using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using ICSharpCode.Core;
using ICSharpCode.Core.Presentation;

namespace ICSharpCode.ShortcutsManagement.Dialogs
{
	/// <summary>
	/// Notification type enumeration
	/// </summary>
	public enum NotificationType
	{
		/// <summary>
		/// A valid gesture is entered so far
		/// </summary>
		Valid,
		
		/// <summary>
		/// Gesture is being entered, but is not valid yet
		/// </summary>
		Invalid,
		
		/// <summary>
		/// Gesture was successfully added to gestures collection
		/// </summary>
		Added,
		
		/// <summary>
		/// Failed to add gesture to gestures collection
		/// </summary>
		Failed,
		
		/// <summary>
		/// Notification message is not displayed
		/// </summary>
		None
	}
	
	/// <summary>
	/// Represents a textbox suited for entering key gestures
	/// </summary>
	public partial class MultiKeyGestureTextBox : UserControl
	{
		/// <summary>
		/// Identifies <see cref="TextBoxBorderThickness"/> dependency property
		/// </summary>
		public static readonly DependencyProperty TextBoxBorderThicknessProperty = DependencyProperty.Register(
			"TextBoxBorderThickness",
			typeof(int),
			typeof(MultiKeyGestureTextBox),
			new FrameworkPropertyMetadata(1, FrameworkPropertyMetadataOptions.AffectsRender));
		
		/// <summary>
		/// Gets or sets text box border thickness
		/// </summary>
		public int TextBoxBorderThickness
		{
			get {
				return (int)GetValue(TextBoxBorderThicknessProperty);
			}
			set {
				SetValue(TextBoxBorderThicknessProperty, value);
			}
		}
		
		/// <summary>
		/// Gets <see cref="KeyGesture" /> entered in text box
		/// </summary>
		public KeyGesture Gesture
		{
			get {
				if (enteredKeyGestureSequence == null || enteredKeyGestureSequence.Count == 0) {
					return null;
				}
				
				if (enteredKeyGestureSequence.Count == 1) {
					return new PartialKeyGesture(enteredKeyGestureSequence.First());
				}
				
				return new MultiKeyGesture(enteredKeyGestureSequence);
			}
		}
		
		/// <summary>
		/// Occurs when gesture entered in text box changes
		/// </summary>
		public event EventHandler GestureChanged;
		
		/// <summary>
		/// Identifies <see cref="NotificationVisibility"/> dependency property
		/// </summary>
		public static readonly DependencyProperty NotificationVisibilityProperty = DependencyProperty.Register(
			"NotificationVisibility",
			typeof(Visibility),
			typeof(MultiKeyGestureTextBox),
			new FrameworkPropertyMetadata(Visibility.Visible, FrameworkPropertyMetadataOptions.AffectsRender));
		
		/// <summary>
		/// Gets or sets value which specifies whether notifications are displayed under textbox control
		/// </summary>
		public Visibility NotificationVisibility
		{
			get {
				return (Visibility)GetValue(NotificationVisibilityProperty);
			}
			set {
				SetValue(NotificationVisibilityProperty, value);
			}
		}
		
		/// <summary>
		/// Identifies <see cref="NotificationType"/> dependency property
		/// </summary>
		public static readonly DependencyProperty NotificationTypeProperty = DependencyProperty.Register(
			"NotificationType",
			typeof(NotificationType),
			typeof(MultiKeyGestureTextBox),
			new FrameworkPropertyMetadata(NotificationType.None, FrameworkPropertyMetadataOptions.AffectsRender));
		
		/// <summary>
		/// Gets or sets notification type
		/// </summary>
		public NotificationType NotificationType
		{
			get {
				return (NotificationType)GetValue(NotificationTypeProperty);
			}
			set {
				SetValue(NotificationTypeProperty, value);
			}
		}
		
		/// <summary>
		/// Identifies <see cref="NotificationText"/> dependency property
		/// </summary>
		public static readonly DependencyProperty NotificationTextProperty = DependencyProperty.Register(
			"NotificationText",
			typeof(string),
			typeof(MultiKeyGestureTextBox),
			new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));
		
		/// <summary>
		/// Gets or sets displayed notification text
		/// </summary>
		public string NotificationText
		{
			get {
				return (string)GetValue(NotificationTextProperty);
			}
			set {
				SetValue(NotificationTextProperty, value);
			}
		}
		
		/// <summary>
		/// Last entered chords
		/// </summary>
		private List<PartialKeyGesture> enteredKeyGestureSequence = new List<PartialKeyGesture>();
		
		/// <summary>
		/// Time when last successfull chord was entered
		/// </summary>
		private DateTime lastEnterTime = DateTime.Now;
		
		/// <summary>
		/// Creates instance of <see cref="MultiKeyGestureTextBox"/>
		/// </summary>
		public MultiKeyGestureTextBox()
		{
			InitializeComponent();
		}
		
		/// <summary>
		/// Displays notifications under gesture text box
		/// </summary>
		/// <param name="notificationText">Notification text</param>
		/// <param name="type">Notification type</param>
		public void DisplayNotification(string notificationText, NotificationType type)
		{
			NotificationText = notificationText;
			NotificationType = type;
		}
		
		/// <summary>
		/// Clears all text area, chords and hides notification
		/// </summary>
		public void Clear()
		{
			enteredKeyGestureSequence = new List<PartialKeyGesture>();
			shortcutTextBox.Text = "";
			DisplayNotification("", NotificationType.None);
		}
		
		/// <summary>
		/// Executed when clicked on "Clear" button to the right from gesture text box
		/// </summary>
		/// <param name="sender">Sender object</param>
		/// <param name="e"><see cref="RoutedEvent" /> supporting data</param>
		private void clearTextBox_Click(object sender, RoutedEventArgs e)
		{
			Clear();
		}
		
		/// <summary>
		/// Executed when text inside textbox changes
		/// </summary>
		/// <param name="sender">Sender object</param>
		/// <param name="e">Event arguments</param>
		void shortcutTextBox_TextChanged(object sender, TextChangedEventArgs e)
		{
			if (GestureChanged != null) {
				GestureChanged.Invoke(sender, new EventArgs());
			}
		}
		
		/// <summary>
		/// Raised before user presses any key inside text box
		/// </summary>
		/// <param name="sender">Sender object</param>
		/// <param name="e">Event argument</param>
		private void TextBox_PreviewKeyDown(object sender, KeyEventArgs e)
		{
			e.Handled = true;
		
			// If a key is holded for a longer time key event is raised repeatedly.
			// We don't want to handle this kind of events
			if (e.IsRepeat) {
				return;
			}
			
			// If delete or backspace button is pressed
			if (e.Key == Key.Back || e.Key == Key.Delete) {
				Clear();
				return;
			}
			
			// Check whether time given for chord entry haven't expired yet
			if (DateTime.Now - lastEnterTime > MultiKeyGesture.DelayBetweenChords) {
				if (enteredKeyGestureSequence.Count > 0) {
					DisplayNotification(StringParser.Parse("${res:ShortcutsManagement.GestureTextBox.TimeExpired}"), NotificationType.Invalid);
				}
				
				Clear();
				lastEnterTime = DateTime.Now;
			}
			
			var partialKeyGesture = new PartialKeyGesture(e);
			
			var lastGesture = enteredKeyGestureSequence.Count > 0 ? enteredKeyGestureSequence.LastOrDefault() : null;
			var isLastGestureSpecialKey = lastGesture != null && (lastGesture.Key >= Key.F1) && (lastGesture.Key <= Key.F24);
			
			var isLastGestureComplete = lastGesture != null && (lastGesture.Key != Key.None || isLastGestureSpecialKey);
			var isContinuedGesture = lastGesture != null && partialKeyGesture.Modifiers - (partialKeyGesture.Modifiers ^ lastGesture.Modifiers) >= 0;
			
			// If continuing previous chord
			if (!isLastGestureComplete && isContinuedGesture) {
				enteredKeyGestureSequence.RemoveAt(enteredKeyGestureSequence.Count - 1);
			} else if (!isLastGestureComplete) {
				// If previous chord is unfinished and second chord is already entered
				// start from scratch. 
				DisplayNotification(StringParser.Parse("${res:ShortcutsManagement.GestureTextBox.SequenceIsNotCoherent}"), NotificationType.Invalid);
				Clear();
			}
			
			// If successfully finished another chord give more time
			if (partialKeyGesture.Key != Key.None) {
				lastEnterTime = DateTime.Now;
			}
			
			enteredKeyGestureSequence.Add(partialKeyGesture);
			
			// Create a multi key gesture if entered more than one chord
			if (enteredKeyGestureSequence.Count > 0) {
				var multiKeyGesture = new MultiKeyGesture(enteredKeyGestureSequence);
				var multiKeyGestureString = new MultiKeyGestureConverter().ConvertToInvariantString(multiKeyGesture);
				shortcutTextBox.Text = multiKeyGestureString;
			} else {
				Clear();
			}
			
			if (!enteredKeyGestureSequence[0].IsFull) {
				DisplayNotification(StringParser.Parse("${res:ShortcutsManagement.GestureTextBox.FirstChordIsIncomplete}"), NotificationType.Invalid);
			} else if (partialKeyGesture.Key == Key.None) {
				DisplayNotification(StringParser.Parse("${res:ShortcutsManagement.GestureTextBox.LastChordIsIncomplete}"), NotificationType.Invalid);
			} else {
				DisplayNotification(StringParser.Parse("${res:ShortcutsManagement.GestureTextBox.GestureIsValid}"), NotificationType.Valid);
			}
		}
	}
}