/** Explicit WeChat channel prefixes so users can separate chat, page, and scheduled tasks. */

export const WECHAT_CHANNEL_PREFIX = Object.freeze({
  CHAT: 'chat',
  PAGE: 'page',
  SCHEDULED_TASK: 'scheduled_task',
});

const PREFIX_ENTRIES = Object.freeze([
  {
    channel: WECHAT_CHANNEL_PREFIX.CHAT,
    pattern: /^【?\s*聊天\s*】?[：:\s]*/iu,
  },
  {
    channel: WECHAT_CHANNEL_PREFIX.PAGE,
    pattern: /^【?\s*(?:改页|做页|页面)\s*】?[：:\s]*/iu,
  },
  {
    channel: WECHAT_CHANNEL_PREFIX.SCHEDULED_TASK,
    pattern: /^【?\s*定时任务\s*】?[：:\s]*/iu,
  },
]);

/**
 * @returns {{ channel: string|null, body: string, hadPrefix: boolean }}
 */
export function parseWechatChannelPrefix(text) {
  const normalized = String(text ?? '').trim();
  if (!normalized) {
    return { channel: null, body: '', hadPrefix: false };
  }
  for (const entry of PREFIX_ENTRIES) {
    if (!entry.pattern.test(normalized)) continue;
    return {
      channel: entry.channel,
      body: normalized.replace(entry.pattern, '').trim(),
      hadPrefix: true,
    };
  }
  return { channel: null, body: normalized, hadPrefix: false };
}

export function stripWechatChannelPrefix(text) {
  return parseWechatChannelPrefix(text).body;
}

export function hasWechatPageChannelPrefix(text) {
  return parseWechatChannelPrefix(text).channel === WECHAT_CHANNEL_PREFIX.PAGE;
}