using System;

using BLToolkit.Properties;

namespace BLToolkit.Common
{
    /// <summary>
    /// This argument adapter class allows either names (strings) or
    /// indices (ints) to be passed to a function.
    /// </summary>
    [System.Diagnostics.DebuggerStepThrough]
    public struct NameOrIndexParameter
    {
        public NameOrIndexParameter(string name)
        {
            if (null == name)
                throw new ArgumentNullException("name");

            if (name.Length == 0)
                throw new ArgumentException(Resources.NameOrIndexParameter_BadName, "name");

            _name  = name;
            _index = 0;
        }

        public NameOrIndexParameter(int index)
        {
            if (index < 0)
                throw new ArgumentException(Resources.NameOrIndexParameter_BadIndex, "index");

            _name  = null;
            _index = index;
        }

        public static implicit operator NameOrIndexParameter(string name)
        {
            return new NameOrIndexParameter(name);
        }

        public static implicit operator NameOrIndexParameter(int index)
        {
            return new NameOrIndexParameter(index);
        }

        #region Public properties
        
        public bool ByName
        {
            get { return null != _name; }
        }

        private readonly string _name;
        public           string  Name
        {
            get
            {
                if (null == _name)
                    throw new InvalidOperationException(
                        "This instance was initialized by index");
                
                 return _name;
            }
        }

        private readonly int _index;
        public           int  Index
        {
            get
            {
                if (null != _name)
                    throw new InvalidOperationException(
                        "This instance was initialized by name");

                return _index;
            }
        }

        #endregion

        #region Static methods

        public static NameOrIndexParameter[] FromStringArray(string[] names)
        {
            return Array.ConvertAll<string, NameOrIndexParameter>(names,
                        delegate(string name) { return new NameOrIndexParameter(name); });
        }

        public static NameOrIndexParameter[] FromIndexArray(int[] indices)
        {
            return Array.ConvertAll<int, NameOrIndexParameter>(indices,
                        delegate(int index) { return new NameOrIndexParameter(index); });
        }

        #endregion
        
        #region System.Object members

        public override bool Equals(object obj)
        {
            if (obj is NameOrIndexParameter)
            {
                NameOrIndexParameter nip = (NameOrIndexParameter)obj;

                if (null != _name && null != nip._name && _name == nip._name)
                    return true; // Same name
                
                if (null == _name && null == nip._name && _index == nip._index)
                    return true; // Same index

                return false;
            }

            if (obj is string)
            {
                string name = (string)obj;
                return (null != _name && _name == name);
            }

            if (obj is int)
            {
                int index = (int)obj;
                return (null == _name && _index == index);
            }

            return false;
        }

        public override int GetHashCode()
        {
            return (null != _name) ? _name.GetHashCode() : _index.GetHashCode();
        }
        
        public override string ToString()
        {
            return _name ?? "#" + _index;
        }

        #endregion

    }
}