using System;
using System.IO;
using System.Text;
using System.Text.Json;
using System.Text.Json.Nodes;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Linq;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;

namespace JellyfinPlugin
{
    public class PlaybackInfoInterceptorStartupFilter : IStartupFilter
    {
        private readonly ILogger<PlaybackInfoInterceptorStartupFilter> _logger;
        private readonly MediaBrowser.Controller.Library.ILibraryManager _libraryManager;

        public PlaybackInfoInterceptorStartupFilter(ILogger<PlaybackInfoInterceptorStartupFilter> logger, MediaBrowser.Controller.Library.ILibraryManager libraryManager)
        {
            _logger = logger;
            _libraryManager = libraryManager;
        }

        public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
        {
            return app =>
            {
                app.Use(InvokeAsync);
                next(app);
            };
        }

        private string? GetCropFromId(string itemId)
        {
            if (Guid.TryParse(itemId, out Guid id))
            {
                var item = _libraryManager.GetItemById(id);
                if (item != null && item.ProviderIds != null)
                {
                    if (item.ProviderIds.TryGetValue("BlackBarCrop", out string? cropData))
                    {
                        return cropData;
                    }
                }
            }
            return null;
        }

        private async Task InvokeAsync(HttpContext context, Func<Task> nextMw)
        {
            var path = context.Request.Path.Value ?? string.Empty;

            var config = Plugin.Instance?.Configuration;
            if (config == null || !config.IsEnabled || config.PlaybackMode == "Client")
            {
                await nextMw().ConfigureAwait(false);
                return;
            }

            // --- HLS STREAM QUERY REWRITE ---
            // If the client requests the m3u8 playlist, we simply tell Jellyfin NOT to allow video stream copy.
            // This elegantly forces transcoding for the BEST supported codec without breaking FFmpeg tags/filters!
            if (path.EndsWith("master.m3u8", StringComparison.OrdinalIgnoreCase) || 
                path.EndsWith("main.m3u8", StringComparison.OrdinalIgnoreCase))
            {
                var matchId = Regex.Match(path, @"/Videos/([^/]+)/", RegexOptions.IgnoreCase);
                if (matchId.Success)
                {
                    var idStr = matchId.Groups[1].Value;
                    var crop = GetCropFromId(idStr);
                    if (crop != null)
                    {
                        var query = Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(context.Request.QueryString.Value);
                        var items = query.SelectMany(x => x.Value, (col, val) => new System.Collections.Generic.KeyValuePair<string, string>(col.Key, val)).ToList();
                        
                        var newQueryString = "?";
                        foreach (var kvp in items)
                        {
                            if (!kvp.Key.Equals("allowVideoStreamCopy", StringComparison.OrdinalIgnoreCase) && 
                                !kvp.Key.Equals("transcodeReasons", StringComparison.OrdinalIgnoreCase))
                            {
                                newQueryString += $"{kvp.Key}={System.Net.WebUtility.UrlEncode(kvp.Value)}&";
                            }
                        }
                        // Force disable stream copy AND provide a valid reason for the dashboard
                        newQueryString += "allowVideoStreamCopy=false&transcodeReasons=VideoResolutionNotSupported";
                        
                        context.Request.QueryString = new QueryString(newQueryString);
                        _logger.LogInformation($"[Black Bar Remover DEBUG] Intercepted HLS request for {idStr}. Appended allowVideoStreamCopy=false and transcodeReasons=VideoResolutionNotSupported.");
                    }
                }
            }

            var match = Regex.Match(path, @"/Items/([^/]+)/PlaybackInfo", RegexOptions.IgnoreCase);
            
            if (!match.Success)
            {
                await nextMw().ConfigureAwait(false);
                return;
            }

            var itemId = match.Groups[1].Value;
            var cropData = GetCropFromId(itemId);
            
            if (cropData == null)
            {
                _logger.LogInformation($"[Black Bar Remover DEBUG] PlaybackInfo request for {itemId}, but no crop found in DB. Skipping interception.");
                await nextMw().ConfigureAwait(false);
                return;
            }

            _logger.LogInformation($"[Black Bar Remover DEBUG] Intercepting PlaybackInfo for {itemId}. Found crop in DB: {cropData}. Forcing transcode.");

            // Kestrel middleware do nadpisania odpowiedzi
            context.Request.Headers.Remove("Accept-Encoding");
            var originalBody = context.Response.Body;
            using var buffer = new MemoryStream();
            context.Response.Body = buffer;

            try
            {
                await nextMw().ConfigureAwait(false);
            }
            catch
            {
                context.Response.Body = originalBody;
                throw;
            }

            context.Response.Body = originalBody;
            buffer.Seek(0, SeekOrigin.Begin);

            var isJson = context.Response.ContentType?.Contains("application/json", StringComparison.OrdinalIgnoreCase) ?? false;
            
            if (!isJson || context.Response.StatusCode != 200)
            {
                await buffer.CopyToAsync(originalBody).ConfigureAwait(false);
                return;
            }

            string json;
            using (var reader = new StreamReader(buffer, Encoding.UTF8, true, 1024, leaveOpen: true))
            {
                json = await reader.ReadToEndAsync().ConfigureAwait(false);
            }

            try
            {
                var root = JsonNode.Parse(json);
                var mediaSources = root?["MediaSources"]?.AsArray();
                if (mediaSources != null)
                {
                    bool modified = false;
                    foreach (var source in mediaSources)
                    {
                        if (source == null) continue;
                        
                        var obj = source.AsObject();
                        
                        // Pobieramy flagi niezależnie od wielkości liter (Jellyfin 10.9+ może używać camelCase)
                        var dpNode = obj.FirstOrDefault(x => x.Key.Equals("SupportsDirectPlay", StringComparison.OrdinalIgnoreCase)).Value;
                        var dsNode = obj.FirstOrDefault(x => x.Key.Equals("SupportsDirectStream", StringComparison.OrdinalIgnoreCase)).Value;
                        
                        var dp = dpNode?.GetValue<bool>() ?? false;
                        var ds = dsNode?.GetValue<bool>() ?? false;

                        if (dp || ds)
                        {
                            // Szukamy oryginalnych kluczy, żeby ich nie zdublować w innym casing-u
                            var dpKey = obj.FirstOrDefault(x => x.Key.Equals("SupportsDirectPlay", StringComparison.OrdinalIgnoreCase)).Key ?? "SupportsDirectPlay";
                            var dsKey = obj.FirstOrDefault(x => x.Key.Equals("SupportsDirectStream", StringComparison.OrdinalIgnoreCase)).Key ?? "SupportsDirectStream";
                            var trKey = obj.FirstOrDefault(x => x.Key.Equals("TranscodingReasons", StringComparison.OrdinalIgnoreCase)).Key ?? "TranscodingReasons";

                            obj[dpKey] = false;
                            obj[dsKey] = false;
                            
                            var transcodingReasons = obj[trKey]?.GetValue<string>();
                            string customReason = "VideoCodecNotSupported"; 

                            if (transcodingReasons == null)
                            {
                                obj[trKey] = customReason;
                            }
                            else if (!transcodingReasons.Contains(customReason))
                            {
                                obj[trKey] = transcodingReasons + "," + customReason;
                            }
                            
                            // Dodatkowo obcinamy wsparcie dla Direct Stream w pod-strumieniach (Jellyfin czasami wymusza z poziomu klienta)
                            var reqKey = obj.FirstOrDefault(x => x.Key.Equals("RequiresOpening", StringComparison.OrdinalIgnoreCase)).Key ?? "RequiresOpening";
                            obj[reqKey] = true;

                            var reqCloseKey = obj.FirstOrDefault(x => x.Key.Equals("RequiresClosing", StringComparison.OrdinalIgnoreCase)).Key ?? "RequiresClosing";
                            obj[reqCloseKey] = true;

                            modified = true;
                            _logger.LogInformation($"[Black Bar Remover DEBUG] Modified PlaybackInfo JSON: forced {dpKey}/{dsKey} to false for MediaSource ID {obj.FirstOrDefault(x => x.Key.Equals("Id", StringComparison.OrdinalIgnoreCase)).Value}");
                        }
                    }

                    if (modified)
                    {
                        json = root!.ToJsonString(new JsonSerializerOptions { WriteIndented = false });
                        _logger.LogInformation($"[Black Bar Remover DEBUG] Successfully rewrote PlaybackInfo JSON to enforce transcoding.");
                    }
                }
            }
            catch (Exception ex)
            {
                _logger.LogWarning($"[Black Bar Remover DEBUG] Error modifying PlaybackInfo JSON: {ex.Message}");
            }

            var bytes = Encoding.UTF8.GetBytes(json);
            context.Response.ContentType = "application/json; charset=utf-8";
            context.Response.ContentLength = bytes.Length;
            context.Response.Headers.Remove("ETag");
            context.Response.Headers.Remove("Last-Modified");
            await originalBody.WriteAsync(bytes, 0, bytes.Length).ConfigureAwait(false);
        }
    }
}