import {
  IEventWithRoomId,
  IResultContext,
  ISearchRequestBody,
  ISearchResponse,
  ISearchResult,
  SearchOrderBy,
} from 'matrix-js-sdk';
import { useCallback } from 'react';
import { useMatrixClient } from '../../hooks/useMatrixClient';

export type ResultItem = {
  rank: number;
  event: IEventWithRoomId;
  context: IResultContext;
};

export type ResultGroup = {
  roomId: string;
  items: ResultItem[];
};

export type SearchResult = {
  nextToken?: string;
  highlights: string[];
  groups: ResultGroup[];
};

// Client-side msgtype post-filter. The Matrix search API cannot filter by
// msgtype server-side, so this is applied to already-returned results.
export type MsgTypeFilter = 'm.image' | 'm.file' | 'm.video';

/**
 * Filter result groups to items whose event msgtype is in `msgTypes` (OR/union).
 * Empty/absent filter returns groups unchanged. Now-empty groups are dropped.
 */
export const filterGroupsByMsgType = (
  groups: ResultGroup[],
  msgTypes: MsgTypeFilter[],
): ResultGroup[] => {
  if (msgTypes.length === 0) return groups;
  const allowed = new Set<string>(msgTypes);
  return groups
    .map((group) => ({
      ...group,
      items: group.items.filter((item) => {
        const msgtype = item.event.content?.msgtype;
        return typeof msgtype === 'string' && allowed.has(msgtype);
      }),
    }))
    .filter((group) => group.items.length > 0);
};

/**
 * Filter result groups to items whose event is currently pinned in its room.
 * `isPinned(roomId, eventId)` returns whether the event is in the room's
 * `m.room.pinned_events` set. When `enabled` is false, groups are returned
 * unchanged. Now-empty groups are dropped.
 */
export const filterGroupsByPinned = (
  groups: ResultGroup[],
  enabled: boolean,
  isPinned: (roomId: string, eventId: string) => boolean,
): ResultGroup[] => {
  if (!enabled) return groups;
  return groups
    .map((group) => ({
      ...group,
      items: group.items.filter((item) => isPinned(group.roomId, item.event.event_id)),
    }))
    .filter((group) => group.items.length > 0);
};

/** Inclusive-range predicate, mirrored from `inRange` in useLocalMessageSearch.ts. */
export const inTsRange = (ts: number, fromTs?: number, toTs?: number): boolean =>
  (fromTs === undefined || ts >= fromTs) && (toTs === undefined || ts <= toTs);

/**
 * Filter result groups to items whose `origin_server_ts` falls within
 * [fromTs, toTs] (inclusive, either bound optional). The Matrix search API
 * has no timestamp filter fields, so server results must be post-filtered
 * here — the same predicate the local/encrypted search already applies.
 * Now-empty groups are dropped.
 */
export const filterGroupsByDateRange = (
  groups: ResultGroup[],
  fromTs?: number,
  toTs?: number,
): ResultGroup[] => {
  if (fromTs === undefined && toTs === undefined) return groups;
  return groups
    .map((group) => ({
      ...group,
      items: group.items.filter((item) => inTsRange(item.event.origin_server_ts, fromTs, toTs)),
    }))
    .filter((group) => group.items.length > 0);
};

/**
 * [Gitea #288] Server search also returns `m.replace` events, so an edited
 * message showed once per version. Fold each edit into its message: one row,
 * at the first position any version ranked, showing the latest text and
 * pointing at the original event (so "jump" lands on the real message).
 */
export const foldEdits = (results: ISearchResult[]): ISearchResult[] => {
  const targetOf = (r: ISearchResult): string => {
    const rel = r.result.content?.['m.relates_to'];
    return rel?.rel_type === 'm.replace' && typeof rel.event_id === 'string'
      ? rel.event_id
      : r.result.event_id;
  };
  const isEdit = (r: ISearchResult) => targetOf(r) !== r.result.event_id;
  const order: string[] = [];
  const originals = new Map<string, ISearchResult>();
  const latestEdit = new Map<string, ISearchResult>();
  results.forEach((r) => {
    const target = targetOf(r);
    if (!originals.has(target) && !latestEdit.has(target)) order.push(target);
    if (!isEdit(r)) {
      originals.set(target, r);
      return;
    }
    const prev = latestEdit.get(target);
    if (!prev || r.result.origin_server_ts > prev.result.origin_server_ts)
      latestEdit.set(target, r);
  });
  return order.map((target) => {
    const original = originals.get(target);
    const edit = latestEdit.get(target);
    const newContent = edit?.result.content?.['m.new_content'];
    if (original && !newContent) return original;
    if (original) {
      return {
        ...original,
        result: {
          ...original.result,
          content: { ...original.result.content, 'm.new_content': newContent },
        },
      };
    }
    // Only an edit matched: show it as its message.
    const only = edit as ISearchResult;
    return { ...only, result: { ...only.result, event_id: target } };
  });
};

const groupSearchResult = (results: ISearchResult[]): ResultGroup[] => {
  const groups: ResultGroup[] = [];

  foldEdits(results).forEach((item) => {
    const roomId = item.result.room_id;
    const resultItem: ResultItem = {
      rank: item.rank,
      event: item.result,
      context: item.context,
    };

    const lastAddedGroup: ResultGroup | undefined = groups[groups.length - 1];
    if (lastAddedGroup && roomId === lastAddedGroup.roomId) {
      lastAddedGroup.items.push(resultItem);
      return;
    }
    groups.push({
      roomId,
      items: [resultItem],
    });
  });

  return groups;
};

const parseSearchResult = (result: ISearchResponse): SearchResult => {
  const roomEvents = result.search_categories.room_events;

  const searchResult: SearchResult = {
    nextToken: roomEvents?.next_batch,
    highlights: roomEvents?.highlights ?? [],
    groups: groupSearchResult(roomEvents?.results ?? []),
  };

  return searchResult;
};

export type MessageSearchParams = {
  term?: string;
  order?: string;
  rooms?: string[];
  senders?: string[];
  fromTs?: number;
  toTs?: number;
  containsUrl?: boolean;
};
export const useMessageSearch = (params: MessageSearchParams) => {
  const mx = useMatrixClient();
  // fromTs/toTs are intentionally not sent to the server (see comment below) —
  // callers post-filter results with filterGroupsByDateRange instead.
  const { term, order, rooms, senders, containsUrl } = params;

  const searchMessages = useCallback(
    async (nextBatch?: string) => {
      if (!term)
        return {
          highlights: [],
          groups: [],
        };
      const limit = 50;

      const requestBody: ISearchRequestBody = {
        search_categories: {
          room_events: {
            event_context: {
              before_limit: 0,
              after_limit: 0,
              include_profile: false,
            },
            filter: {
              limit,
              rooms,
              senders,
              // `RoomEventFilter` has no timestamp bounds — from_ts/to_ts are not
              // Matrix filter fields and the homeserver silently drops them, so the
              // date range is instead enforced client-side (see filterGroupsByDateRange).
              // contains_url is a valid spec field not yet in SDK types.
              ...(containsUrl !== undefined && { contains_url: containsUrl }),
            },
            include_state: false,
            order_by: order as SearchOrderBy.Recent,
            search_term: term,
          },
        },
      };

      const r = await mx.search({
        body: requestBody,
        next_batch: nextBatch === '' ? undefined : nextBatch,
      });
      return parseSearchResult(r);
    },
    [mx, term, order, rooms, senders, containsUrl],
  );

  return searchMessages;
};