<?php
/**
 * Chat Model Manager
 *
 * Resolves the OpenAI chat model selected in settings and loads the list
 * of selectable models from the OpenAI API.
 *
 * @category WordPress
 * @package  AISK
 * @author   Aisk Team <support@aisk.chat>
 * @license  GPL-2.0+ https://www.gnu.org/licenses/gpl-2.0.html
 * @link     https://aisk.chat
 */

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

/**
 * AISK_Model_Manager Class
 *
 * @category WordPress
 * @package  AISK
 * @author   Aisk Team <support@aisk.chat>
 * @license  GPL-2.0+ https://www.gnu.org/licenses/gpl-2.0.html
 * @link     https://aisk.chat
 */
class AISK_Model_Manager {

    // Best quality/cost balance for chat and JSON intent classification
    const DEFAULT_MODEL = 'gpt-4.1-mini';
    const CACHE_KEY = 'aisk_openai_models_';
    const CACHE_TTL = 12 * HOUR_IN_SECONDS;

    // Shown when the OpenAI model list cannot be loaded
    const FALLBACK_MODELS = [
        'gpt-4.1-mini',
        'gpt-4.1',
        'gpt-4.1-nano',
        'gpt-4o-mini',
        'gpt-4o',
    ];

    /**
     * Get the chat model selected in settings
     *
     * @since 2.7.3
     *
     * @return string
     */
    public static function get_chat_model() {
        $settings = get_option( 'aisk_settings', [] );
        $model = isset( $settings['general']['chat_model'] ) ? (string) $settings['general']['chat_model'] : '';

        return self::is_supported( $model ) ? $model : self::DEFAULT_MODEL;
    }

    /**
     * Whether a model works with the request parameters the plugin sends
     * (temperature, max_tokens, penalties, json_object response format).
     * Reasoning models (o-series, gpt-5) reject those parameters.
     *
     * @param string $model Model ID
     *
     * @since 2.7.3
     *
     * @return bool
     */
    public static function is_supported( $model ) {
        return (bool) preg_match( '/^(gpt-4\.1(-mini|-nano)?|gpt-4o(-mini)?|gpt-4-turbo)(-\d{4}-\d{2}-\d{2})?$/', (string) $model );
    }

    /**
     * Load selectable models from the OpenAI API, cached per API key
     *
     * @param bool $refresh Bypass the cache
     *
     * @since 2.7.3
     *
     * @return array { models: string[], default: string, source: 'openai'|'fallback' }
     */
    public static function get_available_models( $refresh = false ) {
        $settings = get_option( 'aisk_settings', [] );
        $api_key = isset( $settings['general']['openai_key'] ) ? $settings['general']['openai_key'] : '';

        $result = [
            'models' => self::FALLBACK_MODELS,
            'default' => self::DEFAULT_MODEL,
            'source' => 'fallback',
        ];

        if ( empty( $api_key ) ) {
            return $result;
        }

        $cache_key = self::CACHE_KEY . md5( $api_key );
        if ( ! $refresh ) {
            $cached = get_transient( $cache_key );
            if ( is_array( $cached ) && ! empty( $cached ) ) {
                $result['models'] = $cached;
                $result['source'] = 'openai';
                return $result;
            }
        }

        $response = wp_remote_get(
            AISK_OPENAI_API_URL . '/models', [
                'headers' => [ 'Authorization' => 'Bearer ' . $api_key ],
                'timeout' => 15,
            ]
        );

        if ( is_wp_error( $response ) || 200 !== wp_remote_retrieve_response_code( $response ) ) {
            return $result;
        }

        $body = json_decode( wp_remote_retrieve_body( $response ), true );
        $models = [];
        foreach ( isset( $body['data'] ) && is_array( $body['data'] ) ? $body['data'] : [] as $item ) {
            if ( isset( $item['id'] ) && self::is_supported( $item['id'] ) ) {
                $models[] = $item['id'];
            }
        }

        if ( empty( $models ) ) {
            return $result;
        }

        // Recommended aliases first, then dated snapshots alphabetically
        usort(
            $models, function ( $a, $b ) {
                $rank_a = array_search( $a, self::FALLBACK_MODELS, true );
                $rank_b = array_search( $b, self::FALLBACK_MODELS, true );
                $rank_a = false === $rank_a ? PHP_INT_MAX : $rank_a;
                $rank_b = false === $rank_b ? PHP_INT_MAX : $rank_b;
                return $rank_a === $rank_b ? strcmp( $a, $b ) : $rank_a <=> $rank_b;
            }
        );

        set_transient( $cache_key, $models, self::CACHE_TTL );

        $result['models'] = $models;
        $result['source'] = 'openai';
        return $result;
    }
}