import { Injectable, Logger } from '@nestjs/common';
import type { WecomPushCondition } from '@dukang/shared-types';
import { RedisService } from '../redis/redis.service';
import { WecomMessagePushService } from '../../integrations/wecom/wecom-message-push.service';
import { ALERT_DEDUPE_TTL_SEC, type AlertLevel } from './alert.constants';

export type AlertNotifyInput = {
  level: AlertLevel;
  category: string;
  title: string;
  detail: string;
  dedupeKey: string;
  dedupeTtlSec?: number;
  /** 覆盖默认事件 key 映射 */
  eventKeys?: WecomPushCondition[];
};

@Injectable()
export class AlertService {
  private readonly logger = new Logger(AlertService.name);

  constructor(
    private readonly redis: RedisService,
    private readonly wecomPush: WecomMessagePushService,
  ) {}

  /** 异步告警，不阻塞调用方 */
  notify(input: AlertNotifyInput): void {
    void this.notifyAsync(input).catch((e) => {
      this.logger.warn(`alert notify failed: ${e instanceof Error ? e.message : String(e)}`);
    });
  }

  async notifyAsync(input: AlertNotifyInput): Promise<boolean> {
    const eventKeys = resolveAlertEventKeys(input);
    const hasAny = await Promise.all(eventKeys.map((k) => this.wecomPush.hasEnabledPushes(k)));
    if (!hasAny.some(Boolean)) return false;

    const ttl = input.dedupeTtlSec ?? ALERT_DEDUPE_TTL_SEC;
    const dedupeRedisKey = `alert:dedupe:${input.dedupeKey}`;
    try {
      const ok = await this.redis.client.set(dedupeRedisKey, '1', 'EX', ttl, 'NX');
      if (ok !== 'OK') return false;
    } catch (e) {
      this.logger.warn(
        `alert dedupe redis error, send anyway: ${e instanceof Error ? e.message : String(e)}`,
      );
    }

    return this.sendMarkdownNow(input, eventKeys);
  }

  private async sendMarkdownNow(
    input: AlertNotifyInput,
    eventKeys: WecomPushCondition[],
  ): Promise<boolean> {
    const envLabel = (process.env.WECOM_ALERT_ENV_LABEL || process.env.NODE_ENV || 'local').trim();
    const now = new Date().toLocaleString('zh-CN', { timeZone: 'Asia/Shanghai' });
    const content = [
      `## [${input.level}] ${escapeMd(input.title)}`,
      `> 环境：<font color="comment">${escapeMd(envLabel)}</font>`,
      `> 类别：<font color="comment">${escapeMd(input.category)}</font>`,
      `> 时间：${escapeMd(now)}`,
      '',
      escapeMd(input.detail).slice(0, 3500),
    ].join('\n');

    let sent = 0;
    for (const eventKey of eventKeys) {
      sent += await this.wecomPush.dispatchMarkdown(eventKey, content, { applyMention: false });
    }
    return sent > 0;
  }
}

function resolveAlertEventKeys(input: AlertNotifyInput): WecomPushCondition[] {
  if (input.eventKeys?.length) return [...new Set(input.eventKeys)];
  if (input.category === 'pay') return ['alert.pay'];
  if (input.category === 'redeem') return ['alert.redeem'];
  if (input.category === 'settlement') return ['alert.settlement'];
  if (input.category === 'ops') return ['alert.ops'];
  return ['alert.system'];
}

/** 轻量转义，保留企微 markdown 的 <font> 标签可用 */
function escapeMd(s: string): string {
  return s.replace(/([\\`*_[\]])/g, '\\$1');
}