using System.Text;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Caching.Memory;
using Nuuru.Server.Data;
using Nuuru.Server.Models;
using Nuuru.Server.Utilities;

namespace Nuuru.Server.Services
{
    public interface IIpCloakService
    {
        Task<string> CloakAsync(string ipAddress);
        Task<string?> UncloakAsync(string cloakedIp);
        Task<ICollection<string>> FindRawIpsByCloakedSubstringAsync(string substring);
    }

    public class IpCloakService : IIpCloakService
    {
        private readonly ApplicationDbContext _context;
        private readonly IMemoryCache _cache;
        private readonly byte[] _key;
        private static readonly TimeSpan CacheDuration = TimeSpan.FromMinutes(30);

        public IpCloakService(ApplicationDbContext context, IMemoryCache cache, IConfiguration configuration)
        {
            _context = context;
            _cache = cache;
            _key = Encoding.UTF8.GetBytes(configuration["IpCloak:Key"]!);
        }

        public async Task<string> CloakAsync(string ipAddress)
        {
            var cacheKey = $"ipcloak:{ipAddress}";
            if (_cache.TryGetValue(cacheKey, out string? cached))
                return cached!;

            var cloaked = IpCloaker.Cloak(ipAddress, _key);
            _cache.Set(cacheKey, cloaked, CacheDuration);

            if (!await _context.IpCloakEntries.AnyAsync(e => e.RawIp == ipAddress))
            {
                _context.IpCloakEntries.Add(new IpCloakEntry
                {
                    RawIp = ipAddress,
                    CloakedIp = cloaked,
                    CreatedAt = DateTime.UtcNow
                });
                await _context.SaveChangesAsync();
            }

            return cloaked;
        }

        public async Task<string?> UncloakAsync(string cloakedIp)
        {
            var cacheKey = $"ipuncloak:{cloakedIp}";
            if (_cache.TryGetValue(cacheKey, out string? cached))
                return cached;

            var rawIp = await _context.IpCloakEntries
                .Where(e => e.CloakedIp == cloakedIp)
                .Select(e => e.RawIp)
                .FirstOrDefaultAsync();

            if (rawIp != null)
                _cache.Set(cacheKey, rawIp, CacheDuration);

            return rawIp;
        }

        public async Task<ICollection<string>> FindRawIpsByCloakedSubstringAsync(string substring)
        {
            return await _context.IpCloakEntries
                .Where(e => e.CloakedIp.Contains(substring))
                .Select(e => e.RawIp)
                .ToHashSetAsync();
        }
    }
}