using System;
using System.Collections.Generic;
using System.Text;

namespace Wayne.ForecourtControl
{
    /// <summary>
    /// A collection representing the allowed fuel grade maximum volume, that should be used within the authorize parameters.
    /// </summary>
    public sealed class FuelGradeMaxVolumes : Wayne.ForecourtControl.IFuelGradeMaxVolumes
    {
        #region Fields

        decimal?[] maxVolumes = new decimal?[Defines.MaxFuelGradeCount];

        #endregion

        #region Construction

        /// <summary>
        /// Internal constructor prohibits creation of this class outside the assembly.
        /// </summary>
        internal FuelGradeMaxVolumes()
        {
        }

        #endregion 

        #region Indexer

        /// <summary>
        /// Indexer returning the maximum volume allowed for the fuel grade.
        /// </summary>
        /// <param name="index">Fuel grade</param>
        /// <exception cref="FuelGradeOutOfRangeException">Thrown if the fuel grade is out of range.</exception>
        public decimal? this[int index]
        {
            get
            {
                EvaluateIndex(index);
                return maxVolumes[index];
            }
            set
            {
                EvaluateIndex(index);
                maxVolumes[index] = value;
            }
        }

        #endregion

        #region Methods

        private void EvaluateIndex(int index)
        {
            if ((index < 0) || (index >= maxVolumes.Length))
                throw new FuelGradeOutOfRangeException(index.ToString(System.Globalization.CultureInfo.InvariantCulture) + " is out of range for fuel grades");
        }

        #endregion

        #region Properties

        /// <summary>
        /// Indicates the number of fuel grades.
        /// </summary>
        public int Count
        {
            get
            {
                return maxVolumes.Length;
            }
        }

        #endregion
    }
}