<?php
/**
 * ForumSearchService —— 论坛帖子检索（ES 增强，默认 LIKE 降级）
 */
declare(strict_types=1);

namespace addon\forum\service;

use addon\forum\model\ForumTopic;
use think\facade\Db;
use ywxapp\library\Search\EsSearch;

class ForumSearchService
{
    protected static function conf(): array
    {
        return [
            'engine' => config('forum.search_engine', 'like'),
            'host'   => config('forum.es_host', 'http://127.0.0.1:9200'),
            'index'  => config('forum.es_index', 'ywxapp_forum'),
        ];
    }

    /**
     * 前台搜索：仅返回 status=1 的帖子
     * @return \think\Paginator
     */
    public static function search(string $kw, int $page = 1, int $size = 20)
    {
        $kw = trim($kw);
        if ($kw === '') {
            return ForumTopic::where('status', 1)->order('id desc')->paginate($size, false, ['page' => $page]);
        }

        $cfg = self::conf();
        if ($cfg['engine'] === 'es') {
            try {
                EsSearch::ensureIndex($cfg['host'], $cfg['index'], ['title', 'content']);
                $ids = EsSearch::search($cfg['host'], $cfg['index'], $kw, ['title', 'content'], 200);
                if (!empty($ids)) {
                    // 保持相关度顺序 + 回表取完整行
                    $list = ForumTopic::with(['board'])
                        ->where('status', 1)
                        ->whereIn('id', $ids)
                        ->select()
                        ->all();
                    $order = array_flip($ids);
                    $list = collect($list)->sortBy(function ($m) use ($order) {
                        return $order[$m->id] ?? PHP_INT_MAX;
                    })->values();
                    // 包装成分页结构（ES 结果集直接返回，分页信息从 ids 推算）
                    $total = count($ids);
                    $coll = $list;
                    $paginator = new \think\Paginator($coll, $size, $page);
                    return $paginator;
                }
            } catch (\RuntimeException $e) {
                // ES 不可用：降级 LIKE
            }
        }

        // 默认 LIKE 分支
        return ForumTopic::with(['board'])
            ->where('status', 1)
            ->where('title', 'like', '%' . addslashes($kw) . '%')
            ->order('id desc')
            ->paginate($size, false, ['page' => $page]);
    }

    /**
     * 同步单条到 ES（发帖/编辑后调用）
     */
    public static function sync(int $topicId): void
    {
        $cfg = self::conf();
        if ($cfg['engine'] !== 'es') {
            return;
        }
        try {
            $t = ForumTopic::find($topicId);
            if (!$t) {
                return;
            }
            EsSearch::ensureIndex($cfg['host'], $cfg['index'], ['title', 'content']);
            if ((int) $t->status !== 1) {
                EsSearch::deleteDoc($cfg['host'], $cfg['index'], $topicId);
                return;
            }
            EsSearch::indexDoc($cfg['host'], $cfg['index'], $topicId, [
                'title'   => $t->title,
                'content' => $t->content,
            ]);
        } catch (\RuntimeException $e) {
            // 静默：索引失败不影响主流程
        }
    }

    /**
     * 删除索引文档
     */
    public static function remove(int $topicId): void
    {
        $cfg = self::conf();
        if ($cfg['engine'] !== 'es') {
            return;
        }
        try {
            EsSearch::deleteDoc($cfg['host'], $cfg['index'], $topicId);
        } catch (\RuntimeException $e) {
        }
    }

    /**
     * 相关帖子推荐：优先 ES more_like_this，未启用 ES 时降级为「同版块 + 标题关键词」相似度
     * @return \addon\forum\model\ForumTopic[]
     */
    public static function related(int $topicId, int $limit = 6): array
    {
        $topic = ForumTopic::find($topicId);
        if (!$topic) {
            return [];
        }
        $cfg = self::conf();
        if ($cfg['engine'] === 'es') {
            try {
                EsSearch::ensureIndex($cfg['host'], $cfg['index'], ['title', 'content']);
                $ids = EsSearch::moreLikeThis(
                    $cfg['host'], $cfg['index'],
                    $topic->title . "\n" . $topic->content,
                    ['title', 'content'], $topicId, $limit
                );
                if (!empty($ids)) {
                    return ForumTopic::with(['board'])
                        ->where('status', 1)
                        ->whereIn('id', $ids)
                        ->select()
                        ->all();
                }
            } catch (\RuntimeException $e) {
                // 降级
            }
        }

        // 降级：同版块 + 标题关键词重叠，按发布时间取最近
        $kw = trim($topic->title);
        return ForumTopic::with(['board'])
            ->where('status', 1)
            ->where('id', '<>', $topicId)
            ->where('board_id', $topic->board_id)
            ->where('title', 'like', '%' . addslashes(mb_substr($kw, 0, 10)) . '%')
            ->order('id desc')
            ->limit($limit)
            ->select()
            ->all();
    }

    /**
     * 附近帖子（GEO/LBS）：Haversine 球面距离过滤，零外部依赖
     * @param float $lat 纬度
     * @param float $lng 经度
     * @param float $radiusKm 半径(千米)，默认 10
     * @param int $limit 返回数量
     * @return \addon\forum\model\ForumTopic[]
     */
    public static function nearby(float $lat, float $lng, float $radiusKm = 10.0, int $limit = 20): array
    {
        if ($lat == 0.0 && $lng == 0.0) {
            return [];
        }
        $lat = (float) $lat;
        $lng = (float) $lng;
        // 地球半径 km
        $R = 6371;
        return ForumTopic::with(['board'])
            ->where('status', 1)
            ->where('lat', '<>', 0)
            ->where('lng', '<>', 0)
            ->fieldRaw("*, ({$R} * acos(cos(radians({$lat})) * cos(radians(lat)) * cos(radians(lng) - radians({$lng})) + sin(radians({$lat})) * sin(radians(lat)))) AS distance_km")
            ->having('distance_km <= ' . floatval($radiusKm))
            ->order('distance_km', 'asc')
            ->limit($limit)
            ->select()
            ->all();
    }
}