using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using 
// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)

using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Threading;
using Tango.Scripting.Editors.Document;
using Tango.Scripting.Editors.Editing;
using System.Windows.Media;

namespace Tango.Scripting.Editors.CodeCompletion
{
    /// <summary>
    /// The code completion window.
    /// </summary>
    public class CompletionWindow : CompletionWindowBase
    {
        readonly CompletionList completionList = new CompletionList();

        public event Action<ICompletionData> InsertionRequest;

        /// <summary>
        /// Gets the completion list used in this completion window.
        /// </summary>
        public CompletionList CompletionList
        {
            get { return completionList; }
        }

        /// <summary>
        /// Creates a new code completion window.
        /// </summary>
        public CompletionWindow(TextArea textArea) : base(textArea)
        {

            // keep height automatic
            this.CloseAutomatically = true;
            this.SizeToContent = SizeToContent.WidthAndHeight;
            this.WindowStyle = WindowStyle.None;
            this.ResizeMode = ResizeMode.NoResize;
            this.Content = completionList;
            // prevent user from resizing window to 0x0
            this.MinHeight = 15;
            this.MinWidth = 30;
            //this.Background = new SolidColorBrush(Color.FromRgb(15, 15, 15));
            this.Foreground = Brushes.Gainsboro;
        }

        public override void ShowCompletion()
        {
            base.ShowCompletion();
            AttachEvents();
        }

        public override void HideCompletion()
        {
            base.HideCompletion();

            foreach (var item in completionList.ListBox.Items)
            {
                var box = completionList.ListBox.ItemContainerGenerator.ContainerFromItem(item) as CompletionListBoxItem;
                if (box != null && box.IsSelected)
                {
                    box.toolTip.IsOpen = false;
                }
            }
        }

        void completionList_InsertionRequested(object sender, EventArgs e)
        {
            HideCompletion();
            // The window must close before Complete() is called.
            // If the Complete callback pushes stacked input handlers, we don't want to pop those when the CC window closes.
            var item = completionList.SelectedItem;
            //if (item != null)
            //    item.Complete(this.TextArea, new AnchorSegment(this.TextArea.Document, this.StartOffset, this.EndOffset - this.StartOffset), e);

            if (item != null)
            {
                InsertionRequest?.Invoke(item);
            }

            completionList.SelectedItem = null;
        }

        void AttachEvents()
        {
            this.completionList.InsertionRequested += completionList_InsertionRequested;
            this.TextArea.Caret.PositionChanged += CaretPositionChanged;
            this.TextArea.MouseWheel += textArea_MouseWheel;
            this.TextArea.PreviewTextInput += textArea_PreviewTextInput;
        }

        /// <inheritdoc/>
        protected override void DetachEvents()
        {
            this.completionList.InsertionRequested -= completionList_InsertionRequested;
            this.TextArea.Caret.PositionChanged -= CaretPositionChanged;
            this.TextArea.MouseWheel -= textArea_MouseWheel;
            this.TextArea.PreviewTextInput -= textArea_PreviewTextInput;
            base.DetachEvents();
        }

        /// <inheritdoc/>
        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (!e.Handled)
            {
                completionList.HandleKey(e);
            }
        }

        void textArea_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {
            e.Handled = RaiseEventPair(this, PreviewTextInputEvent, TextInputEvent,
                                       new TextCompositionEventArgs(e.Device, e.TextComposition));

            if (e.Text == " ")
            {
                HideCompletion();
            }
        }

        void textArea_MouseWheel(object sender, MouseWheelEventArgs e)
        {
            e.Handled = RaiseEventPair(GetScrollEventTarget(),
                                       PreviewMouseWheelEvent, MouseWheelEvent,
                                       new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta));
        }

        UIElement GetScrollEventTarget()
        {
            if (completionList == null)
                return this;
            return completionList.ScrollViewer ?? completionList.ListBox ?? (UIElement)completionList;
        }

        /// <summary>
        /// Gets/Sets whether the completion window should close automatically.
        /// The default value is true.
        /// </summary>
        public bool CloseAutomatically { get; set; }

        /// <inheritdoc/>
        protected override bool CloseOnFocusLost
        {
            get { return this.CloseAutomatically; }
        }

        /// <summary>
        /// When this flag is set, code completion closes if the caret moves to the
        /// beginning of the allowed range. This is useful in Ctrl+Space and "complete when typing",
        /// but not in dot-completion.
        /// Has no effect if CloseAutomatically is false.
        /// </summary>
        public bool CloseWhenCaretAtBeginning { get; set; }

        void CaretPositionChanged(object sender, EventArgs e)
        {
            int offset = this.TextArea.Caret.Offset;
            if (offset == this.StartOffset)
            {
                if (CloseAutomatically && CloseWhenCaretAtBeginning)
                {
                    HideCompletion();
                }
                else
                {
                    completionList.SelectItem(string.Empty);
                }
                return;
            }
            if (offset < this.StartOffset || offset > this.EndOffset)
            {
                if (CloseAutomatically)
                {
                    HideCompletion();
                }
            }
            else
            {
                TextDocument document = this.TextArea.Document;
                if (document != null)
                {
                    completionList.SelectItem(document.GetText(this.StartOffset, offset - this.StartOffset));
                }
            }
        }
    }
}