<?php

namespace Jump;

use \Exception;

/**
 * Loads and validates the search engines defined in searchengines.json.
 *
 * @author Dale Davies <dale@daledavies.co.uk>
 * @license MIT
 */
class SearchEngines {
    private array $default;
    private string $searchfilelocation;
    private array $loadedsearchengines;

    /**
     * Automatically load searchengines.json on instantiation.
     */
    public function __construct(private Config $config, private Cache $cache) {
        $this->config = $config;
        $this->loadedsearchengines = [];
        $this->searchfilelocation = $this->config->get('searchenginesfile');
        $this->cache = $cache;

        // Retrieve search engines from cache. Load from json file if not cached or
        // the cache has expired.
        $this->loadedsearchengines = $this->cache->load(cachename: 'searchengines', callback: function() {
            return $this->load_search_engines_from_json();
        });

    }
    /**
     * Try to load and validate the list of search engines from searchengines.json.
     *
     * Throws an exception if the file cannot be loaded, is empty, or cannot
     * be decoded to an array.
     *
     * @return array AArray of parsed/validated search engine information from searchengines.json
     * @throws Exception If searchengines.json cannot be found.
     */
    private function load_search_engines_from_json(): array {
        $searchengines = [];
        $rawjson = file_get_contents($this->searchfilelocation);
        if ($rawjson === false) {
            throw new Exception('There was a problem loading the searchengines.json file');
        }
        if ($rawjson === '') {
            throw new Exception('The searchengines.json file is empty');
        }
        // Do some checks to see if the JSON decodes into something
        // like what we expect to see...
        $decodedjson = json_decode($rawjson);

        if (!is_array($decodedjson)) {
            throw new Exception('The searchengines.json file is invalid');
        }

        // Build a new array using the values we need...
        foreach ($decodedjson as $item) {
            if (!isset($item->name, $item->url)) {
                throw new Exception('The searchengines.json does not contain the "name" or "url" properties');
            }
            $searchengine = new \stdClass();
            $searchengine->name = $item->name;
            $searchengine->url = $item->url;
            $searchengines[] = $searchengine;
        }

        return $searchengines;
    }

    /**
     * Get the list of loaded search engines.
     *
     * @return array Array of parsed/validated search engine information from searchengines.json
     */
    public function get_search_engines() {
        return $this->loadedsearchengines;
    }
}