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

   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.Windows;
using System.Globalization;
using System.IO;
using System.Linq;
using Xceed.Wpf.Toolkit.Primitives;

namespace Xceed.Wpf.Toolkit
{
  public abstract class CommonNumericUpDown<T> : NumericUpDown<T?> where T : struct, IFormattable, IComparable<T>
  {
    protected delegate bool FromText( string s, NumberStyles style, IFormatProvider provider, out T result );
    protected delegate T FromDecimal( decimal d );

    private FromText _fromText;
    private FromDecimal _fromDecimal;
    private Func<T, T, bool> _fromLowerThan;
    private Func<T, T, bool> _fromGreaterThan;


    #region ParsingNumberStyle

    public static readonly DependencyProperty ParsingNumberStyleProperty =
        DependencyProperty.Register( "ParsingNumberStyle", typeof( NumberStyles ), typeof( CommonNumericUpDown<T> ), new UIPropertyMetadata( NumberStyles.Any ) );

    public NumberStyles ParsingNumberStyle
    {
      get { return ( NumberStyles )GetValue( ParsingNumberStyleProperty ); }
      set { SetValue( ParsingNumberStyleProperty, value ); }
    }

    #endregion //ParsingNumberStyle

    #region Constructors

    protected CommonNumericUpDown( FromText fromText, FromDecimal fromDecimal, Func<T, T, bool> fromLowerThan, Func<T, T, bool> fromGreaterThan )
    {
      if( fromText == null )
        throw new ArgumentNullException( "tryParseMethod" );

      if( fromDecimal == null )
        throw new ArgumentNullException( "fromDecimal" );

      if( fromLowerThan == null )
        throw new ArgumentNullException( "fromLowerThan" );

      if( fromGreaterThan == null )
        throw new ArgumentNullException( "fromGreaterThan" );

      _fromText = fromText;
      _fromDecimal = fromDecimal;
      _fromLowerThan = fromLowerThan;
      _fromGreaterThan = fromGreaterThan;
    }

    #endregion

    protected static void UpdateMetadata( Type type, T? increment, T? minValue, T? maxValue )
    {
      DefaultStyleKeyProperty.OverrideMetadata( type, new FrameworkPropertyMetadata( type ) );
      UpdateMetadataCommon( type, increment, minValue, maxValue );
    }

    private static void UpdateMetadataCommon( Type type, T? increment, T? minValue, T? maxValue )
    {
      IncrementProperty.OverrideMetadata( type, new FrameworkPropertyMetadata( increment ) );
      MaximumProperty.OverrideMetadata( type, new FrameworkPropertyMetadata( maxValue ) );
      MinimumProperty.OverrideMetadata( type, new FrameworkPropertyMetadata( minValue ) );
    }

    protected void TestInputSpecialValue( AllowedSpecialValues allowedValues, AllowedSpecialValues valueToCompare )
    {
      if( ( allowedValues & valueToCompare ) != valueToCompare )
      {
        switch( valueToCompare )
        {
          case AllowedSpecialValues.NaN :
            throw new InvalidDataException( "Value to parse shouldn't be NaN." );
          case AllowedSpecialValues.PositiveInfinity:
            throw new InvalidDataException( "Value to parse shouldn't be Positive Infinity." );
          case AllowedSpecialValues.NegativeInfinity:
            throw new InvalidDataException( "Value to parse shouldn't be Negative Infinity." );
        }
      }
    }

    private bool IsLowerThan( T? value1, T? value2 )
    {
      if( value1 == null || value2 == null )
        return false;

      return _fromLowerThan( value1.Value, value2.Value );
    }

    private bool IsGreaterThan( T? value1, T? value2 )
    {
      if( value1 == null || value2 == null )
        return false;

      return _fromGreaterThan( value1.Value, value2.Value );
    }

    private bool HandleNullSpin()
    {
      if( !Value.HasValue )
      {
        T forcedValue = ( DefaultValue.HasValue )
          ? DefaultValue.Value
          : default( T );

        Value = CoerceValueMinMax( forcedValue );

        return true;
      }
      else if( !Increment.HasValue )
      {
        return true;
      }

      return false;
    }

    internal bool IsValid( T? value )
    {
      return !IsLowerThan( value, Minimum ) && !IsGreaterThan( value, Maximum );
    }

    private T? CoerceValueMinMax( T value )
    {
      if( IsLowerThan( value, Minimum ) )
        return Minimum;
      else if( IsGreaterThan( value, Maximum ) )
        return Maximum;
      else
        return value;
    }

    #region Base Class Overrides

    protected override void OnIncrement()
    {
      if( !HandleNullSpin() )
      {
        // if UpdateValueOnEnterKey is true, 
        // Sync Value on Text only when Enter Key is pressed.
        if( this.UpdateValueOnEnterKey )
        {
          var currentValue = this.ConvertTextToValue( this.TextBox.Text );
          var result = this.IncrementValue( currentValue.Value, Increment.Value );
          var newValue = this.CoerceValueMinMax( result );
          this.TextBox.Text = newValue.Value.ToString( this.FormatString, this.CultureInfo );
        }
        else
        {
          var result = this.IncrementValue( Value.Value, Increment.Value );
          this.Value = this.CoerceValueMinMax( result );
        }
      }
    }

    protected override void OnDecrement()
    {
      if( !HandleNullSpin() )
      {
        // if UpdateValueOnEnterKey is true, 
        // Sync Value on Text only when Enter Key is pressed.
        if( this.UpdateValueOnEnterKey )
        {
          var currentValue = this.ConvertTextToValue( this.TextBox.Text );
          var result = this.DecrementValue( currentValue.Value, Increment.Value );
          var newValue = this.CoerceValueMinMax( result );
          this.TextBox.Text = newValue.Value.ToString( this.FormatString, this.CultureInfo );
        }
        else
        {
          var result = this.DecrementValue( Value.Value, Increment.Value );
          this.Value = this.CoerceValueMinMax( result );
        }
      }
    }

    protected override void OnMinimumChanged( T? oldValue, T? newValue )
    {
      base.OnMinimumChanged( oldValue, newValue );

      if( this.Value.HasValue && this.ClipValueToMinMax )
      {
        this.Value = this.CoerceValueMinMax( this.Value.Value );
      }
    }

    protected override void OnMaximumChanged( T? oldValue, T? newValue )
    {
      base.OnMaximumChanged( oldValue, newValue );

      if( this.Value.HasValue && this.ClipValueToMinMax )
      {
        this.Value = this.CoerceValueMinMax( this.Value.Value );
      }
    }

    protected override T? ConvertTextToValue( string text )
    {
      T? result = null;

      if( String.IsNullOrEmpty( text ) )
        return result;

      // Since the conversion from Value to text using a FormartString may not be parsable,
      // we verify that the already existing text is not the exact same value.
      string currentValueText = ConvertValueToText();
      if( object.Equals( currentValueText, text ) )
        return this.Value;

      result = this.ConvertTextToValueCore( currentValueText, text );

      if( this.ClipValueToMinMax )
      {
        return this.GetClippedMinMaxValue( result );
      }

      ValidateDefaultMinMax( result );

      return result;
    }

    protected override string ConvertValueToText()
    {
      if( Value == null )
        return string.Empty;

      //Manage FormatString of type "{}{0:N2} °" (in xaml) or "{0:N2} °" in code-behind.
      if( FormatString.Contains( "{0" ) )
        return string.Format( CultureInfo, FormatString, Value.Value );

      return Value.Value.ToString( FormatString, CultureInfo );
    }

    protected override void SetValidSpinDirection()
    {
      ValidSpinDirections validDirections = ValidSpinDirections.None;

      // Null increment always prevents spin.
      if( (this.Increment != null) && !IsReadOnly )
      {
        if( IsLowerThan( Value, Maximum ) || !Value.HasValue || !Maximum.HasValue)
          validDirections = validDirections | ValidSpinDirections.Increase;

        if( IsGreaterThan( Value, Minimum ) || !Value.HasValue || !Minimum.HasValue )
          validDirections = validDirections | ValidSpinDirections.Decrease;
      }

      if( Spinner != null )
        Spinner.ValidSpinDirection = validDirections;
    }

    private bool IsPercent( string stringToTest )
    {
      int PIndex = stringToTest.IndexOf( "P" );
      if( PIndex >= 0 )
      {
        //stringToTest contains a "P" between 2 "'", it's considered as text, not percent
        bool isText = (stringToTest.Substring( 0, PIndex ).Contains( "'" )
                      && stringToTest.Substring( PIndex, FormatString.Length - PIndex ).Contains( "'" ));

        return !isText;
      }
      return false;
    }

    private T? ConvertTextToValueCore( string currentValueText, string text )
    {
      T? result;

      if( this.IsPercent( this.FormatString ) )
      {
        result = _fromDecimal( ParsePercent( text, CultureInfo ) );
      }
      else
      {
        T outputValue = new T();
        // Problem while converting new text
        if( !_fromText( text, this.ParsingNumberStyle, CultureInfo, out outputValue ) )
        {
          bool shouldThrow = true;

          // case 164198: Throw when replacing only the digit part of 99° through UI.
          // Check if CurrentValueText is also failing => it also contains special characters. ex : 90°
          T currentValueTextOutputValue;
          if( !_fromText( currentValueText, this.ParsingNumberStyle, CultureInfo, out currentValueTextOutputValue ) )
          {
            // extract non-digit characters
            var currentValueTextSpecialCharacters = currentValueText.Where( c => !Char.IsDigit( c ) );
            var textSpecialCharacters = text.Where( c => !Char.IsDigit( c ) );
            // same non-digit characters on currentValueText and new text => remove them on new Text to parse it again.
            if( currentValueTextSpecialCharacters.Except( textSpecialCharacters ).ToList().Count == 0 )
            {
              foreach( var character in textSpecialCharacters )
              {
                text = text.Replace( character.ToString(), string.Empty );
              }
              // if without the special characters, parsing is good, do not throw
              if( _fromText( text, this.ParsingNumberStyle, CultureInfo, out outputValue ) )
              {
                shouldThrow = false;
              }
            }
          }

          if( shouldThrow )
            throw new InvalidDataException( "Input string was not in a correct format." );
        }
        result = outputValue;
      }
      return result;
    }

    private T? GetClippedMinMaxValue( T? result )
    {
      if( this.IsGreaterThan( result, this.Maximum ) )
        return this.Maximum;
      else if( this.IsLowerThan( result, this.Minimum ) )
        return this.Minimum;
      return result;
    }

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

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

    #endregion //Base Class Overrides


    #region Abstract Methods

    protected abstract T IncrementValue( T value, T increment );

    protected abstract T DecrementValue( T value, T increment );

    #endregion
  }
}