using System;
using System.ComponentModel;
using System.Text.RegularExpressions;

namespace Volian.Svg.Library
{
	[TypeConverter(typeof(MeasurementTypeConverter))]
	public class SvgMeasurement
	{
		#region Operators
		public static SvgMeasurement operator +(SvgMeasurement x1, SvgMeasurement x2)
		{
			E_MeasurementUnits tmpUnits = x1.Units;
			SvgMeasurement tmp = new SvgMeasurement(x1.GetSizeInPoints(DPI) + x2.GetSizeInPoints(DPI),E_MeasurementUnits.PT);
			tmp.Units = x1.Units;
			return tmp;
		}
		public static SvgMeasurement operator -(SvgMeasurement x1, SvgMeasurement x2)
		{
			E_MeasurementUnits tmpUnits = x1.Units;
			SvgMeasurement tmp = new SvgMeasurement(x1.GetSizeInPoints(DPI) - x2.GetSizeInPoints(DPI), E_MeasurementUnits.PT);
			tmp.Units = x1.Units;
			return tmp;
		}
		public static SvgMeasurement operator *(SvgMeasurement x1, float scaler)
		{
			E_MeasurementUnits tmpUnits = x1.Units;
			SvgMeasurement tmp = new SvgMeasurement(x1.GetSizeInPoints(DPI) * scaler, E_MeasurementUnits.PT);
			tmp.Units = x1.Units;
			return tmp;
		}
		public static SvgMeasurement operator *(float scaler, SvgMeasurement x1)
		{
			E_MeasurementUnits tmpUnits = x1.Units;
			SvgMeasurement tmp = new SvgMeasurement(x1.GetSizeInPoints(DPI) * scaler, E_MeasurementUnits.PT);
			tmp.Units = x1.Units;
			return tmp;
		}
		#endregion
		#region DPI
		private static float _DPI;
		public static float DPI
		{
			get
			{
				if (_DPI == 0)
					_DPI = 96;
				return _DPI;
			}
		}
		#endregion
		#region ctor
		public SvgMeasurement() { ;}
		public SvgMeasurement(int value)
		{
			Value = Convert.ToSingle(value);
			_Units = E_MeasurementUnits.PX;
		}
		public SvgMeasurement(float value)
		{
			Value = value;
			_Units = E_MeasurementUnits.PX;
		}
		public SvgMeasurement(float value, E_MeasurementUnits units)
		{
			Value = value;
			_Units = units;
		}
		public SvgMeasurement(string val)
		{
			val = val.Replace("{size}", "10");// B2020-145 BWD SAMG TSG-6 Fix for Base Format {size} parameter rather than font size
			MatchCollection mc = Regex.Matches(val.ToLower(), "([+-]?[.0-9]+)|(in|cm|mm|em|ex|pc|pt|px|percentage)");
			Value = Convert.ToSingle(mc[0].Value);
			if (mc.Count == 2)
			{
				//Console.WriteLine("{0} - '{1}'", val, mc[1].Value.ToUpper());
				_Units = (E_MeasurementUnits)Enum.Parse(typeof(E_MeasurementUnits), mc[1].Value.ToUpper());
			}
			else
				_Units = E_MeasurementUnits.PX;
		}
		#endregion
		#region Properties
		private E_MeasurementUnits _Units;
		public E_MeasurementUnits Units
		{
			get { return _Units; }
			set 
			{
				float tmp = GetSizeInPoints(DPI);
				_Units = value; 
				Value *= (tmp / GetSizeInPoints(DPI));
			}
		}

        public float Value { get; set; }
        #endregion
        #region ToString
        public override string ToString()
		{
			switch (_Units)
			{
				case E_MeasurementUnits.PX: // Default
					return string.Format("{0}", Value);
				case E_MeasurementUnits.PERCENTAGE: // Precentage is preceded by a space
					return string.Format("{0} {1}", Value, _Units);
			}
			return string.Format("{0}{1}", Value, _Units);
		}
		#endregion
		public float GetSizeInPoints(float myDPI)
		{
				switch (_Units)
				{
					case E_MeasurementUnits.PX: //Pixels myDPI per inch 
						return Value * 72F / myDPI;
					case E_MeasurementUnits.PC: //Picas - 6 per inch 
						return Value * 72F / 6F;
					case E_MeasurementUnits.IN: //inches
						return Value * 72F;
					case E_MeasurementUnits.CM: // Centimeter
						return Value * 72F / 2.54F;
					case E_MeasurementUnits.MM: // Millimeter
						return Value * 72F / 25.4F;
					case E_MeasurementUnits.EM: // EMs
						return Value * 72F / 8;
					case E_MeasurementUnits.EX: // EXs
						return Value * 72F / 16;
					default: // Points
						return Value;
				}
		}
        public float GetSizeInPixels(float myDPI) => GetSizeInPoints(myDPI) * myDPI / 72F;
        public float GetSizeInInches(float myDPI) => GetSizeInPoints(myDPI) / 72F;
        public float GetSizeInCentimeters(float myDPI) => GetSizeInPoints(myDPI) * 2.54F / 72F;
		public float GetSizeInMillimeters(float myDPI) => GetSizeInPoints(myDPI) * 25.4F / 72F;
		public float GetSizeInEms(float myDPI) => GetSizeInPoints(myDPI) * 5 / (6 * 72F);
        public float GetSizeInExs(float myDPI) => GetSizeInPoints(myDPI) * 5 / (6 * 72F);
        public float GetSizeInPicas(float myDPI) => GetSizeInPoints(myDPI) * 6 / 72F;

		public static float StringToPoints(string value)
		{
			SvgMeasurement tmp = new SvgMeasurement(value);
			float myPoints = tmp.GetSizeInPoints(72);
			return myPoints;
		}

	}
	public enum E_MeasurementUnits : int
	{
		[Description("Pixels")]
		PX,
		[Description("Points")]
		PT,
		[Description("Inches")]
		IN,
		[Description("Centimeters")]
		CM,
		[Description("Millimeters")]
		MM,
		[Description("EMs")]
		EM,
		[Description("EXs")]
		EX,
		[Description("Percentage")]
		PERCENTAGE,
		[Description("Picas")]
		PC
	}
	public class MeasurementTypeConverter : ExpandableObjectConverter
	{
        public override bool CanConvertTo(ITypeDescriptorContext context, Type t) => t == typeof(String);
        public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destType) => destType == typeof(string) && value is SvgMeasurement ? value.ToString() : base.ConvertTo(context, culture, value, destType);
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type t) => t == typeof(String);
        public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object val) => new SvgMeasurement((string)val);
    }
}