#region MigraDoc - Creating Documents on the Fly
//
// Authors:
//   Stefan Lange
//   Klaus Potzesny
//   David Stephensen
//
// Copyright (c) 2001-2017 empira Software GmbH, Cologne Area (Germany)
//
// http://www.pdfsharp.com
// http://www.migradoc.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using MigraDoc.DocumentObjectModel.publics;

namespace MigraDoc.DocumentObjectModel
{
    /// <summary>
    /// A Unit consists of a numerical value and a UnitType like Centimeter, Millimeter, or Inch.
    /// Several conversions between different measures are supported.
    /// </summary>
    public struct Unit : IFormattable, INullableValue
    {
        /// <summary>
        /// Initializes a new instance of the Unit class with type set to point.
        /// </summary>
        public Unit(double point)
        {
            _value = (float)point;
            _type = UnitType.Point;
            _initialized = true;
        }

        /// <summary>
        /// Initializes a new instance of the Unit class.
        /// Throws System.ArgumentException if <code>type</code> is invalid.
        /// </summary>
        public Unit(double value, UnitType type)
        {
            if (!Enum.IsDefined(typeof(UnitType), type))
                throw new /*InvalidEnum*/ArgumentException(DomSR.InvalidEnumValue(type), "type");

            _value = (float)value;
            _type = type;
            _initialized = true;
        }

        /// <summary>
        /// Determines whether this instance is empty.
        /// </summary>
        public bool IsEmpty
        {
            get { return IsNull; }
        }

        /// <summary>
        /// Gets the value of the unit.
        /// </summary>
        object INullableValue.GetValue()
        {
            return this;
        }

        /// <summary>
        /// Sets the unit to the given value.
        /// </summary>
        void INullableValue.SetValue(object value)
        {
            if (value == null)
                throw new ArgumentNullException("value");

            if (value is Unit)
                this = (Unit)value;
            else
                this = value.ToString();
        }

        /// <summary>
        /// Resets this instance,
        /// i.e. IsNull() will return true afterwards.
        /// </summary>
        void INullableValue.SetNull()
        {
            _value = 0;
            _type = UnitType.Point;
            _initialized = false;
        }

        // Explicit interface implementations cannot contain access specifiers, i.e. they are accessible by a
        // cast operator only, e.g. ((IDomValue)obj).IsNull.
        // Therefore the second IsNull-Property is used as a handy shortcut.
        /// <summary>
        /// Determines whether this instance is null (not set).
        /// </summary>
        bool INullableValue.IsNull
        {
            get { return IsNull; }
        }

        /// <summary>
        /// Determines whether this instance is null (not set).
        /// </summary>
        public bool IsNull
        {
            get { return !_initialized; }
        }

        #region Properties
        /// <summary>
        /// Gets or sets the raw value of the object without any conversion.
        /// To determine the UnitType use property <code>Type</code>.
        /// </summary>
        public double Value
        {
            get { return (IsNull ? 0 : _value); }
            set
            {
                _value = (float)value;
                _initialized = true;
            }
        }

        /// <summary>
        /// Gets the UnitType of the object.
        /// </summary>
        public UnitType Type
        {
            get { return _type; }
            set { _type = value; }
        }

        /// <summary>
        /// Gets or sets the value in point.
        /// </summary>
        public double Point
        {
            get
            {
                if (IsNull)
                    return 0;

                switch (_type)
                {
                    case UnitType.Centimeter:
                        return _value * 72 / 2.54;

                    case UnitType.Inch:
                        return _value * 72;

                    case UnitType.Millimeter:
                        return _value * 72 / 25.4;

                    case UnitType.Pica:
                        return _value * 12;

                    case UnitType.Point:
                        return _value;

                    default:
                        Debug.Assert(false, "Missing unit type.");
                        return 0;
                }
            }
            set
            {
                _value = (float)value;
                _type = UnitType.Point;
                _initialized = true;
            }
        }

        //[Obsolete("Use Point")]
        //public double Pt
        //{
        //    get { return Point; }
        //    set { Point = value; }
        //}

        /// <summary>
        /// Gets or sets the value in centimeter.
        /// </summary>
        public double Centimeter
        {
            get
            {
                if (IsNull)
                    return 0;

                switch (_type)
                {
                    case UnitType.Centimeter:
                        return _value;

                    case UnitType.Inch:
                        return _value * 2.54;

                    case UnitType.Millimeter:
                        return _value / 10;

                    case UnitType.Pica:
                        return _value * 12 * 2.54 / 72;

                    case UnitType.Point:
                        return _value * 2.54 / 72;

                    default:
                        Debug.Assert(false, "Missing unit type");
                        return 0;
                }
            }
            set
            {
                _value = (float)value;
                _type = UnitType.Centimeter;
                _initialized = true;
            }
        }

        //[Obsolete("Use Centimeter")]
        //public double Cm
        //{
        //    get { return Centimeter; }
        //    set { Centimeter = value; }
        //}

        /// <summary>
        /// Gets or sets the value in inch.
        /// </summary>
        public double Inch
        {
            get
            {
                if (IsNull)
                    return 0;

                switch (_type)
                {
                    case UnitType.Centimeter:
                        return _value / 2.54;

                    case UnitType.Inch:
                        return _value;

                    case UnitType.Millimeter:
                        return _value / 25.4;

                    case UnitType.Pica:
                        return _value * 12 / 72;

                    case UnitType.Point:
                        return _value / 72;

                    default:
                        Debug.Assert(false, "Missing unit type");
                        return 0;
                }
            }
            set
            {
                _value = (float)value;
                _type = UnitType.Inch;
                _initialized = true;
            }
        }

        //[Obsolete("Use Inch")]
        //public double In
        //{
        //    get { return Inch; }
        //    set { Inch = value; }
        //}

        /// <summary>
        /// Gets or sets the value in millimeter.
        /// </summary>
        public double Millimeter
        {
            get
            {
                if (IsNull)
                    return 0;

                switch (_type)
                {
                    case UnitType.Centimeter:
                        return _value * 10;

                    case UnitType.Inch:
                        return _value * 25.4;

                    case UnitType.Millimeter:
                        return _value;

                    case UnitType.Pica:
                        return _value * 12 * 25.4 / 72;

                    case UnitType.Point:
                        return _value * 25.4 / 72;

                    default:
                        Debug.Assert(false, "Missing unit type");
                        return 0;
                }
            }
            set
            {
                _value = (float)value;
                _type = UnitType.Millimeter;
                _initialized = true;
            }
        }

        //[Obsolete("Use Millimeter")]
        //public double Mm
        //{
        //    get { return Millimeter; }
        //    set { Millimeter = value; }
        //}

        /// <summary>
        /// Gets or sets the value in pica.
        /// </summary>
        public double Pica
        {
            get
            {
                if (IsNull)
                    return 0;

                switch (_type)
                {
                    case UnitType.Centimeter:
                        return _value * 72 / 2.54 / 12;

                    case UnitType.Inch:
                        return _value * 72 / 12;

                    case UnitType.Millimeter:
                        return _value * 72 / 25.4 / 12;

                    case UnitType.Pica:
                        return _value;

                    case UnitType.Point:
                        return _value / 12;

                    default:
                        Debug.Assert(false, "Missing unit type");
                        return 0;
                }
            }
            set
            {
                _value = (float)value;
                _type = UnitType.Pica;
                _initialized = true;
            }
        }

        //[Obsolete("Use Pica")]
        //public double Pc
        //{
        //    get { return Pica; }
        //    set { Pica = value; }
        //}
        #endregion

        #region Methods
        /// <summary>
        /// Returns the object as string using the format information.
        /// Measure will be added to the end of the string.
        /// </summary>
        public string ToString(System.IFormatProvider formatProvider)
        {
            if (IsNull)
                return 0.ToString(formatProvider);

            string valuestring = _value.ToString(formatProvider) + GetSuffix();
            return valuestring;
        }

        /// <summary>
        /// Returns the object as string using the format.
        /// Measure will be added to the end of the string.
        /// </summary>
        public string ToString(string format)
        {
            if (IsNull)
                return 0.ToString(format);

            string valuestring = _value.ToString(format) + GetSuffix();
            return valuestring;
        }

        /// <summary>
        /// Returns the object as string using the specified format and format information.
        /// Measure will be added to the end of the string.
        /// </summary>
        string IFormattable.ToString(string format, IFormatProvider formatProvider)
        {
            if (IsNull)
                return 0.ToString(format, formatProvider);

            string valuestring = _value.ToString(format, formatProvider) + GetSuffix();
            return valuestring;
        }

        /// <summary>
        /// Returns the object as string. Measure will be added to the end of the string.
        /// </summary>
        public override string ToString()
        {
            if (IsNull)
                return 0.ToString(System.Globalization.CultureInfo.InvariantCulture);

            string valuestring = _value.ToString(System.Globalization.CultureInfo.InvariantCulture) + GetSuffix();
            return valuestring;
        }

        /// <summary>
        /// Returns the type of the object as a string like 'pc', 'cm', or 'in'. Empty string is equal to 'pt'.
        /// </summary>
        string GetSuffix()
        {
            switch (_type)
            {
                case UnitType.Centimeter:
                    return "cm";

                case UnitType.Inch:
                    return "in";

                case UnitType.Millimeter:
                    return "mm";

                case UnitType.Pica:
                    return "pc";

                case UnitType.Point:
                    //Point is default, so leave this blank.
                    return "";

                default:
                    Debug.Assert(false, "Missing unit type");
                    return "";
            }
        }

        /// <summary>
        /// Returns a Unit object. Sets type to centimeter.
        /// </summary>
        public static Unit FromCentimeter(double value)
        {
            Unit unit = Unit.Zero;
            unit._value = (float)value;
            unit._type = UnitType.Centimeter;
            return unit;
        }

        //[Obsolete("Use FromCentimer")]
        //public static Unit FromCm(double value)
        //{
        //    return FromCentimeter(value);
        //}

        /// <summary>
        /// Returns a Unit object. Sets type to millimeter.
        /// </summary>
        public static Unit FromMillimeter(double value)
        {
            Unit unit = Unit.Zero;
            unit._value = (float)value;
            unit._type = UnitType.Millimeter;
            return unit;
        }

        ///// <summary>
        ///// Returns a Unit object. Sets type to millimeter.
        ///// </summary>
        //[Obsolete("Use FromMillimeter")]
        //public static Unit FromMm(double value)
        //{
        //    return FromMillimeter(value);
        //}

        /// <summary>
        /// Returns a Unit object. Sets type to point.
        /// </summary>
        public static Unit FromPoint(double value)
        {
            Unit unit = Unit.Zero;
            unit._value = (float)value;
            unit._type = UnitType.Point;
            return unit;
        }

        /// <summary>
        /// Returns a Unit object. Sets type to inch.
        /// </summary>
        public static Unit FromInch(double value)
        {
            Unit unit = Unit.Zero;
            unit._value = (float)value;
            unit._type = UnitType.Inch;
            return unit;
        }

        /// <summary>
        /// Returns a Unit object. Sets type to pica.
        /// </summary>
        public static Unit FromPica(double value)
        {
            Unit unit = Unit.Zero;
            unit._value = (float)value;
            unit._type = UnitType.Pica;
            return unit;
        }
        #endregion

        /// <summary>
        /// Converts a string to a Unit object.
        /// If the string contains a suffix like 'cm' or 'in' the object will be converted
        /// to the appropriate type, otherwise point is assumed.
        /// </summary>
        public static implicit operator Unit(string value)
        {
            Unit unit = Zero;
            value = value.Trim();

            // For Germans...
            value = value.Replace(',', '.');

            int count = value.Length;
            int valLen = 0;
            for (; valLen < count; )
            {
                char ch = value[valLen];
                if (ch == '.' || ch == '-' || ch == '+' || Char.IsNumber(ch))
                    valLen++;
                else
                    break;
            }

            unit._value = 1;
            try
            {
                unit._value = float.Parse(value.Substring(0, valLen).Trim(), System.Globalization.CultureInfo.InvariantCulture);
            }
            catch (FormatException ex)
            {
                throw new ArgumentException(DomSR.InvalidUnitValue(value), ex);
            }

            string typeStr = value.Substring(valLen).Trim().ToLower();
            unit._type = UnitType.Point;
            switch (typeStr)
            {
                case "cm":
                    unit._type = UnitType.Centimeter;
                    break;

                case "in":
                    unit._type = UnitType.Inch;
                    break;

                case "mm":
                    unit._type = UnitType.Millimeter;
                    break;

                case "pc":
                    unit._type = UnitType.Pica;
                    break;

                case "":
                case "pt":
                    unit._type = UnitType.Point;
                    break;

                default:
                    throw new ArgumentException(DomSR.InvalidUnitType(typeStr));
            }

            return unit;
        }

        /// <summary>
        /// Converts an int to a Unit object with type set to point.
        /// </summary>
        public static implicit operator Unit(int value)
        {
            Unit unit = Zero;
            unit._value = value;
            unit._type = UnitType.Point;
            return unit;
        }

        /// <summary>
        /// Converts a float to a Unit object with type set to point.
        /// </summary>
        public static implicit operator Unit(float value)
        {
            Unit unit = Zero;
            unit._value = value;
            unit._type = UnitType.Point;
            return unit;
        }

        /// <summary>
        /// Converts a double to a Unit object with type set to point.
        /// </summary>
        public static implicit operator Unit(double value)
        {
            Unit unit = Zero;
            unit._value = (float)value;
            unit._type = UnitType.Point;
            return unit;
        }

        /// <summary>
        /// Returns a double value as point.
        /// </summary>
        public static implicit operator double(Unit value)
        {
            return value.Point;
        }

        /// <summary>
        /// Returns a float value as point.
        /// </summary>
        public static implicit operator float(Unit value)
        {
            return (float)value.Point;
        }

        /// <summary>
        /// Memberwise comparison. To compare by value, 
        /// use code like Math.Abs(a.Point - b.Point) &lt; 1e-5.
        /// </summary>
        public static bool operator ==(Unit l, Unit r)
        {
            // ReSharper disable CompareOfFloatsByEqualityOperator
            return (l._initialized == r._initialized && l._type == r._type && l._value == r._value);
            // ReSharper restore CompareOfFloatsByEqualityOperator
        }

        /// <summary>
        /// Memberwise comparison. To compare by value, 
        /// use code like Math.Abs(a.Point - b.Point) &lt; 1e-5.
        /// </summary>
        public static bool operator !=(Unit l, Unit r)
        {
            return !(l == r);
        }

        /// <summary>
        /// Calls base class Equals.
        /// </summary>
        public override bool Equals(Object obj)
        {
            return base.Equals(obj);
        }

        /// <summary>
        /// Calls base class GetHashCode.
        /// </summary>
        public override int GetHashCode()
        {
            return base.GetHashCode();
        }

        /// <summary>
        /// This member is intended to be used by XmlDomainObjectReader only.
        /// </summary>
        public static Unit Parse(string value)
        {
            Unit unit = Zero;
            unit = value;
            return unit;
        }

        /// <summary>
        /// Converts an existing object from one unit into another unit type.
        /// </summary>
        public void ConvertType(UnitType type)
        {
            if (_type == type)
                return;

            switch (type)
            {
                case UnitType.Centimeter:
                    _value = (float)Centimeter;
                    _type = UnitType.Centimeter;
                    break;

                case UnitType.Inch:
                    _value = (float)Inch;
                    _type = UnitType.Inch;
                    break;

                case UnitType.Millimeter:
                    _value = (float)Millimeter;
                    _type = UnitType.Millimeter;
                    break;

                case UnitType.Pica:
                    _value = (float)Pica;
                    _type = UnitType.Pica;
                    break;

                case UnitType.Point:
                    _value = (float)Point;
                    _type = UnitType.Point;
                    break;

                default:
                    if (!Enum.IsDefined(typeof(UnitType), type))
                        throw new ArgumentException(DomSR.InvalidUnitType(type.ToString()));

                    // Remember missing unit type.
                    Debug.Assert(false, "Missing unit type");
                    break;
            }
        }

        /// <summary>
        /// Represents the uninitialized Unit object.
        /// </summary>
        public static readonly Unit Empty = new Unit();

        /// <summary>
        /// Represents an initialized Unit object with value 0 and unit type point.
        /// </summary>
        public static readonly Unit Zero = new Unit(0);

        /// <summary>
        /// Represents the uninitialized Unit object. Same as Unit.Empty.
        /// </summary>
        public static readonly Unit NullValue = Empty;

        bool _initialized;
        float _value;
        UnitType _type;
    }
}