using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using System.Collections.Generic;
using System.Text.RegularExpressions;

using Avalonia;
using Avalonia.Input;
using Avalonia.Controls;
using Avalonia.VisualTree;
using Avalonia.Markup.Xaml;
using Avalonia.LogicalTree;

using BFR.Helpers;
using BFR.DataModels;
using BFR.Operations;

namespace BFR
{
    public partial class MainWindow : Window
    {
        public readonly AvaloniaProperty[] HandledProperties = new AvaloniaProperty[] { TextBox.TextProperty, ComboBox.SelectedItemProperty, NumericUpDown.ValueProperty, CheckBox.IsCheckedProperty };
        private bool HandleEvents = false;

        public async Task OpenDirectoryButtonClick() => OpenDirectory(await new OpenFolderDialog() { Directory = WorkingDirectory }.ShowAsync(this));
        public void OpenDirectory(string directory)
        {
            WorkingDirectory = directory.Replace('\\', '/');
            AllFiles.ReplaceAll(Directory.GetFiles(WorkingDirectory).Select(x => new FileModel(x.Replace('\\', '/'))));
            new Sort() { Mode = SortMode.Natural }.ApplyTo(AllFiles);
            Filter();
        }

        public void FilterChanged(object sender, AvaloniaPropertyChangedEventArgs e)
        {
            if(HandledProperties.Contains(e.Property) && HandleEvents)
                Filter(); // Bind to PropertyChanged
        }
        public void Filter()
        {
            // Filter all files in the directory for those satisfying the given filters
            Files.ReplaceAll(AllFiles.Where(x =>
                (FilterExtension == "" || x.OldExtension == FilterExtension)
                && (FilterFullName ? x.OldFullName : x.OldName).RegexContains(FilterRegex ? FilterPattern : Regex.Escape(FilterPattern))));

            Preview();
        }

        public void PreviewChanged(object sender, AvaloniaPropertyChangedEventArgs e)
        {
            if (HandledProperties.Contains(e.Property) && HandleEvents)
                Preview(); // Bind to PropertyChanged
        }
        public void Preview()
        {
            // Reset all files to how they currently exist
            foreach (var file in Files)
                file.Path = file.OldPath;

            // Apply operations
            foreach (var operation in Operations)
                operation.ApplyTo(Files);

            // Validate that there are any changes, and that the new file names are all unique.
            IsCommitButtonEnabled = 
                Files.Any(x => x.Path != x.OldPath)                                  // Check for changes
                && Files.GroupBy(x => x.Path).All(g => g.Count() == 1)               // Check for duplicates
                && !Files.Any(x => x.FullName == "")                                 // Check for empty file names
                && !Files.Any(x => "?%*:<>|/\\\"".Any(y => x.FullName.Contains(y))); // Check for invalid characters

            // Refresh the file list to guarantee that changes are displayed. TODO: Find a better way to do this.
            Files.ReplaceAll(new List<FileModel>(Files));
        }

        public void AddOperation()
        {
            HandleEvents = false;
            if (Operations.Count >= 1)
                Operations.Insert(
                    SelectedOperation >= 0 ? SelectedOperation + 1 : Operations.Count,
                    OperationTypes[SelectedOperationType].Create());
            else Operations.Add(OperationTypes[SelectedOperationType].Create());
            HandleEvents = true;
            Preview();
        }

        private ListBox OperationsListBox;
        private ListBoxItem DragItem;

        public void DeleteOperation(object sender, PointerReleasedEventArgs e)
        {
            var hoveredItem = (ListBoxItem)OperationsListBox.GetLogicalChildren().FirstOrDefault(x => this.GetVisualsAt(e.GetPosition(this)).Contains(((IVisual)x).GetVisualChildren().First()));
            if(hoveredItem != null) Operations.RemoveAt(OperationsListBox.GetLogicalChildren().ToList().IndexOf(hoveredItem));
            Preview();
        }

        public void StartMoveOperation(object sender, PointerPressedEventArgs e) =>
            DragItem = OperationsListBox.GetLogicalChildren().Cast<ListBoxItem>().Single(x => x.IsPointerOver);

        public void EndMoveOperation(object sender, PointerReleasedEventArgs e)
        {
            var hoveredItem = (ListBoxItem)OperationsListBox.GetLogicalChildren().FirstOrDefault(x => this.GetVisualsAt(e.GetPosition(this)).Contains(((IVisual)x).GetVisualChildren().First()));
            if (DragItem == null ||
                hoveredItem == null ||
                DragItem == hoveredItem)
                return;
            Operations.Move(
                OperationsListBox.GetLogicalChildren().ToList().IndexOf(DragItem),
                OperationsListBox.GetLogicalChildren().ToList().IndexOf(hoveredItem));
            DragItem = null;
            Preview();
        }

        public void Commit()
        {
            foreach (var file in Files)
                if (file.OldPath != file.Path)
                    File.Move(file.OldPath, file.Path);

            UndoStack.Push(new List<FileModel>(Files));
            UndoCount = UndoStack.Count;

            OpenDirectory(WorkingDirectory);
        }

        public void Undo()
        {
            foreach (var file in UndoStack.Pop())
                File.Move(file.Path, file.OldPath);

            UndoCount = UndoStack.Count;
            OpenDirectory(WorkingDirectory);
        }

        public MainWindow() => InitializeComponent();
        private void InitializeComponent()
        {
            AvaloniaXamlLoader.Load(this);
            DataContext = this;
            OpenDirectory(Environment.OSVersion.Platform == PlatformID.Win32NT ? @"C:/Users/" : @"/home/");
            HandleEvents = true;
            OperationsListBox = this.Find<ListBox>("OperationsListBox");
        }
    }
}