import { EventType } from 'matrix-js-sdk';
import { useCallback } from 'react';
import { useMatrixClient } from '../../hooks/useMatrixClient';
import { ResultGroup, ResultItem } from './useMessageSearch';

export type LocalSearchParams = {
  term: string;
  roomIds: string[];
  senders?: string[];
};

export type LocalSearchResult = {
  groups: ResultGroup[];
  /** How many rooms in scope are encrypted */
  encryptedRoomsCount: number;
  /** How many of those had locally cached events to scan */
  searchedRoomsCount: number;
};

/**
 * Client-side full-text search over locally cached events in encrypted rooms.
 * The homeserver cannot search E2EE message content, so we scan whatever the
 * client has already received and decrypted in memory.
 *
 * Limitation: only messages present in the live timeline window are covered.
 * Rooms that haven't been opened yet will return no results.
 */
export const useLocalMessageSearch = () => {
  const mx = useMatrixClient();

  const search = useCallback(
    ({ term, roomIds, senders }: LocalSearchParams): LocalSearchResult => {
      const trimmedTerm = term.trim();
      const senderSet = senders && senders.length > 0 ? new Set(senders) : null;

      // Sender-only mode: no text filter, search all rooms (server can't filter by sender alone)
      const senderOnlyMode = !trimmedTerm && !!senderSet;

      if (!trimmedTerm && !senderSet) {
        return { groups: [], encryptedRoomsCount: 0, searchedRoomsCount: 0 };
      }

      const termLower = trimmedTerm.toLowerCase();
      const groups: ResultGroup[] = [];
      let encryptedRoomsCount = 0;
      let searchedRoomsCount = 0;

      for (const roomId of roomIds) {
        const room = mx.getRoom(roomId);
        if (!room) continue;

        const isEncrypted = !!room.currentState.getStateEvents(EventType.RoomEncryption, '');

        // Text search: encrypted rooms only — server already covers plaintext rooms
        // Sender-only: all rooms — server has no sender-only search
        if (!senderOnlyMode && !isEncrypted) continue;

        if (isEncrypted) encryptedRoomsCount += 1;

        const events = room
          .getUnfilteredTimelineSet()
          .getTimelines()
          .flatMap((tl) => tl.getEvents());
        if (events.length === 0) continue;

        searchedRoomsCount += 1;

        const items: ResultItem[] = [];

        for (let i = 0; i < events.length; i += 1) {
          const event = events[i];

          // In sender-only mode: include all message types; skip non-message events
          if (event.getType() !== EventType.RoomMessage) {
            if (senderOnlyMode) continue;
            const evType = event.getType();
            const isSticker = evType === 'm.sticker';
            const isPoll = evType === 'm.poll.start' || evType === 'org.matrix.msc3381.poll.start';
            if (!isSticker && !isPoll) continue;
          }

          if (event.isDecryptionFailure()) continue;
          if (event.isRedacted()) continue;
          if (senderSet && !senderSet.has(event.getSender() ?? '')) continue;

          // getContent() returns decrypted plaintext regardless of encryption
          const content = event.getContent();

          // Sender-only mode: no text filter needed
          if (!senderOnlyMode) {
            const evType = event.getType();
            const isPoll = evType === 'm.poll.start' || evType === 'org.matrix.msc3381.poll.start';

            let body = '';
            let formattedBody = '';
            if (!isPoll) {
              body = (content.body as string | undefined) ?? '';
              formattedBody = (content.formatted_body as string | undefined) ?? '';
            } else {
              // Poll — index question text and all answer options
              const poll = (content['m.poll'] ??
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                content['org.matrix.msc3381.poll.start']) as any;
              if (poll) {
                const qBody =
                  // eslint-disable-next-line @typescript-eslint/no-explicit-any
                  (poll.question?.['m.text'] as Array<{ body: string }> | undefined)?.[0]?.body ??
                  (poll.question?.body as string | undefined) ??
                  '';
                const answerBodies = ((poll.answers ?? []) as Array<Record<string, unknown>>)
                  .map(
                    (a) =>
                      // eslint-disable-next-line @typescript-eslint/no-explicit-any
                      ((a['m.text'] as Array<{ body: string }> | undefined)?.[0]?.body ??
                        // eslint-disable-next-line @typescript-eslint/no-explicit-any
                        (a['org.matrix.msc3381.poll.answer'] as any)?.body ??
                        '') as string,
                  )
                  .join(' ');
                body = `${qBody} ${answerBodies}`.trim();
              }
            }

            if (
              !body.toLowerCase().includes(termLower) &&
              !formattedBody.toLowerCase().includes(termLower)
            )
              continue;
          }

          // Build a synthetic IEventWithRoomId using decrypted content so the
          // existing SearchResultGroup renderer works without modification.
          const syntheticEvent = {
            room_id: roomId,
            event_id: event.getId() ?? '',
            type: event.getType(),
            sender: event.getSender() ?? '',
            origin_server_ts: event.getTs(),
            content,
            unsigned: event.getUnsigned(),
          };

          items.push({
            rank: 0,
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            event: syntheticEvent as any,
            context: {
              events_before: [],
              events_after: [],
              profile_info: {},
            },
          });
        }

        if (items.length > 0) {
          items.sort((a, b) => (b.event.origin_server_ts ?? 0) - (a.event.origin_server_ts ?? 0));
          groups.push({ roomId, items });
        }
      }

      return { groups, encryptedRoomsCount, searchedRoomsCount };
    },
    [mx],
  );

  return search;
};