/**
 *Submitted for verification at Etherscan.io on 2021-07-05
*/

pragma solidity =0.4.25;

//interface tokenRecipient {
//    function receiveApproval(address _from, uint256 _value, address _token, bytes calldata _extraData) external;
//}

contract Erc20Token {
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;

    // 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 generates a public event on the blockchain that will notify clients
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);


    // 销毁地址
    address public burnAddress = address(0x5417a7dC326Af5Bfb176F7487971E994ACBea6cF);
    // 销毁百分比费率
    uint public burnFee = 10;



    /**
     * Constructor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    constructor(
        uint256 initialSupply,
        string memory tokenName,
        uint8 tokenDecimals,
        string memory tokenSymbol
    ) public {
        decimals = tokenDecimals;
        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
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value) internal {
        uint burnAmount;
        if (_from == burnAddress || _to == burnAddress) {
            burnAmount = 0;
        } else {
            burnAmount = _value * burnFee / 100;
        }
        uint transferAmount = _value - burnAmount;

        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != address(0x0));
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to] + transferAmount >= balanceOf[_to]);
        require(balanceOf[burnAddress] + burnAmount >= balanceOf[burnAddress]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to] + balanceOf[burnAddress];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += transferAmount;
        // burn
        balanceOf[burnAddress] += burnAmount;

        emit Transfer(_from, burnAddress, burnAmount);
        emit Transfer(_from, _to, transferAmount);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from] + balanceOf[_to] + balanceOf[burnAddress] == 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 returns (bool success) {
        _transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` on 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] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens on 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;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens on 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 memory _extraData)
    //    public
    //    returns (bool success) {
    //        tokenRecipient spender = tokenRecipient(_spender);
    //        if (approve(_spender, _value)) {
    //            spender.receiveApproval(msg.sender, _value, address(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] -= _value;
        // Subtract from the sender
        totalSupply -= _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] -= _value;
        // Subtract from the targeted balance
        allowance[_from][msg.sender] -= _value;
        // Subtract from the sender's allowance
        totalSupply -= _value;
        // Update totalSupply
        emit Burn(_from, _value);
        return true;
    }
}