import { NextRequest, NextResponse } from "next/server";
import { PARKS } from "@/lib/parks";
import { openDb, getMonthCalendar } from "@/lib/db";
import type { Park } from "@/lib/scrapers/types";

export interface ParksApiResponse {
  parks: Park[];
  calendar: Record<string, boolean[]>;
  month: string;
  daysInMonth: number;
}

function getDaysInMonth(year: number, month: number): number {
  return new Date(year, month, 0).getDate();
}

function parseMonthParam(
  monthParam: string | null
): { year: number; month: number } | null {
  if (!monthParam) return null;
  const match = monthParam.match(/^(\d{4})-(\d{2})$/);
  if (!match) return null;
  const year = parseInt(match[1], 10);
  const month = parseInt(match[2], 10);
  if (month < 1 || month > 12) return null;
  return { year, month };
}

export async function GET(request: NextRequest): Promise<NextResponse> {
  const monthParam = request.nextUrl.searchParams.get("month");
  const parsed = parseMonthParam(monthParam);

  if (!parsed) {
    return NextResponse.json(
      { error: "Invalid or missing ?month=YYYY-MM parameter" },
      { status: 400 }
    );
  }

  const { year, month } = parsed;
  const daysInMonth = getDaysInMonth(year, month);

  const db = openDb();
  const calendar = getMonthCalendar(db, year, month);
  db.close();

  const response: ParksApiResponse = {
    parks: PARKS,
    calendar,
    month: `${year}-${String(month).padStart(2, "0")}`,
    daysInMonth,
  };

  return NextResponse.json(response, {
    headers: {
      "Cache-Control": "public, s-maxage=3600, stale-while-revalidate=86400",
    },
  });
}