import { Router } from "@oak/oak";
import type { APIResponse } from "../../shared/api.ts";
import type { ChatMessage } from "../../shared/chat.ts";
import { authMiddleware } from "../middleware/auth.ts";
import {
  getChatMessagesAfter,
  getRecentChatMessages,
} from "../services/chat-service.ts";

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

// GET /api/chat — recent messages (ascending). `limit` caps the page size.
// Cursors (ISO created_at, plus the message id to break ties):
//   before/beforeId — the page of older messages preceding it ("load older");
//   after/afterId   — the messages following it (resync after a reconnect);
//                     without afterId the timestamp itself is included.
router.get("/", authMiddleware, (ctx) => {
  const params = ctx.request.url.searchParams;
  const limitParam = params.get("limit");
  const limit = limitParam ? Number(limitParam) : NaN;
  const cappedLimit = Number.isFinite(limit) ? limit : undefined;
  const before = params.get("before");
  const after = params.get("after");
  const messages = after
    ? getChatMessagesAfter(
      { createdAt: after, id: params.get("afterId") ?? undefined },
      cappedLimit,
    )
    : getRecentChatMessages(
      cappedLimit,
      before
        ? { createdAt: before, id: params.get("beforeId") ?? undefined }
        : undefined,
    );
  const responseBody: APIResponse<ChatMessage[]> = {
    success: true,
    data: messages,
  };
  ctx.response.body = responseBody;
});

export default router;