pragma solidity 0.5.11;
/**
* @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;
}
}

/**
* @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 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 transfer control of the contract to a newOwner.
* @param newOwner The address to transfer ownership to.
*/
function transferOwnership(address newOwner) public onlyOwner {
require(newOwner != address(0));
emit OwnershipTransferred(owner, newOwner);
owner = newOwner;
}
}

/**
* @title ERC20Basic
*/
contract ERC20Basic {
uint256 public totalSupply;
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, Ownable {

using SafeMath for uint256;

mapping(address => uint256) balances;

/**
* @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 <= balanceOf(msg.sender));

// SafeMath.sub will throw if there is not enough balance.
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 balance) {
return balances[_owner];
}

}


/**
* @title Standard ERC20 token
*
* @dev Implementation of the basic standard token.
* @dev https://github.com/ethereum/EIPs/issues/20
* @dev 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)) 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(allowed[_from][msg.sender] >= _value);
require(balanceOf(_from) >= _value);
require(balances[_to].add(_value) > balances[_to]); // Check for overflows
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.
* @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) {
// To change the approve amount you first have to reduce the addresses`
// allowance to zero by calling `approve(_spender, 0)` if it is not
// already 0 to mitigate the race condition described here:
// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
require((_value == 0) || (allowed[msg.sender][_spender] == 0));
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 remaining) {
return allowed[_owner][_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
*/
function increaseApproval (address _spender, uint _addedValue) public returns (bool success) {
allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}

function decreaseApproval (address _spender, uint _subtractedValue) public returns (bool success) {
uint 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 Pausable
* @dev Base contract which allows children to implement an emergency stop mechanism.
*/
contract Pausable is StandardToken {
event Pause();
event Unpause();

bool public paused = false;

address public founder;

/**
* @dev modifier to allow actions only when the contract IS paused
*/
modifier whenNotPaused() {
require(!paused || msg.sender == founder);
_;
}

/**
* @dev modifier to allow actions only when the contract IS NOT paused
*/
modifier whenPaused() {
require(paused);
_;
}

/**
* @dev called by the owner to pause, triggers stopped state
*/
function pause() public onlyOwner whenNotPaused {
paused = true;
emit Pause();
}

/**
* @dev called by the owner to unpause, returns to normal state
*/
function unpause() public onlyOwner whenPaused {
paused = false;
emit Unpause();
}
}


contract PausableToken is Pausable {

function transfer(address _to, uint256 _value) public whenNotPaused returns (bool) {
return super.transfer(_to, _value);
}

function transferFrom(address _from, address _to, uint256 _value) public whenNotPaused returns (bool) {
return super.transferFrom(_from, _to, _value);
}

//The functions below surve no real purpose. Even if one were to approve another to spend
//tokens on their behalf, those tokens will still only be transferable when the token contract
//is not paused.

function approve(address _spender, uint256 _value) public whenNotPaused returns (bool) {
return super.approve(_spender, _value);
}

function increaseApproval(address _spender, uint _addedValue) public whenNotPaused returns (bool success) {
return super.increaseApproval(_spender, _addedValue);
}

function decreaseApproval(address _spender, uint _subtractedValue) public whenNotPaused returns (bool success) {
return super.decreaseApproval(_spender, _subtractedValue);
}
}

contract TOKEN is PausableToken {

string public name;
string public symbol;
uint8 public decimals;

/**
* @dev Constructor that gives the founder all of the existing tokens.
*/
constructor() public {
name = "IGSECoin";
symbol = "IGSC";
decimals = 13;
totalSupply = 1000000000000000000000;
founder = msg.sender;
balances[msg.sender] = totalSupply;
emit Transfer(address(0), msg.sender, totalSupply);
}

/** @dev Fires on every freeze of tokens
* @param _owner address The owner address of frozen tokens.
* @param amount uint256 The amount of tokens frozen
*/
event TokenFreezeEvent(address indexed _owner, uint256 amount);

/** @dev Fires on every unfreeze of tokens
* @param _owner address The owner address of unfrozen tokens.
* @param amount uint256 The amount of tokens unfrozen
*/
event TokenUnfreezeEvent(address indexed _owner, uint256 amount);
event TokensBurned(address indexed _owner, uint256 _tokens);


mapping(address => uint256) internal frozenTokenBalances;

function freezeTokens(address _owner, uint256 _value) public onlyOwner {
require(_value <= balanceOf(_owner));
uint256 oldFrozenBalance = getFrozenBalance(_owner);
uint256 newFrozenBalance = oldFrozenBalance.add(_value);
setFrozenBalance(_owner,newFrozenBalance);
emit TokenFreezeEvent(_owner,_value);
}

function unfreezeTokens(address _owner, uint256 _value) public onlyOwner {
require(_value <= getFrozenBalance(_owner));
uint256 oldFrozenBalance = getFrozenBalance(_owner);
uint256 newFrozenBalance = oldFrozenBalance.sub(_value);
setFrozenBalance(_owner,newFrozenBalance);
emit TokenUnfreezeEvent(_owner,_value);
}


function setFrozenBalance(address _owner, uint256 _newValue) internal {
frozenTokenBalances[_owner]=_newValue;
}

function balanceOf(address _owner) view public returns(uint256) {
return getTotalBalance(_owner).sub(getFrozenBalance(_owner));
}

function getTotalBalance(address _owner) view public returns(uint256) {
return balances[_owner];
}
/**
* @dev Gets the amount of tokens which belong to the specified address BUT are frozen now.
* @param _owner The address to query the the balance of.
* @return An uint256 representing the amount of frozen tokens owned by the passed address.
*/

function getFrozenBalance(address _owner) view public returns(uint256) {
return frozenTokenBalances[_owner];
}

/*
* @dev Token burn function
* @param _tokens uint256 amount of tokens to burn
*/
function burnTokens(uint256 _tokens) public onlyOwner {
require(balanceOf(msg.sender) >= _tokens);
balances[msg.sender] = balances[msg.sender].sub(_tokens);
totalSupply = totalSupply.sub(_tokens);
emit TokensBurned(msg.sender, _tokens);
}
}