<?php
/**
 * AKSRT AI SEO — AI SEO 辅助
 *
 * 提供 SEO 标题、描述、关键词建议。
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_AI_SEO {

    private static $instance = null;

    public static function get_instance(): self {
        if (null === self::$instance) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    /**
     * 生成 SEO 建议
     *
     * @param string $title   文章标题
     * @param string $content 文章内容（截取前2000字）
     * @return array{success: bool, data?: array, message?: string}
     */
    public function suggest(string $title, string $content = ''): array {
        // seo_ai_enabled 主开关
        if (class_exists('AKSRT_Settings')) {
            $seo = AKSRT_Settings::get_seo_settings();
            if (empty($seo['seo_ai_enabled'])) {
                return ['success' => false, 'message' => 'AI SEO 功能未启用'];
            }
        }

        if (!class_exists('AKSRT_AI')) {
            return ['success' => false, 'message' => 'AI 模块未加载'];
        }

        $ai = AKSRT_AI::get_instance();
        if (!$ai->is_available()) {
            return ['success' => false, 'message' => 'AI 服务未启用'];
        }

        // 截取内容避免 token 超限
        $content = mb_substr($content, 0, 2000);

        $prompt = AKSRT_AI_Prompt::get_instance()->build_seo_prompt($title, $content);

        $result = $ai->generate($prompt, [
            'max_tokens'  => 500,
            'temperature' => 0.5,
        ]);

        if (!$result['success']) {
            return $result;
        }

        // 解析 JSON 响应
        $parsed = $this->parse_seo_response($result['content']);

        return [
            'success' => true,
            'data'    => $parsed,
        ];
    }

    /**
     * 解析 SEO 响应
     */
    private function parse_seo_response(string $content): array {
        $defaults = [
            'suggested_title'       => '',
            'suggested_description' => '',
            'suggested_keywords'    => [],
        ];

        // 尝试 JSON 解析
        $json = json_decode($content, true);
        if (is_array($json)) {
            return array_merge($defaults, $json);
        }

        // 尝试从文本中提取
        $lines = explode("\n", $content);
        $result = $defaults;
        $current_key = '';

        foreach ($lines as $line) {
            $line = trim($line);
            if (empty($line)) continue;

            if (stripos($line, '标题') !== false || stripos($line, 'title') !== false) {
                $current_key = 'suggested_title';
                $result[$current_key] = trim(preg_replace('/^[^:：]+[:：]\s*/', '', $line));
            } elseif (stripos($line, '描述') !== false || stripos($line, 'description') !== false) {
                $current_key = 'suggested_description';
                $result[$current_key] = trim(preg_replace('/^[^:：]+[:：]\s*/', '', $line));
            } elseif (stripos($line, '关键词') !== false || stripos($line, 'keywords') !== false) {
                $current_key = 'suggested_keywords';
                $keywords_str = trim(preg_replace('/^[^:：]+[:：]\s*/', '', $line));
                $result[$current_key] = array_map('trim', explode(',', $keywords_str));
            }
        }

        return $result;
    }
}