using System;
using AppKit;
using CoreGraphics;
using Foundation;
using System.Collections.Generic;

namespace Cauldron.Macos.SourceWriter
{
	public class SourceTextViewDelegate : NSTextViewDelegate
	{
		#region Computed Properties

		/// <summary>
		/// Gets or sets the text editor.
		/// </summary>
		/// <value>The <see cref="SourceTextView"/> this delegate is attached to.</value>
		public SourceTextView TextEditor { get; set; }

		#endregion

		#region Constructors

		/// <summary>
		/// Initializes a new instance of the <see cref="SourceTextViewDelegate"/> class.
		/// </summary>
		/// <param name="textEditor">Text editor.</param>
		public SourceTextViewDelegate(SourceTextView textEditor)
		{
			this.TextEditor = textEditor;
		}

		#endregion

		#region Override Methods

		/// <summary>
		/// Based on the user preferences set on the parent <see cref="SourceTextView"/>, this
		/// method returns the available list of partial word completions.
		/// </summary>
		/// <returns>The list of word completions that will be presented to the user.</returns>
		/// <param name="textView">The source <see cref="SourceTextView"/>.</param>
		/// <param name="words">
		/// A list of default words automatically provided by OS X in the user's language.
		/// </param>
		/// <param name="charRange">The cursor location where the partial word exists.</param>
		/// <param name="index">
		/// The word that should be selected when the list is displayed (usually 0 meaning the first
		/// item in the list). Pass -1 for no selected items.
		/// </param>
		public override string[] GetCompletions(NSTextView textView, string[] words, NSRange charRange, ref nint index)
		{
			List<string> completions = new();

			// Is auto complete enabled?
			if (TextEditor.AllowAutoComplete)
			{
				// Use keywords in auto complete?
				if (TextEditor.AutoCompleteKeywords)
				{
					// Yes, grab word being expanded
					NSRange range = TextEditor.Formatter.FindWordBoundries(
						TextEditor.TextStorage.Value, charRange);
					string word = TextEditor.TextStorage.Value.Substring(
						(int)range.Location, (int)range.Length);

					// Scan the keywords for the a possible match
					foreach (string keyword in TextEditor.Formatter.Language.Keywords.Keys)
					{
						// Found?
						if (keyword.Contains(word))
						{
							completions.Add(keyword);
						}
					}
				}

				// Use default words?
				if (TextEditor.AutoCompleteDefaultWords)
				{
					// Only if keywords list is empty?
					if (TextEditor.DefaultWordsOnlyIfKeywordsEmpty)
					{
						if (completions.Count == 0)
						{
							// No keywords, add defaults
							completions.AddRange(words);
						}
					}
					else
					{
						// No, always include default words
						completions.AddRange(words);
					}
				}
			}

			// Return results
			return completions.ToArray();
		}

		/// <summary>Called when the cell is clicked.</summary>
		/// <param name="textView">The <see cref="AppKit.TextKit.Formatter.SourceTextView"/>.</param>
		/// <param name="cell">The cell being acted upon.</param>
		/// <param name="cellFrame">The onscreen frame of the cell.</param>
		/// <param name="charIndex">The index of the character clicked.</param>
		/// <remarks>
		/// Because a custom <c>Delegate</c> has been attached to the <c>NSTextView</c>, the normal
		/// events will not work so we are using this method to call custom
		/// <see cref="SourceTextView"/> events instead.
		/// </remarks>
		public override void CellClicked(NSTextView textView, NSTextAttachmentCell cell,
			CGRect cellFrame, nuint charIndex)
		{
			// Pass through to Text Editor event
			TextEditor.RaiseSourceCellClicked(TextEditor,
				new NSTextViewClickedEventArgs(cell, cellFrame, charIndex));
		}

		/// <summary>Called when the cell is double-clicked.</summary>
		/// <param name="textView">The <see cref="SourceTextView"/>.</param>
		/// <param name="cell">The cell being acted upon.</param>
		/// <param name="cellFrame">The onscreen frame of the cell.</param>
		/// <param name="charIndex">The index of the character clicked.</param>
		/// <remarks>
		/// Because a custom <c>Delegate</c> has been attached to the <c>NSTextView</c>, the normal
		/// events will not work so we are using this method to call custom
		/// <see cref="SourceTextView"/> events instead.
		/// </remarks>
		public override void CellDoubleClicked(NSTextView textView, NSTextAttachmentCell cell,
			CGRect cellFrame, nuint charIndex)
		{
			// Pass through to Text Editor event
			TextEditor.RaiseSourceCellDoubleClicked(TextEditor,
				new NSTextViewDoubleClickEventArgs(cell, cellFrame, charIndex));
		}

		/// <summary>Called when the cell is dragged.</summary>
		/// <param name="view">The <see cref="SourceTextView"/>.</param>
		/// <param name="cell">The cell being acted upon.</param>
		/// <param name="rect">The onscreen frame of the cell.</param>
		/// <param name="theevent">An event defining the drag operation.</param>
		/// <remarks>
		/// Because a custom <c>Delegate</c> has been attached to the <c>NSTextView</c>, the normal
		/// events will not work so we are using this method to call custom
		/// <see cref="SourceTextView"/> events instead.
		/// </remarks>
		//public override void DraggedCell(NSTextView view, NSTextAttachmentCell cell, CGRect rect,
		//	NSEvent theevent)
		//{
		//	// Pass through to Text Editor event
		//	TextEditor.RaiseSourceCellDragged(TextEditor, new NSTextViewDraggedCellEventArgs(cell, rect, theevent));
		//}

		/// <summary>Called when the text selection has changed.</summary>
		/// <param name="notification">A notification defining the change.</param>
		/// <remarks>
		/// Because a custom <c>Delegate</c> has been attached to the <c>NSTextView</c>, the normal
		/// events will not work so we are using this method to call custom
		/// <see cref="SourceTextView"/> events instead.
		/// </remarks>
		public override void DidChangeSelection(NSNotification notification)
		{
			// Pass through to Text Editor event
			TextEditor.RaiseSourceSelectionChanged(TextEditor, EventArgs.Empty);
		}

		/// <summary>Called when the typing attributes has changed.</summary>
		/// <param name="notification">A notification defining the change.</param>
		/// <remarks>
		/// Because a custom <c>Delegate</c> has been attached to the <c>NSTextView</c>, the normal
		/// events will not work so we are using this method to call custom
		/// <see cref="SourceTextView"/> events instead.
		/// </remarks>
		public override void DidChangeTypingAttributes(NSNotification notification)
		{
			// Pass through to Text Editor event
			TextEditor.RaiseSourceTypingAttributesChanged(TextEditor, EventArgs.Empty);
		}

		#endregion
	}
}