// 给管理员发提醒邮件（带节流）。
//
// 用途：定时任务（证书/代理体检、用量告警等）需要给站长发提醒，
// 但又不该每天重复刷屏。收件人固定为 MAIL_ADMIN，发件人默认「小赵」。
//
// 节流：同一 dedupeKey 在 minGapHours 内只发一次，时间戳存 KV `notify:last:<key>`。

import type { Env } from '../types';
import { sendMail } from './mail';

export interface AdminNotifyInput {
  subject: string;
  text: string;
  /** 同一 key 在 minGapHours 内只发一次；不传则不节流 */
  dedupeKey?: string;
  minGapHours?: number;
  fromName?: string;
}

export interface AdminNotifyResult {
  ok: boolean;
  sent: boolean;
  throttled?: boolean;
  lastAt?: string;
  error?: string;
}

function escapeHtml(x: string): string {
  return x.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
}

export function textToHtml(subject: string, text: string): string {
  const paras = text
    .split('\n')
    .map((l) =>
      l.trim()
        ? `<p style="margin:0 0 8px">${escapeHtml(l)}</p>`
        : '<p style="margin:0 0 8px">&nbsp;</p>',
    )
    .join('');
  return (
    `<div style="max-width:560px;margin:0 auto;padding:20px;font-family:'PingFang SC','Microsoft YaHei',sans-serif;color:#253830">` +
    `<div style="font-size:15px;font-weight:600;color:#2f9e63;margin-bottom:12px">${escapeHtml(subject)}</div>` +
    `<div style="background:#fff;border:1px solid #e7e9ee;border-radius:10px;padding:16px;font-size:14px;line-height:1.7">${paras}</div>` +
    `<div style="font-size:12px;color:#8a94a6;margin-top:12px">来自 artalk-cf 定时提醒</div></div>`
  );
}

export async function notifyAdmin(env: Env, input: AdminNotifyInput): Promise<AdminNotifyResult> {
  const to = (env.MAIL_ADMIN || '').trim();
  if (!to) return { ok: false, sent: false, error: 'MAIL_ADMIN not configured' };

  const subject = String(input.subject || '').trim().slice(0, 160) || '提醒';
  const text = String(input.text || '').trim().slice(0, 8000);
  if (!text) return { ok: false, sent: false, error: 'text required' };

  const dedupeKey = String(input.dedupeKey || '').trim().slice(0, 60);
  const minGapHours = Math.min(Math.max(input.minGapHours || 0, 0), 24 * 30);
  const throttleKey = dedupeKey ? `notify:last:${dedupeKey}` : '';

  if (throttleKey && minGapHours > 0) {
    const last = await env.RSS_KV.get(throttleKey);
    const lastAt = last ? parseInt(last, 10) : 0;
    if (lastAt && Date.now() - lastAt < minGapHours * 3600 * 1000) {
      return { ok: true, sent: false, throttled: true, lastAt: new Date(lastAt).toISOString() };
    }
  }

  const sent = await sendMail(env, {
    to,
    subject,
    html: textToHtml(subject, text),
    text,
    fromName: input.fromName || '小赵',
  });

  if (sent && throttleKey) {
    try {
      await env.RSS_KV.put(throttleKey, String(Date.now()), { expirationTtl: 60 * 60 * 24 * 90 });
    } catch {
      /* 节流时间戳写失败不影响已发出的邮件 */
    }
  }
  return { ok: sent, sent };
}