pragma solidity ^0.4.24;
/**
 * @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;
    }
}


/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
    address public owner;
    
    event OwnershipRenounced(address indexed previousOwner);
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    constructor() public {
         owner = msg.sender;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
         require(msg.sender == owner);
         _;
    }

    /**
     * @dev Allows the current owner to relinquish control of the contract.
     * @notice Renouncing to ownership will leave the contract without an owner.
     * It will not be possible to call the functions with the `onlyOwner`
     * modifier anymore.
     */
    function renounceOwnership() public onlyOwner {
         emit OwnershipRenounced(owner);
         owner = address(0);
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param _newOwner The address to transfer ownership to.
     */
    function transferOwnership(address _newOwner) public onlyOwner {
         _transferOwnership(_newOwner);
    }

    /**
     * @dev Transfers control of the contract to a newOwner.
     * @param _newOwner The address to transfer ownership to.
     */
    function _transferOwnership(address _newOwner) internal {
         require(_newOwner != address(0));
         emit OwnershipTransferred(owner, _newOwner);
         owner = _newOwner;
    }
}


/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * See https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
    function totalSupply() public view returns (uint256);
    function balanceOf(address who) public view returns (uint256);
    function transfer(address to, uint256 value) public returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
}


/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 is ERC20Basic {
    function allowance(address owner, address spender)
         public view returns (uint256);

    function transferFrom(address from, address to, uint256 value)
         public returns (bool);

    function approve(address spender, uint256 value) public returns (bool);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
    using SafeMath for uint256;

    mapping(address => uint256) balances;

    uint256 totalSupply_;

    /**
     * @dev Total number of tokens in existence
     */
    function totalSupply() public view returns (uint256) {
         return totalSupply_;
    }

    /**
     * @dev Transfer token for a specified address
     * @param _to The address to transfer to.
     * @param _value The amount to be transferred.
     */
    function transfer(address _to, uint256 _value) public returns (bool) {
         require(_to != address(0));
         require(_value <= balances[msg.sender]);

         balances[msg.sender] = balances[msg.sender].sub(_value);
         balances[_to] = balances[_to].add(_value);
         emit Transfer(msg.sender, _to, _value);
         return true;
    }

    /**
     * @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];
    }

}


/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/issues/20
 * Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract StandardToken is ERC20, BasicToken {

    mapping (address => mapping (address => uint256)) internal allowed;

    /**
     * @dev Transfer tokens from one address to another
     * @param _from address The address which you want to send tokens from
     * @param _to address The address which you want to transfer to
     * @param _value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
         require(_to != address(0));
         require(_value <= balances[_from]);
         require(_value <= allowed[_from][msg.sender]);

         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;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * Beware that changing an allowance with this method brings the risk that someone may use both the old
     * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
     * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     * @param _spender The address which will spend the funds.
     * @param _value The amount of tokens to be spent.
     */
    function approve(address _spender, uint256 _value) public returns (bool) {
         allowed[msg.sender][_spender] = _value;
         emit Approval(msg.sender, _spender, _value);
         return true;
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param _owner address The address which owns the funds.
     * @param _spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address _owner, address _spender) public view returns (uint256) {
         return allowed[_owner][_spender];
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when allowed[_spender] == 0. To increment
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * @param _spender The address which will spend the funds.
     * @param _addedValue The amount of tokens to increase the allowance by.
     */
    function increaseApproval(address _spender, uint256 _addedValue) public returns (bool) {
         allowed[msg.sender][_spender] = (allowed[msg.sender][_spender].add(_addedValue));
         emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
         return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when allowed[_spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * @param _spender The address which will spend the funds.
     * @param _subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseApproval(address _spender, uint256 _subtractedValue) public returns (bool) {
         uint256 oldValue = allowed[msg.sender][_spender];
         if (_subtractedValue > oldValue) {
                allowed[msg.sender][_spender] = 0;
         } else {
                allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
         }
         emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
         return true;
    }
}


/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
contract BurnableToken is BasicToken {

    event Burn(address indexed burner, uint256 value);

    /**
     * @dev Burns a specific amount of tokens.
     * @param _value The amount of token to be burned.
     */
    function burn(uint256 _value) public {
         _burn(msg.sender, _value);
    }

    function _burn(address _who, uint256 _value) internal {
         require(_value <= balances[_who]);
         // no need to require value <= totalSupply, since that would imply the
         // sender's balance is greater than the totalSupply, which *should* be an assertion failure

         balances[_who] = balances[_who].sub(_value);
         totalSupply_ = totalSupply_.sub(_value);
         emit Burn(_who, _value);
         emit Transfer(_who, address(0), _value);
    }
}


/**
 * @title Standard Burnable Token
 * @dev Adds burnFrom method to ERC20 implementations
 */
contract StandardBurnableToken is BurnableToken, StandardToken {

    /**
     * @dev Burns a specific amount of tokens from the target address and decrements allowance
     * @param _from address The address which you want to send tokens from
     * @param _value uint256 The amount of token to be burned
     */
    function burnFrom(address _from, uint256 _value) public {
         require(_value <= allowed[_from][msg.sender]);
         // Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
         // this function needs to emit an event with the updated approval.
         allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
         _burn(_from, _value);
    }
}


/**
 * @title Mintable token
 * @dev Simple ERC20 Token example, with mintable token creation
 * Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol
 */
contract MintableToken is StandardToken, Ownable {
    event Mint(address indexed to, uint256 amount);
    event MintFinished();

    bool public mintingFinished = false;

    modifier canMint() {
        require(!mintingFinished);
        _;
    }

    modifier hasMintPermission() {
        require(msg.sender == owner);
        _;
    }

    /**
     * @dev Function to mint tokens
     * @param _to The address that will receive the minted tokens.
     * @param _amount The amount of tokens to mint.
     * @return A boolean that indicates if the operation was successful.
     */
    function mint(address _to, uint256 _amount) hasMintPermission canMint public returns (bool) {
        totalSupply_ = totalSupply_.add(_amount);
        balances[_to] = balances[_to].add(_amount);
        emit Mint(_to, _amount);
        emit Transfer(address(0), _to, _amount);
        return true;
    }

    /**
     * @dev Function to stop minting new tokens.
     * @return True if the operation was successful.
     */
    function finishMinting() onlyOwner canMint public returns (bool) {
        mintingFinished = true;
        emit MintFinished();
        return true;
    }
}


/**
 * @title ABLE Dollar token
 *
 * @dev Implementation of the ABLE Dollar token 
 */
contract AbleDollarToken is Ownable, StandardBurnableToken, MintableToken {

    string public name = "ABLE Dollar X Token";
    string public symbol = "ABLD";
    uint8 public decimals = 18;
    uint public INITIAL_SUPPLY = 1000000000000000000000000000;

    mapping (address => bool) public frozenAccount;

    event Freeze(address target, bool freezed);
    event UnFreeze(address target, bool freezed);

    /**
     * @dev constructor for Able Dollar Token
     */
    constructor() public {
        totalSupply_ = INITIAL_SUPPLY;
        balances[msg.sender] = INITIAL_SUPPLY;
    }

    /**
     * @dev fallback function ***DO NOT OVERRIDE***
     */
    function () external payable {
        revert();
    }

    /**
     * @dev Function to freeze address
     * @param _target The address that will be freezed.
     */
    function freezeAccount(address _target) onlyOwner public {
        require(_target != address(0));
        frozenAccount[_target] = true;
        emit Freeze(_target, true);
    }
    
    /**
     * @dev Function to freeze address
     * @param _target The address that will be freezed.
     */
    function unfreezeAccount(address _target) onlyOwner public {
        require(_target != address(0));
        frozenAccount[_target] = false;
        emit UnFreeze(_target, false);
    }

    /**
     * @dev Transfer token for a specified address
     * @param _to The address to transfer to.
     * @param _value The amount to be transferred.
     */
    function transfer(address _to, uint256 _value) public returns (bool) {
        require(!frozenAccount[msg.sender]);        // Check if sender is frozen
        require(!frozenAccount[_to]);               // Check if recipient is frozen
        return super.transfer(_to,_value);
    }

    /**
     * @dev Transfer tokens from one address to another
     * @param _from address The address which you want to send tokens from
     * @param _to address The address which you want to transfer to
     * @param _value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        require(!frozenAccount[msg.sender]);        // Check if approved is frozen
        require(!frozenAccount[_from]);             // Check if sender is frozen
        require(!frozenAccount[_to]);               // Check if recipient is frozen
        return super.transferFrom(_from, _to, _value);
    }
}