit ExcludeFromDividends(account);
    }
    
    function includeInDividends(address account) external onlyOwner {
    	require(excludedFromDividends[account]);
    	excludedFromDividends[account] = false;

    	emit IncludeInDividends(account);
    }

    function updateClaimWait(uint256 newClaimWait) external onlyOwner {
        require(newClaimWait >= 1200 && newClaimWait <= 86400, "Dividend_Tracker: claimWait must be updated to between 1 and 24 hours");
        require(newClaimWait != claimWait, "Dividend_Tracker: Cannot update claimWait to same value");
        emit ClaimWaitUpdated(newClaimWait, claimWait);
        claimWait = newClaimWait;
    }

    function getLastProcessedIndex() external view returns(uint256) {
    	return lastProcessedIndex;
    }

    function getNumberOfTokenHolders() external view returns(uint256) {
        return tokenHoldersMap.keys.length;
    }