// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.7.0;

// File: SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (_a == 0) {
      return 0;
    }

    c = _a * _b;
    assert(c / _a == _b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
    // assert(_b > 0); // Solidity automatically throws when dividing by 0
    // uint256 c = _a / _b;
    // assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold
    return _a / _b;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
    assert(_b <= _a);
    return _a - _b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    c = _a + _b;
    assert(c >= _a);
    return c;
  }
}

// File: FrozenChecker.sol

/**
 * @title FrozenChecker
 * @dev Check account by frozen rules
 */
library FrozenChecker {

    using SafeMath for uint256;

    /**
     * Rule for each address
     */
    struct Rule {
        uint256 timeT;
        uint8 initPercent;
        uint256[] periods;
        uint8[] percents;
    }

    function check(Rule storage self, uint256 totalFrozenValue) internal view returns (uint256) {
        if (totalFrozenValue == uint256(0)) {
            return 0;
        }
        //uint8 temp = self.initPercent;
        if (self.timeT == uint256(0) || self.timeT > block.timestamp) {
            return totalFrozenValue.sub(totalFrozenValue.mul(self.initPercent).div(100));
        }
        for (uint256 i = 0; i < self.periods.length.sub(1); i = i.add(1)) {
            if (block.timestamp >= self.timeT.add(self.periods[i]) && block.timestamp < self.timeT.add(self.periods[i.add(1)])) {
                return totalFrozenValue.sub(totalFrozenValue.mul(self.percents[i]).div(100));
            }
        }
        if (block.timestamp >= self.timeT.add(self.periods[self.periods.length.sub(1)])) {
            return totalFrozenValue.sub(totalFrozenValue.mul(self.percents[self.periods.length.sub(1)]).div(100));
        }
        return 0;
    }

}

// File: FrozenValidator.sol

library FrozenValidator {
    
    using SafeMath for uint256;
    using FrozenChecker for FrozenChecker.Rule;

    struct Validator {
        mapping(address => IndexValue) data;
        KeyFlag[] keys;
        uint256 size;
    }

    struct IndexValue {
        uint256 keyIndex; 
        FrozenChecker.Rule rule;
        mapping (address => uint256) frozenBalances;
    }

    struct KeyFlag { 
        address key; 
        bool deleted; 
    }

    function addRule(Validator storage self, address key, uint8 initPercent, uint256[] memory periods, uint8[] memory percents) internal returns (bool replaced) {
        //require(self.size <= 10);
        require(key != address(0));
        require(periods.length == percents.length);
        require(periods.length > 0);
        require(periods[0] == uint256(0));
        require(initPercent <= percents[0]);
        for (uint256 i = 1; i < periods.length; i = i.add(1)) {
            require(periods[i.sub(1)] < periods[i]);
            require(percents[i.sub(1)] <= percents[i]);
        }
        require(percents[percents.length.sub(1)] == 100);
        FrozenChecker.Rule memory rule = FrozenChecker.Rule(0, initPercent, periods, percents);
        uint256 keyIndex = self.data[key].keyIndex;
        self.data[key].rule = rule;
        if (keyIndex > 0) {
            return true;
        } else {
            //keyIndex = self.keys.length++;
            keyIndex = self.keys.length;
            self.keys.push();
            self.data[key].keyIndex = keyIndex.add(1);
            self.keys[keyIndex].key = key;
            self.size++;
            return false;
        }
    }

    function removeRule(Validator storage self, address key) internal returns (bool success) {
        uint256 keyIndex = self.data[key].keyIndex;
        if (keyIndex == 0) {
            return false;
        }
        delete self.data[key];
        self.keys[keyIndex.sub(1)].deleted = true;
        self.size--;
        return true;
    }

    function containRule(Validator storage self, address key) internal view returns (bool) {
        return self.data[key].keyIndex > 0;
    }

    function addTimeT(Validator storage self, address addr, uint256 timeT) internal returns (bool) {
        require(timeT > block.timestamp);
        self.data[addr].rule.timeT = timeT;
        return true;
    }

    function addFrozenBalance(Validator storage self, address from, address to, uint256 value) internal returns (uint256) {
        self.data[from].frozenBalances[to] = self.data[from].frozenBalances[to].add(value);
        return self.data[from].frozenBalances[to];
    }

    function validate(Validator storage self, address addr) internal view returns (uint256) {
        uint256 frozenTotal = 0;
        for (uint256 i = iterateStart(self); iterateValid(self, i); i = iterateNext(self, i)) {
            address ruleaddr = iterateGet(self, i);
            FrozenChecker.Rule storage rule = self.data[ruleaddr].rule;
            frozenTotal = frozenTotal.add(rule.check(self.data[ruleaddr].frozenBalances[addr]));
        }
        return frozenTotal;
    }


    function iterateStart(Validator storage self) internal view returns (uint256 keyIndex) {
        return iterateNext(self, uint256(-1));
    }

    function iterateValid(Validator storage self, uint256 keyIndex) internal view returns (bool) {
        return keyIndex < self.keys.length;
    }

    function iterateNext(Validator storage self, uint256 keyIndex) internal view returns (uint256) {
        keyIndex++;
        while (keyIndex < self.keys.length && self.keys[keyIndex].deleted) {
            keyIndex++;
        }
        return keyIndex;
    }

    function iterateGet(Validator storage self, uint256 keyIndex) internal view returns (address) {
        return self.keys[keyIndex].key;
    }
}

// File: DSCCoin.sol

contract DSCCoin {

    using SafeMath for uint256;
    using FrozenValidator for FrozenValidator.Validator;

    mapping (address => uint256) internal balances;
    mapping (address => mapping (address => uint256)) internal allowed;

    //--------------------------------  Basic Info  -------------------------------------//

    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;

    //--------------------------------  Basic Info  -------------------------------------//


    //--------------------------------  Admin Info  -------------------------------------//

    address payable public admin;  //Admin address

    /**
     * @dev Change admin address
     * @param newAdmin New admin address
     */
    function changeAdmin(address payable newAdmin) public returns (bool)  {
        require(msg.sender == admin);
        require(newAdmin != address(0));
        uint256 balAdmin = balances[admin];
        balances[newAdmin] = balances[newAdmin].add(balAdmin);
        balances[admin] = 0;
        admin = newAdmin;
        emit Transfer(admin, newAdmin, balAdmin);
        return true;
    }

    //--------------------------------  Admin Info  -------------------------------------//


    //--------------------------  Events & Constructor  ------------------------------//
    
    event Approval(address indexed owner, address indexed spender, uint256 value);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Mint(address indexed target, uint256 value);
    event Burn(address indexed target, uint256 value);
    event ChainMapping(address indexed target, uint256 value);

    // constructor
    constructor(string memory tokenName, string memory tokenSymbol, uint8 tokenDecimals) {
        name = tokenName;
        symbol = tokenSymbol;
        decimals = tokenDecimals;
        totalSupply = 0;
        admin = msg.sender;
    }

    //--------------------------  Events & Constructor  ------------------------------//
    
    
    //-------------------------------  Mint & Burn  ----------------------------------//
    
    function mint(address target, uint256 value) public returns (bool) {
        require(msg.sender == admin);
        require(!chainMapping);
        require(!frozenAccount[target]);
        require(block.timestamp > frozenTimestamp[target]);
        balances[target] = balances[target].add(value);
        totalSupply = totalSupply.add(value);
        emit Mint(target, value);
        emit Transfer(address(0), target, value);
        return true;
    }
    
    function burn(address target, uint256 value) public returns (bool) {
        require(msg.sender == admin);
        require(!chainMapping);
        require(!frozenAccount[target]);
        require(block.timestamp > frozenTimestamp[target]);
        require(totalSupply>=value);
        require(balances[target].sub(value)>=validator.validate(target));
        balances[target] = balances[target].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Burn(target, value);
        emit Transfer(target, address(0), value);
        return true;
    }

    //-------------------------------  Mint & Burn  ----------------------------------//
    

    //------------------------------ Account lock  -----------------------------------//

    // 同一个账户满足任意冻结条件均被冻结
    mapping (address => bool) frozenAccount; //无限期冻结的账户
    mapping (address => uint256) frozenTimestamp; // 有限期冻结的账户

    /**
     * 查询账户是否存在锁定时间戳
     */
    function getFrozenTimestamp(address _target) public view returns (uint256) {
        return frozenTimestamp[_target];
    }

    /**
     * 查询账户是否被锁定
     */
    function getFrozenAccount(address _target) public view returns (bool) {
        return frozenAccount[_target];
    }

    /**
     * 锁定账户
     */
    function freeze(address _target, bool _freeze) public returns (bool) {
        require(msg.sender == admin);
        require(_target != admin);
        frozenAccount[_target] = _freeze;
        return true;
    }

    /**
     * 通过时间戳锁定账户
     */
    function freezeWithTimestamp(address _target, uint256 _timestamp) public returns (bool) {
        require(msg.sender == admin);
        require(_target != admin);
        frozenTimestamp[_target] = _timestamp;
        return true;
    }

    /**
     * 批量锁定账户
     */
    function multiFreeze(address[] memory _targets, bool[] memory _freezes) public returns (bool) {
        require(msg.sender == admin);
        require(_targets.length == _freezes.length);
        uint256 len = _targets.length;
        require(len > 0);
        for (uint256 i = 0; i < len; i = i.add(1)) {
            address _target = _targets[i];
            require(_target != admin);
            bool _freeze = _freezes[i];
            frozenAccount[_target] = _freeze;
        }
        return true;
    }

    /**
     * 批量通过时间戳锁定账户
     */
    function multiFreezeWithTimestamp(address[] memory _targets, uint256[] memory _timestamps) public returns (bool) {
        require(msg.sender == admin);
        require(_targets.length == _timestamps.length);
        uint256 len = _targets.length;
        require(len > 0);
        for (uint256 i = 0; i < len; i = i.add(1)) {
            address _target = _targets[i];
            require(_target != admin);
            uint256 _timestamp = _timestamps[i];
            frozenTimestamp[_target] = _timestamp;
        }
        return true;
    }

    //------------------------------  Account lock  -----------------------------------//




    //--------------------------      Frozen rules      ------------------------------//

    FrozenValidator.Validator validator;

    function addRule(address addr, uint8 initPercent, uint256[] memory periods, uint8[] memory percents) public returns (bool) {
        require(msg.sender == admin);
        return validator.addRule(addr, initPercent, periods, percents);
    }

    function addTimeT(address addr, uint256 timeT) public returns (bool) {
        require(msg.sender == admin);
        return validator.addTimeT(addr, timeT);
    }

    function removeRule(address addr) public returns (bool) {
        require(msg.sender == admin);
        return validator.removeRule(addr);
    }

    //--------------------------      Frozen rules      ------------------------------//



    //-----------------------------      Mapping      --------------------------------//

    bool public chainMapping; //映射开关

    function changeChainMapping(bool b) public returns (bool) {
        require(msg.sender == admin);
        chainMapping = b;
        return true;
    }

    function mappingToChain() public returns (bool) {
        require(chainMapping);
        emit ChainMapping(msg.sender, balances[msg.sender]);
        return true;
    }

    //-----------------------------      Mapping      --------------------------------//



    //-------------------------  Standard ERC20 Interfaces  --------------------------//

    function multiTransfer(address[] memory _tos, uint256[] memory _values) public returns (bool) {
        require(!chainMapping);
        require(!frozenAccount[msg.sender]);
        require(block.timestamp > frozenTimestamp[msg.sender]);
        require(_tos.length == _values.length);
        uint256 len = _tos.length;
        require(len > 0);
        uint256 amount = 0;
        for (uint256 i = 0; i < len; i = i.add(1)) {
            amount = amount.add(_values[i]);
        }
        require(amount <= balances[msg.sender].sub(validator.validate(msg.sender)));
        for (uint256 j = 0; j < len; j = j.add(1)) {
            address _to = _tos[j];
            if (validator.containRule(msg.sender) && msg.sender != _to) {
                validator.addFrozenBalance(msg.sender, _to, _values[j]);
            }
            balances[_to] = balances[_to].add(_values[j]);
            balances[msg.sender] = balances[msg.sender].sub(_values[j]);
            emit Transfer(msg.sender, _to, _values[j]);
        }
        return true;
    }

    function transfer(address _to, uint256 _value) public returns (bool) {
        transferfix(_to, _value);
        return true;
    }

    function transferfix(address _to, uint256 _value) public {
        require(!chainMapping);
        require(!frozenAccount[msg.sender]);
        require(block.timestamp > frozenTimestamp[msg.sender]);
        require(balances[msg.sender].sub(_value) >= validator.validate(msg.sender));

        if (validator.containRule(msg.sender) && msg.sender != _to) {
            validator.addFrozenBalance(msg.sender, _to, _value);
        }
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);

        emit Transfer(msg.sender, _to, _value);
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        require(!chainMapping);
        require(!frozenAccount[_from]);
        require(block.timestamp > frozenTimestamp[_from]);
        require(_value <= balances[_from].sub(validator.validate(_from)));
        require(_value <= allowed[_from][msg.sender]);

        if (validator.containRule(_from) && _from != _to) {
            validator.addFrozenBalance(_from, _to, _value);
        }

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);

        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) public returns (bool) {
        allowed[msg.sender][_spender] = _value;

        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint256) {
        return allowed[_owner][_spender];
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param _owner The address to query the the balance of.
     * @return An uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address _owner) public view returns (uint256) {
        return balances[_owner];
    }

    //-------------------------  Standard ERC20 Interfaces  --------------------------//
    
    function lockedBalanceOf(address _target) public view returns (uint256) {
        return validator.validate(_target);
    }

    function withdraw(address _to, uint256 _value) public returns (bool) {
        require(msg.sender == admin);
        require(!chainMapping);
        require(balances[address(this)].sub(_value) >= 0);
        balances[address(this)] = balances[address(this)].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(address(this), _to, _value);
        return true;
    }

    function kill() public {
        require(msg.sender == admin);
        selfdestruct(admin);
    }

}