<?php
/**
 * @package AKSRT
 */

namespace AKSRT\Admin;

defined('ABSPATH') || exit;

class AIController extends ControllerBase {

    private static $instance = null;

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

    public function register_routes(): void {
        register_rest_route(self::API_NAMESPACE, '/ai/status', [
            'methods'             => 'GET',
            'callback'            => [$this, 'get_status'],
            'permission_callback' => [$this, 'check_logged_in'],
        ]);

        register_rest_route(self::API_NAMESPACE, '/ai/settings', [
            'methods'             => 'POST',
            'callback'            => [$this, 'update_settings'],
            'permission_callback' => [$this, 'check_permission'],
        ]);

        register_rest_route(self::API_NAMESPACE, '/ai/seo-generate', [
            'methods'             => 'POST',
            'callback'            => [$this, 'seo_generate'],
            'permission_callback' => [$this, 'check_logged_in'],
        ]);

        register_rest_route(self::API_NAMESPACE, '/ai/seo-suggest', [
            'methods'             => 'POST',
            'callback'            => [$this, 'seo_suggest'],
            'permission_callback' => [$this, 'check_write_assist'],
        ]);

        register_rest_route(self::API_NAMESPACE, '/ai/summary-suggest', [
            'methods'             => 'POST',
            'callback'            => [$this, 'summary_suggest'],
            'permission_callback' => [$this, 'check_write_assist'],
        ]);

        register_rest_route(self::API_NAMESPACE, '/ai/tags-suggest', [
            'methods'             => 'POST',
            'callback'            => [$this, 'tags_suggest'],
            'permission_callback' => [$this, 'check_write_assist'],
        ]);
    }

    public function check_logged_in(): bool {
        return is_user_logged_in();
    }

    /**
     * 投稿/编辑写作辅助：已登录且可编辑文章或允许前台投稿。
     */
    public function check_write_assist(): bool {
        if (!is_user_logged_in()) {
            return false;
        }
        if (current_user_can('edit_posts')) {
            return true;
        }
        if (class_exists('\AKSRT\Core\FrontSubmit')) {
            return (bool) \AKSRT\Core\FrontSubmit::get_instance()->can_submit();
        }
        return false;
    }

    public function get_status(): \WP_REST_Response {
        if (!class_exists('\AKSRT\Ai\AI')) {
            return $this->success(['data' => [
                'enabled'    => false,
                'provider'   => 'none',
                'configured' => false,
                'available'  => false,
                'backend'    => 'none',
            ]]);
        }

        return $this->success(['data' => \AKSRT\Ai\AI::get_instance()->get_status()]);
    }

    public function update_settings(\WP_REST_Request $request): \WP_REST_Response {
        if (!class_exists('\AKSRT\Ai\AI')) {
            return $this->error(__('AI 模块未加载', 'aksrt'), 500);
        }

        $params  = $this->get_json_params($request);
        $allowed = [
            'enabled'    => 'bool',
            'provider'   => 'string',
            'api_key'    => 'string',
            'api_base'   => 'url',
            'model'      => 'string',
            'max_tokens' => 'int',
            'rate_limit' => 'int',
        ];

        $config = [];
        foreach ($allowed as $key => $type) {
            if (!isset($params[$key])) {
                continue;
            }
            switch ($type) {
                case 'bool':
                    $config[$key] = !empty($params[$key]);
                    break;
                case 'int':
                    $config[$key] = (int) $params[$key];
                    break;
                case 'url':
                    $config[$key] = esc_url_raw((string) $params[$key]);
                    break;
                default:
                    $config[$key] = sanitize_text_field((string) $params[$key]);
            }
        }

        $success = \AKSRT\Ai\AI::get_instance()->update_config($config);
        if ($success) {
            return $this->success([
                'message' => __('AI 设置已保存', 'aksrt'),
                'data'    => \AKSRT\Ai\AI::get_instance()->get_status(),
            ]);
        }
        return $this->error(__('保存失败', 'aksrt'));
    }

    /**
     * POST /ai/seo-generate — 从 post/term 实体生成 SEO 三字段。
     */
    public function seo_generate(\WP_REST_Request $request): \WP_REST_Response {
        if (!class_exists('\AKSRT\Ai\AISEO')) {
            return $this->error(__('AI SEO 模块未加载', 'aksrt'), 500);
        }

        $params = $this->get_json_params($request);
        $type   = sanitize_key((string) ($params['type'] ?? 'post'));
        $id     = absint($params['id'] ?? 0);

        if (!in_array($type, ['post', 'term'], true) || $id <= 0) {
            return $this->error(__('参数错误', 'aksrt'), 422);
        }

        if ($type === 'post') {
            if (!current_user_can('edit_post', $id)) {
                return $this->error(__('权限不足，无法编辑此文章', 'aksrt'), 403);
            }
        } else {
            if (!current_user_can('edit_term', $id)) {
                return $this->error(__('权限不足，无法编辑此分类/标签', 'aksrt'), 403);
            }
        }

        $result = \AKSRT\Ai\AISEO::get_instance()->generate_fields($type, $id);
        if (empty($result['success'])) {
            return $this->error((string) ($result['message'] ?? __('生成失败', 'aksrt')));
        }

        return $this->success(['data' => $result['data']]);
    }

    public function seo_suggest(\WP_REST_Request $request): \WP_REST_Response {
        if (!class_exists('\AKSRT\Ai\AISEO')) {
            return $this->error(__('AI SEO 模块未加载', 'aksrt'), 500);
        }

        $params  = $this->get_json_params($request);
        $title   = sanitize_text_field((string) ($params['title'] ?? ''));
        $content = wp_kses_post((string) ($params['content'] ?? ''));
        $post_id = absint($params['post_id'] ?? 0);

        if ($post_id > 0 && !current_user_can('edit_post', $post_id)) {
            return $this->error(__('权限不足', 'aksrt'), 403);
        }

        if ($title === '') {
            return $this->error(__('标题不能为空', 'aksrt'));
        }

        $result = \AKSRT\Ai\AISEO::get_instance()->suggest($title, $content);
        if (!empty($result['success'])) {
            return $this->success(['data' => $result['data']]);
        }

        return $this->error((string) ($result['message'] ?? __('生成失败', 'aksrt')));
    }

    public function summary_suggest(\WP_REST_Request $request): \WP_REST_Response {
        if (!class_exists('\AKSRT\Ai\AI') || !class_exists('\AKSRT\Ai\AIPrompt')) {
            return $this->error(__('AI 模块未加载', 'aksrt'), 500);
        }

        $params  = $this->get_json_params($request);
        // Accept JSON body or form body (some admin contexts strip JSON).
        if ($params === []) {
            $params = $request->get_params();
            if (!is_array($params)) {
                $params = [];
            }
        }

        $title   = sanitize_text_field((string) ($params['title'] ?? ''));
        $raw     = (string) ($params['content'] ?? '');
        // Keep readable text; strip tags for emptiness / prompt length.
        $plain   = trim(wp_strip_all_tags(html_entity_decode($raw, ENT_QUOTES | ENT_HTML5, 'UTF-8')));
        $content = $plain !== '' ? $plain : trim(wp_strip_all_tags(wp_kses_post($raw)));
        $max_len = max(50, min(500, (int) ($params['max_length'] ?? 200)));

        if ($content === '') {
            return $this->error(__('内容不能为空，请先在编辑器填写正文后再生成摘要', 'aksrt'), 422);
        }

        $ai = \AKSRT\Ai\AI::get_instance();
        if (!$ai->is_available()) {
            return $this->error(
                __('AI 服务未启用或未配置。请到「扩展 → AI 辅助」启用并填写 API Key（或配置 WordPress AI Connectors）。', 'aksrt'),
                503
            );
        }

        // Prefer excerpt-oriented prompt when title is present.
        $prompt_builder = \AKSRT\Ai\AIPrompt::get_instance();
        if ($title !== '' && method_exists($prompt_builder, 'build_excerpt_prompt')) {
            $prompt = $prompt_builder->build_excerpt_prompt($title, $content);
        } else {
            $prompt = $prompt_builder->build_summary_prompt($content, $max_len);
        }

        $result = $ai->generate_text($prompt, [
            'max_tokens'  => min(600, max(120, $max_len * 2)),
            'temperature' => 0.5,
            'system_instruction' => __('你是中文内容编辑，只输出摘要正文，不要标题、前缀或 Markdown。', 'aksrt'),
        ]);

        if (!empty($result['success'])) {
            $summary = trim((string) ($result['content'] ?? ''));
            if ($summary === '') {
                return $this->error(__('AI 返回内容为空，请稍后重试或检查模型配置', 'aksrt'), 502);
            }
            // Soft trim to requested length (characters).
            if (function_exists('mb_substr') && mb_strlen($summary) > $max_len + 20) {
                $summary = mb_substr($summary, 0, $max_len);
            }
            return $this->success([
                'data' => [
                    'summary' => $summary,
                    'backend' => (string) ($result['backend'] ?? ''),
                ],
            ]);
        }

        $message = trim((string) ($result['message'] ?? ''));
        if ($message === '') {
            $message = __('生成失败', 'aksrt');
        }

        // Upstream/provider failures are not client validation errors.
        $status = 502;
        if (str_contains($message, '未启用') || str_contains($message, '未配置')) {
            $status = 503;
        } elseif (str_contains($message, '频繁')) {
            $status = 429;
        }

        return $this->error($message, $status);
    }

    public function tags_suggest(\WP_REST_Request $request): \WP_REST_Response {
        if (!class_exists('\AKSRT\Ai\AI') || !class_exists('\AKSRT\Ai\AIPrompt')) {
            return $this->error(__('AI 模块未加载', 'aksrt'), 500);
        }

        $params  = $this->get_json_params($request);
        $title   = sanitize_text_field((string) ($params['title'] ?? ''));
        $content = wp_kses_post((string) ($params['content'] ?? ''));

        if ($title === '' && trim(wp_strip_all_tags($content)) === '') {
            return $this->error(__('标题或内容不能为空', 'aksrt'));
        }

        $prompt = \AKSRT\Ai\AIPrompt::get_instance()->build_tags_prompt($title, $content);
        $result = \AKSRT\Ai\AI::get_instance()->generate_text($prompt, [
            'max_tokens'  => 300,
            'temperature' => 0.5,
        ]);

        if (!empty($result['success'])) {
            $tags = json_decode((string) $result['content'], true);
            if (!is_array($tags)) {
                $tags = array_filter(array_map('trim', explode(',', (string) $result['content'])));
            }
            $tags = array_values(array_map('sanitize_text_field', $tags));
            return $this->success(['data' => ['tags' => $tags]]);
        }

        return $this->error((string) ($result['message'] ?? __('生成失败', 'aksrt')));
    }
}