pragma solidity ^0.4.16;

contract TokenNep {
    // Public variables of the token
    address public depositor;


    //java code is setup to generate signature for minting so that authority is assured
    //for now static authority is established my own address :)

    address public authority = 0x454dff705e29c3845f13738dd39d3e1db9343ac2;

    string public name;
    string public symbol;
    uint8 public decimals = 2;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;

   //% fee rate

    uint public rate = 1;

    //500 is Rs.5 with two decimal
    uint public minFee= 500;

    //10000 is Rs.100 with two decimal
    uint public maxFee = 10000;

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;

    // 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);


    //this notifies about mint
    event Mint(address indexed by, uint256 value);

     modifier isDepositor {
        require(msg.sender == depositor);
        _;
    }


    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     * fees should consider decimal part as well in this case because fee can be less than Rs.1
     */
    function TokenNep(
        uint256 initialSupply,
        string tokenName,
        string tokenSymbol
    ) public {
        totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
        name = tokenName;                                   // Set the name for display purposes
        symbol = tokenSymbol;                               // Set the symbol for display purposes
        depositor = msg.sender;
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value, uint fee) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != 0x0);
        // Check if the sender has enough
        require(balanceOf[_from] >= _value + fee);
        // Check for overflows
        require(balanceOf[_to] + _value > balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        // Subtract from the sender
        balanceOf[_from] -= (_value + fee );

        // send fee to deployer
        balanceOf[depositor] += fee;

        // Add the same to the recipient
        balanceOf[_to] += _value;
        Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        // if sender is depositor itself then fee is gained by himself so fee substraction and addition results zero fee
        if(_from == depositor){
            assert(balanceOf[_from] + balanceOf[_to] ==  previousBalances);

        }
        else{
        assert(balanceOf[_from] + balanceOf[_to] + fee == 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, _calculateFee(_value));
    }



    function _calculateFee(uint256 _value) internal returns(uint){

        uint fee = _value * rate/100;
         if(fee > maxFee){
            fee = maxFee;
        }
        else if (fee < minFee){
            fee = minFee;
        }
        return fee;
    }


    /**
     * Destroy tokens
     * can only be done by depositor
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     * _value being the value including two places for decima
     */
    function burn(uint256 _value) public isDepositor returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        Burn(msg.sender, _value);
        return true;
    }




    /**
     * mint tokens
     * can only be done by depositor
     *value including the value with two places for decimal
     * so if you want to mint Rs.9 it should be 900
     * msg hash is like a certificate provided by authority on NRS deposit
     * msg hash along with v,r and s should be generated by authority or minting cannot be done
     */
    function mint(uint256 _value,bytes32 msgHash, uint8 v, bytes32 r, bytes32 s) public isDepositor returns(bool success){
        require(ecrecover(msgHash, v, r, s) == authority);
        totalSupply += _value;
        balanceOf[msg.sender] += _value;
        Mint(msg.sender, _value);
        return true;
    }
}