pragma solidity ^0.4.15;

/**
* assert(2 + 2 is 4 - 1 thats 3) Quick Mafs 
*/
library QuickMafs {
    function mul(uint256 _a, uint256 _b) internal pure returns (uint256) {
        uint256 c = _a * _b;
        assert(_a == 0 || 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;
        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;
    }
}


/** 
* The ownable contract contains an owner address. This give us simple ownership privledges and can allow ownship transfer. 
*/
contract Ownable {

     /** 
     * The owner/admin of the contract
     */ 
     address public owner;
    
     /**
     * Constructor for contract. Sets The contract creator to the default owner.
     */
     function Ownable() public {
         owner = msg.sender;
     }
    
    /**
    * Modifier to apply to methods to restrict access to the owner
    */
     modifier onlyOwner(){
         require(msg.sender == owner);
         _; //Placeholder for method content
     }
    
    /**
    * Transfer the ownership to a new owner can only be done by the current owner. 
    */
    function transferOwnership(address _newOwner) public onlyOwner {
    
        //Only make the change if required
        if (_newOwner != address(0)) {
            owner = _newOwner;
        }
    }
}


/**
*  ERC Token Standard #20 Interface
*/
contract ERC20 {
    
    /**
    * Get the total token supply
    */
    function totalSupply() public constant returns (uint256 _totalSupply);
    
    /**
    * Get the account balance of another account with address _owner
    */
    function balanceOf(address _owner) public constant returns (uint256 balance);
    
    /**
    * Send _amount of tokens to address _to
    */
    function transfer(address _to, uint256 _amount) public returns (bool success);
    
    /**
    * Send _amount of tokens from address _from to address _to
    */
    function transferFrom(address _from, address _to, uint256 _amount) public returns (bool success);
    
    /**
    * Allow _spender to withdraw from your account, multiple times, up to the _amount.
    * If this function is called again it overwrites the current allowance with _amount.
    * this function is required for some DEX functionality
    */
    function approve(address _spender, uint256 _amount) public returns (bool success);
    
    /**
    * Returns the amount which _spender is still allowed to withdraw from _owner
    */
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining);
    
    /**
    * Triggered when tokens are transferred.
    */
    event Transfer(address indexed _from, address indexed _to, uint256 _amount);
    
    /**
    * Triggered whenever approve(address _spender, uint256 _amount) is called.
    */
    event Approval(address indexed _owner, address indexed _spender, uint256 _amount);
}


/**
* The CTN Token
*/
contract Token is ERC20, Ownable {

    using QuickMafs for uint256;
    
    string public constant SYMBOL = "CTN";
    string public constant NAME = "Crypto Trust Network";
    uint8 public constant DECIMALS = 18;
    
    /**
    * Total supply of tokens
    */
    uint256 totalTokens;
    
    /**
    * The initial supply of coins before minting
     */
    uint256 initialSupply;
    
    /**
    * Balances for each account
    */
    mapping(address => uint256) balances;
    
    /**
    * Whos allowed to withdrawl funds from which accounts
    */
    mapping(address => mapping (address => uint256)) allowed;
    
    /**
     * If the token is tradable
     */ 
     bool tradable;
     
    /**
    * The address to store the initialSupply
    */
    address public vault;
    
    /**
    * If the coin can be minted
    */
    bool public mintingFinished = false;
    
    /**
     * Event for when new coins are created 
     */
    event Mint(address indexed _to, uint256 _value);
    
    /**
    * Event that is fired when token sale is over
    */
    event MintFinished();
    
    /**
     * Tokens can now be traded
     */ 
    event TradableTokens(); 
    
    /**
     * Allows this coin to be traded between users
     */ 
    modifier isTradable(){
        require(tradable);
        _;
    }
    
    /**
     * If this coin can be minted modifier
     */
    modifier canMint() {
        require(!mintingFinished);
        _;
    }
    
    /**
    * Initializing the token, setting the owner, initial supply & vault
    */
    function Token() public {
        initialSupply = 4500000 * 1 ether;
        totalTokens = initialSupply;
        tradable = false;
        vault = 0x6e794AAA2db51fC246b1979FB9A9849f53919D1E; 
        balances[vault] = balances[vault].add(initialSupply); //Set initial supply to the vault
    }
    
    /**
    * Obtain current total supply of CTN tokens 
    */
    function totalSupply() public constant returns (uint256 totalAmount) {
          totalAmount = totalTokens;
    }
    
    /**
    * Get the initial supply of CTN coins 
    */
    function baseSupply() public constant returns (uint256 initialAmount) {
          initialAmount = initialSupply;
    }
    
    /**
    * Returns the balance of a wallet
    */ 
    function balanceOf(address _address) public constant returns (uint256 balance) {
        return balances[_address];
    }
    
    /**
    * Transfer CTN between wallets
    */ 
    function transfer(address _to, uint256 _amount) public isTradable returns (bool) {
        balances[msg.sender] = balances[msg.sender].sub(_amount);
        balances[_to] = balances[_to].add(_amount);
        Transfer(msg.sender, _to, _amount);
        return true;
    }

    /**
    * Send _amount of tokens from address _from to address _to
    * The transferFrom method is used for a withdraw workflow, allowing contracts to send
    * tokens on your behalf, for example to "deposit" to a contract address and/or to charge
    * fees in sub-currencies; the command should fail unless the _from account has
    * deliberately authorized the sender of the message via some mechanism; we propose
    * these standardized APIs for approval:
    */
    function transferFrom(
        address _from,
        address _to,
        uint256 _amount
    ) public isTradable returns (bool success) 
    {
        var _allowance = allowed[_from][msg.sender];
    
        /** 
        *   QuickMaf will roll back any changes so no need to check before these operations
        */
        balances[_to] = balances[_to].add(_amount);
        balances[_from] = balances[_from].sub(_amount);
        allowed[_from][msg.sender] = _allowance.sub(_amount);
        Transfer(_from, _to, _amount);
        return true;  
    }

    /**
    * Allows an address to transfer money out this is administered by the contract owner who can specify how many coins an account can take.
    * Needs to be called to feault the amount to 0 first -> https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    */
    function approve(address _spender, uint256 _amount) public returns (bool) {
        /**
        *Set the amount they are able to spend to 0 first so that transaction ordering cannot allow multiple withdrawls asyncly
        *This function always requires to calls if a user has an amount they can withdrawl.
        */
        require((_amount == 0) || (allowed[msg.sender][_spender] == 0));
    
        allowed[msg.sender][_spender] = _amount;
        Approval(msg.sender, _spender, _amount);
        return true;
    }


    /**
     * Check the amount of tokens the owner has allowed to a spender
     */
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
         return allowed[_owner][_spender];
    }

    /**
     * Makes the coin tradable between users cannot be undone
     */
    function makeTradable() public onlyOwner {
        tradable = true;
        TradableTokens();
    }
    
    /**
    * Mint tokens to users
    */
    function mint(address _to, uint256 _amount) public onlyOwner canMint returns (bool) {
        totalTokens = totalTokens.add(_amount);
        balances[_to] = balances[_to].add(_amount);
        Mint(_to, _amount);
        return true;
    }

    /**
    * Function to stop minting tokens irreversable
    */
    function finishMinting() public onlyOwner returns (bool) {
        mintingFinished = true;
        MintFinished();
        return true;
    }
}


/**
* The initial crowdsale of the token
*/
contract Sale is Ownable {


    using QuickMafs for uint256;
    
    /**
     * The hard cap of the token sale
     */
    uint256 hardCap;
    
    /**
     * The soft cap of the token sale
     */
    uint256 softCap;
    
    /**
     * The bonus cap for the token sale
     */
    uint256 bonusCap;
    
    /**
     * How many tokens you get per ETH
     */
    uint256 tokensPerETH;
    
    /** 
    * //the start time of the sale (new Date("Jan 22 2018 18:00:00 GMT").getTime() / 1000)
    */
    uint256 public start = 1516644000;
                
    
    /**
     * The end time of the sale (new Date("Feb 22 2018 18:00:00 GMT").getTime() / 1000)
     */ 
    uint256 public end = 1519322400;
    
    /**
     * Two months after the sale ends used to retrieve unclaimed refunds (new Date("Apr 22 2018 18:00:00 GMT").getTime() / 1000)
     */
    uint256 public twoMonthsLater = 1524420000;
    
    /**
    * Token for minting purposes
    */
    Token public token;
    
    /**
    * The address to store eth in during sale 
    */
    address public vault;
    
    
    /**
    * How much ETH each user has sent to this contract. For softcap unmet refunds
    */
    mapping(address => uint256) investments;
    
    
    /**
    * Every purchase during the sale
    */
    event TokenSold(address recipient, uint256 etherAmount, uint256 ctnAmount, bool preSale, bool bonus);
    
    
    /**
    * Triggered when tokens are transferred.
    */
    event PriceUpdated(uint256 amount);
    
    /**
    * Only make certain changes before the sale starts
    */
    modifier isPreSale(){
         require(now < start);
        _;
    }
    
    /**
    * Is the sale still on
    */
    modifier isSaleOn() {
        require(now >= start && now <= end);
        _;
    }
    
    /**
    * Has the sale completed
    */
    modifier isSaleFinished() {
        
        bool hitHardCap = token.totalSupply().sub(token.baseSupply()) >= hardCap;
        require(now > end || hitHardCap);
        
        _;
    }
    
    /**
    * Has the sale completed
    */
    modifier isTwoMonthsLater() {
        require(now > twoMonthsLater);
        _;
    }
    
    /**
    * Make sure we are under the hardcap
    */
    modifier isUnderHardCap() {
    
        bool underHard = token.totalSupply().sub(token.baseSupply()) <= hardCap;
        require(underHard);
        _;
    }
    
    /**
    * Make sure we are over the soft cap
    */
    modifier isOverSoftCap() {
        bool overSoft = token.totalSupply().sub(token.baseSupply()) >= softCap;
        require(overSoft);
        _;
    }
    
    /**
    * Make sure we are over the soft cap
    */
    modifier isUnderSoftCap() {
        bool underSoft = token.totalSupply().sub(token.baseSupply()) < softCap;
        require(underSoft);
        _;
    }
    
    /** 
    *   The token sale constructor
    */
    function Sale() public {
        hardCap = 10500000 * 1 ether;
        softCap = 500000 * 1 ether;
        bonusCap = 2000000 * 1 ether;
        tokensPerETH = 630; //Tokens per 1 ETH
        token = new Token();
        vault = 0x6e794AAA2db51fC246b1979FB9A9849f53919D1E; 
    }
    
    /**
    * Fallback function which receives ether and created the appropriate number of tokens for the 
    * msg.sender.
    */
    function() external payable {
        //If we can not purchase tokens presale then try purchase them normally
        if ( now < start ) {
            purchaseTokensPreSale(msg.sender);
        } else {
            purchaseTokens(msg.sender);
        }
    }
       
    /**
    * If the soft cap has not been reached and the sale is over investors can reclaim their funds
    */ 
    function refund() public isSaleFinished isUnderSoftCap {
        uint256 amount = investments[msg.sender];
        investments[msg.sender] = investments[msg.sender].sub(amount);
        msg.sender.transfer(amount);
    }
    
    /**
    * Withdrawl the funds from the contract.
    * Make the token tradeable and finish minting
    */ 
    function withdrawl() public isSaleFinished isOverSoftCap {
        vault.transfer(this.balance);
        
        //Stop minting of the token and make the token tradeable
        token.finishMinting();
        token.makeTradable();
    }
    
    /**
    * Update the ETH price for the token sale
    */
    function updatePrice(uint256 _newPrice) public onlyOwner isPreSale {
        tokensPerETH = _newPrice;
        PriceUpdated(_newPrice);
    }

    /**
    * Temp function for change start times for debuging
     */
    function updateStart(uint256 _newStart) public onlyOwner {
        start = _newStart;
    }
    
    /**
    * The pre sale purchase of tokens. Is avaliable up until the soft cap is hit.
     */
    function purchaseTokensPreSale(address recipient) public isUnderSoftCap isPreSale payable {    
        uint256 amount = msg.value;
        uint256 tokens = tokensPerETH.mul(amount);

        //Tokens purchased pre sale get an additional 25% CTN
        tokens = tokens.add(tokens.div(4));
     
        //Add the amount to a users investment total
        investments[msg.sender] = investments[msg.sender].add(msg.value);
        
        token.mint(recipient, tokens);
        
        TokenSold(recipient, amount, tokens, true, true);
    }
    
    /**
    * Allows user to buy coins if we are under the hardcap also adds a bonus if under the bonus amount
    */
    function purchaseTokens(address recipient) public isUnderHardCap isSaleOn payable {
        uint256 amount = msg.value;
        uint256 tokens = tokensPerETH.mul(amount);
        bool bonus = false;
        
        if (token.totalSupply().sub(token.baseSupply()) < bonusCap) {          
            bonus = true;

            //Tokens purchased before the bonus cap get an additional 20% CTN
            tokens = tokens.add(tokens.div(5));
        }

        //Add the amount to user investment total
        investments[msg.sender] = investments[msg.sender].add(msg.value);
        
        token.mint(recipient, tokens);
        
        TokenSold(recipient, amount, tokens, false, bonus);
    }
    
    /**
     * Withdrawl the funds from the contract.
     * Make the token tradeable and finish minting
     */ 
    function cleanup() public isTwoMonthsLater {
        vault.transfer(this.balance);
        token.finishMinting();
        token.makeTradable();
    }
    
    function destroy() public onlyOwner isTwoMonthsLater {
         token.finishMinting();
         token.makeTradable();
         token.transferOwnership(owner);
         selfdestruct(vault);
    }
    
    /**
     * Get the ETH balance of this contract
     */ 
    function getBalance() public constant returns (uint256 totalAmount) {
          totalAmount = this.balance;
    }
}