<?php

// Class that communicates with various exchanges via HTTP
class AGC_Exchange {
	// this function converts other WooCommerce currencies to USD because the crypto exchanges only have prices in USD
    public static function get_order_total_in_usd($total, $fromCurr) {        

        if ($fromCurr === 'USD') {
            return $total;
        }

        $transientKey = $curr . '_to_USD';
        $conversionRate = get_transient( $transientKey );

        if ($conversionRate !== false) {
            return $total * $conversionRate;
        }

        $response = wp_remote_get('https://free.currencyconverterapi.com/api/v5/convert?q=' . $curr . '_' . 'USD');

        if ( is_wp_error( $response ) || $response['response']['code'] !== 200) {
            throw new \Exception( 'Could not reach the currency conversion service. Please try again.' );      
        }

        $body = json_decode($response['body']);

        $conversionRate = $body->{'results'}->{$curr . '_USD'}->{'val'};      

        set_transient($transientKey, $conversionRate, 3600);
        $priceInUsd = $total * $conversionRate;

        return $priceInUsd;
    }

    // gets crypto to USD conversion from an API
    public static function get_cryptocompare_price($cryptoId, $updateInterval) {
        $transientKey = 'cryptocompare_' . $cryptoId . '_price';
        $cryptocomparePrice = get_transient($transientKey);
        
        // if transient is found in database just return it
        if ($cryptocomparePrice !== false) {
            return $cryptocomparePrice;
        }

        // if no transient is found we need to hit the api again
        $response = wp_remote_get('https://min-api.cryptocompare.com/data/price?fsym=' . $cryptoId . '&tsyms=USD');

        if ( is_wp_error( $response ) || $response['response']['code'] !== 200) {
            AGC_Util::log(__FILE__, __LINE__, print_r($response, true));
            return 0;
        }

        $responseBody = json_decode( $response['body'] );

        $cryptocomparePrice = (float) $responseBody->{'USD'};

        //cache value for X min to reduce api calls        
        set_transient($transientKey, $cryptocomparePrice, $updateInterval);

        return $cryptocomparePrice;
    }

    // gets crypto to USD conversion from an API
    public static function get_hitbtc_price($cryptoId, $updateInterval) {
        $transientKey = 'hitbtc_' . $cryptoId . '_price';
        $hitbtcPrice = get_transient($transientKey);

        if ($hitbtcPrice !== false) {
            return $hitbtcPrice;
        }

        $response = wp_remote_get('https://api.hitbtc.com/api/2/public/ticker/' . $cryptoId . 'USD');

        if ( is_wp_error( $response ) || $response['response']['code'] !== 200) {
            return 0;
        }

        $responseBody = json_decode( $response['body']);
        $hitbtcPrice = (float) $responseBody->{'last'};

        set_transient($transientKey, $hitbtcPrice, $updateInterval);
        return $hitbtcPrice;
    }

    // gets crypto to USD conversion from an API
    public static function get_gateio_price($cryptoId, $updateInterval) {
        $transientKey = 'gateio_' . $cryptoId . '_price';
        $gateioPrice = get_transient($transientKey);

        if ($gateioPrice !== false) {
            return $gateioPrice;
        }

        $response = wp_remote_get('https://data.gateio.io/api2/1/ticker/' . strtolower($cryptoId) . '_usdt');

        if ( is_wp_error( $response ) || $response['response']['code'] !== 200) {
            return 0;
        }

        $responseBody = json_decode( $response['body'] );
        $gateioPrice = (float) $responseBody->{'last'};

        set_transient($transientKey, $gateioPrice, $updateInterval);

        return $gateioPrice;
    }

    // gets crypto to USD conversion from an API
    public static function get_bittrex_price($cryptoId, $updateInterval) {
        $transientKey = 'bittrex_' . $cryptoId . '_price';
        $bittrexPrice = get_transient($transientKey);

        if ($bittrexPrice !== false) {
            return $bittrexPrice;
        }

        $response = wp_remote_get('https://bittrex.com/api/v1.1/public/getticker?market=USDT-' . $cryptoId);

        if ( is_wp_error( $response ) || $response['response']['code'] !== 200) {
            return 0;
        }

        $responseBody = json_decode( $response['body']);
        $bittrexPrice = (float) $responseBody->{'result'}->{'Last'};

        set_transient($transientKey, $bittrexPrice, $updateInterval);

        return $bittrexPrice;
    }

    // gets crypto to USD conversion from an API
    public static function get_poloniex_price($cryptoId, $updateInterval) {
        $transientKey = 'poloniex_' . $cryptoId . '_price';
        $poloniexPrice = get_transient($transientKey);

        if ($poloniexPrice !== false) {
            return $poloniexPrice;
        }

        $endTime = time();

        // time interval we fetch trades for
        $duration = 1800;

        $startTime = $endTime - $duration;

        $response = wp_remote_get('https://poloniex.com/public?command=returnTradeHistory&currencyPair=USDT_' . $cryptoId . '&start=' . $startTime . '&end=' . $endTime);

        if ( is_wp_error( $response ) || $response['response']['code'] !== 200) {
            return 0;
        }

        $responseBody = json_decode($response['body']);

        // average all trades fetched
        $totalTradeValue = 0;
        $numTrades = 0;

        foreach ($responseBody as $trade) {
            if ($trade->{'type'} === 'sell') {
                $totalTradeValue += (float) $trade->{'rate'};        
                $numTrades++;
            }
        }

        // if no trades are return 0 so the price is not used
        if ($numTrades === 0) {
            return 0;
        }

        $poloniexPrice = $totalTradeValue / $numTrades;

        set_transient($transientKey, $poloniexPrice, $updateInterval);

        return $poloniexPrice;
    }
}

?>