// Vulnerability label: TD1
pragma solidity 0.4.25;
// ----------------------------------------------------------------------------
// 'SCALE' contract
//
// Symbol      : SCALE
// Name        : Scalecoin
// Total supply: 21,000,000
// Decimals    : 18
//
// Copyright (c) 2018 Scale Blockchain
// Contract designed by: GDO Infotech Pvt Ltd (https://GDO.co.in) 
// ----------------------------------------------------------------------------
   
    /**
     * @title SafeMath
     * @dev Math operations with safety checks that throw on error
     */
    library SafeMath {
      function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
          return 0;
        }
        uint256 c = a * b;
        assert(c / a == b);
        return c;
      }
    
      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 c;
      }
    
      function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b <= a);
        return a - b;
      }
    
      function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
      }
    }
    
    contract owned {
        address public owner;
        using SafeMath for uint256;
        
        constructor() public {
            owner = msg.sender;
        }
    
        modifier onlyOwner {
            require(msg.sender == owner);
            _;
        }
    
        function transferOwnership(address newOwner) onlyOwner public {
            owner = newOwner;
        }
    }
    
    interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external ; }
    
    contract TokenERC20 {
        // Public variables of the token
        using SafeMath for uint256;
        string public name = "Scalecoin";
        string public symbol = "SCALE";
        uint8 public decimals = 18;         // 18 decimals is the strongly suggested default, avoid changing it
        uint256 public totalSupply          = 21000000 * (1 ether);   
        uint256 public tokensForCrowdsale   = 20000000 * (1 ether);
        uint256 public tokensForTeam        = 4000000  * (1 ether);
        uint256 public tokensForOwner       = 1000000  * (1 ether);
        
        address public teamWallet = 0x824C6785d5bD0b883E0E550649203796675F0012

;
    
        // This creates an array with all balances
        mapping (address => uint256) public balanceOf;
        mapping (address => mapping (address => uint256)) public allowance;
    
        // This generates a public event on the blockchain that will notify clients
        event Transfer(address indexed from, address indexed to, uint256 value);
    
        // This notifies clients about the amount burnt
        event Burn(address indexed from, uint256 value);
    
        /**
         * Constrctor function
         *
         * Initializes contract with initial supply tokens to the creator of the contract
         */
        constructor() public {
             
            balanceOf[this] = tokensForCrowdsale;          // 16 Million will remain in contract for crowdsale
            balanceOf[teamWallet] = tokensForTeam;         // 4 Million will be allocated to Team
            balanceOf[msg.sender] = tokensForOwner;        // 1 Million will be sent to contract owner

        }
    
        /**
         * Internal transfer, only can be called by this contract
         */
        function _transfer(address _from, address _to, uint _value) internal {
            // Prevent transfer to 0x0 address. Use burn() instead
            require(_to != 0x0);
            // Check if the sender has enough
            require(balanceOf[_from] >= _value);
            // Check for overflows
            require(balanceOf[_to].add(_value) > balanceOf[_to]);
            // Save this for an assertion in the future
            uint previousBalances = balanceOf[_from].add(balanceOf[_to]);
            // Subtract from the sender
            balanceOf[_from] = balanceOf[_from].sub(_value);
            // Add the same to the recipient
            balanceOf[_to] = balanceOf[_to].add(_value);
            emit Transfer(_from, _to, _value);
            // Asserts are used to use static analysis to find bugs in your code. They should never fail
            assert(balanceOf[_from].add(balanceOf[_to]) == previousBalances);
        }
    
        /**
         * Transfer tokens
         *
         * Send `_value` tokens to `_to` from your account
         *
         * @param _to The address of the recipient
         * @param _value the amount to send
         */
        function transfer(address _to, uint256 _value) public {
            _transfer(msg.sender, _to, _value);
        }
    
        /**
         * Transfer tokens from other address
         *
         * Send `_value` tokens to `_to` in behalf of `_from`
         *
         * @param _from The address of the sender
         * @param _to The address of the recipient
         * @param _value the amount to send
         */
        function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
            require(_value <= allowance[_from][msg.sender]);     // Check allowance
            allowance[_from][msg.sender] = allowance[_from][msg.sender].sub(_value);
            _transfer(_from, _to, _value);
            return true;
        }
    
        /**
         * Set allowance for other address
         *
         * Allows `_spender` to spend no more than `_value` tokens in your behalf
         *
         * @param _spender The address authorized to spend
         * @param _value the max amount they can spend
         */
        function approve(address _spender, uint256 _value) public
            returns (bool success) {
            allowance[msg.sender][_spender] = _value;
            return true;
        }
    
        /**
         * Set allowance for other address and notify
         *
         * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
         *
         * @param _spender The address authorized to spend
         * @param _value the max amount they can spend
         * @param _extraData some extra information to send to the approved contract
         */
        function approveAndCall(address _spender, uint256 _value, bytes _extraData)
            public
            returns (bool success) {
            tokenRecipient spender = tokenRecipient(_spender);
            if (approve(_spender, _value)) {
                spender.receiveApproval(msg.sender, _value, this, _extraData);
                return true;
            }
        }
    
        /**
         * Destroy tokens
         *
         * Remove `_value` tokens from the system irreversibly
         *
         * @param _value the amount of money to burn
         */
        function burn(uint256 _value) public returns (bool success) {
            require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
            balanceOf[msg.sender] = balanceOf[msg.sender].sub(_value);            // Subtract from the sender
            totalSupply = totalSupply.sub(_value);                      // Updates totalSupply
           emit Burn(msg.sender, _value);
            return true;
        }
    
        /**
         * Destroy tokens from other account
         *
         * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
         *
         * @param _from the address of the sender
         * @param _value the amount of money to burn
         */
        function burnFrom(address _from, uint256 _value) public returns (bool success) {
            require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
            require(_value <= allowance[_from][msg.sender]);    // Check allowance
            balanceOf[_from] = balanceOf[_from].sub(_value);                         // Subtract from the targeted balance
            allowance[_from][msg.sender] = allowance[_from][msg.sender].sub(_value);             // Subtract from the sender's allowance
            totalSupply = totalSupply.sub(_value);                              // Update totalSupply
          emit  Burn(_from, _value);
            return true;
        }
    }
    
    /******************************************/
    /*       ADVANCED TOKEN STARTS HERE       */
    /******************************************/
    
    contract Scalecoin is owned, TokenERC20 {

        using SafeMath for uint256;
        uint256 public startTime = 0; //client wants ICO run Infinite time, so startTimeStamp 0
        uint256 public endTime = 9999999999999999999999; //and entTimeStamp higher number
        uint256 public exchangeRate = 20000; // this is how many tokens for 1 Ether
        uint256 public tokensSold = 0; // how many tokens sold in crowdsale
        
        mapping (address => bool) public frozenAccount;
    
        /* This generates a public event on the blockchain that will notify clients */
        event FrozenFunds(address target, bool frozen);
    
        /* Initializes contract with initial supply tokens to the creator of the contract */
        constructor() TokenERC20() public {}

        /* Internal transfer, only can be called by this contract */
        function _transfer(address _from, address _to, uint _value) internal {
            require (_to != 0x0);                               // Prevent transfer to 0x0 address. Use burn() instead
            require (balanceOf[_from] >= _value);               // Check if the sender has enough
            require (balanceOf[_to].add(_value) >= balanceOf[_to]); // Check for overflows
            require(!frozenAccount[_from]);                     // Check if sender is frozen
            require(!frozenAccount[_to]);                       // Check if recipient is frozen
            balanceOf[_from] = balanceOf[_from].sub(_value);                         // Subtract from the sender
            balanceOf[_to] = balanceOf[_to].add(_value);                           // Add the same to the recipient
            emit Transfer(_from, _to, _value);
        }
        
        //@dev fallback function, only accepts ether if ICO is running or Reject
        function () payable public {
            require(endTime > now);
            require(startTime < now);
            uint ethervalueWEI=msg.value;
            // calculate token amount to be sent
            uint256 token = ethervalueWEI.mul(exchangeRate); //weiamount * price
            tokensSold = tokensSold.add(token);
            _transfer(this, msg.sender, token);              // makes the transfers
            forwardEherToOwner();
        }
        
        //Automatocally forwards ether from smart contract to owner address
        function forwardEherToOwner() internal {
            owner.transfer(msg.value); 
          }
        
        //function to start an ICO.
        //It requires: start and end timestamp, exchange rate in Wei, and token amounts to allocate for the ICO
        //It will transfer allocated amount to the smart contract
        function startIco(uint256 start,uint256 end, uint256 exchangeRateInWei, uint256 TokensAllocationForICO) onlyOwner public {
            require(start < end);
            uint256 tokenAmount = TokensAllocationForICO.mul(1 ether);
            require(balanceOf[msg.sender] > tokenAmount);
            startTime=start;
            endTime=end;
            exchangeRate = exchangeRateInWei;
            approve(this,tokenAmount);
            transfer(this,tokenAmount);
        }       
        
        //Stops an ICO.
        //It will also transfer remaining tokens to owner
        function stopICO() onlyOwner public{
            endTime = 0;
            uint256 tokenAmount=balanceOf[this];
            _transfer(this, msg.sender, tokenAmount);
        }
        
        //function to check wheter ICO is running or not.
        function isICORunning() public view returns(bool){
            if(endTime > now && startTime < now){
                return true;                
            }else{
                return false;
            }
        }
        
        //Function to set ICO Exchange rate. 
        function setICOExchangeRate(uint256 newExchangeRate) onlyOwner public {
            exchangeRate=newExchangeRate;
        }
        
        //Just in case, owner wants to transfer Tokens from contract to owner address
        function manualWithdrawToken(uint256 _amount) onlyOwner public {
            uint256 tokenAmount = _amount.mul(1 ether);
            _transfer(this, msg.sender, tokenAmount);
          }
          
        //Just in case, owner wants to transfer Ether from contract to owner address
        function manualWithdrawEther()onlyOwner public{
            uint256 amount=address(this).balance;
            owner.transfer(amount);
        }
        
        /// @notice Create `mintedAmount` tokens and send it to `target`
        /// @param target Address to receive the tokens
        /// @param mintedAmount the amount of tokens it will receive
        function mintToken(address target, uint256 mintedAmount) onlyOwner public {
            balanceOf[target] = balanceOf[target].add(mintedAmount);
            totalSupply = totalSupply.add(mintedAmount);
           emit Transfer(0, this, mintedAmount);
           emit Transfer(this, target, mintedAmount);
        }
    
        /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
        /// @param target Address to be frozen
        /// @param freeze either to freeze it or not
        function freezeAccount(address target, bool freeze) onlyOwner public {
            frozenAccount[target] = freeze;
          emit  FrozenFunds(target, freeze);
        }



    }