import { fail, handleOptions, json } from "../_shared/http.ts";
import { requireUser } from "../_shared/supabase.ts";

const PAGE_SIZE = 20;

Deno.serve(async (req) => {
  const preflight = handleOptions(req);
  if (preflight) return preflight;

  if (req.method !== "POST") return fail("Method not allowed", 405);

  const { client, user, error: userError } = await requireUser(req);
  if (!user) return fail(userError ?? "Unauthorized", 401);

  let body: {
    channel_id?: string;
    schedule_id?: string;
    stop_name?: string;
    offset?: number;
    limit?: number;
  };
  try {
    body = await req.json();
  } catch {
    return fail("Invalid JSON body");
  }

  const channelId = (body.channel_id ?? "").trim();
  const scheduleId = (body.schedule_id ?? "").trim();
  const stopName = (body.stop_name ?? "").trim();
  const offset = Math.max(0, typeof body.offset === "number" ? body.offset : 0);
  const limit = Math.min(100, Math.max(1, typeof body.limit === "number" ? body.limit : PAGE_SIZE));

  if (!channelId) return fail("channel_id is required");
  if (!scheduleId) return fail("schedule_id is required");
  if (!stopName) return fail("stop_name is required");

  const { data: schedule, error: scheduleError } = await client
    .from("operations_schedules")
    .select("id, channel_id")
    .eq("id", scheduleId)
    .eq("channel_id", channelId)
    .maybeSingle();

  if (scheduleError) return fail(scheduleError.message, 400);
  if (!schedule) return fail("forbidden", 403);

  const { data: tripRows, error: tripError } = await client
    .from("operations_trips")
    .select("id, trip_number, duty_number, bus_work_number, direction")
    .eq("schedule_id", scheduleId);

  if (tripError) return fail(tripError.message, 500);

  const trips = (tripRows ?? []) as {
    id: string;
    trip_number: string;
    duty_number: string;
    bus_work_number: string;
    direction: string;
  }[];

  if (trips.length === 0) return json({ schedule: [], has_more: false });

  const tripIds = trips.map((t) => t.id);
  const tripById = Object.fromEntries(trips.map((t) => [t.id, t]));

  const { data: stopRows, error: stopError } = await client
    .from("operations_trip_stops")
    .select("trip_id, scheduled_time")
    .in("trip_id", tripIds)
    .eq("stop_name", stopName);

  if (stopError) return fail(stopError.message, 500);

  const rows = (stopRows ?? []) as { trip_id: string; scheduled_time: string | null }[];

  const result = rows
    .map((row) => {
      const trip = tripById[row.trip_id];
      if (!trip) return null;
      return { trip, scheduled_time: row.scheduled_time ?? null };
    })
    .filter(Boolean) as { trip: typeof trips[0]; scheduled_time: string | null }[];

  result.sort((a, b) => {
    const aNum = parseInt(a.trip.trip_number, 10);
    const bNum = parseInt(b.trip.trip_number, 10);
    if (!isNaN(aNum) && !isNaN(bNum)) return aNum - bNum;
    return a.trip.trip_number.localeCompare(b.trip.trip_number);
  });

  const page = result.slice(offset, offset + limit);
  const hasMore = offset + limit < result.length;

  return json({ schedule: page, has_more: hasMore });
});