using System;
using System.Collections.Generic;

using Avalonia;
using Avalonia.Collections;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Input;
using Avalonia.Layout;
using Avalonia.Media;
using Avalonia.VisualTree;

namespace SourceGit.Views
{
    public class RevisionFileTreeNodeToggleButton : ToggleButton
    {
        protected override Type StyleKeyOverride => typeof(ToggleButton);

        protected override void OnPointerPressed(PointerPressedEventArgs e)
        {
            if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed &&
                DataContext is ViewModels.RevisionFileTreeNode { IsFolder: true } node)
            {
                var tree = this.FindAncestorOfType<RevisionFileTreeView>();
                tree?.ToggleNodeIsExpanded(node);
            }

            e.Handled = true;
        }
    }

    public class RevisionTreeNodeIcon : UserControl
    {
        public static readonly StyledProperty<ViewModels.RevisionFileTreeNode> NodeProperty =
            AvaloniaProperty.Register<RevisionTreeNodeIcon, ViewModels.RevisionFileTreeNode>(nameof(Node));

        public ViewModels.RevisionFileTreeNode Node
        {
            get => GetValue(NodeProperty);
            set => SetValue(NodeProperty, value);
        }

        public static readonly StyledProperty<bool> IsExpandedProperty =
            AvaloniaProperty.Register<RevisionTreeNodeIcon, bool>(nameof(IsExpanded));

        public bool IsExpanded
        {
            get => GetValue(IsExpandedProperty);
            set => SetValue(IsExpandedProperty, value);
        }

        static RevisionTreeNodeIcon()
        {
            NodeProperty.Changed.AddClassHandler<RevisionTreeNodeIcon>((icon, _) => icon.UpdateContent());
            IsExpandedProperty.Changed.AddClassHandler<RevisionTreeNodeIcon>((icon, _) => icon.UpdateContent());
        }

        private void UpdateContent()
        {
            var node = Node;
            if (node?.Backend == null)
            {
                Content = null;
                return;
            }

            var obj = node.Backend;
            switch (obj.Type)
            {
                case Models.ObjectType.Blob:
                    CreateContent("Icons.File", new Thickness(0, 0, 0, 0));
                    break;
                case Models.ObjectType.Commit:
                    CreateContent("Icons.Submodule", new Thickness(0, 0, 0, 0));
                    break;
                default:
                    CreateContent(node.IsExpanded ? "Icons.Folder.Open" : "Icons.Folder.Fill", new Thickness(0, 2, 0, 0), Brushes.Goldenrod);
                    break;
            }
        }

        private void CreateContent(string iconKey, Thickness margin, IBrush fill = null)
        {
            var geo = this.FindResource(iconKey) as StreamGeometry;
            if (geo == null)
                return;

            var icon = new Avalonia.Controls.Shapes.Path()
            {
                Width = 14,
                Height = 14,
                Margin = margin,
                HorizontalAlignment = HorizontalAlignment.Left,
                VerticalAlignment = VerticalAlignment.Center,
                Data = geo,
            };

            if (fill != null)
                icon.Fill = fill;

            Content = icon;
        }
    }

    public partial class RevisionFileTreeView : UserControl
    {
        public static readonly StyledProperty<string> RevisionProperty =
            AvaloniaProperty.Register<RevisionFileTreeView, string>(nameof(Revision));

        public string Revision
        {
            get => GetValue(RevisionProperty);
            set => SetValue(RevisionProperty, value);
        }

        public AvaloniaList<ViewModels.RevisionFileTreeNode> Rows
        {
            get => _rows;
        }

        public RevisionFileTreeView()
        {
            InitializeComponent();
        }

        public void ToggleNodeIsExpanded(ViewModels.RevisionFileTreeNode node)
        {
            _disableSelectionChangingEvent = true;
            node.IsExpanded = !node.IsExpanded;

            var depth = node.Depth;
            var idx = _rows.IndexOf(node);
            if (idx == -1)
                return;

            if (node.IsExpanded)
            {
                var subtree = GetChildrenOfTreeNode(node);
                if (subtree != null && subtree.Count > 0)
                {
                    var subrows = new List<ViewModels.RevisionFileTreeNode>();
                    MakeRows(subrows, subtree, depth + 1);
                    _rows.InsertRange(idx + 1, subrows);
                }
            }
            else
            {
                var removeCount = 0;
                for (int i = idx + 1; i < _rows.Count; i++)
                {
                    var row = _rows[i];
                    if (row.Depth <= depth)
                        break;

                    removeCount++;
                }
                _rows.RemoveRange(idx + 1, removeCount);
            }

            _disableSelectionChangingEvent = false;
        }

        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
        {
            base.OnPropertyChanged(change);

            if (change.Property == RevisionProperty)
            {
                _tree.Clear();
                _rows.Clear();

                var vm = DataContext as ViewModels.CommitDetail;
                if (vm == null || vm.Commit == null)
                {
                    GC.Collect();
                    return;
                }

                var objects = vm.GetRevisionFilesUnderFolder(null);
                if (objects == null || objects.Count == 0)
                {
                    GC.Collect();
                    return;
                }

                foreach (var obj in objects)
                    _tree.Add(new ViewModels.RevisionFileTreeNode { Backend = obj });

                _tree.Sort((l, r) =>
                {
                    if (l.IsFolder == r.IsFolder)
                        return string.Compare(l.Name, r.Name, StringComparison.Ordinal);
                    return l.IsFolder ? -1 : 1;
                });

                var topTree = new List<ViewModels.RevisionFileTreeNode>();
                MakeRows(topTree, _tree, 0);
                _rows.AddRange(topTree);
                GC.Collect();
            }
        }

        private void OnTreeNodeContextRequested(object sender, ContextRequestedEventArgs e)
        {
            if (DataContext is ViewModels.CommitDetail vm &&
                sender is Grid { DataContext: ViewModels.RevisionFileTreeNode { Backend: { } obj } } grid)
            {
                if (obj.Type != Models.ObjectType.Tree)
                {
                    var menu = vm.CreateRevisionFileContextMenu(obj);
                    grid.OpenContextMenu(menu);
                }
            }

            e.Handled = true;
        }

        private void OnTreeNodeDoubleTapped(object sender, TappedEventArgs e)
        {
            if (sender is Grid { DataContext: ViewModels.RevisionFileTreeNode { IsFolder: true } node })
            {
                var posX = e.GetPosition(this).X;
                if (posX < node.Depth * 16 + 16)
                    return;

                ToggleNodeIsExpanded(node);
            }
        }

        private void OnRowsSelectionChanged(object sender, SelectionChangedEventArgs _)
        {
            if (_disableSelectionChangingEvent)
                return;

            if (sender is ListBox { SelectedItem: ViewModels.RevisionFileTreeNode node } && DataContext is ViewModels.CommitDetail vm)
            {
                if (!node.IsFolder)
                    vm.ViewRevisionFile(node.Backend);
                else
                    vm.ViewRevisionFile(null);
            }
        }

        private List<ViewModels.RevisionFileTreeNode> GetChildrenOfTreeNode(ViewModels.RevisionFileTreeNode node)
        {
            if (!node.IsFolder)
                return null;

            if (node.Children.Count > 0)
                return node.Children;

            var vm = DataContext as ViewModels.CommitDetail;
            if (vm == null)
                return null;

            var objects = vm.GetRevisionFilesUnderFolder(node.Backend.Path + "/");
            if (objects == null || objects.Count == 0)
                return null;

            foreach (var obj in objects)
                node.Children.Add(new ViewModels.RevisionFileTreeNode() { Backend = obj });

            node.Children.Sort((l, r) =>
            {
                if (l.IsFolder == r.IsFolder)
                    return string.Compare(l.Name, r.Name, StringComparison.Ordinal);
                return l.IsFolder ? -1 : 1;
            });

            return node.Children;
        }

        private void MakeRows(List<ViewModels.RevisionFileTreeNode> rows, List<ViewModels.RevisionFileTreeNode> nodes, int depth)
        {
            foreach (var node in nodes)
            {
                node.Depth = depth;
                rows.Add(node);

                if (!node.IsExpanded || !node.IsFolder)
                    continue;

                MakeRows(rows, node.Children, depth + 1);
            }
        }

        private List<ViewModels.RevisionFileTreeNode> _tree = new List<ViewModels.RevisionFileTreeNode>();
        private AvaloniaList<ViewModels.RevisionFileTreeNode> _rows = new AvaloniaList<ViewModels.RevisionFileTreeNode>();
        private bool _disableSelectionChangingEvent = false;
    }
}