using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using Microsoft.Win32;
using TechnologyAssembler.Core.IO;

namespace HashCalculator.GUI
{
    internal abstract class NotifyPropertyChanged : INotifyPropertyChanged
    {
        #region INotifyPropertyChanged
        public event PropertyChangedEventHandler? PropertyChanged;

        protected void Notify(string name)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
        }

        protected void SetField<X>(ref X field, X value, [CallerMemberName] string? propertyName = null)
        {
            if (propertyName == null)
            {
                throw new InvalidOperationException();
            }

            if (EqualityComparer<X>.Default.Equals(field, value))
            {
                return;
            }

            field = value;

            Notify(propertyName);
        }
        #endregion
    }

    [SuppressMessage("Microsoft.Performance", "CA1812")]
    internal class ViewModel : NotifyPropertyChanged
    {
        public MainInputViewModel MainInput { get; } = new MainInputViewModel();
        public BigInputViewModel BigEntryInput { get; } = new BigInputViewModel();
        public InputBarViewModel AssetIdInput { get; } = new InputBarViewModel();

        private Visibility _bigInputVisibility = Visibility.Collapsed;
        public Visibility BigInputVisibility
        {
            get => _bigInputVisibility;
            set => SetField(ref _bigInputVisibility, value);
        }

        private InputEntry? _mainInputResult; // if not null
        private string? _bigManifest;

        public ViewModel()
        {
        }

        [SuppressMessage("Design", "CA1031:不捕获常规异常类型", Justification = "<挂起>")]
        public async Task OnMainInputDecided(InputEntry selected)
        {
            BigInputVisibility = Visibility.Collapsed;
            switch (selected.Type)
            {
                case InputEntryType.BinaryFile:
                    CopyableBox.ShowDialog(async cancel =>
                    {
                        try
                        {
                            var hash = await Task.Run(() =>
                            {
                                return SageHash.CalculateBinaryHash(File.ReadAllBytes(selected.Value));
                            }).ConfigureAwait(false);
                            return $"使用Sage Hash计算出的哈希值：{hash:X8} （十进制 {hash}）\r\n"
                                + "注意这是以大小写敏感模式计算出的哈希值，与素材ID（大小写不敏感）的哈希其实并不完全一样";
                        }
                        catch (Exception exception)
                        {
                            return exception.ToString();
                        }
                    });
                    break;
                case InputEntryType.BigFile:
                    BigInputVisibility = Visibility.Visible;
                    throw new NotImplementedException();
                case InputEntryType.ManifestFile:
                    await ProcessManifest(selected).ConfigureAwait(true);
                    break;
                case InputEntryType.XmlFile:
                    throw new NotImplementedException();
                default:
                    throw new NotSupportedException();
            }
        }

        public async Task ProcessManifest(InputEntry entry)
        {
            var content = await Task.Run(() =>
            {
                using var stream = File.OpenRead(entry.Value);
                return new ManifestContent(entry.Text, stream);
            }).ConfigureAwait(true);
            await ProcessManifest(content).ConfigureAwait(true);
        }

        public async Task ProcessManifest(ManifestContent content)
        {
            throw new NotImplementedException();
        }
    }

    internal class InputBarViewModel : NotifyPropertyChanged
    {
        private IEnumerable<InputEntry>? _items;
        public virtual IEnumerable<InputEntry>? Items
        {
            get => _items;
            set => SetField(ref _items, value);
        }

        private InputEntry? _selectedItem;
        public virtual InputEntry? SelectedItem
        {
            get => _selectedItem;
            set => SetField(ref _selectedItem, value);
        }

        private string? _text;
        public virtual string? Text
        {
            get => _text;
            set => SetField(ref _text, value);
        }
    }

    internal class MainInputViewModel : InputBarViewModel
    {
        private readonly FileSystemSuggestions _suggestions = new FileSystemSuggestions();

        private int _selectedIndex;
        public int SelectedIndex
        {
            get => _selectedIndex;
            set
            {
                if (value == 0)
                {
                    if (Items.Count() <= 1)
                    {
                        value = -1;
                    }
                    else
                    {
                        value = _selectedIndex < value ? 1 : -1;
                    }
                }
                SetField(ref _selectedIndex, value);
            }
        }

        public override string? Text
        {
            get => base.Text;
            set
            {
                base.Text = value;
                if (value != SelectedItem?.ToString())
                {
                    UpdateList(value);
                }
            }
        }

        public Command<MainWindow> BrowseCommand { get; }
        public Command<ViewModel> SelectCommand { get; }

        public MainInputViewModel()
        {
            Items = Enumerable.Empty<InputEntry>();
            BrowseCommand = new Command<MainWindow>(window =>
            {
                var dialog = new OpenFileDialog
                {
                    Multiselect = false,
                    ValidateNames = true
                };
                if (dialog.ShowDialog(window) == true)
                {
                    Text = dialog.FileName;
                }
                return Task.CompletedTask;
            });
            SelectCommand = new Command<ViewModel>(async viewModel =>
            {
                if(SelectedItem?.IsValid != true)
                {
                    return;
                }

                try
                {
                    BrowseCommand.CanExecuteValue = false;
                    SelectCommand.CanExecuteValue = false;
                    await viewModel.OnMainInputDecided(SelectedItem).ConfigureAwait(true);
                }
                finally
                {
                    BrowseCommand.CanExecuteValue = true;
                    SelectCommand.CanExecuteValue = true;
                    SelectedIndex = -1;
                }
            });
        }

        private void UpdateList(string? path)
        {
            bool candidateFound = false;
            var result = _suggestions.ProvideFileSystemSuggestions(path);
            InputEntry? first = result.FirstOrDefault();
            if (first != null)
            {
                if (new FileInfo(path!).FullName == new FileInfo(first.Value).FullName)
                {
                    candidateFound = true;
                }
            }

            if (!string.IsNullOrEmpty(path))
            {
                result = result.Prepend(new InputEntry(InputEntryType.Text, path!, path!));
            }
            Items = result;

            if (candidateFound)
            {
                SelectedIndex = 1;
            }
        }
    }

    [SuppressMessage("Design", "CA1001:具有可释放字段的类型应该是可释放的", Justification = "<挂起>")]
    internal class BigInputViewModel : NotifyPropertyChanged
    {
        private CancellationTokenSource? _currentCancellator = null;

        private IEnumerable<ManifestContent>? _manifests;
        public IEnumerable<ManifestContent>? Manifests
        {
            get => _manifests;
            set => SetField(ref _manifests, value);
        }

        private ManifestContent? _selectedManifest;
        public ManifestContent? SelectedManifest
        {
            get => _selectedManifest;
            set
            {
                SetField(ref _selectedManifest, value);
                SelectCommand.CanExecuteValue = value != null;
            }
        }

        public Command<ViewModel> SelectCommand { get; }

        public BigInputViewModel()
        {
            SelectCommand = new Command<ViewModel>(viewModel => viewModel.ProcessManifest(SelectedManifest!));
        }

        public async Task LoadBig(string path)
        {
            using var cancellator = _currentCancellator = new CancellationTokenSource();
            var saved = Interlocked.Exchange(ref _currentCancellator, cancellator);
            saved?.Cancel();
            
            var token = cancellator.Token;
            try
            {
                using var big = await Task.Run(() => new BigFile(path), token).ConfigureAwait(true);
                var manifests = await Task.Run(() =>
                {
                    var manifests = big.GetFiles(string.Empty, "*.manifest", VirtualSearchOptionType.AllDirectories);
                    var modManifests = from manifest in manifests
                                       where FileNameStartsWith(manifest, "mod")
                                       select manifest;
                    var globalDataManifests = from manifest in manifests
                                              where FileNameStartsWith(manifest, "mapmetadata")
                                              select manifest;
                    var firstManifests = modManifests.Concat(globalDataManifests);
                    var otherManifests = from manifest in manifests
                                         where !firstManifests.Contains(manifest)
                                         select manifest;

                    var list = new List<ManifestContent>();
                    foreach (var path in firstManifests.Concat(otherManifests))
                    {
                        token.ThrowIfCancellationRequested();
                        using var stream = big.OpenStream(path);
                        list.Add(new ManifestContent(path, stream));
                    }
                    return list;
                }, token).ConfigureAwait(true);

                if (!token.IsCancellationRequested)
                {
                    Manifests = manifests;
                }
            }
            catch (OperationCanceledException) { }

            Interlocked.CompareExchange(ref _currentCancellator, null, cancellator);
        }

        private static bool FileNameStartsWith(string path, string what)
        {
            return Path.GetFileName(path).StartsWith(what, StringComparison.OrdinalIgnoreCase);
        }
    }

    internal class ManifestContent
    {
        public string Name { get; }
        public byte[] Data { get; }

        public ManifestContent(string name, Stream stream)
        {
            Name = name;
            using var memoryStream = new MemoryStream();
            stream.CopyTo(memoryStream);
            Data = memoryStream.ToArray();
        }

        public override string ToString()
        {
            return Name;
        }
    }
}