import { useMemo } from 'react';
import { useParams } from 'react-router-dom';
import { useMatrixClient } from '../../../hooks/useMatrixClient';
import { getCanonicalAliasRoomId, isRoomAlias } from '../../../utils/matrix';

export const ACTIVE_SPACE_KEY = 'vojo.activeSpaceId';

const readPersisted = (): string | null => {
  try {
    return localStorage.getItem(ACTIVE_SPACE_KEY);
  } catch {
    return null;
  }
};

const safeDecode = (raw: string): string | undefined => {
  try {
    return decodeURIComponent(raw);
  } catch {
    return undefined;
  }
};

// Resolves the active Space for the channels segment. Priority:
//   1. URL `:spaceIdOrAlias` param (if joined-orphan)
//   2. localStorage['vojo.activeSpaceId'] (if joined-orphan)
//   3. first joined-orphan Space
// Returns undefined when the user has 0 joined orphan spaces. Persistence
// (writing to localStorage) lives in `Channels.tsx`, where the inner
// route already has the resolved space context — at the index `/channels/`
// route, useParams().spaceIdOrAlias is always undefined.
export const useActiveSpace = (orphanSpaceIds: string[]): string | undefined => {
  const mx = useMatrixClient();
  const { spaceIdOrAlias } = useParams();
  const orphanSet = useMemo(() => new Set(orphanSpaceIds), [orphanSpaceIds]);

  const urlSpaceId = useMemo(() => {
    if (!spaceIdOrAlias) return undefined;
    const decoded = safeDecode(spaceIdOrAlias);
    if (!decoded) return undefined;
    const resolved = isRoomAlias(decoded) ? getCanonicalAliasRoomId(mx, decoded) : decoded;
    return resolved && orphanSet.has(resolved) ? resolved : undefined;
  }, [mx, spaceIdOrAlias, orphanSet]);

  const persistedSpaceId = useMemo(() => {
    const stored = readPersisted();
    return stored && orphanSet.has(stored) ? stored : undefined;
  }, [orphanSet]);

  return urlSpaceId ?? persistedSpaceId ?? orphanSpaceIds[0];
};