using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Services.RunOnce
{
    public class CacheCleanerService : IHostedService
    {
        private readonly ILogger<CacheCleanerService> _logger;
        private readonly IServiceScopeFactory _serviceScopeFactory;

        public CacheCleanerService(
            IServiceScopeFactory serviceScopeFactory,
            ILogger<CacheCleanerService> logger)
        {
            _serviceScopeFactory = serviceScopeFactory;
            _logger = logger;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            using IServiceScope scope = _serviceScopeFactory.CreateScope();
            await using TvContext dbContext = scope.ServiceProvider.GetRequiredService<TvContext>();

            if (Directory.Exists(FileSystemLayout.LegacyImageCacheFolder))
            {
                _logger.LogInformation("Migrating channel logos from legacy image cache folder");

                List<string> logos = await dbContext.Channels
                    .SelectMany(c => c.Artwork)
                    .Where(a => a.ArtworkKind == ArtworkKind.Logo)
                    .Map(a => a.Path)
                    .ToListAsync(cancellationToken);

                ILocalFileSystem localFileSystem = scope.ServiceProvider.GetRequiredService<ILocalFileSystem>();
                foreach (string logo in logos)
                {
                    string legacyPath = Path.Combine(FileSystemLayout.LegacyImageCacheFolder, logo);
                    if (File.Exists(legacyPath))
                    {
                        string subfolder = logo.Substring(0, 2);
                        string newPath = Path.Combine(FileSystemLayout.LogoCacheFolder, subfolder, logo);
                        await localFileSystem.CopyFile(legacyPath, newPath);
                    }
                }

                _logger.LogInformation("Deleting legacy image cache folder");
                Directory.Delete(FileSystemLayout.LegacyImageCacheFolder, true);
            }
        }

        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    }
}