using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.Serialization;
using System.Text;

namespace Raytheon.Units
{
    /// <summary>
    /// This class represents energy.  
    /// 
    /// It has no constructors.  Instead, it provides multiple methods for creating objects of this 
    /// type.  Those methods are of the form FromXXX, where XXX is a unit (e.g. FromJoulesPerCmSqrd).
    /// 
    /// Properties (e.g. JoulesPerCmSqrd) are provided to convert the value to other units and return 
    /// as type double.
    /// </summary>
    [Serializable]
    [DataContract]
    public class Energy
    {
        public enum Unit
        {
            JoulesPerCmSqrd,
            MillijoulesPerCmSqrd
        }

        public static IDictionary<Unit, List<string>> UnitAbbreviations = new Dictionary<Unit, List<string>>()
        {
            {Unit.JoulesPerCmSqrd, new List<string>(){ "J/cm^2" } },
            {Unit.MillijoulesPerCmSqrd, new List<string>(){ "mJ/cm^2" } },
        };

        private const Unit DefaultUnits = Unit.JoulesPerCmSqrd;

        [DataMember(Name = "Energy", IsRequired = true)]
        private double _energy; // joules/centimeter^2

        // map: unit => abbreviation, conversion method and property
        private static IDictionary<Unit, UnitInfo<Energy>> _unitInfo = new Dictionary<Unit, UnitInfo<Energy>>()
        {
            { Unit.JoulesPerCmSqrd, new UnitInfo<Energy>(UnitAbbreviations[Unit.JoulesPerCmSqrd], FromJoulesPerCmSqrd, typeof(Energy).GetProperty("JoulesPerCmSqrd").GetGetMethod()) },
            { Unit.MillijoulesPerCmSqrd, new UnitInfo<Energy>(UnitAbbreviations[Unit.MillijoulesPerCmSqrd], FromMillijoulesPerCmSqrd, typeof(Energy).GetProperty("MillijoulesPerCmSqrd").GetGetMethod()) }
        };

        /// <summary>
        /// Prevents a default instance of the <see cref="Energy"/> class from being created.  
        /// Use FromXXX methods to create objects of this type.
        /// </summary>
        /// <exception cref="System.Exception">No one should be calling this, it is only here to prevent users from creating default object</exception>
        private Energy()
        {
            throw new InvalidOperationException("No one should be calling this, it is only here to prevent users from creating default object");
        }

        /// <summary>
        /// ctor used by this class to create objects in FromXXX methods 
        /// </summary>
        /// <param name="energy">The energy - joules/cm^2.</param>
        private Energy(double energy)
        {
            _energy = energy;
        }

        #region conversion properties

        /// <summary>
        /// Returns joules/cm^2 as type double
        /// </summary>
        /// <value>
        /// joules/cm^2
        /// </value>
        
        public double JoulesPerCmSqrd
        {
            get { return _energy; }
        }

        /// <summary>
        /// Returns joules/cm^2 as type double
        /// </summary>
        /// <value>
        /// joules/cm^2
        /// </value>
        
        public double MillijoulesPerCmSqrd
        {
            get { return _energy * 1000; }
        }

        #endregion

        #region creation methods

        /// <summary>
        /// Returns Energy object interpreting passed value as joules/cm^2
        /// </summary>
        /// <param name="joulesPerCmSqrd">joules/cm^2</param>
        /// <returns></returns>
        
        public static Energy FromJoulesPerCmSqrd(double joulesPerCmSqrd)
        {
            return new Energy(joulesPerCmSqrd);
        }

        /// <summary>
        /// Returns Energy object interpreting passed value as joules/cm^2
        /// </summary>
        /// <param name="joulesPerCmSqrd">joules/cm^2</param>
        /// <returns></returns>
        
        public static Energy FromMillijoulesPerCmSqrd(double joulesPerCmSqrd)
        {
            return new Energy(joulesPerCmSqrd / 1000);
        }

        #endregion

        public override bool Equals(object obj)
        {
            Energy e = obj as Energy;

            return (e == null) ? false : (this._energy == e._energy);
        }

        public override int GetHashCode()
        {
            return _energy.GetHashCode();
        }

        #region binary operators

        // not implementing %, &, |, ^, <<, >>

        
        public static Energy operator +(Energy left, Energy right)
        {
            if (null == left)
                throw new ArgumentNullException("left", "Cannot add a null Energy");

            if (null == right)
                throw new ArgumentNullException("right", "Cannot add null Energy");

            return new Energy(left._energy + right._energy);
        }

        
        public static Energy operator -(Energy left, Energy right)
        {
            if (null == left)
                throw new ArgumentNullException("left", "Cannot subtract a null Energy");

            if (null == right)
                throw new ArgumentNullException("right", "Cannot subtract a null Energy");

            return new Energy(left._energy - right._energy);
        }

        
        public static Energy operator *(Energy energy, double scalar)
        {
            if (null == energy)
                throw new ArgumentNullException("energy", "Cannot multiply a null Energy");

            return new Energy(energy._energy * scalar);
        }

        
        public static Energy operator *(double scalar, Energy energy)
        {
            if (null == energy)
                throw new ArgumentNullException("energy", "Cannot multiply a null Energy");

            return new Energy(scalar * energy._energy);
        }

        
        public static Energy operator /(Energy energy, double scalar)
        {
            if (null == energy)
                throw new ArgumentNullException("energy", "Cannot divide a null Energy");

            if (0.0 == scalar)
                throw new DivideByZeroException("Cannot divide Energy by 0");

            return new Energy(energy._energy / scalar);
        }

        #endregion

        #region comparison operators

        public static bool operator ==(Energy left, Energy right)
        {
            bool bReturn = false;
            if (object.ReferenceEquals(left, null))
            {
                if (object.ReferenceEquals(right, null))
                {
                    //both are null, so we are ==
                    bReturn = true;
                }
            }
            else
            {
                if (!object.ReferenceEquals(left, null) &&
                    !object.ReferenceEquals(right, null))
                {
                    bReturn = left._energy == right._energy;
                }
            }
            return bReturn;
        }

        public static bool operator !=(Energy left, Energy right)
        {
            return !(left == right);
        }

        
        public static bool operator <(Energy left, Energy right)
        {
            if (null == left)
                throw new ArgumentNullException("left", "Cannot compare null Energy");

            if (null == right)
                throw new ArgumentNullException("right", "Cannot compare null Energy");

            return (left._energy < right._energy);
        }

        
        public static bool operator >(Energy left, Energy right)
        {
            if (null == left)
                throw new ArgumentNullException("left", "Cannot compare null Energy");

            if (null == right)
                throw new ArgumentNullException("right", "Cannot compare null Energy");

            return (left._energy > right._energy);
        }

        
        public static bool operator <=(Energy left, Energy right)
        {
            if (null == left)
                throw new ArgumentNullException("left", "Cannot compare null Energy");

            if (null == right)
                throw new ArgumentNullException("right", "Cannot compare null Energy");

            return (left._energy <= right._energy);
        }

        
        public static bool operator >=(Energy left, Energy right)
        {
            if (null == left)
                throw new ArgumentNullException("left", "Cannot compare null Energy");

            if (null == right)
                throw new ArgumentNullException("right", "Cannot compare null Energy");

            return (left._energy >= right._energy);
        }

        #endregion

        #region operators with other classes

        // no operators right now

        #endregion

        #region parsing

        public static Energy Parse(string s)
        {
            return Common.Parse(s, _unitInfo);
        }

        public static bool TryParse(string s, out Energy value)
        {
            try
            {
                value = Energy.Parse(s);
                return true;
            }
            catch (Exception)
            {
                value = null;
                return false;
            }
        }

        #endregion

        /// <summary>
        /// Returns a string appended with default units (e.g. "1.23 m/sec^2").
        /// </summary>
        /// <returns>
        /// A string that represents this instance
        /// </returns>
        public override string ToString()
        {
            return ToString(DefaultUnits);
        }

        /// <summary>
        /// overload that returns a string appended with specified units (e.g. "1.23 ft/sec^2").
        /// </summary>
        /// <param name="units"></param>
        /// <returns></returns>
        public string ToString(Unit units)
        {
            double value = (double)_unitInfo[units].PropertyGetter.Invoke(this, null);

            return $"{value} {_unitInfo[units].Abbreviation[0]}";
        }
    }
}