"use client";

/**
 * useMentionSources — the R3 mention popup's data sources, scoped to one
 * workspace (all of them are the caller's already-visible content — no extra
 * scoping beyond the sidebar; the Security section rule).
 *
 *   People    — workspace members (the Phase-2 members endpoint, exists).
 *   Teams     — the workspace's teams (the Phase-2 teams endpoint, exists).
 *   Pages     — the page tree (the sidebar's `usePageTree`, reused — no new
 *               endpoint; the search runs client-side over it, R3 decision).
 *   Databases — the workspace's databases (`GET /workspaces/:wid/databases`,
 *               the small list endpoint the R3 spec adds — already present).
 *
 * Each source is a TanStack query (cached — the sidebar already fetches
 * members + the tree, so those are usually warm). The popup's fuzzy search is
 * client-side over the fetched lists (`buildMentionGroups`), not per-keypress
 * network.
 */
import { useMemo } from "react";
import { useQuery } from "@tanstack/react-query";
import { workspaceApi } from "@/lib/api";
import { useWorkspaceMembers } from "@/hooks/use-workspace";
import { usePageTree } from "@/hooks/use-pages";
import type { MentionSource } from "@/components/mentions/mention-model";
import type { PageTreeEntry } from "@/lib/types";

/** Flatten a (nested) page tree to the leaf entries the popup can mention. */
function flattenPages(entries: PageTreeEntry[] | undefined): { id: string; title: string }[] {
  const out: { id: string; title: string }[] = [];
  const walk = (list: PageTreeEntry[] | undefined) => {
    for (const e of list ?? []) {
      out.push({ id: e.id, title: e.title });
      if (e.children) walk(e.children);
    }
  };
  walk(entries);
  return out;
}

export function useMentionSources(workspaceId: string) {
  const enabled = workspaceId.length > 0;

  const { data: members, isLoading: loadingMembers } = useWorkspaceMembers(workspaceId);
  const { data: tree, isLoading: loadingTree } = usePageTree(workspaceId);
  const { data: teams, isLoading: loadingTeams } = useQuery({
    queryKey: ["workspaces", workspaceId, "teams"],
    queryFn: () => workspaceApi.teams(workspaceId),
    enabled
  });
  const { data: databases, isLoading: loadingDatabases } = useQuery({
    queryKey: ["workspaces", workspaceId, "databases"],
    queryFn: () => workspaceApi.databases(workspaceId, { limit: 50 }),
    enabled
  });

  const source = useMemo<MentionSource>(
    () => ({
      people: (members ?? []).map((m) => m.user),
      teams: (teams ?? []).map((t) => ({ id: t.id, name: t.name, memberCount: t.memberCount })),
      pages: flattenPages(tree),
      databases: (databases ?? []).map((d) => ({ id: d.id, title: d.title, icon: d.icon }))
    }),
    [members, teams, tree, databases]
  );

  return {
    source,
    isLoading: loadingMembers || loadingTree || loadingTeams || loadingDatabases
  };
}