using Google.Protobuf;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using Tango.PMR.Common;

namespace Tango.PMR
{
    /// <summary>
    /// Contains helper class for encoding and decoding PMR messages.
    /// </summary>
    public static class MessageFactory
    {
        private static Dictionary<MessageType, Type> _pmrTypes;
        private static MethodInfo _parseTangoMessageMethod;

        static MessageFactory()
        {
            _parseTangoMessageMethod = typeof(MessageFactory).GetMethod("ParseTangoMessage", BindingFlags.Public | BindingFlags.Static);

            _pmrTypes = new Dictionary<MessageType, Type>();
            var types = typeof(MessageFactory).Assembly.GetTypes().ToList();

            foreach (var value in Enum.GetValues(typeof(MessageType)).OfType<MessageType>())
            {
                var type = types.SingleOrDefault(x => x.Name == value.ToOriginalName());

                if (type != null)
                {
                    _pmrTypes.Add(value, type);
                }
            }
        }

        /// <summary>
        /// Creates a new <see cref="TangoMessage{T}"/>.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static TangoMessage<T> CreateTangoMessage<T>() where T : IMessage<T>
        {
            TangoMessage<T> tango = new TangoMessage<T>(Activator.CreateInstance<T>(), ParseMessageType(typeof(T).Name));
            return tango;
        }

        /// <summary>
        /// Creates a new <see cref="TangoMessage{T}"/>.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static TangoMessage<T> CreateTangoMessage<T>(T message) where T : IMessage<T>
        {
            TangoMessage<T> tango = CreateTangoMessage<T>();
            tango.Message = message;
            return tango;
        }

        /// <summary>
        /// Creates a new <see cref="TangoMessage{T}"/>.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static TangoMessage<T> CreateTangoMessage<T>(String token) where T : IMessage<T>
        {
            TangoMessage<T> tango = CreateTangoMessage<T>();
            tango.Container.Token = token;
            return tango;
        }

        /// <summary>
        /// Creates a new <see cref="TangoMessage{T}"/>.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static TangoMessage<T> CreateTangoMessage<T>(T message, String token) where T : IMessage<T>
        {
            TangoMessage<T> tango = CreateTangoMessage<T>(token);
            tango.Message = message;
            return tango;
        }

        /// <summary>
        /// Parses the specified tango message type from the specified byte array.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="data">The data.</param>
        /// <returns></returns>
        public static TangoMessage<T> ParseTangoMessage<T>(byte[] data) where T : IMessage<T>
        {
            MessageContainer container = MessageContainer.Parser.ParseFrom(data);
            MessageParser<T> parser = new MessageParser<T>(() => Activator.CreateInstance<T>());
            TangoMessage<T> tango = new TangoMessage<T>(parser.ParseFrom(container.Data), container.Type);
            return tango;
        }

        /// <summary>
        /// Parses the specified tango message type from the specified message container.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="data">The data.</param>
        /// <returns></returns>
        public static TangoMessage<T> ParseTangoMessageFromContainer<T>(MessageContainer container) where T : IMessage<T>
        {
            MessageParser<T> parser = new MessageParser<T>(() => Activator.CreateInstance<T>());
            TangoMessage<T> tango = new TangoMessage<T>(parser.ParseFrom(container.Data), container.Type);
            tango.Container = container;
            return tango;
        }

        /// <summary>
        /// Parses an unknown tango message from the specified byte array.
        /// </summary>
        /// <param name="data">The data.</param>
        /// <returns></returns>
        public static ITangoMessage ParseTangoMessageAgnostic(byte[] data)
        {
            MessageContainer container = MessageContainer.Parser.ParseFrom(data);
            IMessage message = ExtractMessageFromContainer(container);
            return (ITangoMessage)_parseTangoMessageMethod.MakeGenericMethod(message.GetType()).Invoke(null, new[] { data });
        }

        /// <summary>
        /// Parses the message from the specified container.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="container">The container.</param>
        /// <returns></returns>
        public static T ExtractMessageFromContainer<T>(MessageContainer container) where T : IMessage<T>
        {
            MessageParser<T> parser = new MessageParser<T>(() => Activator.CreateInstance<T>());
            return parser.ParseFrom(container.Data);
        }

        /// <summary>
        /// Parses the message from the specified container.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="container">The container.</param>
        /// <returns></returns>
        public static IMessage ExtractMessageFromContainer(MessageContainer container)
        {
            var type = _pmrTypes[container.Type];
            MessageParser parser = type.GetProperty("Parser").GetValue(container) as MessageParser;
            return parser.ParseFrom(container.Data);
        }

        /// <summary>
        /// Parses a message container from the specified byte array.
        /// </summary>
        /// <param name="data">The data.</param>
        /// <returns></returns>
        public static MessageContainer ParseContainer(byte[] data)
        {
            MessageContainer container = MessageContainer.Parser.ParseFrom(data);
            return container;
        }

        /// <summary>
        /// Parses a message container from the specified byte array containing JSON data.
        /// </summary>
        /// <param name="data">The data.</param>
        /// <returns></returns>
        public static MessageContainer ParseContainerJson(byte[] data)
        {
            MessageContainer container = MessageContainer.Parser.ParseJson(Encoding.UTF8.GetString(data));
            return container;
        }

        /// <summary>
        /// Parses the specified text to a PMR <see cref="MessageType"/>.
        /// </summary>
        /// <param name="text">The text.</param>
        /// <returns></returns>
        /// <exception cref="InvalidCastException">Could not parse message type " + text</exception>
        public static MessageType ParseMessageType(String text)
        {
            MessageType t;
            if (Enum.TryParse<MessageType>(text, true, out t))
            {
                return t;
            }
            else
            {
                throw new InvalidCastException("Message type " + text + " was not found on PMR MessageType enumeration!");
            }
        }
    }
}