pragma solidity ^0.4.20;

/*
	Built for the community. 
	Supported by the community. 

	“Equality... is when you don't feel the existence of word”
	Talees Rizvi

	“The world is round so that friendship may encircle it.”
	Pierre Teilhard de Chardin

	What? 
	We are a clone simple as that. 
	But we differentiate in the way we pay our divs. 
	More for the community. 
	- Buys - 35% fee goes to all current token holders. 
	- Sells - 15% fee to all current tokens holders. And it’s lower because you shouldn’t have to pay the sane fee exiting. You deserve more. 
	- Transfers - 0% fee! We have plans for games and we don't want that to be an obstacle!
	- Masternode - you get 7% from deposit of all players who enter using your Masternode . 

	Who toiled night and day on this project to make this possible for you? 
	Clumsier - solidity developer, website 
	Bungalogic - website developer, concept and design, graphics. 
*/

contract ProofOfCommunity {
    /*=================================
    =            MODIFIERS            =
    =================================*/
    // only people with tokens
    modifier onlyBagholders() {
        require(myTokens() > 0);
        _;
    }

    // only people with profits
    modifier onlyStronghands() {
        require(myDividends(true) > 0);
        _;
    }

    // administrators can:
    // -> change the name of the contract
    // -> change the name of the token
    // -> change the PoS difficulty (How many tokens it costs to hold a masternode, in case it gets crazy high later)
    // they CANNOT:
    // -> take funds
    // -> disable withdrawals
    // -> kill the contract
    // -> change the price of tokens
    modifier onlyAdministrator(){
        address _customerAddress = msg.sender;
        require(administrators[_customerAddress]);
        _;
    }


    // ensures that the first tokens in the contract will be equally distributed
    // meaning, no divine dump will be ever possible
    // result: healthy longevity.
    modifier antiEarlyWhale(uint256 _amountOfEthereum){
        address _customerAddress = msg.sender;

        // are we still in the vulnerable phase?
        // if so, enact anti early whale protocol
        if( onlyAmbassadors && ((totalEthereumBalance() - _amountOfEthereum) <= ambassadorQuota_ )){
            require(
                // is the customer in the ambassador list?
                ambassadors_[_customerAddress] == true &&

                // does the customer purchase exceed the max ambassador quota?
                (ambassadorAccumulatedQuota_[_customerAddress] + _amountOfEthereum) <= ambassadorMaxPurchase_

            );

            // updated the accumulated quota
            ambassadorAccumulatedQuota_[_customerAddress] = SafeMath.add(ambassadorAccumulatedQuota_[_customerAddress], _amountOfEthereum);

            // execute
            _;
        } else {
            // in case the ether count drops low, the ambassador phase won't reinitiate
            onlyAmbassadors = false;
            _;
        }
    }

    /*==============================
    =            EVENTS            =
    ==============================*/
    event onTokenPurchase(
        address indexed customerAddress,
        uint256 incomingEthereum,
        uint256 tokensMinted,
        address indexed referredBy
    );

    event onTokenSell(
        address indexed customerAddress,
        uint256 tokensBurned,
        uint256 ethereumEarned
    );

    event onReinvestment(
        address indexed customerAddress,
        uint256 ethereumReinvested,
        uint256 tokensMinted
    );

    event onWithdraw(
        address indexed customerAddress,
        uint256 ethereumWithdrawn
    );

    // ERC20
    event Transfer(
        address indexed from,
        address indexed to,
        uint256 tokens
    );

    /*=====================================
    =            CONFIGURABLES            =
    =====================================*/
    string public name = "ProofOfCommunity";
    string public symbol = "POC";
    uint8 constant public decimals = 18;
    uint8 constant internal entryFee_ = 35; // 35% to enter our community
    uint8 constant internal refferalFee_ = 20; // 20% from enter fee divs or 7% for each invite, great for inviting new members for our community
    uint8 constant internal exitFee_ = 15; // 15% for selling
    uint256 constant internal tokenPriceInitial_ = 0.0000001 ether;
    uint256 constant internal tokenPriceIncremental_ = 0.00000001 ether;
    uint256 constant internal magnitude = 2**64;

    // proof of stake (defaults at 100 tokens)
    uint256 public stakingRequirement = 100e18;

    // ambassador program
    mapping(address => bool) internal ambassadors_;
    uint256 constant internal ambassadorMaxPurchase_ = 1 ether;
    uint256 constant internal ambassadorQuota_ = 20 ether;

    // referral program
    mapping(address => uint256) internal referrals;
    mapping(address => bool) internal isUser;
    address[] public usersAddresses;

   /*================================
    =            DATASETS            =
    ================================*/
    // amount of shares for each address (scaled number)
    mapping(address => uint256) internal tokenBalanceLedger_;
    mapping(address => uint256) internal referralBalance_;
    mapping(address => int256) internal payoutsTo_;
    mapping(address => uint256) internal ambassadorAccumulatedQuota_;
    uint256 internal tokenSupply_ = 0;
    uint256 internal profitPerShare_;

    // administrator list (see above on what they can do)
    mapping(address => bool) public administrators;

    // when this is set to true, only ambassadors can purchase tokens (this prevents a whale premine, it ensures a fairly distributed upper pyramid)
    bool public onlyAmbassadors = true;

    /*=======================================
    =            PUBLIC FUNCTIONS            =
    =======================================*/
    /*
    * -- APPLICATION ENTRY POINTS --
    */
    function ProofOfCommunity()
        public
    {
        // add administrators here with their wallets

  		// bungalogic
		// Website developer, concept and design. Community
		administrators[0xBa21d01125D6932ce8ABf3625977899Fd2C7fa30] = true;
		ambassadors_[0xBa21d01125D6932ce8ABf3625977899Fd2C7fa30] = true;

		// clumsier 
		// Solidity Developer, website,  PoG 
		administrators[msg.sender] = true;
		ambassadors_[msg.sender] = true;
    }


    /**
     * Converts all incoming ethereum to tokens for the caller, and passes down the referral addy (if any)
     */
    function buy(address _referredBy)
        public
        payable
        returns(uint256)
    {
        purchaseTokens(msg.value, _referredBy);
    }

    /**
     * Fallback function to handle ethereum that was send straight to the contract
     * Unfortunately we cannot use a referral address this way.
     */
    function()
        payable
        public
    {
        purchaseTokens(msg.value, 0x0);
    }

    /* Converts all of caller's dividends to tokens. */
    function reinvest() onlyStronghands() public {
        // fetch dividends
        uint256 _dividends = myDividends(false); // retrieve ref. bonus later in the code

        // pay out the dividends virtually
        address _customerAddress = msg.sender;
        payoutsTo_[_customerAddress] +=  (int256) (_dividends * magnitude);

        // retrieve ref. bonus
        _dividends += referralBalance_[_customerAddress];
        referralBalance_[_customerAddress] = 0;

        // dispatch a buy order with the virtualized "withdrawn dividends"
        uint256 _tokens = purchaseTokens(_dividends, 0x0);

        // fire event
        onReinvestment(_customerAddress, _dividends, _tokens);
    }

    /* Alias of sell() and withdraw(). */
    function exit() public {
        // get token count for caller & sell them all
        address _customerAddress = msg.sender;
        uint256 _tokens = tokenBalanceLedger_[_customerAddress];
        if(_tokens > 0) sell(_tokens);

        // lambo delivery service
        withdraw();
    }

    /* Withdraws all of the callers earnings. */
    function withdraw() onlyStronghands() public {
        // setup data
        address _customerAddress = msg.sender;
        uint256 _dividends = myDividends(false); // get ref. bonus later in the code

        // update dividend tracker
        payoutsTo_[_customerAddress] +=  (int256) (_dividends * magnitude);

        // add ref. bonus
        _dividends += referralBalance_[_customerAddress];
        referralBalance_[_customerAddress] = 0;

        // lambo delivery service
        _customerAddress.transfer(_dividends);

        // fire event
        onWithdraw(_customerAddress, _dividends);
    }

    /* Liquifies tokens to ethereum. */
    function sell(uint256 _amountOfTokens) onlyBagholders() public {
        // setup data
        address _customerAddress = msg.sender;
        // russian hackers BTFO
        require(_amountOfTokens <= tokenBalanceLedger_[_customerAddress]);
        uint256 _tokens = _amountOfTokens;
        uint256 _ethereum = tokensToEthereum_(_tokens);
        uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, exitFee_), 100);
        uint256 _taxedEthereum = SafeMath.sub(_ethereum, _dividends);

        // burn the sold tokens
        tokenSupply_ = SafeMath.sub(tokenSupply_, _tokens);
        tokenBalanceLedger_[_customerAddress] = SafeMath.sub(tokenBalanceLedger_[_customerAddress], _tokens);

        // update dividends tracker
        int256 _updatedPayouts = (int256) (profitPerShare_ * _tokens + (_taxedEthereum * magnitude));
        payoutsTo_[_customerAddress] -= _updatedPayouts;

        // dividing by zero is a bad idea
        if (tokenSupply_ > 0) {
            // update the amount of dividends per token
            profitPerShare_ = SafeMath.add(profitPerShare_, (_dividends * magnitude) / tokenSupply_);
        }

        // fire event
        onTokenSell(_customerAddress, _tokens, _taxedEthereum);
    }


    /* Transfer tokens from the caller to a new holder. * No fee! */
    function transfer(address _toAddress, uint256 _amountOfTokens) onlyBagholders() public returns(bool) {
        // setup
        address _customerAddress = msg.sender;

        // make sure we have the requested tokens
        // also disables transfers until ambassador phase is over
        // ( we dont want whale premines )
        require(!onlyAmbassadors && _amountOfTokens <= tokenBalanceLedger_[_customerAddress]);

        // withdraw all outstanding dividends first
        if(myDividends(true) > 0) withdraw();

        // exchange tokens
        tokenBalanceLedger_[_customerAddress] = SafeMath.sub(tokenBalanceLedger_[_customerAddress], _amountOfTokens);
        tokenBalanceLedger_[_toAddress] = SafeMath.add(tokenBalanceLedger_[_toAddress], _amountOfTokens);

        // update dividend trackers
        payoutsTo_[_customerAddress] -= (int256) (profitPerShare_ * _amountOfTokens);
        payoutsTo_[_toAddress] += (int256) (profitPerShare_ * _amountOfTokens);

        // fire event
        Transfer(_customerAddress, _toAddress, _amountOfTokens);

        // ERC20
        return true;

    }

    /*----------  ADMINISTRATOR ONLY FUNCTIONS  ----------*/
    /**
     * In case the amassador quota is not met, the administrator can manually disable the ambassador phase.
     */
    function disableInitialStage()
        onlyAdministrator()
        public
    {
        onlyAmbassadors = false;
    }

    /**
     * In case one of us dies, we need to replace ourselves.
     */
    function setAdministrator(address _identifier, bool _status)
        onlyAdministrator()
        public
    {
        administrators[_identifier] = _status;
    }

    /**
     * Precautionary measures in case we need to adjust the masternode rate.
     */
    function setStakingRequirement(uint256 _amountOfTokens)
        onlyAdministrator()
        public
    {
        stakingRequirement = _amountOfTokens;
    }

    /**
     * If we want to rebrand, we can.
     */
    function setName(string _name)
        onlyAdministrator()
        public
    {
        name = _name;
    }

    /**
     * If we want to rebrand, we can.
     */
    function setSymbol(string _symbol)
        onlyAdministrator()
        public
    {
        symbol = _symbol;
    }


    /*----------  HELPERS AND CALCULATORS  ----------*/
    /**
     * Method to view the current Ethereum stored in the contract
     * Example: totalEthereumBalance()
     */
    function totalEthereumBalance()
        public
        view
        returns(uint)
    {
        return this.balance;
    }

    /**
     * Retrieve the total token supply.
     */
    function totalSupply()
        public
        view
        returns(uint256)
    {
        return tokenSupply_;
    }

    /**
     * Retrieve the tokens owned by the caller.
     */
    function myTokens()
        public
        view
        returns(uint256)
    {
        address _customerAddress = msg.sender;
        return balanceOf(_customerAddress);
    }

    function referralsOf(address _customerAddress)
        public
        view
        returns(uint256)
    {
        return referrals[_customerAddress];
    }

    function totalUsers()
        public
        view
        returns(uint256)
    {
        return usersAddresses.length;
    }

    /**
     * Retrieve the dividends owned by the caller.
     * If `_includeReferralBonus` is to to 1/true, the referral bonus will be included in the calculations.
     * The reason for this, is that in the frontend, we will want to get the total divs (global + ref)
     * But in the internal calculations, we want them separate.
     */
    function myDividends(bool _includeReferralBonus)
        public
        view
        returns(uint256)
    {
        address _customerAddress = msg.sender;
        return _includeReferralBonus ? dividendsOf(_customerAddress) + referralBalance_[_customerAddress] : dividendsOf(_customerAddress) ;
    }

    /**
     * Retrieve the token balance of any single address.
     */
    function balanceOf(address _customerAddress)
        view
        public
        returns(uint256)
    {
        return tokenBalanceLedger_[_customerAddress];
    }

    /**
     * Retrieve the dividend balance of any single address.
     */
    function dividendsOf(address _customerAddress)
        view
        public
        returns(uint256)
    {
        return (uint256) ((int256)(profitPerShare_ * tokenBalanceLedger_[_customerAddress]) - payoutsTo_[_customerAddress]) / magnitude;
    }

    /**
     * Return the buy price of 1 individual token.
     */
    function sellPrice()
        public
        view
        returns(uint256)
    {
        // our calculation relies on the token supply, so we need supply. Doh.
        if(tokenSupply_ == 0){
            return tokenPriceInitial_ - tokenPriceIncremental_;
        } else {
            uint256 _ethereum = tokensToEthereum_(1e18);
            uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, exitFee_), 100);
            uint256 _taxedEthereum = SafeMath.sub(_ethereum, _dividends);
            return _taxedEthereum;
        }
    }

    /**
     * Return the sell price of 1 individual token.
     */
    function buyPrice()
        public
        view
        returns(uint256)
    {
        // our calculation relies on the token supply, so we need supply. Doh.
        if(tokenSupply_ == 0){
            return tokenPriceInitial_ + tokenPriceIncremental_;
        } else {
            uint256 _ethereum = tokensToEthereum_(1e18);
            uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, entryFee_), 100);
            uint256 _taxedEthereum = SafeMath.add(_ethereum, _dividends);
            return _taxedEthereum;
        }
    }

    /**
     * Function for the frontend to dynamically retrieve the price scaling of buy orders.
     */
    function calculateTokensReceived(uint256 _ethereumToSpend)
        public
        view
        returns(uint256)
    {
        uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereumToSpend, entryFee_), 100);
        uint256 _taxedEthereum = SafeMath.sub(_ethereumToSpend, _dividends);
        uint256 _amountOfTokens = ethereumToTokens_(_taxedEthereum);

        return _amountOfTokens;
    }

    /**
     * Function for the frontend to dynamically retrieve the price scaling of sell orders.
     */
    function calculateEthereumReceived(uint256 _tokensToSell)
        public
        view
        returns(uint256)
    {
        require(_tokensToSell <= tokenSupply_);
        uint256 _ethereum = tokensToEthereum_(_tokensToSell);
        uint256 _dividends = SafeMath.div(SafeMath.mul(_ethereum, exitFee_), 100);
        uint256 _taxedEthereum = SafeMath.sub(_ethereum, _dividends);
        return _taxedEthereum;
    }


    /*==========================================
    =            INTERNAL FUNCTIONS            =
    ==========================================*/
    function purchaseTokens(uint256 _incomingEthereum, address _referredBy)
        antiEarlyWhale(_incomingEthereum)
        internal
        returns(uint256)
    {
        // data setup
        address _customerAddress = msg.sender;
        uint256 _undividedDividends = SafeMath.div(SafeMath.mul(_incomingEthereum, entryFee_), 100);
        uint256 _referralBonus = SafeMath.div(SafeMath.mul(_undividedDividends, refferalFee_), 100);
        uint256 _dividends = SafeMath.sub(_undividedDividends, _referralBonus);
        uint256 _taxedEthereum = SafeMath.sub(_incomingEthereum, _undividedDividends);
        uint256 _amountOfTokens = ethereumToTokens_(_taxedEthereum);
        uint256 _fee = _dividends * magnitude;

        // no point in continuing execution if OP is a poorfag russian hacker
        // prevents overflow in the case that the pyramid somehow magically starts being used by everyone in the world
        // (or hackers)
        // and yes we know that the safemath function automatically rules out the "greater then" equasion.
        require(_amountOfTokens > 0 && (SafeMath.add(_amountOfTokens,tokenSupply_) > tokenSupply_));

        // is the user referred by a masternode?
        if(
            // is this a referred purchase?
            _referredBy != 0x0000000000000000000000000000000000000000 &&

            // no cheating!
            _referredBy != _customerAddress &&

            // does the referrer have at least X whole tokens?
            // i.e is the referrer a Kekly chad masternode
            tokenBalanceLedger_[_referredBy] >= stakingRequirement
        ){
            // wealth redistribution
            referralBalance_[_referredBy] = SafeMath.add(referralBalance_[_referredBy], _referralBonus);

            if (isUser[_customerAddress] == false) {
            	referrals[_referredBy]++;
            }     

        } else {
            // no ref purchase
            // add the referral bonus back to the global dividends cake
            _dividends = SafeMath.add(_dividends, _referralBonus);
            _fee = _dividends * magnitude;
        }

        if (isUser[_customerAddress] == false ) {
        	isUser[_customerAddress] = true;
        	usersAddresses.push(_customerAddress);
        }

        // we can't give people infinite ethereum
        if(tokenSupply_ > 0){

            // add tokens to the pool
            tokenSupply_ = SafeMath.add(tokenSupply_, _amountOfTokens);

            // take the amount of dividends gained through this transaction, and allocates them evenly to each shareholder
            profitPerShare_ += (_dividends * magnitude / (tokenSupply_));

            // calculate the amount of tokens the customer receives over his purchase
            _fee = _fee - (_fee-(_amountOfTokens * (_dividends * magnitude / (tokenSupply_))));

        } else {
            // add tokens to the pool
            tokenSupply_ = _amountOfTokens;
        }

        // update circulating supply & the ledger address for the customer
        tokenBalanceLedger_[_customerAddress] = SafeMath.add(tokenBalanceLedger_[_customerAddress], _amountOfTokens);

        // Tells the contract that the buyer doesn't deserve dividends for the tokens before they owned them;
        //really i know you think you do but you don't
        int256 _updatedPayouts = (int256) ((profitPerShare_ * _amountOfTokens) - _fee);
        payoutsTo_[_customerAddress] += _updatedPayouts;

        // fire event
        onTokenPurchase(_customerAddress, _incomingEthereum, _amountOfTokens, _referredBy);

        return _amountOfTokens;
    }

    /**
     * Calculate Token price based on an amount of incoming ethereum
     * It's an algorithm, hopefully we gave you the whitepaper with it in scientific notation;
     * Some conversions occurred to prevent decimal errors or underflows / overflows in solidity code.
     */
    function ethereumToTokens_(uint256 _ethereum)
        internal
        view
        returns(uint256)
    {
        uint256 _tokenPriceInitial = tokenPriceInitial_ * 1e18;
        uint256 _tokensReceived =
         (
            (
                // underflow attempts BTFO
                SafeMath.sub(
                    (sqrt
                        (
                            (_tokenPriceInitial**2)
                            +
                            (2*(tokenPriceIncremental_ * 1e18)*(_ethereum * 1e18))
                            +
                            (((tokenPriceIncremental_)**2)*(tokenSupply_**2))
                            +
                            (2*(tokenPriceIncremental_)*_tokenPriceInitial*tokenSupply_)
                        )
                    ), _tokenPriceInitial
                )
            )/(tokenPriceIncremental_)
        )-(tokenSupply_)
        ;

        return _tokensReceived;
    }

    /**
     * Calculate token sell value.
     * It's an algorithm, hopefully we gave you the whitepaper with it in scientific notation;
     * Some conversions occurred to prevent decimal errors or underflows / overflows in solidity code.
     */
     function tokensToEthereum_(uint256 _tokens)
        internal
        view
        returns(uint256)
    {

        uint256 tokens_ = (_tokens + 1e18);
        uint256 _tokenSupply = (tokenSupply_ + 1e18);
        uint256 _etherReceived =
        (
            // underflow attempts BTFO
            SafeMath.sub(
                (
                    (
                        (
                            tokenPriceInitial_ +(tokenPriceIncremental_ * (_tokenSupply/1e18))
                        )-tokenPriceIncremental_
                    )*(tokens_ - 1e18)
                ),(tokenPriceIncremental_*((tokens_**2-tokens_)/1e18))/2
            )
        /1e18);
        return _etherReceived;
    }


    //This is where all your gas goes, sorry
    //Not sorry, you probably only paid 1 gwei
    function sqrt(uint x) internal pure returns (uint y) {
        uint z = (x + 1) / 2;
        y = x;
        while (z < y) {
            y = z;
            z = (x / z + z) / 2;
        }
    }
}

/**
 * @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) {
        if (a == 0) {
            return 0;
        }
        uint256 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 c;
    }

    /**
    * @dev Substracts 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) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}