<?php

declare(strict_types=1);

namespace app\common\service;

use support\Log;
use support\Redis;
use Throwable;

/**
 * 通过 Redis 列表在不同进程间投递 WebSocket 事件。
 *
 * 入队失败统一返回 false 并写 ws 日志（runtime/logs/ws.log），便于排查"为什么没有推送"。
 */
final class GameWebSocketEventBus
{
    private const KEY_QUEUE = 'dfw:v1:ws:event:queue';
    private const MAX_BATCH = 100;

    /**
     * @param array<string, mixed> $data
     * @return bool 是否成功入队（false 表示 Redis 不可用或参数非法，调用方应避免标记"已推送"）
     */
    public static function publish(string $topic, array $data): bool
    {
        $topic = trim($topic);
        if ($topic === '') {
            return false;
        }
        $payload = [
            'topic' => $topic,
            'event' => $topic,
            'data' => $data,
            'server_time' => time(),
        ];
        $json = json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
        if (!is_string($json) || $json === '') {
            Log::channel('ws')->warning('publish skip: invalid json payload', [
                'topic' => $topic,
            ]);
            return false;
        }
        try {
            $len = Redis::lPush(self::KEY_QUEUE, $json);
            $ok = is_numeric($len) && (int) $len > 0;
            if ($ok) {
                $uid = filter_var($data['user_id'] ?? 0, FILTER_VALIDATE_INT);
                Log::channel('ws')->info('publish', [
                    'topic' => $topic,
                    'user_id' => $uid === false ? 0 : (int) $uid,
                    'queue_len_after' => (int) $len,
                    'payload_size' => strlen($json),
                ]);
            } else {
                Log::channel('ws')->warning('publish lpush returned non-positive', [
                    'topic' => $topic,
                    'returned' => $len,
                ]);
            }
            return $ok;
        } catch (Throwable $e) {
            Log::channel('ws')->error('publish failed (redis exception)', [
                'topic' => $topic,
                'error' => $e->getMessage(),
            ]);
            Log::warning('ws event bus publish failed', [
                'topic' => $topic,
                'error' => $e->getMessage(),
            ]);
            return false;
        }
    }

    /**
     * @return list<array{topic:string,event:string,data:array<string,mixed>,server_time:int}>
     */
    public static function popBatch(int $limit = self::MAX_BATCH): array
    {
        if ($limit <= 0) {
            return [];
        }
        if ($limit > self::MAX_BATCH) {
            $limit = self::MAX_BATCH;
        }

        $out = [];
        try {
            for ($i = 0; $i < $limit; $i++) {
                $raw = Redis::rPop(self::KEY_QUEUE);
                if (!is_string($raw) || $raw === '') {
                    break;
                }
                $decoded = json_decode($raw, true);
                if (!is_array($decoded)) {
                    continue;
                }
                $topicRaw = $decoded['topic'] ?? '';
                $eventRaw = $decoded['event'] ?? '';
                $dataRaw = $decoded['data'] ?? [];
                $serverTimeRaw = $decoded['server_time'] ?? time();
                if (!is_string($topicRaw) || trim($topicRaw) === '') {
                    continue;
                }
                $topic = trim($topicRaw);
                $event = is_string($eventRaw) && trim($eventRaw) !== '' ? trim($eventRaw) : $topic;
                $data = is_array($dataRaw) ? $dataRaw : [];
                $serverTime = filter_var($serverTimeRaw, FILTER_VALIDATE_INT);
                if ($serverTime === false || $serverTime <= 0) {
                    $serverTime = time();
                }
                $out[] = [
                    'topic' => $topic,
                    'event' => $event,
                    'data' => $data,
                    'server_time' => $serverTime,
                ];
            }
        } catch (Throwable $e) {
            Log::channel('ws')->error('popBatch failed (redis exception)', [
                'error' => $e->getMessage(),
                'popped' => count($out),
            ]);
            return $out;
        }

        return $out;
    }

    /**
     * 当前队列堆积长度（监控用）。
     */
    public static function queueLength(): int
    {
        try {
            $len = Redis::lLen(self::KEY_QUEUE);
            return is_numeric($len) ? (int) $len : 0;
        } catch (Throwable) {
            return -1;
        }
    }
}