pragma solidity 0.4.24;

import "openzeppelin-solidity/contracts/math/SafeMath.sol";
import "../upgradeability/EternalStorage.sol";
import "./DecimalShiftBridge.sol";
import "./Ownable.sol";

contract BasicTokenBridge is EternalStorage, Ownable, DecimalShiftBridge {
    using SafeMath for uint256;

    event DailyLimitChanged(uint256 newLimit);
    event ExecutionDailyLimitChanged(uint256 newLimit);

    bytes32 internal constant MIN_PER_TX = 0xbbb088c505d18e049d114c7c91f11724e69c55ad6c5397e2b929e68b41fa05d1; // keccak256(abi.encodePacked("minPerTx"))
    bytes32 internal constant MAX_PER_TX = 0x0f8803acad17c63ee38bf2de71e1888bc7a079a6f73658e274b08018bea4e29c; // keccak256(abi.encodePacked("maxPerTx"))
    bytes32 internal constant DAILY_LIMIT = 0x4a6a899679f26b73530d8cf1001e83b6f7702e04b6fdb98f3c62dc7e47e041a5; // keccak256(abi.encodePacked("dailyLimit"))
    bytes32 internal constant EXECUTION_MAX_PER_TX = 0xc0ed44c192c86d1cc1ba51340b032c2766b4a2b0041031de13c46dd7104888d5; // keccak256(abi.encodePacked("executionMaxPerTx"))
    bytes32 internal constant EXECUTION_DAILY_LIMIT = 0x21dbcab260e413c20dc13c28b7db95e2b423d1135f42bb8b7d5214a92270d237; // keccak256(abi.encodePacked("executionDailyLimit"))

    function totalSpentPerDay(uint256 _day) public view returns (uint256) {
        return uintStorage[keccak256(abi.encodePacked("totalSpentPerDay", _day))];
    }

    function totalExecutedPerDay(uint256 _day) public view returns (uint256) {
        return uintStorage[keccak256(abi.encodePacked("totalExecutedPerDay", _day))];
    }

    function dailyLimit() public view returns (uint256) {
        return uintStorage[DAILY_LIMIT];
    }

    function executionDailyLimit() public view returns (uint256) {
        return uintStorage[EXECUTION_DAILY_LIMIT];
    }

    function maxPerTx() public view returns (uint256) {
        return uintStorage[MAX_PER_TX];
    }

    function executionMaxPerTx() public view returns (uint256) {
        return uintStorage[EXECUTION_MAX_PER_TX];
    }

    function minPerTx() public view returns (uint256) {
        return uintStorage[MIN_PER_TX];
    }

    function withinLimit(uint256 _amount) public view returns (bool) {
        uint256 nextLimit = totalSpentPerDay(getCurrentDay()).add(_amount);
        return dailyLimit() >= nextLimit && _amount <= maxPerTx() && _amount >= minPerTx();
    }

    function withinExecutionLimit(uint256 _amount) public view returns (bool) {
        uint256 nextLimit = totalExecutedPerDay(getCurrentDay()).add(_amount);
        return executionDailyLimit() >= nextLimit && _amount <= executionMaxPerTx();
    }

    function getCurrentDay() public view returns (uint256) {
        return now / 1 days;
    }

    function addTotalSpentPerDay(uint256 _day, uint256 _value) internal {
        uintStorage[keccak256(abi.encodePacked("totalSpentPerDay", _day))] = totalSpentPerDay(_day).add(_value);
    }

    function addTotalExecutedPerDay(uint256 _day, uint256 _value) internal {
        uintStorage[keccak256(abi.encodePacked("totalExecutedPerDay", _day))] = totalExecutedPerDay(_day).add(_value);
    }

    function setDailyLimit(uint256 _dailyLimit) external onlyOwner {
        require(_dailyLimit > maxPerTx() || _dailyLimit == 0);
        uintStorage[DAILY_LIMIT] = _dailyLimit;
        emit DailyLimitChanged(_dailyLimit);
    }

    function setExecutionDailyLimit(uint256 _dailyLimit) external onlyOwner {
        require(_dailyLimit > executionMaxPerTx() || _dailyLimit == 0);
        uintStorage[EXECUTION_DAILY_LIMIT] = _dailyLimit;
        emit ExecutionDailyLimitChanged(_dailyLimit);
    }

    function setExecutionMaxPerTx(uint256 _maxPerTx) external onlyOwner {
        require(_maxPerTx < executionDailyLimit());
        uintStorage[EXECUTION_MAX_PER_TX] = _maxPerTx;
    }

    function setMaxPerTx(uint256 _maxPerTx) external onlyOwner {
        require(_maxPerTx == 0 || (_maxPerTx > minPerTx() && _maxPerTx < dailyLimit()));
        uintStorage[MAX_PER_TX] = _maxPerTx;
    }

    function setMinPerTx(uint256 _minPerTx) external onlyOwner {
        require(_minPerTx > 0 && _minPerTx < dailyLimit() && _minPerTx < maxPerTx());
        uintStorage[MIN_PER_TX] = _minPerTx;
    }

    /**
    * @dev Retrieves maximum available bridge amount per one transaction taking into account maxPerTx() and dailyLimit() parameters.
    * @return minimum of maxPerTx parameter and remaining daily quota.
    */
    function maxAvailablePerTx() public view returns (uint256) {
        uint256 _maxPerTx = maxPerTx();
        uint256 _dailyLimit = dailyLimit();
        uint256 _spent = totalSpentPerDay(getCurrentDay());
        uint256 _remainingOutOfDaily = _dailyLimit > _spent ? _dailyLimit - _spent : 0;
        return _maxPerTx < _remainingOutOfDaily ? _maxPerTx : _remainingOutOfDaily;
    }

    function _setLimits(uint256[3] _limits) internal {
        require(
            _limits[2] > 0 && // minPerTx > 0
                _limits[1] > _limits[2] && // maxPerTx > minPerTx
                _limits[0] > _limits[1] // dailyLimit > maxPerTx
        );

        uintStorage[DAILY_LIMIT] = _limits[0];
        uintStorage[MAX_PER_TX] = _limits[1];
        uintStorage[MIN_PER_TX] = _limits[2];

        emit DailyLimitChanged(_limits[0]);
    }

    function _setExecutionLimits(uint256[2] _limits) internal {
        require(_limits[1] < _limits[0]); // foreignMaxPerTx < foreignDailyLimit

        uintStorage[EXECUTION_DAILY_LIMIT] = _limits[0];
        uintStorage[EXECUTION_MAX_PER_TX] = _limits[1];

        emit ExecutionDailyLimitChanged(_limits[0]);
    }
}