using System.Windows.Controls;

namespace System.Windows.Forms
{
    public partial class ListView : Control
    {
        private bool mouseMoved;
        private bool doubleClicked;
        private ListViewItem selectedItemAtMouseDown;
        private ListViewItem editedItem;
        
        protected new CustomControls.ListView control { get; }

        internal System.Windows.Controls.GridView GridView { get; }

        public ListViewItemCollection Items { get; }

        public ListViewGroupCollection Groups { get; }

        public ColumnHeaderCollection Columns { get; }

        public SelectedListViewItemCollection SelectedItems { get; }

        public SelectedIndexCollection SelectedIndices { get; }

        private CheckedListViewItemCollection checkedItems;
        public CheckedListViewItemCollection CheckedItems
        {
            get
            {
                if (checkedItems == null)
                    BuildCheckedItems();
                return checkedItems;
            }
        }

        private CheckedIndexCollection checkedIndices;
        public CheckedIndexCollection CheckedIndices
        {
            get
            {
                if (checkedIndices == null)
                    BuildCheckedIndices();
                return checkedIndices;
            }
        }

        private View view;
        public View View
        {
            get => view;
            set
            {
                view = value;
                if (view == View.Details)
                    control.View = GridView;
                else
                    control.View = null;
            }
        }


        private ImageList imageList;
        public ImageList LargeImageList
        {
            get => imageList;
            set
            {
                imageList = value;
                ResetImageList();
            }
        }

        public ImageList SmallImageList
        {
            get => LargeImageList;
            set => LargeImageList = value;
        }

        public bool HideSelection { get; set; } // TODO?

        public bool LabelEdit { get; set; }

        public bool UseCompatibleStateImageBehavior { get; set; } // ignored

        public bool ShowGroups { get; set; } // TODO?

        public bool CheckBoxes { get; set; } // TODO?

        public bool FullRowSelect { get; set; } // TODO?

        public ItemActivation Activation { get; set; } // TODO?

        public ListViewAlignment Alignment { get; set; } // TODO?

        private ColumnHeaderStyle headerStyle;
        public ColumnHeaderStyle HeaderStyle
        {
            get => headerStyle;
            set
            {
                headerStyle = value;
                if (value == ColumnHeaderStyle.None)
                {
                    this.GridView.ColumnHeaderContainerStyle = (System.Windows.Style)control.Resources["HiddenHeader"];
                }
            }
        }

        public bool MultiSelect
        {
            get => control.SelectionMode == Windows.Controls.SelectionMode.Extended;
            set => control.SelectionMode = value ? Windows.Controls.SelectionMode.Extended : Windows.Controls.SelectionMode.Single;
        }

        public new event MouseEventHandler MouseClick;
        public new event MouseEventHandler MouseDoubleClick;
        public new event EventHandler DoubleClick;

        public event LabelEditEventHandler AfterLabelEdit;
        public event LabelEditEventHandler BeforeLabelEdit;
        public event EventHandler SelectedIndexChanged;
        public event ItemDragEventHandler ItemDrag;
        public event ItemCheckedEventHandler ItemChecked; // TODO?
        public event ColumnClickEventHandler ColumnClick;

        private ListViewItem ItemHitTest(Point point, bool textOnly = false)
        {
            var item = control.InputHitTest(point);
            if (!textOnly && FullRowSelect && item != null && item is FrameworkElement element && element.DataContext is ListViewItem itm)
                return itm;

            if (item is TextBlock txt && txt.Name == "PART_TextBlock")
                return txt.DataContext as ListViewItem;
            if (!textOnly && item is Image img && img.Name == "PART_Image")
                return img.DataContext as ListViewItem;
            return null;
        }

        private void ResetImageList()
        {
            foreach (var item in Items)
                item.ResetImageSource();
        }

        private void BuildCheckedItems()
        {
            // TODO?
            checkedItems = new CheckedListViewItemCollection();
        }

        private void BuildCheckedIndices()
        {
            // TODO?
            checkedIndices = new CheckedIndexCollection();
        }

        private void ListView_OnColumnClick(object sender, RoutedEventArgs e)
        {
            var column = e.OriginalSource as GridViewColumnHeader;
            if (column != null)
            {
                int index = GridView.Columns.IndexOf(column.Column);
                if (index != -1)
                    OnColumnClick(new ColumnClickEventArgs(index));
            }
        }

        protected new virtual void OnDoubleClick(EventArgs e) => DoubleClick?.Invoke(this, e);

        protected new virtual void OnMouseDoubleClick(MouseEventArgs e) => MouseDoubleClick?.Invoke(this, e);

        protected new virtual void OnMouseClick(MouseEventArgs e) => MouseClick?.Invoke(this, e);

        protected virtual void OnAfterLabelEdit(LabelEditEventArgs e) => AfterLabelEdit?.Invoke(this, e);

        protected virtual void OnBeforeLabelEdit(LabelEditEventArgs e) => BeforeLabelEdit?.Invoke(this, e);

        protected virtual void OnSelectionChanged(EventArgs e)
        {
            OnSelectedIndexChanged(e);
        }

        protected virtual void OnSelectedIndexChanged(EventArgs e) => SelectedIndexChanged?.Invoke(this, e);

        protected virtual void OnItemDrag(ItemDragEventArgs e) => ItemDrag?.Invoke(this, e);

        protected virtual void OnItemChecked(ItemCheckedEventArgs e) => ItemChecked?.Invoke(this, e);

        protected virtual void OnColumnClick(ColumnClickEventArgs e) => ColumnClick?.Invoke(this, e);

        internal void DoItemSelect(ListViewItem item)
        {
            // do not rely on control.SelectedItems because of strange behavior (sometimes it can return duplicate items)
            // instead, use own selected items list and keep it in sync with ListView.IsSelected and also with Items list (item remove/clear)
            if (item.Selected)
            {
                SelectedItems.InternalAdd(item);
            }
            else
            {
                SelectedItems.InternalRemove(item);
            }

            OnSelectionChanged(EventArgs.Empty);
        }

        internal void DoItemRemove(ListViewItem item)
        {
            if (SelectedItems.InternalRemove(item))
            {
                OnSelectionChanged(EventArgs.Empty);
            }
        }

        internal void DoItemsClear()
        {
            SelectedItems.InternalClear();
        }

        internal void DoOnAfterLabelEdit(LabelEditEventArgs e) => OnAfterLabelEdit(e);

        internal void DoOnBeforeLabelEdit(LabelEditEventArgs e) => OnBeforeLabelEdit(e);

        internal void SetEditedItem(ListViewItem item) => editedItem = item;

        internal void AcceptEdit() => editedItem?.EndEdit(false);

        internal void CancelEdit() => editedItem?.EndEdit(true);

        public void BeginUpdate() { }
        
        public void EndUpdate() { }

        public ListViewItem GetItemAt(int x, int y) => ItemHitTest(new Point(x / DpiScale, y / DpiScale));

        public ListViewItem GetItemAt(Drawing.Point point) => GetItemAt(point.X, point.Y);


        public ListView()
        {
            control = new();
            SetControl(control);

            Items = new(this);
            Groups = new(this);
            SelectedItems = new(this);
            SelectedIndices = new(this);
            Columns = new(this);
            GridView = new();

            control.AcceptEdit += (sender, e) => AcceptEdit();
            control.CancelEdit += (sender, e) => CancelEdit();
            // we use our own SelectionChanged based on ListViewItem.IsSelected property
            // (due to async nature of control.SelectionChanged which is inconsistent with SWF)
            //control.SelectionChanged += (sender, e) => OnSelectionChanged(e);
            control.PreviewMouseDown += (sender, e) =>
            {
                mouseMoved = false;
                selectedItemAtMouseDown = SelectedItems.Count == 1 ? SelectedItems[0] : null;
                if (e.ClickCount == 2)
                    doubleClicked = true;
            };
            control.MouseMove += (sender, e) =>
            {
                if (e.LeftButton == Input.MouseButtonState.Pressed)
                {
                    var item = ItemHitTest(e.GetPosition(control));
                    if (item != null)
                        OnItemDrag(new ItemDragEventArgs(MouseButtons.Left, item));
                    mouseMoved = true;
                }
            };
            control.PreviewMouseUp += (sender, e) =>
            {
                var args = Helper.GetMouseEventArgs(control, e);
                var pos = e.GetPosition(control);
                var item = ItemHitTest(pos);
                if (doubleClicked)
                {
                    doubleClicked = false;
                    if (item != null)
                    {
                        OnDoubleClick(e);
                        OnMouseDoubleClick(args);
                    }
                }
                else
                {
                    if (!mouseMoved && item != null)
                    {
                        OnMouseClick(args);
                        if (e.ChangedButton == Input.MouseButton.Left && selectedItemAtMouseDown == item && LabelEdit && ItemHitTest(pos, true) == item)
                            item.BeginEdit();
                    }
                }
            };

            control.AddHandler(GridViewColumnHeader.ClickEvent, new RoutedEventHandler(ListView_OnColumnClick));
            control.FocusVisualStyle = null;
            control.ItemsSource = Items;
        }
    }
}