<?php
/**
 * Native generation languages for the AiGude Vision model.
 *
 * AiGude generates descriptions natively in a fixed set of languages. This class
 * reads that list from the Credits API and caches it, and provides the language
 * code helpers the prompt UI needs. Unlike the translation provider metadata,
 * this endpoint is public, so the list is available before a server is configured.
 */

if (!defined('ABSPATH')) {
    exit;
}

class AIGUDE_Native_Language_Service {
    /** Client-facing model name sent to the API. */
    public const MODEL = 'aigude-vision-v1';

    /** Transient holding the fetched language list. */
    private const TRANSIENT = 'aigude_native_languages';

    /** Cache lifetime for the language list. */
    private const TTL = DAY_IN_SECONDS;

    /**
     * Languages AiGude generates natively, used when the endpoint is unreachable.
     *
     * @var string[]
     */
    private const FALLBACK_CODES = [
        'en', 'de', 'es', 'fr', 'it', 'pt', 'nl',
        'ja', 'ko', 'ar', 'zh', 'ru', 'hi', 'tr', 'he',
    ];

    /**
     * Request-scoped cache to avoid repeated transient reads.
     *
     * @var array<string, array<string, string>>
     */
    private static array $cache = [];

    /**
     * Return the native generation languages, keyed by lowercase 2-letter code.
     *
     * @param bool $force If true, bypass transient + static cache.
     * @return array<string, array{code:string,name:string,description:string,locale:string,default_prompt:string}>
     */
    public static function get_languages(bool $force = false): array {
        if (!$force && !empty(self::$cache)) {
            return self::$cache;
        }

        if (!$force) {
            $cached = get_transient(self::TRANSIENT);
            if (is_array($cached) && !empty($cached)) {
                self::$cache = $cached;
                return $cached;
            }
        }

        $languages = [];
        $url = add_query_arg(['model' => self::MODEL], AIGUDE_Tools_Plugin::get_native_languages_url());

        // No apikey header: this endpoint is public, so the list works before a server is configured.
        $response = wp_remote_get($url, ['timeout' => 5]);

        if (!is_wp_error($response) && (int) wp_remote_retrieve_response_code($response) === 200) {
            $json = json_decode(wp_remote_retrieve_body($response), true);
            foreach ((array) ($json['languages'] ?? []) as $entry) {
                if (!is_array($entry) || empty($entry['code'])) {
                    continue;
                }
                $code = strtolower(trim((string) $entry['code']));
                if ($code === '') {
                    continue;
                }
                $languages[$code] = [
                    'code'           => $code,
                    'name'           => (string) ($entry['name'] ?? strtoupper($code)),
                    'description'    => (string) ($entry['description'] ?? ''),
                    'locale'         => (string) ($entry['locale'] ?? ''),
                    'default_prompt' => (string) ($entry['default_prompt'] ?? ''),
                ];
            }
        }

        if (empty($languages)) {
            foreach (self::FALLBACK_CODES as $code) {
                $languages[$code] = [
                    'code'           => $code,
                    'name'           => strtoupper($code),
                    'description'    => '',
                    'locale'         => '',
                    'default_prompt' => '',
                ];
            }
            self::log_language_source(false, count($languages));
        } else {
            set_transient(self::TRANSIENT, $languages, self::TTL);
            self::log_language_source(true, count($languages));
        }

        self::$cache = $languages;
        return $languages;
    }

    /**
     * Whether AiGude generates natively in the given language.
     */
    public static function is_supported(string $code): bool {
        $base = self::base_code($code);
        if ($base === '') {
            return false;
        }
        return isset(self::get_languages()[$base]);
    }

    /**
     * Reduce any locale or provider language code to a lowercase 2-letter base code.
     *
     * Handles WordPress locales including formal variants (de_DE_formal → de,
     * nl_NL_formal → nl) and provider codes (EN-US → en). Returns an empty string
     * for 'auto', empty input, or anything that does not yield two letters.
     */
    public static function base_code(string $code): string {
        $trimmed = strtolower(trim($code));
        if ($trimmed === '' || $trimmed === 'auto') {
            return '';
        }

        $base = preg_replace('/[^a-z]/', '', substr($trimmed, 0, 2));
        return strlen((string) $base) === 2 ? (string) $base : '';
    }

    /**
     * The site locale reduced to a native base code.
     */
    public static function site_base_code(): string {
        return self::base_code(get_locale());
    }

    /**
     * Language a prompt defaults to: the site language when AiGude generates natively in it,
     * otherwise English. Every prompt must declare a language, so there is no "unset" state.
     */
    public static function default_prompt_lang(): string {
        $base = self::site_base_code();
        return self::is_supported($base) ? $base : 'en';
    }

    /**
     * Emit a debug log describing where the language list originated.
     */
    private static function log_language_source(bool $fromApi, int $count): void {
        AIGUDE_Tools_Plugin::log(
            sprintf(
                'Native languages loaded from %s (%d entries).',
                $fromApi ? 'API' : 'fallback list',
                $count
            )
        );
    }
}