packages/core/src/plan-reminders.ts

import { BOT_PROVIDERS, isBotDeliveryProvider, type BotProvider } from './bot-chat-settings.js';
import { compileCronExpression, type CronCompileError } from './cron-expression.js';

export const PLAN_REMINDER_TITLE_MAX_CHARS = 120;
export const PLAN_REMINDER_NOTE_MAX_CHARS = 1000;
export const PLAN_REMINDER_DELIVERY_CHAT_ID_MAX_CHARS = 160;
export const PLAN_REMINDER_CRON_EXPRESSION_MAX_CHARS = 80;
export const PLAN_REMINDER_MAX_DELAY_MS = 366 * 24 * 60 * 60 * 1000;
export const PLAN_REMINDER_RUN_HISTORY_LIMIT = 10;

export const PLAN_REMINDER_STATUSES = ['scheduled', 'paused', 'completed'] as const;
export type PlanReminderStatus = (typeof PLAN_REMINDER_STATUSES)[number];

export const PLAN_REMINDER_RUN_STATUSES = ['triggered', 'blocked', 'failed'] as const;
export type PlanReminderRunStatus = (typeof PLAN_REMINDER_RUN_STATUSES)[number];

export type PlanReminderBlockReason = 'incognito_active' | 'bot_delivery_unavailable';

export const PLAN_REMINDER_RECURRENCES = ['none', 'daily', 'weekly', 'monthly', 'cron'] as const;
export type PlanReminderRecurrence = (typeof PLAN_REMINDER_RECURRENCES)[number];
export type PlanReminderRecurringFrequency = Exclude<PlanReminderRecurrence, 'none' | 'cron'>;

export type PlanReminderSchedule =
  | PlanReminderOnceSchedule
  | PlanReminderRecurringSchedule
  | PlanReminderCronSchedule;
export type PlanReminderDeliveryTarget =
  | PlanReminderLocalDeliveryTarget
  | PlanReminderBotDeliveryTarget;

export interface PlanReminderLocalDeliveryTarget {
  channel: 'local';
}

export interface PlanReminderBotDeliveryTarget {
  channel: 'bot';
  platform: BotProvider;
  chatId: string;
}

export interface PlanReminderOnceSchedule {
  kind: 'once';
  runAt: number;
}

export interface PlanReminderRecurringSchedule {
  kind: 'recurring';
  startAt: number;
  recurrence: PlanReminderRecurringFrequency;
}

export interface PlanReminderCronSchedule {
  kind: 'cron';
  startAt: number;
  expression: string;
}

export interface PlanReminderRunRecord {
  id: string;
  at: number;
  status: PlanReminderRunStatus;
  message: string;
  blockReason?: PlanReminderBlockReason;
}

export interface PlanReminder {
  id: string;
  title: string;
  note: string;
  schedule: PlanReminderSchedule;
  delivery: PlanReminderDeliveryTarget;
  status: PlanReminderStatus;
  enabled: boolean;
  createdAt: number;
  updatedAt: number;
  nextRunAt?: number;
  lastRun?: PlanReminderRunRecord;
  runs: PlanReminderRunRecord[];
  runCount: number;
}

export interface CreatePlanReminderInput {
  title: unknown;
  note?: unknown;
  runAt: unknown;
  recurrence?: unknown;
  cronExpression?: unknown;
  delivery?: unknown;
}

export interface UpdatePlanReminderInput {
  title?: unknown;
  note?: unknown;
  runAt?: unknown;
  recurrence?: unknown;
  cronExpression?: unknown;
  delivery?: unknown;
  enabled?: unknown;
}

export type PlanReminderNormalizeResult<T> =
  | { ok: true; value: T }
  | {
      ok: false;
      reason:
        | 'invalid_title'
        | 'invalid_note'
        | 'invalid_run_at'
        | 'invalid_recurrence'
        | 'invalid_cron'
        | 'invalid_delivery'
        | 'invalid_enabled';
      message: string;
    };

type PlanReminderNormalizeErrorReason = Extract<
  PlanReminderNormalizeResult<never>,
  { ok: false }
>['reason'];

export function isPlanReminderStatus(value: unknown): value is PlanReminderStatus {
  return typeof value === 'string' && (PLAN_REMINDER_STATUSES as readonly string[]).includes(value);
}

export function normalizeCreatePlanReminderInput(
  input: unknown,
  now: number,
): PlanReminderNormalizeResult<{
  title: string;
  note: string;
  schedule: PlanReminderSchedule;
  delivery: PlanReminderDeliveryTarget;
  nextRunAt: number;
}> {
  if (typeof input !== 'object' || input === null || Array.isArray(input)) {
    return invalid('invalid_title', 'Plan reminder input must be an object');
  }
  const record = input as CreatePlanReminderInput;
  const title = normalizePlanReminderTitle(record.title);
  if (!title.ok) return title;
  const note = normalizePlanReminderNote(record.note);
  if (!note.ok) return note;
  const runAt = normalizePlanReminderRunAt(record.runAt, now);
  if (!runAt.ok) return runAt;
  const recurrence = normalizePlanReminderRecurrence(record.recurrence);
  if (!recurrence.ok) return recurrence;
  const cronExpression = normalizePlanReminderCronExpressionForRecurrence(
    recurrence.value,
    record.cronExpression,
  );
  if (!cronExpression.ok) return cronExpression;
  const delivery = normalizePlanReminderDeliveryTarget(record.delivery);
  if (!delivery.ok) return delivery;
  const schedule = createPlanReminderSchedule(runAt.value, recurrence.value, cronExpression.value);
  const nextRunAt = nextPlanReminderRunAtAfter(schedule, now);
  if (typeof nextRunAt !== 'number') {
    return invalid('invalid_cron', 'Plan reminder cron expression has no run within one year');
  }
  return {
    ok: true,
    value: { title: title.value, note: note.value, schedule, delivery: delivery.value, nextRunAt },
  };
}

export function normalizeUpdatePlanReminderInput(
  input: unknown,
  now: number,
): PlanReminderNormalizeResult<{
  title?: string;
  note?: string;
  runAt?: number;
  recurrence?: PlanReminderRecurrence;
  cronExpression?: string;
  delivery?: PlanReminderDeliveryTarget;
  enabled?: boolean;
}> {
  if (typeof input !== 'object' || input === null || Array.isArray(input)) {
    return invalid('invalid_title', 'Plan reminder update must be an object');
  }
  const record = input as UpdatePlanReminderInput;
  const patch: {
    title?: string;
    note?: string;
    runAt?: number;
    recurrence?: PlanReminderRecurrence;
    cronExpression?: string;
    delivery?: PlanReminderDeliveryTarget;
    enabled?: boolean;
  } = {};
  if (record.title !== undefined) {
    const title = normalizePlanReminderTitle(record.title);
    if (!title.ok) return title;
    patch.title = title.value;
  }
  if (record.note !== undefined) {
    const note = normalizePlanReminderNote(record.note);
    if (!note.ok) return note;
    patch.note = note.value;
  }
  if (record.runAt !== undefined) {
    const runAt = normalizePlanReminderRunAt(record.runAt, now);
    if (!runAt.ok) return runAt;
    patch.runAt = runAt.value;
  }
  if (record.recurrence !== undefined) {
    const recurrence = normalizePlanReminderRecurrence(record.recurrence);
    if (!recurrence.ok) return recurrence;
    patch.recurrence = recurrence.value;
  }
  if (record.cronExpression !== undefined) {
    const cronExpression = normalizePlanReminderCronExpression(record.cronExpression);
    if (!cronExpression.ok) return cronExpression;
    patch.cronExpression = cronExpression.value;
  }
  if (Object.prototype.hasOwnProperty.call(record, 'delivery')) {
    const delivery = normalizePlanReminderDeliveryTarget(record.delivery);
    if (!delivery.ok) return delivery;
    patch.delivery = delivery.value;
  }
  if (record.enabled !== undefined) {
    if (typeof record.enabled !== 'boolean') {
      return invalid('invalid_enabled', 'Plan reminder enabled must be a boolean');
    }
    patch.enabled = record.enabled;
  }
  return { ok: true, value: patch };
}

export function normalizePlanReminderTitle(input: unknown): PlanReminderNormalizeResult<string> {
  if (typeof input !== 'string') {
    return invalid('invalid_title', 'Plan reminder title must be a string');
  }
  const title = input.normalize('NFC').replace(/\s+/g, ' ').trim();
  if (title.length === 0) {
    return invalid('invalid_title', 'Plan reminder title cannot be empty');
  }
  if (Array.from(title).length > PLAN_REMINDER_TITLE_MAX_CHARS) {
    return invalid(
      'invalid_title',
      `Plan reminder title must be ${PLAN_REMINDER_TITLE_MAX_CHARS} characters or fewer`,
    );
  }
  return { ok: true, value: title };
}

export function normalizePlanReminderNote(input: unknown): PlanReminderNormalizeResult<string> {
  if (input === undefined || input === null) return { ok: true, value: '' };
  if (typeof input !== 'string') {
    return invalid('invalid_note', 'Plan reminder note must be a string');
  }
  const note = input.normalize('NFC').replace(/\r\n?/g, '\n').trim();
  if (Array.from(note).length > PLAN_REMINDER_NOTE_MAX_CHARS) {
    return invalid(
      'invalid_note',
      `Plan reminder note must be ${PLAN_REMINDER_NOTE_MAX_CHARS} characters or fewer`,
    );
  }
  return { ok: true, value: note };
}

export function normalizePlanReminderRunAt(
  input: unknown,
  now: number,
): PlanReminderNormalizeResult<number> {
  let value: number;
  if (typeof input === 'number') {
    value = input;
  } else if (typeof input === 'string' && input.trim().length > 0) {
    value = Date.parse(input);
  } else {
    return invalid('invalid_run_at', 'Plan reminder runAt must be a timestamp or ISO date string');
  }
  if (!Number.isFinite(value)) {
    return invalid('invalid_run_at', 'Plan reminder runAt must be a valid time');
  }
  const runAt = Math.trunc(value);
  if (runAt < now) {
    return invalid('invalid_run_at', 'Plan reminder runAt must be in the future');
  }
  if (runAt - now > PLAN_REMINDER_MAX_DELAY_MS) {
    return invalid('invalid_run_at', 'Plan reminder runAt must be within one year');
  }
  return { ok: true, value: runAt };
}

export function normalizePlanReminderRecurrence(
  input: unknown,
): PlanReminderNormalizeResult<PlanReminderRecurrence> {
  if (input === undefined || input === null || input === '' || input === 'none') {
    return { ok: true, value: 'none' };
  }
  if (typeof input !== 'string') {
    return invalid('invalid_recurrence', 'Plan reminder recurrence must be a string');
  }
  if (!PLAN_REMINDER_RECURRENCES.includes(input as PlanReminderRecurrence)) {
    return invalid(
      'invalid_recurrence',
      'Plan reminder recurrence must be none, daily, weekly, monthly, or cron',
    );
  }
  return { ok: true, value: input as PlanReminderRecurrence };
}

export function normalizePlanReminderCronExpression(
  input: unknown,
): PlanReminderNormalizeResult<string> {
  if (typeof input !== 'string') {
    return invalid('invalid_cron', 'Plan reminder cron expression must be a string');
  }
  const expression = input.normalize('NFC').replace(/\s+/g, ' ').trim();
  if (expression.length === 0) {
    return invalid('invalid_cron', 'Plan reminder cron expression cannot be empty');
  }
  if (Array.from(expression).length > PLAN_REMINDER_CRON_EXPRESSION_MAX_CHARS) {
    return invalid(
      'invalid_cron',
      `Plan reminder cron expression must be ${PLAN_REMINDER_CRON_EXPRESSION_MAX_CHARS} characters or fewer`,
    );
  }
  const compiled = compileCronExpression(expression, { profile: 'plan-reminder-v1' });
  if (!compiled.ok) return invalid('invalid_cron', planReminderCronErrorMessage(compiled.error));
  return { ok: true, value: expression };
}

function normalizePlanReminderCronExpressionForRecurrence(
  recurrence: PlanReminderRecurrence,
  input: unknown,
): PlanReminderNormalizeResult<string | undefined> {
  if (recurrence !== 'cron') return { ok: true, value: undefined };
  const cronExpression = normalizePlanReminderCronExpression(input);
  if (!cronExpression.ok) return cronExpression;
  return cronExpression;
}

export function normalizePlanReminderDeliveryTarget(
  input: unknown,
): PlanReminderNormalizeResult<PlanReminderDeliveryTarget> {
  if (input === undefined || input === null) return { ok: true, value: { channel: 'local' } };
  if (typeof input !== 'object' || Array.isArray(input)) {
    return invalid('invalid_delivery', 'Plan reminder delivery must be an object');
  }
  const record = input as Partial<PlanReminderDeliveryTarget>;
  if (record.channel === 'local') return { ok: true, value: { channel: 'local' } };
  if (record.channel !== 'bot') {
    return invalid('invalid_delivery', 'Plan reminder delivery channel must be local or bot');
  }
  const platform = (record as Partial<PlanReminderBotDeliveryTarget>).platform;
  if (!isBotProvider(platform)) {
    return invalid('invalid_delivery', 'Plan reminder bot delivery platform is not supported');
  }
  if (!isBotDeliveryProvider(platform)) {
    return invalid(
      'invalid_delivery',
      'Plan reminder bot delivery platform is not enabled for delivery',
    );
  }
  const chatId = normalizePlanReminderDeliveryChatId(
    (record as Partial<PlanReminderBotDeliveryTarget>).chatId,
  );
  if (!chatId.ok) return chatId;
  return {
    ok: true,
    value: {
      channel: 'bot',
      platform,
      chatId: chatId.value,
    },
  };
}

export function normalizePlanReminderDeliveryChatId(
  input: unknown,
): PlanReminderNormalizeResult<string> {
  if (typeof input !== 'string') {
    return invalid('invalid_delivery', 'Plan reminder bot chatId must be a string');
  }
  const chatId = input
    .normalize('NFC')
    .replace(/[\u0000-\u001F\u007F-\u009F]+/g, ' ')
    .replace(/[\p{Cf}]+/gu, ' ')
    .replace(/\s+/g, ' ')
    .trim();
  if (chatId.length === 0) {
    return invalid('invalid_delivery', 'Plan reminder bot chatId cannot be empty');
  }
  if (Array.from(chatId).length > PLAN_REMINDER_DELIVERY_CHAT_ID_MAX_CHARS) {
    return invalid(
      'invalid_delivery',
      `Plan reminder bot chatId must be ${PLAN_REMINDER_DELIVERY_CHAT_ID_MAX_CHARS} characters or fewer`,
    );
  }
  return { ok: true, value: chatId };
}

export function formatPlanReminderDeliveryTarget(delivery: PlanReminderDeliveryTarget): string {
  if (delivery.channel === 'local') return '本地提醒';
  return `${botProviderLabel(delivery.platform)} · ${delivery.chatId}`;
}

export function formatPlanReminderDeliveryMessage(
  reminder: Pick<PlanReminder, 'title' | 'note'>,
): string {
  const lines = [`计划提醒：${reminder.title}`];
  if (reminder.note.trim()) lines.push('', reminder.note.trim());
  return lines.join('\n');
}

export function createPlanReminderSchedule(
  runAt: number,
  recurrence: PlanReminderRecurrence,
  cronExpression?: string,
): PlanReminderSchedule {
  if (recurrence === 'none') return { kind: 'once', runAt };
  if (recurrence === 'cron') {
    if (!cronExpression) throw new Error('Plan reminder cron expression is required');
    return { kind: 'cron', startAt: runAt, expression: cronExpression };
  }
  return { kind: 'recurring', startAt: runAt, recurrence };
}

export function planReminderScheduleStartAt(schedule: PlanReminderSchedule): number {
  return schedule.kind === 'once' ? schedule.runAt : schedule.startAt;
}

export function nextPlanReminderRunAtAfter(
  schedule: PlanReminderSchedule,
  after: number,
): number | undefined {
  if (schedule.kind === 'once') return schedule.runAt > after ? schedule.runAt : undefined;
  if (schedule.kind === 'cron') return nextCronRunAtAfter(schedule, after);
  if (schedule.startAt > after) return schedule.startAt;
  return nextRecurringRunAt(schedule, after);
}

export function isPlanReminderDue(reminder: PlanReminder, now: number): boolean {
  return (
    reminder.enabled &&
    reminder.status === 'scheduled' &&
    typeof reminder.nextRunAt === 'number' &&
    reminder.nextRunAt <= now
  );
}

export function nextPlanReminderStateAfterTrigger(
  reminder: PlanReminder,
  run: PlanReminderRunRecord,
): PlanReminder {
  const runs = appendPlanReminderRun(reminder.runs, run);
  const nextRunAt = nextPlanReminderRunAtAfter(reminder.schedule, run.at);
  if (typeof nextRunAt === 'number') {
    return {
      ...reminder,
      status: 'scheduled',
      enabled: true,
      nextRunAt,
      lastRun: run,
      runs,
      runCount: reminder.runCount + 1,
      updatedAt: run.at,
    };
  }
  return {
    ...reminder,
    status: 'completed',
    enabled: false,
    nextRunAt: undefined,
    lastRun: run,
    runs,
    runCount: reminder.runCount + 1,
    updatedAt: run.at,
  };
}

export function appendPlanReminderRun(
  runs: readonly PlanReminderRunRecord[] | undefined,
  run: PlanReminderRunRecord,
): PlanReminderRunRecord[] {
  return [run, ...(runs ?? [])].slice(0, PLAN_REMINDER_RUN_HISTORY_LIMIT);
}

function nextRecurringRunAt(schedule: PlanReminderRecurringSchedule, after: number): number {
  if (schedule.recurrence === 'daily') {
    const dayMs = 24 * 60 * 60 * 1000;
    const steps = Math.floor((after - schedule.startAt) / dayMs) + 1;
    return schedule.startAt + steps * dayMs;
  }
  if (schedule.recurrence === 'weekly') {
    const weekMs = 7 * 24 * 60 * 60 * 1000;
    const steps = Math.floor((after - schedule.startAt) / weekMs) + 1;
    return schedule.startAt + steps * weekMs;
  }
  let next = schedule.startAt;
  for (let i = 0; i < 480 && next <= after; i += 1) {
    next = addMonthsClamped(schedule.startAt, i + 1);
  }
  return next > after ? next : addMonthsClamped(after, 1);
}

function addMonthsClamped(anchor: number, monthOffset: number): number {
  const date = new Date(anchor);
  const targetYear = date.getFullYear();
  const targetMonth = date.getMonth() + monthOffset;
  const day = date.getDate();
  const lastDay = new Date(targetYear, targetMonth + 1, 0).getDate();
  return new Date(
    targetYear,
    targetMonth,
    Math.min(day, lastDay),
    date.getHours(),
    date.getMinutes(),
    date.getSeconds(),
    date.getMilliseconds(),
  ).getTime();
}

function nextCronRunAtAfter(schedule: PlanReminderCronSchedule, after: number): number | undefined {
  const compiled = compileCronExpression(schedule.expression, { profile: 'plan-reminder-v1' });
  if (!compiled.ok) return undefined;
  return (
    compiled.value.nextAfter(after, {
      notBefore: schedule.startAt,
      notAfter: after + PLAN_REMINDER_MAX_DELAY_MS,
    }) ?? undefined
  );
}

function planReminderCronErrorMessage(error: CronCompileError): string {
  switch (error.code) {
    case 'invalid_field_count':
      return 'Plan reminder cron expression must have exactly 5 fields';
    case 'unsupported_syntax':
      return 'Plan reminder cron fields support only numbers, *, ranges, lists, and steps';
    case 'empty_list_item':
      return 'Plan reminder cron field contains an empty list item';
    case 'invalid_step':
      return 'Plan reminder cron field has an invalid step';
    case 'invalid_range':
      return 'Plan reminder cron field has an invalid range';
    case 'reversed_range':
      return 'Plan reminder cron range start must be before its end';
    case 'invalid_integer':
      return 'Plan reminder cron field values must be integers';
    case 'out_of_range':
      return `Plan reminder cron field value must be between ${error.min} and ${error.max}`;
    case 'empty_field':
      return 'Plan reminder cron field cannot be empty';
    case 'unsatisfiable':
      return 'Plan reminder cron expression has no run within one year';
  }
}

function isBotProvider(value: unknown): value is BotProvider {
  return typeof value === 'string' && (BOT_PROVIDERS as readonly string[]).includes(value);
}

function botProviderLabel(provider: BotProvider): string {
  switch (provider) {
    case 'telegram':
      return 'Telegram';
    case 'feishu':
      return '飞书';
    case 'wecom':
      return '企业微信';
    case 'wechat':
      return '微信';
    case 'discord':
      return 'Discord';
    case 'dingtalk':
      return '钉钉';
    case 'qq':
      return 'QQ';
    case 'slack':
      return 'Slack';
  }
}

function invalid<T extends PlanReminderNormalizeErrorReason>(
  reason: T,
  message: string,
): Extract<PlanReminderNormalizeResult<never>, { ok: false }> {
  return { ok: false, reason, message };
}