import { NextRequest, NextResponse } from "next/server";
import type { LocationResponse } from "@/types/location";
import { locationDb, Location, deviceDb, userDb } from "@/lib/db";
import { auth } from "@/lib/auth";

/**
 * GET /api/locations
 *
 * Fetches location data from local SQLite cache.
 * The MQTT subscriber automatically writes new locations to the cache.
 *
 * Query parameters:
 * - username: Filter by device tracker ID
 * - timeRangeHours: Filter by time range (e.g., 1, 3, 6, 12, 24)
 * - startTime: Custom range start (ISO string)
 * - endTime: Custom range end (ISO string)
 * - limit: Maximum number of records (default: 1000)
 */
export async function GET(request: NextRequest) {
  try {
    // Check authentication
    const session = await auth();
    if (!session?.user) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    // Get user's allowed device IDs for filtering locations
    const userId = (session.user as any).id;
    const role = (session.user as any).role;
    const sessionUsername = session.user.name || '';

    // Get list of device IDs the user is allowed to access
    const userDeviceIds = userDb.getAllowedDeviceIds(userId, role, sessionUsername);

    // If user has no devices, return empty response
    if (userDeviceIds.length === 0) {
      return NextResponse.json({
        success: true,
        current: null,
        history: [],
        total_points: 0,
        last_updated: new Date().toISOString(),
      });
    }

    const searchParams = request.nextUrl.searchParams;
    const username = searchParams.get('username') || undefined;
    const timeRangeHours = searchParams.get('timeRangeHours')
      ? parseInt(searchParams.get('timeRangeHours')!, 10)
      : undefined;
    const startTime = searchParams.get('startTime') || undefined;
    const endTime = searchParams.get('endTime') || undefined;
    const limit = searchParams.get('limit')
      ? parseInt(searchParams.get('limit')!, 10)
      : 1000;

    // Read from local SQLite with filters
    let locations = locationDb.findMany({
      user_id: 0, // Always filter for MQTT devices
      username,
      timeRangeHours,
      startTime,
      endTime,
      limit,
    });

    // Filter locations to only include user's devices
    locations = locations.filter(loc => loc.username && userDeviceIds.includes(loc.username));

    // Normalize locations: Ensure speed, battery, and display_time are correct
    locations = locations.map(loc => {
      // Generate display_time if missing or regenerate from timestamp
      const displayTime = loc.display_time || new Date(loc.timestamp).toLocaleString('de-DE', {
        timeZone: 'Europe/Berlin',
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
        hour: '2-digit',
        minute: '2-digit',
        second: '2-digit'
      });

      return {
        ...loc,
        display_time: displayTime,
        speed: loc.speed !== undefined && loc.speed !== null ? Number(loc.speed) : null,
        battery: loc.battery !== undefined && loc.battery !== null ? Number(loc.battery) : null,
      };
    });

    // Get actual total count from database (not limited by 'limit' parameter)
    const stats = locationDb.getStats();

    // Return data in standard format
    const response: LocationResponse = {
      success: true,
      current: locations.length > 0 ? locations[0] : null,
      history: locations,
      total_points: stats.total, // Use actual total from DB, not limited results
      last_updated: locations.length > 0 ? locations[0].timestamp : new Date().toISOString(),
    };

    return NextResponse.json(response);
  } catch (error) {
    console.error("Error fetching locations:", error);
    return NextResponse.json(
      {
        error: "Failed to fetch locations",
        details: error instanceof Error ? error.message : "Unknown error"
      },
      { status: 500 }
    );
  }
}