<?php

namespace AffiliateX\Amazon\Api;

use AffiliateX\Amazon\AmazonConfig;

defined('ABSPATH') or exit;

/**
 * Amazon API base class to create a new Amazon API request
 * 
 * @package AffiliateX
 */
abstract class AmazonApiBase{
    /**
     * Amazon configuration data
     *
     * @var AmazonConfig
     */
    protected $configs;

    public function __construct()
    {
        $this->configs = new AmazonConfig();
    }

    /**
     * Get Amazon partner type
     *
     * @return string
     */
    protected function get_partner_type() : string
    {
        return "Associates";
    }

    /**
     * Get Amazon API resources, for example "Images.Primary.Small"
     *
     * @return array
     */
    protected function get_resources() : array
    {
        return [
            'ItemInfo.Title',
            'ItemInfo.Features',
            'Offers.Listings.Price',
            'Offers.Listings.SavingBasis',
            'BrowseNodeInfo.WebsiteSalesRank',
            'Images.Primary.Small',
            'Images.Primary.Medium',
            'Images.Primary.Large',
            'Images.Variants.Small',
            'Images.Variants.Medium',
            'Images.Variants.Large',
        ];
    }

    /**
     * Get Amazon API search index
     *
     * @return string
     */
    protected function get_search_index() : string
    {
        return "All";
    }

    /**
     * Get API headers
     *
     * @return array
     */
    protected function get_headers() : array
    {
        return [
            'content-encoding' => 'amz-1.0',
            'content-type' => 'application/json; charset=utf-8',
            'host' => $this->configs->host,
            'x-amz-target' => 'com.amazon.paapi5.v1.ProductAdvertisingAPIv1.' . $this->get_target()
        ];
    }

    /**
     * Get API signature, inlcudes header with authenticatiob token
     *
     * @return AmazonApiSignature
     */
    public function get_signature() : AmazonApiSignature
    {
        $signature = new AmazonApiSignature ($this->configs->api_key, $this->configs->api_secret);
        $signature->set_region_name($this->configs->region);
        $signature->set_service_name("ProductAdvertisingAPI");
        $signature->set_path($this->get_path());
        $signature->set_payload($this->get_payload());
        $signature->set_request_method("POST");

        foreach($this->get_headers() as $header_name => $header_value){
            $signature->add_header($header_name, $header_value);
        }

        return $signature;
    }

    /**
     * Get API payload, contains json encoded body
     *
     * @return string
     */
    protected function get_payload() : string
    {
        $default_attributes = [
            'PartnerType' => $this->get_partner_type(),
            'PartnerTag' => $this->configs->tracking_id,
            'Resources' => $this->get_resources(),
            'LanguagesOfPreference' => [$this->configs->get_language()]
        ];

        $attributes = $this->get_params();
        $attributes = \wp_parse_args($attributes, $default_attributes);
        $attributes = json_encode($attributes);

        return $attributes;
    }

    /**
     * Get API endpoint
     *
     * @return string
     */
    protected function get_endpoint() : string
    {
        $end_point = sprintf('https://%s%s',
            $this->configs->host,
            $this->get_path()
        );

        return $end_point;
    }

    /**
     * Get results from API response
     *
     * @return bool|array
     */
    public function get_result()
    {
        if($this->configs->is_settings_empty()){
            return false;
        }
        
        $signature = $this->get_signature();
        
        if(!$signature){
            return false;
        }

        $response = \wp_remote_post(
            $this->get_endpoint(),
            [
                'method' => 'POST',
                'body' => $this->get_payload(),
                'headers' => $signature->get_headers(),
            ]
        );

        if(\is_wp_error($response)){
            return false;
        }

        $response = \wp_remote_retrieve_body($response);
        $response = json_decode($response, true);

        if(json_last_error() !== JSON_ERROR_NONE){
            return false;
        }

        return $response;
    }

    /**
     * Get Amazon API path to place after endpoint
     *
     * @param string $path
     * @return string
     */
    abstract protected function get_path() : string;

    /**
     * Get Amazon API parameters for search query
     *
     * @return array
     */
    abstract protected function get_params() : array;

    /**
     * Get Amazon API target type
     *
     * @return string
     */
    abstract protected function get_target() : string;
}