import { IconName, IconSrc } from 'folds';

import {
  EventTimeline,
  EventTimelineSet,
  EventType,
  IMentions,
  IPowerLevelsContent,
  IPushRule,
  IPushRules,
  ISendEventResponse,
  JoinRule,
  MatrixClient,
  MatrixEvent,
  MsgType,
  NotificationCountType,
  RelationType,
  Room,
  RoomMember,
} from 'matrix-js-sdk';
import { CryptoBackend } from 'matrix-js-sdk/lib/common-crypto/CryptoBackend';
import { AccountDataEvent } from '../../types/matrix/accountData';
import {
  IRoomCreateContent,
  Membership,
  MessageEvent,
  NotificationType,
  RoomToParents,
  RoomType,
  StateEvent,
  UnreadInfo,
} from '../../types/matrix/room';
import { getMutedThreads, ThreadNotificationsContent } from './threadNotifications';
import { getMxIdLocalPart } from './matrix';

export const getStateEvent = (
  room: Room,
  eventType: StateEvent,
  stateKey = '',
): MatrixEvent | undefined =>
  room.getLiveTimeline().getState(EventTimeline.FORWARDS)?.getStateEvents(eventType, stateKey) ??
  undefined;

export const getStateEvents = (room: Room, eventType: StateEvent): MatrixEvent[] =>
  room.getLiveTimeline().getState(EventTimeline.FORWARDS)?.getStateEvents(eventType) ?? [];

// Typed state-event write helper.
//
// matrix-js-sdk's `sendStateEvent` typed overload rejects the fork's custom
// `StateEvent` enum values (the `io.lotus.*` / `im.ponies.*` / etc. values in
// `types/matrix/room.ts`), and casting the event type to `any` at each call site
// also collapses the `content` argument to `any`. We centralize the single
// `as any` cast here so every call site keeps its own `content` type checked.
export function sendStateEvent<T extends object>(
  mx: MatrixClient,
  roomId: string,
  eventType: StateEvent,
  content: T,
  stateKey = '',
): Promise<ISendEventResponse> {
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  return mx.sendStateEvent(roomId, eventType as any, content, stateKey);
}

export const getAccountData = (
  mx: MatrixClient,
  eventType: AccountDataEvent | string,
): MatrixEvent | undefined => mx.getAccountData(eventType as any);

export const getMDirects = (mDirectEvent: MatrixEvent): Set<string> => {
  const roomIds = new Set<string>();
  const userIdToDirects = mDirectEvent?.getContent();

  if (userIdToDirects === undefined) return roomIds;

  Object.keys(userIdToDirects).forEach((userId) => {
    const directs = userIdToDirects[userId];
    if (Array.isArray(directs)) {
      directs.forEach((id) => {
        if (typeof id === 'string') roomIds.add(id);
      });
    }
  });

  return roomIds;
};

export const isDirectInvite = (room: Room | null, myUserId: string | null): boolean => {
  if (!room || !myUserId) return false;
  const me = room.getMember(myUserId);
  const memberEvent = me?.events?.member;
  const content = memberEvent?.getContent();
  return content?.is_direct === true;
};

export const isSpace = (room: Room | null): boolean => {
  if (!room) return false;
  const event = getStateEvent(room, StateEvent.RoomCreate);
  if (!event) return false;
  return event.getContent().type === RoomType.Space;
};

export const isRoom = (room: Room | null): boolean => {
  if (!room) return false;
  const event = getStateEvent(room, StateEvent.RoomCreate);
  if (!event) return true;
  return event.getContent().type !== RoomType.Space;
};

export const isUnsupportedRoom = (room: Room | null): boolean => {
  if (!room) return false;
  const event = getStateEvent(room, StateEvent.RoomCreate);
  if (!event) return true; // Consider room unsupported if m.room.create event doesn't exist
  return event.getContent().type !== undefined && event.getContent().type !== RoomType.Space;
};

export function isValidChild(mEvent: MatrixEvent): boolean {
  return (
    mEvent.getType() === StateEvent.SpaceChild &&
    Array.isArray(mEvent.getContent<{ via: string[] }>().via)
  );
}

export const getAllParents = (roomToParents: RoomToParents, roomId: string): Set<string> => {
  const allParents = new Set<string>();

  const addAllParentIds = (rId: string) => {
    if (allParents.has(rId)) return;
    allParents.add(rId);

    const parents = roomToParents.get(rId);
    parents?.forEach((id) => addAllParentIds(id));
  };
  addAllParentIds(roomId);
  allParents.delete(roomId);
  return allParents;
};

export const getSpaceChildren = (room: Room) =>
  getStateEvents(room, StateEvent.SpaceChild).reduce<string[]>((filtered, mEvent) => {
    const stateKey = mEvent.getStateKey();
    if (isValidChild(mEvent) && stateKey) {
      filtered.push(stateKey);
    }
    return filtered;
  }, []);

export const mapParentWithChildren = (
  roomToParents: RoomToParents,
  roomId: string,
  children: string[],
) => {
  const allParents = getAllParents(roomToParents, roomId);
  children.forEach((childId) => {
    if (allParents.has(childId)) {
      // Space cycle detected.
      return;
    }
    const parents = roomToParents.get(childId) ?? new Set<string>();
    parents.add(roomId);
    roomToParents.set(childId, parents);
  });
};

export const getRoomToParents = (mx: MatrixClient): RoomToParents => {
  const map: RoomToParents = new Map();
  mx.getRooms()
    .filter((room) => isSpace(room))
    .forEach((room) => mapParentWithChildren(map, room.roomId, getSpaceChildren(room)));

  return map;
};

export const getOrphanParents = (roomToParents: RoomToParents, roomId: string): string[] => {
  const parents = getAllParents(roomToParents, roomId);
  const orphanParents = Array.from(parents).filter(
    (parentRoomId) => !roomToParents.has(parentRoomId),
  );

  return orphanParents;
};

export const isMutedRule = (rule: IPushRule) =>
  // Check for empty actions (new spec) or dont_notify (deprecated)
  (rule.actions.length === 0 || rule.actions[0] === 'dont_notify') &&
  rule.conditions?.[0]?.kind === 'event_match';

export const findMutedRule = (overrideRules: IPushRule[], roomId: string) =>
  overrideRules.find((rule) => rule.rule_id === roomId && isMutedRule(rule));

export const getNotificationType = (mx: MatrixClient, roomId: string): NotificationType => {
  let roomPushRule: IPushRule | undefined;
  try {
    roomPushRule = mx.getRoomPushRule('global', roomId);
  } catch {
    roomPushRule = undefined;
  }

  if (!roomPushRule) {
    const overrideRules = mx.getAccountData(EventType.PushRules)?.getContent<IPushRules>()
      ?.global?.override;
    if (!overrideRules) return NotificationType.Default;

    return findMutedRule(overrideRules, roomId) ? NotificationType.Mute : NotificationType.Default;
  }

  if (roomPushRule.actions[0] === 'notify') return NotificationType.AllMessages;
  return NotificationType.MentionsAndKeywords;
};

const NOTIFICATION_EVENT_TYPES = [
  'm.room.create',
  'm.room.message',
  'm.room.encrypted',
  'm.room.member',
  'm.sticker',
  // Polls (MSC3381) are real content the server can count toward a room's total.
  // Recognizing them keeps a poll-only unread from being walked past by the
  // read-receipt/tail scans (roomHaveUnread, readReceiptCoversTail).
  'm.poll.start',
  'org.matrix.msc3381.poll.start',
];
// In-room device-verification requests are sent as m.room.message with this
// msgtype (the rest of the flow — start/accept/key/mac/done/cancel — uses its own
// event types, already excluded above). They're crypto control messages, not chat.
const VERIFICATION_REQUEST_MSGTYPE = 'm.key.verification.request';
export const isNotificationEvent = (mEvent: MatrixEvent) => {
  const eType = mEvent.getType();
  if (!NOTIFICATION_EVENT_TYPES.includes(eType)) {
    return false;
  }
  if (eType === 'm.room.member') return false;
  // Don't badge/notify a verification request — otherwise a stale one at the tail
  // of a DM re-lights the room's unread dot on every fresh sync (cache clear).
  if (eType === 'm.room.message' && mEvent.getContent().msgtype === VERIFICATION_REQUEST_MSGTYPE) {
    return false;
  }

  if (mEvent.isRedacted()) return false;
  if (mEvent.getRelation()?.rel_type === 'm.replace') return false;

  return true;
};

// In-room device verification is a small burst at the tail of a DM: the
// `m.key.verification.request` message plus the `m.key.verification.*` flow
// (ready/start/key/mac/done/cancel). A COMPLETED request keeps the server/SDK
// Total notification count > 0 forever — it's a plain `m.room.message`, so it
// matches the default DM push rule and there's no recency gate — so the DM
// re-lights as unread on every fresh sync.
export const isVerificationFlowEvent = (mEvent: MatrixEvent): boolean => {
  // getType() returns the CLEAR type once decrypted; while still encrypted we
  // can't tell, so this returns false and callers treat that as "not confirmed".
  const eType = mEvent.getType();
  if (eType.startsWith('m.key.verification.')) return true;
  if (eType === 'm.room.message') {
    return mEvent.getContent().msgtype === VERIFICATION_REQUEST_MSGTYPE;
  }
  return false;
};

// True iff the room has any thread carrying a real unread notification. A room's
// server/SDK Total INCLUDES its threads, and `markAsRead` clears every thread
// unconditionally, so any tail-based suppression must bail when a thread is
// genuinely unread — otherwise it would hide (or wrongly ack) a real thread reply.
export const roomHasUnreadThread = (room: Room): boolean =>
  room
    .getThreads()
    .some(
      (thread) => room.getThreadUnreadNotificationCount(thread.id, NotificationCountType.Total) > 0,
    );

// True iff a room's ENTIRE unread span (tail → the user's read receipt) is
// nothing but verification-flow events — i.e. the only "unread" is a completed
// device verification, not a real message. Conservative: returns false when the
// read marker isn't in the loaded timeline (can't confirm the span) or while the
// tail is still encrypted (undecryptable → unknown), so it never suppresses or
// auto-reads a genuine unread message.
export const unreadIsOnlyVerification = (room: Room, userId: string | null): boolean => {
  if (!userId) return false;
  if (roomHasUnreadThread(room)) return false;
  const readUpToId = room.getEventReadUpTo(userId);
  const liveEvents = room.getLiveTimeline().getEvents();
  let sawVerification = false;
  for (let i = liveEvents.length - 1; i >= 0; i -= 1) {
    const event = liveEvents[i];
    if (!event) return false;
    if (event.getId() === readUpToId) return sawVerification;
    if (isNotificationEvent(event) && !isVerificationFlowEvent(event)) return false;
    if (isVerificationFlowEvent(event)) sawVerification = true;
  }
  return false;
};

// True iff the user's read receipt already covers the room's entire notifiable
// tail: walking from the newest live event, we reach the receipt's event without
// crossing any notification-worthy event. In that case there is demonstrably
// nothing real left to read, so a lingering Total > 0 is a spurious SDK count.
// matrix-js-sdk's `fixNotificationCountOnDecryption` only ever INCREMENTS an
// encrypted room's Total, and `addReceipt`'s auto-clear-to-zero only fires when
// the tail event is the user's own — so a count inflated in an earlier state
// (before a receipt covered the tail, e.g. by a since-corrupted/undecryptable
// event) is never decremented and keeps a genuinely-read room lit across cold
// starts. Anchoring on the read receipt is safe: a genuine unread would sit AFTER
// the receipt and stop the walk at `isNotificationEvent`. Conservative: returns
// false when the receipt isn't in the loaded window (can't confirm) or a thread
// is genuinely unread.
export const readReceiptCoversTail = (room: Room, userId: string | null): boolean => {
  if (!userId) return false;
  if (roomHasUnreadThread(room)) return false;
  const readUpToId = room.getEventReadUpTo(userId);
  if (!readUpToId) return false;
  const liveEvents = room.getLiveTimeline().getEvents();
  for (let i = liveEvents.length - 1; i >= 0; i -= 1) {
    const event = liveEvents[i];
    if (!event) return false;
    if (event.getId() === readUpToId) return true;
    if (isNotificationEvent(event)) return false;
  }
  return false;
};

export const roomHaveNotification = (room: Room): boolean => {
  const total = room.getUnreadNotificationCount(NotificationCountType.Total);
  const highlight = room.getUnreadNotificationCount(NotificationCountType.Highlight);

  return total > 0 || highlight > 0;
};

export const roomHaveUnread = (mx: MatrixClient, room: Room) => {
  const userId = mx.getUserId();
  if (!userId) return false;
  const readUpToId = room.getEventReadUpTo(userId);
  const liveEvents = room.getLiveTimeline().getEvents();

  if (liveEvents[liveEvents.length - 1]?.getSender() === userId) {
    return false;
  }

  for (let i = liveEvents.length - 1; i >= 0; i -= 1) {
    const event = liveEvents[i];
    if (!event) return false;
    if (event.getId() === readUpToId) return false;
    if (isNotificationEvent(event)) return true;
  }
  return true;
};

export const getUnreadInfo = (
  room: Room,
  mutedThreads?: Set<string>,
  mx?: MatrixClient,
): UnreadInfo => {
  let total = room.getUnreadNotificationCount(NotificationCountType.Total);
  let highlight = room.getUnreadNotificationCount(NotificationCountType.Highlight);

  // Server room totals INCLUDE per-thread notification counts, so subtract any
  // explicitly muted thread's counts back out (clamped at zero) to keep muted
  // threads from contributing to the room badge (P4-1).
  if (mutedThreads && mutedThreads.size > 0) {
    mutedThreads.forEach((threadId) => {
      total -= room.getThreadUnreadNotificationCount(threadId, NotificationCountType.Total) ?? 0;
      highlight -=
        room.getThreadUnreadNotificationCount(threadId, NotificationCountType.Highlight) ?? 0;
    });
    if (total < 0) total = 0;
    if (highlight < 0) highlight = 0;
  }

  const resolvedTotal = highlight > total ? highlight : total;

  // Suppress a spurious Total when the room isn't really unread. Two safe cases,
  // both requiring `mx` (backward-compatible for callers/tests without it) and a
  // highlight-free count (a real mention must never be hidden):
  //   1. the entire unread span is a completed device verification, or
  //   2. the user's read receipt already covers the whole notifiable tail (the
  //      SDK re-inflated an encrypted-room count past a receipt that genuinely
  //      covers everything — e.g. a permanently-undecryptable event).
  if (
    mx &&
    resolvedTotal > 0 &&
    highlight === 0 &&
    (unreadIsOnlyVerification(room, mx.getUserId()) || readReceiptCoversTail(room, mx.getUserId()))
  ) {
    return { roomId: room.roomId, highlight: 0, total: 0 };
  }

  return {
    roomId: room.roomId,
    highlight,
    total: resolvedTotal,
  };
};

export const getUnreadInfos = (
  mx: MatrixClient,
  content?: ThreadNotificationsContent,
): UnreadInfo[] => {
  const unreadInfos = mx.getRooms().reduce<UnreadInfo[]>((unread, room) => {
    if (room.isSpaceRoom()) return unread;
    if (room.getMyMembership() !== 'join') return unread;
    if (getNotificationType(mx, room.roomId) === NotificationType.Mute) return unread;

    if (roomHaveNotification(room) || roomHaveUnread(mx, room)) {
      const mutedThreads = content ? getMutedThreads(content, room.roomId) : undefined;
      const info = getUnreadInfo(room, mutedThreads, mx);
      // Skip a phantom {0,0} entry: a room whose ONLY unread is a muted thread has
      // roomHaveNotification true (the server room total includes the muted
      // thread's count), but getUnreadInfo subtracts it back to zero. Pushing it
      // would still light the nav row + pollute "unread only" filters. Keep it
      // only if there's real unread (count > 0) or a genuine unread marker. The
      // unreadIsOnlyVerification/readReceiptCoversTail guards below mirror the
      // getUnreadInfo suppression: roomHaveUnread returning `true` here already
      // implies both are false (they only report `true` once the receipt covers
      // the tail, exactly where roomHaveUnread returns `false`), so the guards are
      // defensive insurance against divergence, not load-bearing.
      if (
        info.total > 0 ||
        info.highlight > 0 ||
        (roomHaveUnread(mx, room) &&
          !unreadIsOnlyVerification(room, mx.getUserId()) &&
          !readReceiptCoversTail(room, mx.getUserId()))
      ) {
        unread.push(info);
      }
    }

    return unread;
  }, []);
  return unreadInfos;
};

export const getRoomIconSrc = (
  icons: Record<IconName, IconSrc>,
  roomType?: string,
  joinRule?: JoinRule,
): IconSrc => {
  if (roomType === 'm.server_notice') return icons.Warning;

  if (roomType === RoomType.Space) {
    if (joinRule === JoinRule.Public) return icons.SpaceGlobe;
    if (
      joinRule === JoinRule.Invite ||
      joinRule === JoinRule.Knock ||
      joinRule === JoinRule.Private
    ) {
      return icons.SpaceLock;
    }
    return icons.Space;
  }

  if (roomType === RoomType.Call) {
    if (joinRule === JoinRule.Public) return icons.VolumeHighGlobe;
    if (
      joinRule === JoinRule.Invite ||
      joinRule === JoinRule.Knock ||
      joinRule === JoinRule.Private
    ) {
      return icons.VolumeHighLock;
    }
    return icons.VolumeHigh;
  }

  if (joinRule === JoinRule.Public) return icons.HashGlobe;
  if (
    joinRule === JoinRule.Invite ||
    joinRule === JoinRule.Knock ||
    joinRule === JoinRule.Private
  ) {
    return icons.HashLock;
  }
  return icons.Hash;
};

export const getRoomAvatarUrl = (
  mx: MatrixClient,
  room: Room,
  size: 32 | 96 = 32,
  useAuthentication = false,
): string | undefined => {
  const mxcUrl = room.getMxcAvatarUrl();
  return mxcUrl
    ? (mx.mxcUrlToHttp(mxcUrl, size, size, 'crop', undefined, false, useAuthentication) ??
        undefined)
    : undefined;
};

export const getDirectRoomAvatarUrl = (
  mx: MatrixClient,
  room: Room,
  size: 32 | 96 = 32,
  useAuthentication = false,
): string | undefined => {
  const mxcUrl = room.getAvatarFallbackMember()?.getMxcAvatarUrl();

  if (!mxcUrl) {
    return getRoomAvatarUrl(mx, room, size, useAuthentication);
  }

  return (
    mx.mxcUrlToHttp(mxcUrl, size, size, 'crop', undefined, false, useAuthentication) ?? undefined
  );
};

export const trimReplyFromBody = (body: string): string => {
  const match = body.match(/^> <.+?> .+\n(>.*\n)*?\n/m);
  if (!match) return body;
  return body.slice(match[0].length);
};

export const trimReplyFromFormattedBody = (formattedBody: string): string => {
  const suffix = '</mx-reply>';
  const i = formattedBody.lastIndexOf(suffix);
  if (i < 0) {
    return formattedBody;
  }
  return formattedBody.slice(i + suffix.length);
};

export const parseReplyBody = (userId: string, body: string) =>
  `> <${userId}> ${body.replace(/\n/g, '\n> ')}\n\n`;

export const parseReplyFormattedBody = (
  roomId: string,
  userId: string,
  eventId: string,
  formattedBody: string,
): string => {
  const replyToLink = `<a href="https://matrix.to/#/${encodeURIComponent(
    roomId,
  )}/${encodeURIComponent(eventId)}">In reply to</a>`;
  const userLink = `<a href="https://matrix.to/#/${encodeURIComponent(userId)}">${userId}</a>`;

  return `<mx-reply><blockquote>${replyToLink}${userLink}<br />${formattedBody}</blockquote></mx-reply>`;
};

export const getMemberDisplayName = (room: Room, userId: string): string | undefined => {
  const member = room.getMember(userId);
  const name = member?.rawDisplayName;
  if (name === userId) return undefined;
  return name;
};

export const getMemberName = (room: Room, userId: string): string =>
  getMemberDisplayName(room, userId) ?? getMxIdLocalPart(userId) ?? userId;

export const getMemberSearchStr = (
  member: RoomMember,
  query: string,
  mxIdToName: (mxId: string) => string,
): string[] => [
  member.rawDisplayName === member.userId ? mxIdToName(member.userId) : member.rawDisplayName,
  query.startsWith('@') || query.indexOf(':') > -1 ? member.userId : mxIdToName(member.userId),
];

export const getMemberAvatarMxc = (room: Room, userId: string): string | undefined => {
  const member = room.getMember(userId);
  return member?.getMxcAvatarUrl();
};

export const isMembershipChanged = (mEvent: MatrixEvent): boolean =>
  mEvent.getContent().membership !== mEvent.getPrevContent().membership ||
  mEvent.getContent().reason !== mEvent.getPrevContent().reason;

export const decryptAllTimelineEvent = async (mx: MatrixClient, timeline: EventTimeline) => {
  const crypto = mx.getCrypto();
  if (!crypto) return;
  const decryptionPromises = timeline
    .getEvents()
    .filter((event) => event.isEncrypted())
    .reverse()
    .map((event) => event.attemptDecryption(crypto as CryptoBackend, { isRetry: true }));
  await Promise.allSettled(decryptionPromises);
};

export const getReactionContent = (eventId: string, key: string, shortcode?: string) => ({
  'm.relates_to': {
    event_id: eventId,
    key,
    rel_type: 'm.annotation',
  },
  shortcode,
});

export const getEventReactions = (timelineSet: EventTimelineSet, eventId: string) =>
  timelineSet.relations.getChildEventsForEvent(
    eventId,
    RelationType.Annotation,
    EventType.Reaction,
  );

export const getEventEdits = (timelineSet: EventTimelineSet, eventId: string, eventType: string) =>
  timelineSet.relations.getChildEventsForEvent(eventId, RelationType.Replace, eventType);

export const getLatestEdit = (
  targetEvent: MatrixEvent,
  editEvents: MatrixEvent[],
): MatrixEvent | undefined => {
  const eventByTargetSender = (rEvent: MatrixEvent) =>
    rEvent.getSender() === targetEvent.getSender();
  return editEvents.sort((m1, m2) => m2.getTs() - m1.getTs()).find(eventByTargetSender);
};

export const getEditedEvent = (
  mEventId: string,
  mEvent: MatrixEvent,
  timelineSet: EventTimelineSet,
): MatrixEvent | undefined => {
  const edits = getEventEdits(timelineSet, mEventId, mEvent.getType());
  return edits && getLatestEdit(mEvent, edits.getRelations());
};

export const canEditEvent = (mx: MatrixClient, mEvent: MatrixEvent) => {
  const content = mEvent.getContent();
  const relationType = content['m.relates_to']?.rel_type;
  return (
    mEvent.getSender() === mx.getUserId() &&
    (!relationType || relationType === RelationType.Thread) &&
    mEvent.getType() === MessageEvent.RoomMessage &&
    (content.msgtype === MsgType.Text ||
      content.msgtype === MsgType.Emote ||
      content.msgtype === MsgType.Notice)
  );
};

/**
 * Whether the current user can edit the *caption* of a media message. Captions
 * are authored for image/video only (see msgContent.ts): the caption is the
 * event `body` when it differs from `filename`. Editing only changes the caption
 * — the media (url/info/file) is preserved.
 */
export const canEditCaption = (mx: MatrixClient, mEvent: MatrixEvent) => {
  const content = mEvent.getContent();
  const relationType = content['m.relates_to']?.rel_type;
  return (
    mEvent.getSender() === mx.getUserId() &&
    (!relationType || relationType === RelationType.Thread) &&
    mEvent.getType() === MessageEvent.RoomMessage &&
    (content.msgtype === MsgType.Image || content.msgtype === MsgType.Video) &&
    // Require the MSC2530 filename so a caption has a well-defined empty state
    // (body === filename) — media from clients that omit filename isn't caption-
    // editable (and renderCaption never shows a caption for it anyway).
    typeof content.filename === 'string'
  );
};

/** Editable as a text message, or has an editable media caption. */
export const canEditEventOrCaption = (mx: MatrixClient, mEvent: MatrixEvent) =>
  canEditEvent(mx, mEvent) || canEditCaption(mx, mEvent);

export const getLatestEditableEvt = (
  timeline: EventTimeline,
  canEdit: (mEvent: MatrixEvent) => boolean,
): MatrixEvent | undefined => {
  const events = timeline.getEvents();

  for (let i = events.length - 1; i >= 0; i -= 1) {
    const evt = events[i];
    if (canEdit(evt)) return evt;
  }
  return undefined;
};

export const reactionOrEditEvent = (mEvent: MatrixEvent) =>
  mEvent.getRelation()?.rel_type === RelationType.Annotation ||
  mEvent.getRelation()?.rel_type === RelationType.Replace;

export const getMentionContent = (userIds: string[], room: boolean): IMentions => {
  const mMentions: IMentions = {};
  if (userIds.length > 0) {
    mMentions.user_ids = userIds;
  }
  if (room) {
    mMentions.room = true;
  }

  return mMentions;
};

export const getCommonRooms = (
  mx: MatrixClient,
  rooms: string[],
  otherUserId: string,
): string[] => {
  const commonRooms: string[] = [];

  rooms.forEach((roomId) => {
    const room = mx.getRoom(roomId);
    if (!room || room.getMyMembership() !== Membership.Join) return;

    const common = room.hasMembershipState(otherUserId, Membership.Join);
    if (common) {
      commonRooms.push(roomId);
    }
  });

  return commonRooms;
};

export const bannedInRooms = (mx: MatrixClient, rooms: string[], otherUserId: string): boolean =>
  rooms.some((roomId) => {
    const room = mx.getRoom(roomId);
    if (!room || room.getMyMembership() !== Membership.Join) return false;

    const banned = room.hasMembershipState(otherUserId, Membership.Ban);
    return banned;
  });

export const getAllVersionsRoomCreator = (room: Room): Set<string> => {
  const creators = new Set<string>();

  const createEvent = getStateEvent(room, StateEvent.RoomCreate);
  const createContent = createEvent?.getContent<IRoomCreateContent>();
  const creator = createEvent?.getSender();
  if (typeof creator === 'string') creators.add(creator);

  if (createContent && Array.isArray(createContent.additional_creators)) {
    createContent.additional_creators.forEach((c) => {
      if (typeof c === 'string') creators.add(c);
    });
  }

  return creators;
};

export const guessPerfectParent = (
  mx: MatrixClient,
  roomId: string,
  parents: string[],
): string | undefined => {
  if (parents.length === 1) {
    return parents[0];
  }

  const getSpecialUsers = (rId: string): string[] => {
    const specialUsers: Set<string> = new Set();

    const r = mx.getRoom(rId);
    if (!r) return [];

    getAllVersionsRoomCreator(r).forEach((c) => specialUsers.add(c));

    const powerLevels = getStateEvent(
      r,
      StateEvent.RoomPowerLevels,
    )?.getContent<IPowerLevelsContent>();

    const { users_default: usersDefault, users } = powerLevels ?? {};
    const defaultPower = typeof usersDefault === 'number' ? usersDefault : 0;

    if (typeof users === 'object')
      Object.keys(users).forEach((userId) => {
        if (users[userId] > defaultPower) {
          specialUsers.add(userId);
        }
      });

    return Array.from(specialUsers);
  };

  let perfectParent: string | undefined;
  let score = 0;

  const roomSpecialUsers = getSpecialUsers(roomId);
  parents.forEach((parentId) => {
    const parentSpecialUsers = getSpecialUsers(parentId);
    const matchedUsersCount = parentSpecialUsers.filter((userId) =>
      roomSpecialUsers.includes(userId),
    ).length;

    if (matchedUsersCount > score) {
      score = matchedUsersCount;
      perfectParent = parentId;
    }
  });

  return perfectParent;
};