import { Router } from "@oak/oak";
import { authMiddleware } from "../middleware/auth.ts";
import {
  type APIResponse,
  type Dump,
  type FollowStatus,
  type PaginatedData,
} from "../model/interfaces.ts";
import { parsePagination } from "../lib/pagination.ts";
import {
  followPlaylist,
  followUser,
  getFollowedPlaylistsDumpFeed,
  getFollowedUsersDumpFeed,
  getFollowStatus,
  unfollowPlaylist,
  unfollowUser,
} from "../services/follow-service.ts";
import { getCategoryIdBySlug } from "../services/category-service.ts";

// Resolves the optional ?category=<slug> filter. Returns the matching category
// id, or "missing" when a slug was given but matches nothing (so the feed comes
// back empty rather than unfiltered), or undefined when no filter was requested.
function resolveCategoryFilter(
  params: URLSearchParams,
): string | "missing" | undefined {
  const slug = params.get("category");
  if (!slug) return undefined;
  return getCategoryIdBySlug(slug) ?? "missing";
}

const EMPTY_FEED: { items: Dump[]; total: number } = { items: [], total: 0 };

const router = new Router({ prefix: "/api/follows" });

// Static routes first to prevent Oak matching "status"/"feed" as a :param

// GET /api/follows/status
router.get("/status", authMiddleware, (ctx) => {
  const status = getFollowStatus(ctx.state.user.userId);
  const body: APIResponse<FollowStatus> = { success: true, data: status };
  ctx.response.body = body;
});

// GET /api/follows/feed/users?page=&limit=
router.get("/feed/users", authMiddleware, (ctx) => {
  const { page, limit } = parsePagination(ctx.request.url.searchParams);
  const categoryId = resolveCategoryFilter(ctx.request.url.searchParams);
  const { items, total } = categoryId === "missing"
    ? EMPTY_FEED
    : getFollowedUsersDumpFeed(ctx.state.user.userId, page, limit, categoryId);
  const data: PaginatedData<Dump> = {
    items,
    total,
    hasMore: page * limit < total,
  };
  const body: APIResponse<PaginatedData<Dump>> = { success: true, data };
  ctx.response.body = body;
});

// GET /api/follows/feed/playlists?page=&limit=
router.get("/feed/playlists", authMiddleware, (ctx) => {
  const { page, limit } = parsePagination(ctx.request.url.searchParams);
  const categoryId = resolveCategoryFilter(ctx.request.url.searchParams);
  const { items, total } = categoryId === "missing"
    ? EMPTY_FEED
    : getFollowedPlaylistsDumpFeed(
      ctx.state.user.userId,
      page,
      limit,
      categoryId,
    );
  const data: PaginatedData<Dump> = {
    items,
    total,
    hasMore: page * limit < total,
  };
  const body: APIResponse<PaginatedData<Dump>> = { success: true, data };
  ctx.response.body = body;
});

// POST /api/follows/users/:userId
router.post("/users/:userId", authMiddleware, (ctx) => {
  followUser(ctx.state.user.userId, ctx.params.userId);
  ctx.response.status = 204;
});

// DELETE /api/follows/users/:userId
router.delete("/users/:userId", authMiddleware, (ctx) => {
  unfollowUser(ctx.state.user.userId, ctx.params.userId);
  ctx.response.status = 204;
});

// POST /api/follows/playlists/:playlistId
router.post("/playlists/:playlistId", authMiddleware, (ctx) => {
  followPlaylist(ctx.state.user.userId, ctx.params.playlistId);
  ctx.response.status = 204;
});

// DELETE /api/follows/playlists/:playlistId
router.delete("/playlists/:playlistId", authMiddleware, (ctx) => {
  unfollowPlaylist(ctx.state.user.userId, ctx.params.playlistId);
  ctx.response.status = 204;
});

export default router;