import { Injectable, Logger, OnModuleDestroy, OnModuleInit } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import Redis from 'ioredis';

/**
 * Redis 客户端封装。
 *
 * IAM 对 Redis 是硬依赖：Token 黑名单 / 权限缓存 / active_jtis 列表 / DataScope 缓存 / 部门树缓存。
 * Redis 不可用时，上层服务必须 fail secure（拒绝访问），不得降级为跳过检查。
 * 详见 docs/standards/09-iam-security.md §5.3.5。
 */
@Injectable()
export class RedisService implements OnModuleInit, OnModuleDestroy {
  private readonly logger = new Logger(RedisService.name);
  private client!: Redis;

  constructor(private readonly config: ConfigService) {}

  onModuleInit() {
    const host = this.config.get<string>('redis.host') || 'localhost';
    const port = this.config.get<number>('redis.port') || 6379;
    const password = this.config.get<string>('redis.password');

    this.client = new Redis({
      host,
      port,
      password: password || undefined,
      lazyConnect: false,
      maxRetriesPerRequest: 3,
      enableOfflineQueue: false,
    });

    this.client.on('error', (err) => {
      this.logger.error(`Redis 连接错误：${err.message}`);
    });
    this.client.on('connect', () => {
      this.logger.log(`Redis 已连接：${host}:${port}`);
    });
  }

  async onModuleDestroy() {
    if (this.client) await this.client.quit();
  }

  getClient(): Redis {
    if (!this.client) throw new Error('Redis 客户端未初始化');
    return this.client;
  }

  async ping(): Promise<string> {
    return this.client.ping();
  }

  async get(key: string): Promise<string | null> {
    return this.client.get(key);
  }

  async setEx(key: string, ttlSeconds: number, value: string): Promise<void> {
    await this.client.set(key, value, 'EX', ttlSeconds);
  }

  async del(...keys: string[]): Promise<number> {
    if (keys.length === 0) return 0;
    return this.client.del(...keys);
  }

  async exists(key: string): Promise<boolean> {
    return (await this.client.exists(key)) === 1;
  }

  async sAdd(key: string, ...members: string[]): Promise<number> {
    return this.client.sadd(key, ...members);
  }

  async sRem(key: string, ...members: string[]): Promise<number> {
    return this.client.srem(key, ...members);
  }

  async sMembers(key: string): Promise<string[]> {
    return this.client.smembers(key);
  }

  async expire(key: string, ttlSeconds: number): Promise<void> {
    await this.client.expire(key, ttlSeconds);
  }

  async getJson<T>(key: string): Promise<T | null> {
    const raw = await this.get(key);
    if (!raw) return null;
    try {
      return JSON.parse(raw) as T;
    } catch {
      return null;
    }
  }

  async setJson<T>(key: string, ttlSeconds: number, value: T): Promise<void> {
    await this.setEx(key, ttlSeconds, JSON.stringify(value));
  }
}