// SPDX-License-Identifier: MIT

pragma solidity ^0.7.5;

library LowGasSafeMath {
    /// @notice Returns x + y, reverts if sum overflows uint256
    /// @param x The augend
    /// @param y The addend
    /// @return z The sum of x and y
    function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x + y) >= x);
    }

    function add32(uint32 x, uint32 y) internal pure returns (uint32 z) {
        require((z = x + y) >= x);
    }

    /// @notice Returns x - y, reverts if underflows
    /// @param x The minuend
    /// @param y The subtrahend
    /// @return z The difference of x and y
    function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require((z = x - y) <= x);
    }

    function sub32(uint32 x, uint32 y) internal pure returns (uint32 z) {
        require((z = x - y) <= x);
    }

    /// @notice Returns x * y, reverts if overflows
    /// @param x The multiplicand
    /// @param y The multiplier
    /// @return z The product of x and y
    function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
        require(x == 0 || (z = x * y) / x == y);
    }

    /// @notice Returns x + y, reverts if overflows or underflows
    /// @param x The augend
    /// @param y The addend
    /// @return z The sum of x and y
    function add(int256 x, int256 y) internal pure returns (int256 z) {
        require((z = x + y) >= x == (y >= 0));
    }

    /// @notice Returns x - y, reverts if overflows or underflows
    /// @param x The minuend
    /// @param y The subtrahend
    /// @return z The difference of x and y
    function sub(int256 x, int256 y) internal pure returns (int256 z) {
        require((z = x - y) <= x == (y >= 0));
    }

    function div(uint256 x, uint256 y) internal pure returns(uint256 z){
        require(y > 0);
        z=x/y;
    }
}

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);
}

library Address {

    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _functionCallWithValue(
        address target, 
        bytes memory data, 
        uint256 weiValue, 
        string memory errorMessage
    ) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(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");

        // solhint-disable-next-line avoid-low-level-calls
        (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
    ) private 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);
            }
        }
    }

    function addressToString(address _address) internal pure returns(string memory) {
        bytes32 _bytes = bytes32(uint256(_address));
        bytes memory HEX = "0123456789abcdef";
        bytes memory _addr = new bytes(42);

        _addr[0] = '0';
        _addr[1] = 'x';

        for(uint256 i = 0; i < 20; i++) {
            _addr[2+i*2] = HEX[uint8(_bytes[i + 12] >> 4)];
            _addr[3+i*2] = HEX[uint8(_bytes[i + 12] & 0x0f)];
        }

        return string(_addr);

    }
}

contract OwnableData {
    address public owner;
    IERC20 public BlackSwanToken;
    address public Nodes;
    address public pendingOwner;
}

contract Ownable is OwnableData {
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /// @notice `owner` defaults to msg.sender on construction.
    constructor() {
        owner = msg.sender;
        emit OwnershipTransferred(address(0), msg.sender);
    }

    /// @notice Transfers ownership to `newOwner`. Either directly or claimable by the new pending owner.
    /// Can only be invoked by the current `owner`.
    /// @param newOwner Address of the new owner.
    /// @param direct True if `newOwner` should be set immediately. False if `newOwner` needs to use `claimOwnership`.
    /// @param renounce Allows the `newOwner` to be `address(0)` if `direct` and `renounce` is True. Has no effect otherwise.
    function transferOwnership(
        address newOwner,
        bool direct,
        bool renounce
    ) public onlyOwner {
        if (direct) {
            // Checks
            require(newOwner != address(0) || renounce, "Ownable: zero address");

            // Effects
            emit OwnershipTransferred(owner, newOwner);
            owner = newOwner;
            pendingOwner = address(0);
        } else {
            // Effects
            pendingOwner = newOwner;
        }
    }

    /// @notice Needs to be called by `pendingOwner` to claim ownership.
    function claimOwnership() public {
        address _pendingOwner = pendingOwner;

        // Checks
        require(msg.sender == _pendingOwner, "Ownable: caller != pending owner");

        // Effects
        emit OwnershipTransferred(owner, _pendingOwner);
        owner = _pendingOwner;
        pendingOwner = address(0);
    }

    function setBlackSwanToken(IERC20 _blackSwanToken) public {
        require(msg.sender == owner, "Ownable: caller is not the owner");
        BlackSwanToken = _blackSwanToken;
    } 

    function setNodesAddress(address _nodes) public {
        require(msg.sender == owner, "Ownable: caller is not the owner");
        Nodes = _nodes;
    }
    /// @notice Only allows the `owner` to execute the function.
    modifier onlyOwner() {
        require(msg.sender == owner, "Ownable: caller is not the owner");
        _;
    }

    /// @notice Only allows the `owner` to execute the function.
    modifier onlyBlackSwan() {
        require(msg.sender == address(BlackSwanToken), "Ownable: caller is not the Black Swan");
        _;
    }

    modifier onlyNodes() {
        require(msg.sender == Nodes, "Ownable: caller is not the nodes");
        _;
    }

}

contract BlackSwanRewardPool is Ownable {
    using LowGasSafeMath for uint;
    using LowGasSafeMath for uint32;
    struct NftData{
        uint nodeType;
        address owner;
        uint256 lastClaim;
    }
    uint256[] public rewardRates;
    mapping (uint => NftData) public nftInfo;
    uint public totalNodes;

    constructor(IERC20 _blackSwanToken) {     
        BlackSwanToken = _blackSwanToken;
    }
    
    receive() external payable {

  	}

    function addNodeInfo(uint _nftId, uint _nodeType, address _owner) external onlyNodes returns (bool success) {
        require(nftInfo[_nftId].owner == address(0), "Node already exists");
        nftInfo[_nftId].nodeType = _nodeType;
        nftInfo[_nftId].owner = _owner;
        nftInfo[_nftId].lastClaim = block.timestamp;
        totalNodes++;
        return true;
    }

    function updateNodeOwner(uint _nftId, address _owner) external onlyNodes returns (bool success) {
        require(nftInfo[_nftId].owner != address(0), "Node does not exist");
        nftInfo[_nftId].owner = _owner;
        return true;
    }

    function updateRewardRates(uint256[] memory _rewardRates) external onlyOwner {
        require(_rewardRates.length >= rewardRates.length);
        // Reward rate per day for each type of node (1e9 = 1 BlackSwanToken)
        for (uint i = 1; i < totalNodes; i++) {
            claimReward(i);
        }
        rewardRates = _rewardRates;
    }    

    function pendingRewardFor(uint _nftId) public view returns (uint256 _reward) {
        uint _nodeType = nftInfo[_nftId].nodeType;
        uint _lastClaim = nftInfo[_nftId].lastClaim;
        uint _daysSinceLastClaim = ((block.timestamp - _lastClaim).mul(1e9)) / 86400;
        _reward = (_daysSinceLastClaim * rewardRates[_nodeType]).div(1e9);
        return _reward;
    }

    function claimReward(uint _nftId) public returns (bool success) {
        uint _reward = pendingRewardFor(_nftId);
        if(_reward > 0) {
            nftInfo[_nftId].lastClaim = block.timestamp;
            BlackSwanToken.transfer(nftInfo[_nftId].owner, _reward);
        }
        return true;
    }

}