namespace Modbus.Data
{
    using System;
    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Diagnostics.CodeAnalysis;
    using System.Linq;

    using Utility;

    /// <summary>
    ///     Event args for read write actions performed on the DataStore.
    /// </summary>
    public class DataStoreEventArgs : EventArgs
    {
        private DataStoreEventArgs(ushort startAddress, ModbusDataType modbusDataType)
        {
            StartAddress = startAddress;
            ModbusDataType = modbusDataType;
        }

        /// <summary>
        ///     Type of Modbus data (e.g. Holding register).
        /// </summary>
        public ModbusDataType ModbusDataType { get; }

        /// <summary>
        ///     Start address of data.
        /// </summary>
        public ushort StartAddress { get; }

        /// <summary>
        ///     Data that was read or written.
        /// </summary>
        [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures")]
        public DiscriminatedUnion<ReadOnlyCollection<bool>, ReadOnlyCollection<ushort>> Data { get; private set; }

        internal static DataStoreEventArgs CreateDataStoreEventArgs<T>(ushort startAddress, ModbusDataType modbusDataType, IEnumerable<T> data)
        {
            if (data == null)
            {
                throw new ArgumentNullException(nameof(data));
            }

            DataStoreEventArgs eventArgs;

            if (typeof(T) == typeof(bool))
            {
                var a = new ReadOnlyCollection<bool>(data.Cast<bool>().ToArray());

                eventArgs = new DataStoreEventArgs(startAddress, modbusDataType)
                {
                    Data = DiscriminatedUnion<ReadOnlyCollection<bool>, ReadOnlyCollection<ushort>>.CreateA(a)
                };
            }
            else if (typeof(T) == typeof(ushort))
            {
                var b = new ReadOnlyCollection<ushort>(data.Cast<ushort>().ToArray());

                eventArgs = new DataStoreEventArgs(startAddress, modbusDataType)
                {
                    Data = DiscriminatedUnion<ReadOnlyCollection<bool>, ReadOnlyCollection<ushort>>.CreateB(b)
                };
            }
            else
            {
                throw new ArgumentException("Generic type T should be of type bool or ushort");
            }

            return eventArgs;
        }
    }
}