using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace LanDiscovery.Services
{
    public class OuiVendorLookupService
    {
        private readonly Dictionary<string, string> _ouiDatabase = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);

        public OuiVendorLookupService()
        {
            // Load common vendors for MVP immediate gratification
            _ouiDatabase["00:0C:29"] = "VMware";
            _ouiDatabase["00:50:56"] = "VMware";
            _ouiDatabase["00:15:5D"] = "Microsoft (Hyper-V)";
            _ouiDatabase["B8:27:EB"] = "Raspberry Pi";
            _ouiDatabase["DC:A6:32"] = "Raspberry Pi";
            _ouiDatabase["E4:5F:01"] = "Raspberry Pi";
            _ouiDatabase["00:11:32"] = "Synology";
            _ouiDatabase["F0:9F:C2"] = "Ubiquiti";
            _ouiDatabase["74:83:C2"] = "Ubiquiti";
            _ouiDatabase["18:E8:29"] = "Ubiquiti";
            _ouiDatabase["AC:87:A3"] = "Apple";
            _ouiDatabase["00:1A:11"] = "Google";
            _ouiDatabase["52:54:00"] = "QEMU/KVM";
            
            // TODO: Load full "oui.txt" if present in Assets
        }

        public string GetVendor(string macAddress)
        {
            if (string.IsNullOrEmpty(macAddress)) return "";

            // Normalize MAC: 00-11-22 -> 00:11:22
            var formatted = macAddress.Replace("-", ":").ToUpper();
            
            // Check first 3 bytes (XX:XX:XX)
            if (formatted.Length >= 8)
            {
                var prefix = formatted.Substring(0, 8); // "00:11:22"
                if (_ouiDatabase.TryGetValue(prefix, out var vendor))
                {
                    return vendor;
                }
            }

            return "Unknown";
        }
    }
}