<?php
public function callback()
    {
        Log::info('=== CALLBACK. ' . 'User id: '.Input::get('userid').', tx hash: '.Input::get('txid'));

        /* the url structure is different, so different segments of URI */
        if ( Input::get( 'cryptotype' ) ) {
            $this->crypto_type_id = Input::get( 'cryptotype' );
        }

        $server_callback_secret = Config::get( 'bitcoin.callback_secret' );

        if ( $server_callback_secret != Input::get( 'secret' )) {
            Log::error( '#callback: ' . SECRET_MISMATCH . ', full URL:  ' . Request::fullUrl() );
            return Response::json( ['#callback: ' . SECRET_MISMATCH] );
        }
        /*--------------------------------------------*/

        /*sends callback on receive notification
        gets a transaction hash id
        calls bitcoind via RPC to get transaction info
        calls a web url specified in the user account
        called from /home/api/walletnotify.sh
        sudo curl http://127.0.0.1/api/callback/?txid=a6eb6a8c2a66dbdfeb87faf820492222a80c2db3422706bdc1eb3bff0dbe8ab1&local=n00nez&loginname=ammm&password=PsQWsO4sDLwqTxxx&debug=1*/

        $tx_id = Input::get( 'txid' ); // check if not null
        if ( ! $tx_id ) {
            Log::error( "#callback, no tx id: " . NO_TX_ID );
            return Response::json( ['error' => NO_TX_ID] );
        }

        $user_id = Input::get('userid');
        if ( ! $user_id ) {
            // TODO daaaaamn
            // return here with error
        }
        $this->user = User::find($user_id);

        // TODO if user is not set here. decide how to set user
        $this->bitcoin_core->setRpcConnection($this->user->rpc_connection);

        try {
            $tx_info = $this->bitcoin_core->gettransaction( $tx_id );
        } catch ( Exception $e ) {
            Log::error( '#callback: get transaction exception: ' . $e->getMessage() );
            return Response::json( ['error' => '#callback: get transaction exception: ' . $e->getMessage()] );
        }

        $confirms      = $tx_info['confirmations'];
        $block_hash    = isset( $tx_info['blockhash'] ) ? $tx_info['blockhash'] : null;
        $block_index   = isset( $tx_info['blockindex'] ) ? $tx_info['blockindex'] : null;
        $block_time    = isset( $tx_info['blocktime'] ) ? $tx_info['blocktime'] : null;
        $time          = $tx_info['time'];
        $time_received = $tx_info['timereceived'];
        $fee           = isset($tx_info['fee']) ? abs( bcmul($tx_info['fee'], SATOSHIS_FRACTION)) : null;

        $transaction_details = $tx_info["details"];

        /* Get input addresses */
        $addresses = array();
        $raw_tx = $this->bitcoin_core->getrawtransaction( $tx_id, 1 );

        foreach($raw_tx['vin'] as $i) {
            $i_raw_tx = $this->bitcoin_core->getrawtransaction( $i['txid'], 1 );
            $addresses[] = $i_raw_tx['vout'][$i['vout']]['scriptPubKey']['addresses'][0];
        }

        foreach ($transaction_details as $tx)
        {
            $to_address    = $tx['address']; // address where transaction was sent to. from address may be multiple inputs which means many addresses
            $account_name  = $tx['account'];
            $address_from  = $addresses[0];
            $category      = $tx['category'];
            $btc_amount    = $tx["amount"];

            if ( ( Input::get( 'debug' ) or API_DEBUG == true ) ) {
                $this->print_debug( $tx_id, $tx_info, $block_hash, $block_index, $block_time, $account_name, $to_address, $category, $btc_amount );
            }

            /******************* START of checking if its outgoing transaction *******************/
            if ( $btc_amount < 0 )
            {
                $this->processOutgoingTransaction( $user_id, $btc_amount, $to_address, $tx_id, $confirms );
                continue; // loop more in case there is something
            }
            /******************* END of checking if its outgoing transaction *******************/

            Log::info( "Address $to_address, amount (BTC): $btc_amount, confirms: $confirms received transaction id $tx_id" );

            /* whether new transaction or notify was fired on 1st confirmation */
            $transaction_model = Transaction::getTransactionByTxIdAndAddress( $tx_id, $to_address );
            $satoshi_amount    = bcmul( $btc_amount, SATOSHIS_FRACTION );
            $is_own_address = false; // if not own address, then unknown address received transaction

            /* create common data for transaction */
            $common_data = [
                'tx_id'             => $tx_id,
                'user_id'           => $this->user->id,
                'crypto_amount'     => $satoshi_amount,
                'network_fee'       => $fee,
                'crypto_type_id'    => $this->crypto_type_id,
                'address_to'        => $to_address,
                'address_from'      => $address_from,
                'confirmations'     => $confirms,
                'block_hash'        => $block_hash,
                'block_index'       => $block_index,
                'block_time'        => $block_time,
                'tx_time'           => $time,
                'tx_timereceived'   => $time_received,
                'tx_category'       => $category,
                'address_account'   => $account_name,
            ];

            /******************* START processing the invoicing callback **************/
            $invoice_address_model = InvoiceAddress::getAddress( $to_address );
            if ( $invoice_address_model ) {
                $is_own_address = true;
                $this->processInvoiceAddress($transaction_model, $invoice_address_model, $common_data, $satoshi_amount);
                continue; // continue into the next loop
            }
            /*************** END processing the invoicing callback **************/

            /*************************************************************************************/
            /* at this point its not the invoicing address, lookup address in address table
            /*************************************************************************************/

            /************* It is incoming transaction, because it is sent to some of the inner addresses *************/
            $address_model = Address::getAddress( $to_address );
            if ( $address_model )
            {
                $is_own_address = true;
                $this->processUserAddress($transaction_model, $address_model, $common_data, $satoshi_amount);
                continue;
            }

            /* The receiving address wasn't in the database, so its not tied to any API user, but generated outside API directly in bitcoin core*/
            if ( !$is_own_address )
            {
                /* This can be enabled when needed to save payment for unknown address received
                 * but because we have change addresses that are used in 'sendmany', we don't want to bloat transactions table */
                //$this->processUnknownAddress( $confirms, $transaction_model, $common_data, $btc_amount, $to_address, $satoshi_amount );
                continue;
            }
        }

        return '*ok*'; // just dummy return, since it's not being processed on other end. the return is processed in fetchUrl()

    }