import crypto from 'node:crypto';
import {
  addLocalDays,
  formatLocalTime,
  localDateLabel,
  nextDailyRunAt,
  normalizeTimezone,
  startOfLocalDay,
} from './schedule-time.mjs';

const DEFAULT_TIMEZONE = 'Asia/Shanghai';

function nowMs() {
  return Date.now();
}

function rowToItem(row) {
  if (!row) return null;
  return {
    id: row.id,
    userId: row.user_id,
    kind: row.kind,
    title: row.title,
    description: row.description ?? null,
    status: row.status,
    startAt: row.start_at == null ? null : Number(row.start_at),
    endAt: row.end_at == null ? null : Number(row.end_at),
    dueAt: row.due_at == null ? null : Number(row.due_at),
    allDay: Boolean(row.all_day),
    timezone: row.timezone || DEFAULT_TIMEZONE,
    location: row.location ?? null,
    createdAt: Number(row.created_at),
    updatedAt: Number(row.updated_at),
  };
}

function rowToDigest(row) {
  if (!row) return null;
  return {
    id: row.id,
    userId: row.user_id,
    hour: Number(row.hour),
    minute: Number(row.minute),
    timezone: row.timezone || DEFAULT_TIMEZONE,
    channel: row.channel || 'wechat',
    status: row.status,
    nextRunAt: Number(row.next_run_at),
    lastRunAt: row.last_run_at == null ? null : Number(row.last_run_at),
    attempts: Number(row.attempts ?? 0),
  };
}

function formatTodoDigest(items, { now = nowMs(), timezone = DEFAULT_TIMEZONE } = {}) {
  const date = localDateLabel(now, timezone);
  if (!items.length) {
    return `${date} 待办记录\n\n今天暂时没有待办。`;
  }
  const lines = [`${date} 待办记录`, ''];
  items.forEach((item, index) => {
    const time = item.dueAt || item.startAt ? `（${formatLocalTime(item.dueAt || item.startAt, timezone)}）` : '';
    lines.push(`${index + 1}. ${item.title}${time}`);
  });
  return lines.join('\n');
}

export function createScheduleService(pool, options = {}) {
  const defaultTimezone = normalizeTimezone(options.defaultTimezone || process.env.H5_DEFAULT_TIMEZONE);
  const clock = options.clock || { now: nowMs };

  const createItem = async ({
    userId,
    kind = 'task',
    title,
    description = null,
    startAt = null,
    endAt = null,
    dueAt = null,
    allDay = false,
    timezone = defaultTimezone,
    location = null,
    sourceChannel = 'agent',
    sourceSessionId = null,
    sourceMessageId = null,
    sourceText = null,
    metadata = null,
  }) => {
    if (!userId) throw new Error('缺少用户');
    const cleanTitle = String(title ?? '').trim();
    if (!cleanTitle) throw new Error('缺少待办标题');
    const safeKind = kind === 'event' ? 'event' : 'task';
    const id = crypto.randomUUID();
    const ts = clock.now();
    await pool.query(
      `INSERT INTO h5_schedule_items
       (id, user_id, kind, title, description, status, start_at, end_at, due_at, all_day,
        timezone, location, source_channel, source_session_id, source_message_id, source_text,
        metadata_json, created_at, updated_at)
       VALUES (?, ?, ?, ?, ?, 'active', ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
      [
        id,
        userId,
        safeKind,
        cleanTitle,
        description,
        startAt,
        endAt,
        dueAt,
        allDay ? 1 : 0,
        normalizeTimezone(timezone),
        location,
        sourceChannel,
        sourceSessionId,
        sourceMessageId,
        sourceText,
        metadata ? JSON.stringify(metadata) : null,
        ts,
        ts,
      ],
    );
    return {
      id,
      userId,
      kind: safeKind,
      title: cleanTitle,
      startAt,
      endAt,
      dueAt,
      allDay: Boolean(allDay),
      timezone: normalizeTimezone(timezone),
      status: 'active',
      createdAt: ts,
      updatedAt: ts,
    };
  };

  const listItems = async ({ userId, from = null, to = null, status = 'active', limit = 100 } = {}) => {
    if (!userId) throw new Error('缺少用户');
    const clauses = ['user_id = ?', 'deleted_at IS NULL'];
    const params = [userId];
    if (status) {
      clauses.push('status = ?');
      params.push(status);
    }
    if (from != null && to != null) {
      clauses.push(
        `(
          (start_at IS NOT NULL AND start_at >= ? AND start_at < ?)
          OR (due_at IS NOT NULL AND due_at >= ? AND due_at < ?)
          OR (start_at IS NULL AND due_at IS NULL)
        )`,
      );
      params.push(from, to, from, to);
    }
    params.push(Math.max(1, Math.min(500, Number(limit) || 100)));
    const [rows] = await pool.query(
      `SELECT *
       FROM h5_schedule_items
       WHERE ${clauses.join(' AND ')}
       ORDER BY COALESCE(start_at, due_at, 9223372036854775807), created_at
       LIMIT ?`,
      params,
    );
    return rows.map(rowToItem);
  };

  const listTodayTodoItems = async ({ userId, timezone = defaultTimezone, now = clock.now() } = {}) => {
    const start = startOfLocalDay(now, timezone);
    const end = addLocalDays(start, 1, timezone);
    return listItems({ userId, from: start, to: end, status: 'active', limit: 200 });
  };

  const createDailyTodoDigest = async ({
    userId,
    hour,
    minute = 0,
    timezone = defaultTimezone,
    channel = 'wechat',
    sourceChannel = 'agent',
    sourceSessionId = null,
    sourceMessageId = null,
    sourceText = null,
  }) => {
    if (!userId) throw new Error('缺少用户');
    const safeHour = Number(hour);
    const safeMinute = Number(minute);
    if (!Number.isInteger(safeHour) || safeHour < 0 || safeHour > 23) {
      throw new Error('提醒小时无效');
    }
    if (!Number.isInteger(safeMinute) || safeMinute < 0 || safeMinute > 59) {
      throw new Error('提醒分钟无效');
    }
    const tz = normalizeTimezone(timezone);
    const nextRunAt = nextDailyRunAt({
      hour: safeHour,
      minute: safeMinute,
      timezone: tz,
      now: clock.now(),
    });
    const id = crypto.randomUUID();
    const ts = clock.now();
    await pool.query(
      `INSERT INTO h5_schedule_digest_subscriptions
       (id, user_id, digest_type, hour, minute, timezone, channel, status, next_run_at,
        source_channel, source_session_id, source_message_id, source_text, created_at, updated_at)
       VALUES (?, ?, 'todo_day', ?, ?, ?, ?, 'active', ?, ?, ?, ?, ?, ?, ?)
       ON DUPLICATE KEY UPDATE
         hour = VALUES(hour),
         minute = VALUES(minute),
         timezone = VALUES(timezone),
         channel = VALUES(channel),
         status = 'active',
         next_run_at = VALUES(next_run_at),
         source_channel = VALUES(source_channel),
         source_session_id = VALUES(source_session_id),
         source_message_id = VALUES(source_message_id),
         source_text = VALUES(source_text),
         updated_at = VALUES(updated_at)`,
      [
        id,
        userId,
        safeHour,
        safeMinute,
        tz,
        channel,
        nextRunAt,
        sourceChannel,
        sourceSessionId,
        sourceMessageId,
        sourceText,
        ts,
        ts,
      ],
    );
    const [rows] = await pool.query(
      `SELECT * FROM h5_schedule_digest_subscriptions
       WHERE user_id = ? AND digest_type = 'todo_day' AND channel = ?
       LIMIT 1`,
      [userId, channel],
    );
    return rowToDigest(rows[0]) || {
      id,
      userId,
      hour: safeHour,
      minute: safeMinute,
      timezone: tz,
      channel,
      status: 'active',
      nextRunAt,
      lastRunAt: null,
      attempts: 0,
    };
  };

  const listDueDigestSubscriptions = async ({ now = clock.now(), limit = 50 } = {}) => {
    const [rows] = await pool.query(
      `SELECT *
       FROM h5_schedule_digest_subscriptions
       WHERE next_run_at <= ?
         AND (status = 'active' OR (status = 'locked' AND locked_until IS NOT NULL AND locked_until <= ?))
       ORDER BY next_run_at ASC
       LIMIT ?`,
      [now, now, Math.max(1, Math.min(200, Number(limit) || 50))],
    );
    return rows.map(rowToDigest);
  };

  const lockDigestSubscription = async (id, { now = clock.now(), lockMs = 120_000 } = {}) => {
    const lockedUntil = now + lockMs;
    const [result] = await pool.query(
      `UPDATE h5_schedule_digest_subscriptions
       SET status = 'locked', locked_until = ?, attempts = attempts + 1, updated_at = ?
       WHERE id = ? AND (status = 'active' OR (status = 'locked' AND locked_until IS NOT NULL AND locked_until <= ?))`,
      [lockedUntil, now, id, now],
    );
    if (Number(result?.affectedRows ?? 0) !== 1) return null;
    const [rows] = await pool.query(
      `SELECT * FROM h5_schedule_digest_subscriptions WHERE id = ? LIMIT 1`,
      [id],
    );
    return rowToDigest(rows[0]);
  };

  const markDigestSent = async (subscription, { now = clock.now() } = {}) => {
    const nextRunAt = nextDailyRunAt({
      hour: subscription.hour,
      minute: subscription.minute,
      timezone: subscription.timezone,
      now: now + 1000,
    });
    await pool.query(
      `UPDATE h5_schedule_digest_subscriptions
       SET status = 'active', next_run_at = ?, last_run_at = ?, locked_until = NULL,
           last_error = NULL, updated_at = ?
       WHERE id = ?`,
      [nextRunAt, now, now, subscription.id],
    );
    return { ...subscription, status: 'active', nextRunAt, lastRunAt: now };
  };

  const markDigestFailed = async (subscription, error, { now = clock.now(), retryMs = 10 * 60 * 1000, maxAttempts = 5 } = {}) => {
    const attempts = Number(subscription.attempts ?? 0);
    const status = attempts >= maxAttempts ? 'failed' : 'active';
    const nextRunAt = status === 'active' ? now + retryMs : subscription.nextRunAt;
    await pool.query(
      `UPDATE h5_schedule_digest_subscriptions
       SET status = ?, next_run_at = ?, locked_until = NULL, last_error = ?, updated_at = ?
       WHERE id = ?`,
      [status, nextRunAt, String(error?.message ?? error ?? '发送失败').slice(0, 500), now, subscription.id],
    );
  };

  const logDelivery = async ({ subscriptionId, userId, channel = 'wechat', status, providerMessageId = null, errorCode = null, errorMessage = null }) => {
    await pool.query(
      `INSERT INTO h5_schedule_delivery_logs
       (id, reminder_id, subscription_id, user_id, channel, status, provider_message_id,
        error_code, error_message, created_at)
       VALUES (?, NULL, ?, ?, ?, ?, ?, ?, ?, ?)`,
      [
        crypto.randomUUID(),
        subscriptionId,
        userId,
        channel,
        status,
        providerMessageId,
        errorCode,
        errorMessage ? String(errorMessage).slice(0, 500) : null,
        clock.now(),
      ],
    );
  };

  const buildTodoDigestText = async ({ userId, timezone = defaultTimezone, now = clock.now() }) => {
    const items = await listTodayTodoItems({ userId, timezone, now });
    return formatTodoDigest(items, { now, timezone });
  };

  return {
    createItem,
    listItems,
    listTodayTodoItems,
    createDailyTodoDigest,
    listDueDigestSubscriptions,
    lockDigestSubscription,
    markDigestSent,
    markDigestFailed,
    logDelivery,
    buildTodoDigestText,
  };
}