import { serve } from "https://deno.land/std@0.168.0/http/server.ts";

const corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type',
};

interface IPLocationResponse {
  country: string;
  countryCode: string;
  measurementSystem: 'metric' | 'imperial';
}

serve(async (req) => {
  // Handle CORS preflight requests
  if (req.method === 'OPTIONS') {
    return new Response(null, { headers: corsHeaders });
  }

  try {
    // Get the client's IP address
    const forwarded = req.headers.get('x-forwarded-for');
    const realIP = req.headers.get('x-real-ip');
    const clientIP = forwarded?.split(',')[0] || realIP || '8.8.8.8'; // fallback to Google DNS for testing
    
    console.log('Detecting location for IP:', clientIP);

    // Use a free IP geolocation service with proper error handling
    let geoResponse;
    try {
      geoResponse = await fetch(`http://ip-api.com/json/${clientIP}?fields=status,country,countryCode`);
    } catch (fetchError) {
      console.error('Network error fetching location data:', fetchError);
      throw new Error('Network error: Unable to reach geolocation service');
    }
    
    if (!geoResponse.ok) {
      throw new Error(`Geolocation service returned ${geoResponse.status}: ${geoResponse.statusText}`);
    }
    
    let geoData;
    try {
      geoData = await geoResponse.json();
    } catch (parseError) {
      console.error('Failed to parse geolocation response:', parseError);
      throw new Error('Invalid response format from geolocation service');
    }
    
    if (geoData.status !== 'success') {
      throw new Error(`Geolocation failed: ${geoData.message || 'Invalid location data'}`);
    }

    // Countries that primarily use imperial system
    const imperialCountries = ['US', 'LR', 'MM']; // USA, Liberia, Myanmar
    const measurementSystem = imperialCountries.includes(geoData.countryCode) ? 'imperial' : 'metric';

    const result: IPLocationResponse = {
      country: geoData.country,
      countryCode: geoData.countryCode,
      measurementSystem
    };

    console.log('Location detected:', result);

    return new Response(
      JSON.stringify(result),
      { 
        headers: { 
          ...corsHeaders, 
          'Content-Type': 'application/json' 
        } 
      }
    );

  } catch (error) {
    console.error('Error detecting location:', error);
    
    // Return default (metric) on error
    const defaultResult: IPLocationResponse = {
      country: 'Unknown',
      countryCode: 'XX',
      measurementSystem: 'metric'
    };

    return new Response(
      JSON.stringify(defaultResult),
      { 
        headers: { 
          ...corsHeaders, 
          'Content-Type': 'application/json' 
        },
        status: 200 // Return 200 even on error to provide fallback
      }
    );
  }
});