/*
file:       token
version:    4.2
The Greatest Tao is formless
-----------------------------------------------------------------
*/

pragma solidity ^0.4.24;

///
//Math operations with safety checks
///
contract SafeMath {
  function safeMul(uint256 a, uint256 b) internal pure returns (uint256)  {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function safeDiv(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b > 0);
    uint256 c = a / b;
    assert(a == b * c + a % b);
    return c;
  }

  function safeSub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function safeAdd(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c>=a && c>=b);
    return c;
  }

}
///
contract owned {
    address public owner;

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
        owner = newOwner;
    }
}


///
// ERC Token Standard #20 Interface
///
interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }


///
contract TokenERC20 is SafeMath{
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 18;
    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);

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    constructor(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
    }
    

    /**
     * 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
        uint256 mbalanceofto = SafeMath.safeAdd(balanceOf[_to], _value);
        require(mbalanceofto > balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = SafeMath.safeAdd(balanceOf[_from],balanceOf[_to]);
        // Subtract from the sender
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from],_value);
        // Add the same to the recipient
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to],_value);
        //
        uint currentBalances = SafeMath.safeAdd(balanceOf[_from],balanceOf[_to]);
        emit Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(currentBalances == 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` 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] = SafeMath.safeSub(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 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;
        emit Approval(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] = SafeMath.safeSub(balanceOf[msg.sender], _value);            // Subtract from the sender
        _totalSupply = SafeMath.safeSub(_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] = SafeMath.safeSub(balanceOf[_from], _value);                         // Subtract from the targeted balance
        // Subtract from the sender's allowance
        allowance[_from][msg.sender] = SafeMath.safeSub(allowance[_from][msg.sender], _value);             
        _totalSupply = SafeMath.safeSub(_totalSupply,_value);                              // Update totalSupply
        emit Burn(_from, _value);
        return true;
    }
}

/******************************************/
/*       ADVANCED TOKEN STARTS HERE       */
/******************************************/

contract BOSCToken is owned, TokenERC20 {

    uint256 public buyPrice=2000;   
    uint256 public sellPrice=2500;     
    uint public minBalanceForAccounts;
    uint256 linitialSupply=428679360;
    string ltokenName='BOSC';
    string ltokenSymbol='BOSC';
    

    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(linitialSupply, ltokenName, ltokenSymbol) public {
    }

    /*Get total Token Supply*/
    function totalSupply() public constant returns (uint totalsupply) {
        totalsupply = _totalSupply ;
    }

      
    /* 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 (SafeMath.safeAdd(balanceOf[_to],_value) >= balanceOf[_to]); // Check for overflows
        require(!frozenAccount[_from]);                     // Check if sender is frozen
        require(!frozenAccount[_to]);                       // Check if recipient is frozen
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value);                         // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);  // Add the same to the recipient
        emit Transfer(_from, _to, _value);
    }

    /// @notice Create `mintedAmount` tokens and send it to `target`
    function mintToken(address target, uint256 mintedAmount) onlyOwner public {
        balanceOf[target] = SafeMath.safeAdd(balanceOf[target],mintedAmount);
        _totalSupply = SafeMath.safeAdd(_totalSupply, mintedAmount);
        emit Transfer(0, this, mintedAmount);
        emit Transfer(this, target, mintedAmount);
    }

    /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
    function freezeAccount(address target, bool freeze) onlyOwner public {
        frozenAccount[target] = freeze;
        emit FrozenFunds(target, freeze);
    }

    /// @notice Allow users to buy tokens for `newBuyPrice` eth and sell tokens for `newSellPrice` eth
    function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner public {
        sellPrice = newSellPrice;
        buyPrice = newBuyPrice;
    }

    ///default function
    function () public payable {
    }
}