<?php

namespace app\components;

use \Exception as Exception;

class Shopify {

    public $shop_domain;
    private $token;
    private $api_key;
    private $secret;
    private $last_response_headers = null;

    public function __construct($shop_domain, $token, $api_key, $secret) {

        $this->name = "Shopify";
        $this->shop_domain = $shop_domain;
        $this->token = $token;
        $this->api_key = $api_key;
        $this->secret = $secret;
    }

    // Get the URL required to request authorization
    public function getAuthorizeUrl($scope, $redirect_url = '') {

        $url = "http://{$this->shop_domain}/admin/oauth/authorize?client_id={$this->api_key}&scope=" . urlencode($scope);
        if ($redirect_url != '') {
            $url .= "&redirect_uri=" . urlencode($redirect_url);
        }
        return $url;
    }

    // Once the User has authorized the app, call this with the code to get the access token
    public function getAccessToken($code) {

        // POST to  POST https://SHOP_NAME.myshopify.com/admin/oauth/access_token
        $url = "https://{$this->shop_domain}/admin/oauth/access_token";
        $payload = "client_id={$this->api_key}&client_secret={$this->secret}&code=$code";
        $response = $this->curlHttpApiRequest('POST', $url, '', $payload, array());
        $response = json_decode($response, true);
        if (isset($response['access_token']))
            return $response['access_token'];
        return '';
    }

    public function callsMade() {
        return $this->shopApiCallLimitParam(0);
    }

    public function callLimit() {

        return $this->shopApiCallLimitParam(1);
    }

    public function callsLeft() {

        $call_left = $this->callLimit() - $this->callsMade();
        if ($call_left <= 8) {
            sleep(20);
        }
        sleep(1);
        return $this->callLimit() - $this->callsMade();
    }

    public function call($method, $path, $params = array()) {

        $baseurl = "https://{$this->shop_domain}/";

        $url = $baseurl . ltrim($path, '/');
        $query = in_array($method, array('GET', 'DELETE')) ? $params : array();
        $payload = in_array($method, array('POST', 'PUT')) ? json_encode($params) : array();
        $request_headers = in_array($method, array('POST', 'PUT')) ? array("Content-Type: application/json; charset=utf-8", 'Expect:') : array();

        // add auth headers
        $request_headers[] = 'X-Shopify-Access-Token: ' . $this->token;

        $response = $this->curlHttpApiRequest($method, $url, $query, $payload, $request_headers);
        $response = json_decode($response, true);
        if (isset($response['errors']) or ( $this->last_response_headers['http_status_code'] >= 400)) {
            //throw new ShopifyApiException($method, $path, $params, $this->last_response_headers, $response);
            return $response;
        }

        return (is_array($response) and ( count($response) > 0)) ? array_shift($response) : $response;
    }

    public function validateSignature($query) {

        if (!is_array($query) || empty($query['hmac']) || !is_string($query['hmac']))
            return false;

        $dataString = array();
        foreach ($query as $key => $value) {
            if (!in_array($key, array('shop', 'timestamp', 'code')))
                continue;

            $key = str_replace('=', '%3D', $key);
            $key = str_replace('&', '%26', $key);
            $key = str_replace('%', '%25', $key);

            $value = str_replace('&', '%26', $value);
            $value = str_replace('%', '%25', $value);

            $dataString[] = $key . '=' . $value;
        }
        sort($dataString);

        $string = implode("&", $dataString);

        $signatureBin = mhash(MHASH_SHA256, $string, $this->secret);
        $signature = bin2hex($signatureBin);

        return $query['hmac'] == $signature;
    }

    private function curlHttpApiRequest($method, $url, $query = '', $payload = '', $request_headers = array()) {

        $url = $this->curlAppendQuery($url, $query);
        $ch = curl_init($url);
        $this->curlSetopts($ch, $method, $payload, $request_headers);
        $response = curl_exec($ch);
        $errno = curl_errno($ch);
        $error = curl_error($ch);
        curl_close($ch);

        if ($errno)
            throw new ShopifyCurlException($error, $errno);
        list($message_headers, $message_body) = preg_split("/\r\n\r\n|\n\n|\r\r/", $response, 2);
        $this->last_response_headers = $this->curlParseHeaders($message_headers);

        return $message_body;
    }

    private function curlAppendQuery($url, $query) {

        if (empty($query))
            return $url;
        if (is_array($query))
            return "$url?" . http_build_query($query);
        else
            return "$url?$query";
    }

    private function curlSetopts($ch, $method, $payload, $request_headers) {

        curl_setopt($ch, CURLOPT_HEADER, true);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($ch, CURLOPT_MAXREDIRS, 3);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($ch, CURLOPT_USERAGENT, 'ohShopify-php-api-client');
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 90);
        curl_setopt($ch, CURLOPT_TIMEOUT, 90);

        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $method);
        if (!empty($request_headers))
            curl_setopt($ch, CURLOPT_HTTPHEADER, $request_headers);

        if ($method != 'GET' && !empty($payload)) {
            if (is_array($payload))
                $payload = http_build_query($payload);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
        }
    }

    private function curlParseHeaders($message_headers) {

        $header_lines = preg_split("/\r\n|\n|\r/", $message_headers);
        $headers = array();
        list(, $headers['http_status_code'], $headers['http_status_message']) = explode(' ', trim(array_shift($header_lines)), 3);
        foreach ($header_lines as $header_line) {
            list($name, $value) = explode(':', $header_line, 2);
            $name = strtolower($name);
            $headers[$name] = trim($value);
        }

        return $headers;
    }

    private function shopApiCallLimitParam($index) {

        if ($this->last_response_headers == null) {
            throw new Exception('Cannot be called before an API call.');
        }
        $params = explode('/', $this->last_response_headers['http_x_shopify_shop_api_call_limit']);
        return (int) $params[$index];
    }
}

class ShopifyCurlException extends Exception {
    
}

class ShopifyApiException extends Exception {

    protected $method;
    protected $path;
    protected $params;
    protected $response_headers;
    protected $response;

    function __construct($method, $path, $params, $response_headers, $response) {
        $this->method = $method;
        $this->path = $path;
        $this->params = $params;
        $this->response_headers = $response_headers;
        $this->response = $response;

        parent::__construct($response_headers['http_status_message'], $response_headers['http_status_code']);
    }

    function getMethod() {
        return $this->method;
    }

    function getPath() {
        return $this->path;
    }

    function getParams() {
        return $this->params;
    }

    function getResponseHeaders() {
        return $this->response_headers;
    }

    function getResponse() {
        return $this->response;
    }
}