using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Emby;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.Interfaces.Runtime;
using LanguageExt;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Core.Emby
{
    public class EmbyPathReplacementService : IEmbyPathReplacementService
    {
        private readonly ILogger<EmbyPathReplacementService> _logger;
        private readonly IMediaSourceRepository _mediaSourceRepository;
        private readonly IRuntimeInfo _runtimeInfo;

        public EmbyPathReplacementService(
            IMediaSourceRepository mediaSourceRepository,
            IRuntimeInfo runtimeInfo,
            ILogger<EmbyPathReplacementService> logger)
        {
            _mediaSourceRepository = mediaSourceRepository;
            _runtimeInfo = runtimeInfo;
            _logger = logger;
        }

        public async Task<string> GetReplacementEmbyPath(int libraryPathId, string path)
        {
            List<EmbyPathReplacement> replacements =
                await _mediaSourceRepository.GetEmbyPathReplacementsByLibraryId(libraryPathId);

            return GetReplacementEmbyPath(replacements, path);
        }

        public string GetReplacementEmbyPath(
            List<EmbyPathReplacement> pathReplacements,
            string path,
            bool log = true)
        {
            Option<EmbyPathReplacement> maybeReplacement = pathReplacements
                .SingleOrDefault(
                    r =>
                    {
                        string separatorChar = IsWindows(r.EmbyMediaSource, path) ? @"\" : @"/";
                        string prefix = r.EmbyPath.EndsWith(separatorChar)
                            ? r.EmbyPath
                            : r.EmbyPath + separatorChar;
                        return path.StartsWith(prefix);
                    });

            return maybeReplacement.Match(
                replacement =>
                {
                    string finalPath = path.Replace(replacement.EmbyPath, replacement.LocalPath);
                    if (IsWindows(replacement.EmbyMediaSource, path) && !_runtimeInfo.IsOSPlatform(OSPlatform.Windows))
                    {
                        finalPath = finalPath.Replace(@"\", @"/");
                    }
                    else if (!IsWindows(replacement.EmbyMediaSource, path) &&
                             _runtimeInfo.IsOSPlatform(OSPlatform.Windows))
                    {
                        finalPath = finalPath.Replace(@"/", @"\");
                    }

                    if (log)
                    {
                        _logger.LogDebug(
                            "Replacing emby path {EmbyPath} with {LocalPath} resulting in {FinalPath}",
                            replacement.EmbyPath,
                            replacement.LocalPath,
                            finalPath);
                    }

                    return finalPath;
                },
                () => path);
        }

        private static bool IsWindows(EmbyMediaSource embyMediaSource, string path)
        {
            bool isUnc = Uri.TryCreate(path, UriKind.Absolute, out Uri uri) && uri.IsUnc;
            return isUnc || embyMediaSource.OperatingSystem.ToLowerInvariant().StartsWith("windows");
        }
    }
}