/*************************************************************************************

   Extended WPF Toolkit

   Copyright (C) 2007-2013 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://wpftoolkit.codeplex.com/license 

   For more features, controls, and fast professional support,
   pick up the Plus Edition at http://xceed.com/wpf_toolkit

   Stay informed: follow @datagrid on Twitter or Like http://facebook.com/datagrids

  ***********************************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Data;
using System.Windows.Input;
using Xceed.Wpf.Toolkit.Primitives;

namespace Xceed.Wpf.Toolkit.Primitives
{
  public abstract class DateTimeUpDownBase<T> : UpDownBase<T>
  {
    #region Members

    internal List<DateTimeInfo> _dateTimeInfoList = new List<DateTimeInfo>();
    internal DateTimeInfo _selectedDateTimeInfo;
    internal bool _fireSelectionChangedEvent = true;
    internal bool _processTextChanged = true;

    #endregion //Members

    #region Properties

    #region CurrentDateTimePart

    public static readonly DependencyProperty CurrentDateTimePartProperty = DependencyProperty.Register( "CurrentDateTimePart", typeof( DateTimePart )
      , typeof( DateTimeUpDownBase<T> ), new UIPropertyMetadata( DateTimePart.Other, OnCurrentDateTimePartChanged ) );
    public DateTimePart CurrentDateTimePart
    {
      get
      {
        return (DateTimePart)GetValue( CurrentDateTimePartProperty );
      }
      set
      {
        SetValue( CurrentDateTimePartProperty, value );
      }
    }

    private static void OnCurrentDateTimePartChanged( DependencyObject o, DependencyPropertyChangedEventArgs e )
    {
      DateTimeUpDownBase<T> dateTimeUpDownBase = o as DateTimeUpDownBase<T>;
      if( dateTimeUpDownBase != null )
        dateTimeUpDownBase.OnCurrentDateTimePartChanged( (DateTimePart)e.OldValue, (DateTimePart)e.NewValue );
    }

    protected virtual void OnCurrentDateTimePartChanged( DateTimePart oldValue, DateTimePart newValue )
    {
      this.Select( this.GetDateTimeInfo( newValue ) );
    }

    #endregion //CurrentDateTimePart

    #region Step

    public static readonly DependencyProperty StepProperty = DependencyProperty.Register( "Step", typeof( int )
      , typeof( DateTimeUpDownBase<T> ), new UIPropertyMetadata( 1, OnStepChanged ) );
    public int Step
    {
      get
      {
        return (int)GetValue( StepProperty );
      }
      set
      {
        SetValue( StepProperty, value );
      }
    }

    private static void OnStepChanged( DependencyObject o, DependencyPropertyChangedEventArgs e )
    {
      var dateTimeUpDownBase = o as DateTimeUpDownBase<T>;
      if( dateTimeUpDownBase != null )
        dateTimeUpDownBase.OnStepChanged( (int)e.OldValue, (int)e.NewValue );
    }

    protected virtual void OnStepChanged( int oldValue, int newValue )
    {
    }

    #endregion //Step

    #endregion

    #region Constructors

    internal DateTimeUpDownBase()
    {
      this.InitializeDateTimeInfoList( this.Value );
      this.Loaded += this.DateTimeUpDownBase_Loaded;
    }

    #endregion

    #region BaseClass Overrides

    public override void OnApplyTemplate()
    {
      if( this.TextBox != null )
      {
        this.TextBox.SelectionChanged -= this.TextBox_SelectionChanged;
      }

      base.OnApplyTemplate();

      if( this.TextBox != null )
      {
        this.TextBox.SelectionChanged += this.TextBox_SelectionChanged;
      }
    }

    protected override void OnPreviewKeyDown( KeyEventArgs e )
    {
      int selectionStart = ( _selectedDateTimeInfo != null ) ? _selectedDateTimeInfo.StartPosition : 0;
      int selectionLength = ( _selectedDateTimeInfo != null ) ? _selectedDateTimeInfo.Length : 0;

      switch( e.Key )
      {
        case Key.Enter:
          {
            if( !IsReadOnly )
            {
              _fireSelectionChangedEvent = false;
              BindingExpression binding = BindingOperations.GetBindingExpression( TextBox, System.Windows.Controls.TextBox.TextProperty );
              binding.UpdateSource();
              _fireSelectionChangedEvent = true;
            }
            return;
          }
        case Key.Add:
          if( this.AllowSpin && !this.IsReadOnly )
          {
            this.DoIncrement();
            e.Handled = true;
          }
          _fireSelectionChangedEvent = false;
          break;
        case Key.Subtract:
          if( this.AllowSpin && !this.IsReadOnly )
          {
            this.DoDecrement();
            e.Handled = true;
          }
          _fireSelectionChangedEvent = false;
          break;
        case Key.OemSemicolon:
          if( this.IsCurrentValueValid() && ( Keyboard.Modifiers == ModifierKeys.Shift ) )
          {
            this.PerformKeyboardSelection( selectionStart + selectionLength );
            e.Handled = true;
          }
          _fireSelectionChangedEvent = false;
          break;
        case Key.OemPeriod:
        case Key.OemComma:
        case Key.OemQuotes:
        case Key.OemMinus:
        case Key.Divide:
        case Key.Decimal: 
        case Key.Right:
          if( this.IsCurrentValueValid() )
          {
            this.PerformKeyboardSelection( selectionStart + selectionLength );
            e.Handled = true;
          }
          _fireSelectionChangedEvent = false;
          break;
        case Key.Left:
          if( this.IsCurrentValueValid() )
          {
            this.PerformKeyboardSelection( selectionStart > 0 ? selectionStart - 1 : 0 );
            e.Handled = true;
          }
          _fireSelectionChangedEvent = false;
          break;
        default:
          {
            _fireSelectionChangedEvent = false;
            break;
          }
      }

      base.OnPreviewKeyDown( e );
    }

    #endregion

    #region Event Hanlders

    private void TextBox_SelectionChanged( object sender, RoutedEventArgs e )
    {
      if( _fireSelectionChangedEvent )
        this.PerformMouseSelection();
      else
        _fireSelectionChangedEvent = true;
    }

    private void DateTimeUpDownBase_Loaded( object sender, RoutedEventArgs e )
    {
      this.InitSelection();
    }

    #endregion

    #region Methods

    protected virtual void InitializeDateTimeInfoList( T value )
    {
    }

    protected virtual bool IsCurrentValueValid()
    {
      return true;
    }

    protected virtual void PerformMouseSelection()
    {
      this.Select( this.GetDateTimeInfo( TextBox.SelectionStart ) );
    }

    protected virtual bool IsLowerThan( T value1, T value2 )
    {
      return false;
    }

    protected virtual bool IsGreaterThan( T value1, T value2 )
    {
      return false;
    }

    internal DateTimeInfo GetDateTimeInfo( int selectionStart )
    {
      return _dateTimeInfoList.FirstOrDefault( ( info ) =>
                              ( info.StartPosition <= selectionStart ) && ( selectionStart < ( info.StartPosition + info.Length ) ) );
    }

    internal DateTimeInfo GetDateTimeInfo( DateTimePart part )
    {
      return _dateTimeInfoList.FirstOrDefault( ( info ) =>info.Type == part );
    }

    internal void Select( DateTimeInfo info )
    {
      if( (info != null) && !info.Equals( _selectedDateTimeInfo ) && ( this.TextBox != null) && !string.IsNullOrEmpty( this.TextBox.Text ) )
      {
        _fireSelectionChangedEvent = false;
        this.TextBox.Select( info.StartPosition, info.Length );
        _fireSelectionChangedEvent = true;
        _selectedDateTimeInfo = info;
#if VS2008
        this.CurrentDateTimePart = info.Type;
#else
        this.SetCurrentValue( DateTimeUpDownBase<T>.CurrentDateTimePartProperty, info.Type );
#endif
      }
    }

    internal T CoerceValueMinMax( T value )
    {
      if( this.IsLowerThan( value, this.Minimum ) )
        return this.Minimum;
      else if( this.IsGreaterThan( value, this.Maximum ) )
        return this.Maximum;
      else
        return value;
    }

    internal void ValidateDefaultMinMax( T value )
    {
      // DefaultValue is always accepted.
      if( object.Equals( value, this.DefaultValue ) )
        return;

      if( this.IsLowerThan( value, this.Minimum ) )
        throw new ArgumentOutOfRangeException( "Minimum", String.Format( "Value must be greater than MinValue of {0}", this.Minimum ) );
      else if( this.IsGreaterThan( value, this.Maximum ) )
        throw new ArgumentOutOfRangeException( "Maximum", String.Format( "Value must be less than MaxValue of {0}", this.Maximum ) );
    }

    internal T GetClippedMinMaxValue( T value )
    {
      if( this.IsGreaterThan( value, this.Maximum ) )
        return this.Maximum;
      else if( this.IsLowerThan( value, this.Minimum ) )
        return this.Minimum;
      return value;
    }

    protected internal virtual void PerformKeyboardSelection( int nextSelectionStart )
    {
      this.TextBox.Focus();

      if( !this.UpdateValueOnEnterKey )
      {
        this.CommitInput();
      }

      int selectedDateStartPosition = ( _selectedDateTimeInfo != null ) ? _selectedDateTimeInfo.StartPosition : 0;
      int direction = nextSelectionStart - selectedDateStartPosition;
      if( direction > 0 )
      {
        this.Select( this.GetNextDateTimeInfo( nextSelectionStart ) );
      }
      else
      {
        this.Select( this.GetPreviousDateTimeInfo( nextSelectionStart - 1 ) );
      }
    }    

    private DateTimeInfo GetNextDateTimeInfo( int nextSelectionStart )
    {
      DateTimeInfo nextDateTimeInfo = this.GetDateTimeInfo( nextSelectionStart );
      if( nextDateTimeInfo == null )
      {
        nextDateTimeInfo = _dateTimeInfoList.First();
      }

      DateTimeInfo initialDateTimeInfo = nextDateTimeInfo;

      while( nextDateTimeInfo.Type == DateTimePart.Other )
      {
        nextDateTimeInfo = this.GetDateTimeInfo( nextDateTimeInfo.StartPosition + nextDateTimeInfo.Length );
        if( nextDateTimeInfo == null )
        {
          nextDateTimeInfo = _dateTimeInfoList.First();
        }
        if( object.Equals( nextDateTimeInfo, initialDateTimeInfo ) )
          throw new InvalidOperationException( "Couldn't find a valid DateTimeInfo." );
      }
      return nextDateTimeInfo;
    }

    private DateTimeInfo GetPreviousDateTimeInfo( int previousSelectionStart )
    {
      DateTimeInfo previousDateTimeInfo = this.GetDateTimeInfo( previousSelectionStart );
      if( previousDateTimeInfo == null )
      {
        if( _dateTimeInfoList.Count > 0 )
        {
          previousDateTimeInfo = _dateTimeInfoList.Last();
        }
      }

      DateTimeInfo initialDateTimeInfo = previousDateTimeInfo;

      while( (previousDateTimeInfo != null) && (previousDateTimeInfo.Type == DateTimePart.Other) )
      {
        previousDateTimeInfo = this.GetDateTimeInfo( previousDateTimeInfo.StartPosition - 1 );
        if( previousDateTimeInfo == null )
        {
          previousDateTimeInfo = _dateTimeInfoList.Last();
        }
        if( object.Equals( previousDateTimeInfo, initialDateTimeInfo ) )
          throw new InvalidOperationException( "Couldn't find a valid DateTimeInfo." );
      }
      return previousDateTimeInfo;
    }

    private void InitSelection()
    {
      if( _selectedDateTimeInfo == null )
      {
        this.Select( (this.CurrentDateTimePart != DateTimePart.Other) ? this.GetDateTimeInfo( this.CurrentDateTimePart ) : this.GetDateTimeInfo( 0 ) );
      }
    }

    #endregion
  }
}