import { IContent, MatrixClient, Method } from 'matrix-js-sdk';
import type { ScheduledMessage } from '../state/scheduledMessages';

/**
 * Schedule a message via MSC4140 (delayed messages).
 * Synapse implementation: pass org.matrix.msc4140.delay on the standard
 * /v3/rooms send endpoint. The server stores the event and returns delay_id
 * instead of event_id.
 */
export async function scheduleMessage(
  mx: MatrixClient,
  roomId: string,
  content: IContent,
  sendAtMs: number,
): Promise<string> {
  // MSC4140 delayed events are PUT straight to /send/m.room.message, bypassing
  // the SDK's encryptEventIfNeeded pipeline — the body would land on the server
  // (and later in the timeline) in the clear. Refuse rather than leak; the
  // composer also hides the Schedule button in encrypted rooms.
  if (mx.getRoom?.(roomId)?.hasEncryptionStateEvent()) {
    throw new Error('Scheduled messages are not supported in encrypted rooms.');
  }
  // A past/near target floors at 1000ms (send ~immediately) — an intentional,
  // tested contract; the ScheduleMessageModal already guards ≥60s in the future.
  const delayMs = Math.max(1000, Math.round(sendAtMs - Date.now()));
  const txnId = `sched_${Date.now()}_${Math.random().toString(36).slice(2)}`;
  const path = `/rooms/${encodeURIComponent(roomId)}/send/m.room.message/${txnId}`;
  // Use standard v3 prefix with the MSC4140 delay query param.
  const res = (await mx.http.authedRequest(
    Method.Put,
    path,
    {
      'org.matrix.msc4140.delay': delayMs,
    },
    content,
  )) as { delay_id: string };
  return res.delay_id;
}

/**
 * Cancel a scheduled message via MSC4140.
 */
export async function cancelScheduledMessage(mx: MatrixClient, delayId: string): Promise<void> {
  const path = `/delayed_events/${encodeURIComponent(delayId)}`;
  await mx.http.authedRequest(
    Method.Post,
    path,
    undefined,
    { action: 'cancel' },
    { prefix: '/_matrix/client/unstable/org.matrix.msc4140' },
  );
}

export async function restartScheduledMessage(mx: MatrixClient, delayId: string): Promise<void> {
  const path = `/delayed_events/${encodeURIComponent(delayId)}`;
  await mx.http.authedRequest(
    Method.Post,
    path,
    undefined,
    { action: 'restart' },
    { prefix: '/_matrix/client/unstable/org.matrix.msc4140' },
  );
}

/**
 * Send a scheduled message immediately via MSC4140 (`action: 'send'`) — the
 * server dispatches the stored delayed event now, as a normal timeline event,
 * instead of waiting for its timeout.
 */
export async function sendScheduledMessageNow(mx: MatrixClient, delayId: string): Promise<void> {
  const path = `/delayed_events/${encodeURIComponent(delayId)}`;
  await mx.http.authedRequest(
    Method.Post,
    path,
    undefined,
    { action: 'send' },
    { prefix: '/_matrix/client/unstable/org.matrix.msc4140' },
  );
}

type DelayedEventItem = {
  delay_id?: unknown;
  room_id?: unknown;
  type?: unknown;
  state_key?: unknown;
  content?: unknown;
  delay?: unknown;
  delay_ms?: unknown;
  running_since?: unknown;
  delayed_since_ts?: unknown;
};

/**
 * [Gitea #322] Pure: the user's pending scheduled messages from an MSC4140
 * `GET /delayed_events` response. Synapse answers `{ delayed_events: [...] }`;
 * the current MSC shape is `{ scheduled: [...] }`. Call-membership delayed
 * events share the endpoint, so only non-state `m.room.message`s are kept.
 */
export function parseDelayedEvents(res: unknown): ScheduledMessage[] {
  if (!res || typeof res !== 'object') return [];
  const r = res as { delayed_events?: unknown; scheduled?: unknown };
  const list = Array.isArray(r.delayed_events) ? r.delayed_events : r.scheduled;
  if (!Array.isArray(list)) return [];
  const out: ScheduledMessage[] = [];
  list.forEach((raw: DelayedEventItem) => {
    if (!raw || typeof raw !== 'object') return;
    if (raw.type !== 'm.room.message' || raw.state_key !== undefined) return;
    if (typeof raw.delay_id !== 'string' || typeof raw.room_id !== 'string') return;
    if (!raw.content || typeof raw.content !== 'object') return;
    const delay = Number(raw.delay ?? raw.delay_ms);
    const since = Number(raw.running_since ?? raw.delayed_since_ts);
    if (!Number.isFinite(delay) || !Number.isFinite(since)) return;
    out.push({
      delayId: raw.delay_id,
      roomId: raw.room_id,
      content: raw.content as IContent,
      sendAt: since + delay,
    });
  });
  return out;
}

/** The user's pending scheduled messages, as the server has them. */
export async function fetchScheduledMessages(mx: MatrixClient): Promise<ScheduledMessage[]> {
  const res = await mx.http.authedRequest(Method.Get, '/delayed_events', undefined, undefined, {
    prefix: '/_matrix/client/unstable/org.matrix.msc4140',
  });
  return parseDelayedEvents(res);
}

/** Group by room, the shape of `scheduledMessagesAtom`. */
export function groupScheduledByRoom(msgs: ScheduledMessage[]): Map<string, ScheduledMessage[]> {
  const map = new Map<string, ScheduledMessage[]>();
  msgs.forEach((m) => map.set(m.roomId, [...(map.get(m.roomId) ?? []), m]));
  map.forEach((list) => list.sort((a, b) => a.sendAt - b.sendAt));
  return map;
}