using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using Havok;
using NLog;
using Sandbox.Engine.Networking;
using Sandbox.Engine.Utils;
using Sandbox.Game;
using Sandbox.Game.Gui;
using Torch.API;
using Torch.API.Managers;
using Torch.Managers;
using Torch.Server.ViewModels;
using VRage;
using VRage.FileSystem;
using VRage.Game;
using VRage.Game.ObjectBuilder;
using VRage.ObjectBuilders;
using VRage.Plugins;

namespace Torch.Server.Managers
{
    public class InstanceManager : Manager
    {
        private const string CONFIG_NAME = "SpaceEngineers-Dedicated.cfg";

        public event Action<ConfigDedicatedViewModel> InstanceLoaded;
        public ConfigDedicatedViewModel DedicatedConfig { get; set; }
        private static readonly Logger Log = LogManager.GetLogger(nameof(InstanceManager));
        [Dependency]
        private FilesystemManager _filesystemManager;

        public InstanceManager(ITorchBase torchInstance) : base(torchInstance)
        {
            
        }
        
        public void LoadInstance(string path, bool validate = true)
        {
            Log.Info($"Loading instance {path}");

            if (validate)
                ValidateInstance(path);

            MyFileSystem.Reset();
            MyFileSystem.Init("Content", path);
            //Initializes saves path. Why this isn't in Init() we may never know.
            MyFileSystem.InitUserSpecific(null);

            var configPath = Path.Combine(path, CONFIG_NAME);
            if (!File.Exists(configPath))
            {
                Log.Error($"Failed to load dedicated config at {path}");
                return;
            }

            var config = new MyConfigDedicated<MyObjectBuilder_SessionSettings>(configPath);
            config.Load(configPath);

            DedicatedConfig = new ConfigDedicatedViewModel(config);

            var worldFolders = Directory.EnumerateDirectories(Path.Combine(Torch.Config.InstancePath, "Saves"));

            foreach (var f in worldFolders)
            {
                if (!string.IsNullOrEmpty(f) && File.Exists(Path.Combine(f, "Sandbox.sbc")))
                    DedicatedConfig.Worlds.Add(new WorldViewModel(f));
            }

            if (DedicatedConfig.Worlds.Count == 0)
            {
                Log.Warn($"No worlds found in the current instance {path}.");
                return;
            }

            SelectWorld(DedicatedConfig.LoadWorld ?? DedicatedConfig.Worlds.First().WorldPath, false);

            InstanceLoaded?.Invoke(DedicatedConfig);
        }

        public void SelectWorld(string worldPath, bool modsOnly = true)
        {
            DedicatedConfig.LoadWorld = worldPath;
            DedicatedConfig.SelectedWorld = DedicatedConfig.Worlds.FirstOrDefault(x => x.WorldPath == worldPath);
        }

        public void SelectWorld(WorldViewModel world, bool modsOnly = true)
        {
            DedicatedConfig.LoadWorld = world.WorldPath;
            DedicatedConfig.SelectedWorld = world;
        }

        public void ImportSelectedWorldConfig()
        {
            ImportWorldConfig(DedicatedConfig.SelectedWorld, false);
        }

        private void ImportWorldConfig(WorldViewModel world, bool modsOnly = true)
        {
            var sb = new StringBuilder();
            foreach (var mod in world.Checkpoint.Mods)
                sb.AppendLine(mod.PublishedFileId.ToString());

            DedicatedConfig.Mods = world.Checkpoint.Mods.Select(x => x.PublishedFileId).ToList();

            Log.Debug("Loaded mod list from world");

            if (!modsOnly)
                DedicatedConfig.SessionSettings = world.Checkpoint.Settings;
        }

        private void ImportWorldConfig(bool modsOnly = true)
        {
            if (string.IsNullOrEmpty(DedicatedConfig.LoadWorld))
                return;

            var sandboxPath = Path.Combine(DedicatedConfig.LoadWorld, "Sandbox.sbc");

            if (!File.Exists(sandboxPath))
                return;

            try
            {
                MyObjectBuilderSerializer.DeserializeXML(sandboxPath, out MyObjectBuilder_Checkpoint checkpoint, out ulong sizeInBytes);
                if (checkpoint == null)
                {
                    Log.Error($"Failed to load {DedicatedConfig.LoadWorld}, checkpoint null ({sizeInBytes} bytes, instance {Torch.Config.InstancePath})");
                    return;
                }

                var sb = new StringBuilder();
                foreach (var mod in checkpoint.Mods)
                    sb.AppendLine(mod.PublishedFileId.ToString());

                DedicatedConfig.Mods = checkpoint.Mods.Select(x => x.PublishedFileId).ToList();

                Log.Debug("Loaded mod list from world");

                if (!modsOnly)
                    DedicatedConfig.SessionSettings = new SessionSettingsViewModel(checkpoint.Settings);
            }
            catch (Exception e)
            {
                Log.Error($"Error loading mod list from world, verify that your mod list is accurate. '{DedicatedConfig.LoadWorld}'.");
                Log.Error(e);
            }
        }

        public void SaveConfig()
        {
            DedicatedConfig.Save(Path.Combine(Torch.Config.InstancePath, CONFIG_NAME));
            Log.Info("Saved dedicated config.");

            try
            {
                var sandboxPath = Path.Combine(DedicatedConfig.LoadWorld, "Sandbox.sbc");
                MyObjectBuilderSerializer.DeserializeXML(sandboxPath, out MyObjectBuilder_Checkpoint checkpoint, out ulong sizeInBytes);
                if (checkpoint == null)
                {
                    Log.Error($"Failed to load {DedicatedConfig.LoadWorld}, checkpoint null ({sizeInBytes} bytes, instance {Torch.Config.InstancePath})");
                    return;
                }

                checkpoint.SessionName = DedicatedConfig.WorldName;
                checkpoint.Settings = DedicatedConfig.SessionSettings;
                checkpoint.Mods.Clear();
                foreach (var modId in DedicatedConfig.Model.Mods)
                    checkpoint.Mods.Add(new MyObjectBuilder_Checkpoint.ModItem(modId));

                MyObjectBuilderSerializer.SerializeXML(sandboxPath, false, checkpoint);

                //MyLocalCache.SaveCheckpoint(checkpoint, DedicatedConfig.LoadWorld);
                Log.Info("Saved world config.");
            }
            catch (Exception e)
            {
                Log.Error("Failed to write sandbox config, changes will not appear on server");
                Log.Error(e);
            }
        }

        /// <summary>
        /// Ensures that the given path is a valid server instance.
        /// </summary>
        private void ValidateInstance(string path)
        {
            Directory.CreateDirectory(Path.Combine(path, "Saves"));
            Directory.CreateDirectory(Path.Combine(path, "Mods"));
            var configPath = Path.Combine(path, CONFIG_NAME);
            if (File.Exists(configPath))
                return;

            var config = new MyConfigDedicated<MyObjectBuilder_SessionSettings>(configPath);
            config.Save(configPath);
        }
    }

    public class WorldViewModel : ViewModel
    {
        private static readonly Logger Log = LogManager.GetCurrentClassLogger();

        public string FolderName { get; set; }
        public string WorldPath { get; }
        public long WorldSizeKB { get; }
        private string _checkpointPath;
        public CheckpointViewModel Checkpoint { get; private set; }

        public WorldViewModel(string worldPath)
        {
            WorldPath = worldPath;
            WorldSizeKB = new DirectoryInfo(worldPath).GetFiles().Sum(x => x.Length) / 1024;
            _checkpointPath = Path.Combine(WorldPath, "Sandbox.sbc");
            FolderName = Path.GetFileName(worldPath);
            BeginLoadCheckpoint();
        }

        public async Task SaveCheckpointAsync()
        {
            await Task.Run(() =>
            {
                using (var f = File.Open(_checkpointPath, FileMode.Create))
                    MyObjectBuilderSerializer.SerializeXML(f, Checkpoint);
            });
        }

        private void BeginLoadCheckpoint()
        {
            Task.Run(() =>
            {
                Log.Info($"Preloading checkpoint {_checkpointPath}");
                MyObjectBuilderSerializer.DeserializeXML(_checkpointPath, out MyObjectBuilder_Checkpoint checkpoint);
                Checkpoint = new CheckpointViewModel(checkpoint);
                OnPropertyChanged(nameof(Checkpoint));
            });
        }
    }
}