using AS1024.GeoFeed.Core.Interfaces;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System.Runtime.CompilerServices;

namespace AS1024.GeoFeed.Core.GeoFeedLocalCache
{
    public class GeoFeedCacheService : IHostedService
    {
        private readonly ILogger<GeoFeedCacheService> logger;
        private readonly IGeoFeedProvider feedProvider;
        private readonly IHost host;

        public GeoFeedCacheService(ILogger<GeoFeedCacheService> logger,
        IGeoFeedProvider feedProvider,
        IHost host)
        {
            this.logger = logger;
            this.feedProvider = feedProvider;
            this.host = host;
        }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            _ = StartPerioidicSync(cancellationToken);
            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            return Task.CompletedTask;
        }

        public async Task<bool> StartPerioidicSync(CancellationToken Token)
        {
            await DBContextMigrate();

            List<GeoFeedCacheEntry> geoFeedCacheEntry = [];
            while (!Token.IsCancellationRequested)
            {
                logger.LogInformation("Running on disk fallback cache process...");
                try
                {
                    using var scope = host.Services.CreateScope();
                    using var dbContext = scope.ServiceProvider.GetRequiredService<GeoFeedCacheDbContext>();
                    var results = await feedProvider.GetGeoFeedData();

                    results.ForEach(x =>
                    {
                        geoFeedCacheEntry.Add(new()
                        {
                            Prefix = x.Prefix,
                            GeolocCity = x.GeolocCity,
                            GeolocCountry = x.GeolocCountry,
                            GeolocHasLocation = x.GeolocHasLocation,
                            GeolocPostalCode = x.GeolocPostalCode,
                            GeolocRegion = x.GeolocRegion
                        });
                    });

                    if (dbContext.GeoFeedCacheEntries.Any())
                    {
                        dbContext.GeoFeedCacheEntries.RemoveRange(dbContext.GeoFeedCacheEntries.ToArray());
                    }
                    await dbContext.AddRangeAsync(geoFeedCacheEntry, Token);
                    await dbContext.SaveChangesAsync(Token);
                }
                catch (Exception ex)
                {
                    logger.LogWarning("On disk cache failed to run. Waiting on 30 minutes before retry...");
                }
                await Task.Delay(TimeSpan.FromMinutes(30));
            }

            return false;
        }

        private async Task DBContextMigrate()
        {
            using IServiceScope scope = host.Services.CreateScope();
            using GeoFeedCacheDbContext? dbContext =
                scope.ServiceProvider.GetService<GeoFeedCacheDbContext>();
#pragma warning disable CS8602 // Dereference of a possibly null reference.
            if (dbContext.Database.GetPendingMigrations().Any()) {
                await dbContext.Database.MigrateAsync();
            }
#pragma warning restore CS8602 // Dereference of a possibly null reference.

        }
    }
}