using System;
using System.Collections.Generic;
using System.Linq;

namespace Encompass
{
    internal class MessageManager
    {
        private readonly TimeManager timeManager;

        private readonly Dictionary<Type, List<IMessage>> messageTypeToMessages = new Dictionary<Type, List<IMessage>>();

        private readonly List<(IMessage, double)> delayedMessages = new List<(IMessage, double)>();
        private readonly List<(IMessage, double)> delayedMessagesIgnoringTimeDilation = new List<(IMessage, double)>();

        public MessageManager(TimeManager timeManager)
        {
            this.timeManager = timeManager;
        }

        internal void RegisterMessageType(Type messageType)
        {
            if (!messageTypeToMessages.ContainsKey(messageType))
            {
                messageTypeToMessages.Add(messageType, new List<IMessage>());
            }
        }

        internal void AddMessage(IMessage message)
        {
            var type = message.GetType();

            messageTypeToMessages[type].Add(message);
        }

        internal void AddMessageDelayed(IMessage message, double time)
        {
            if (!messageTypeToMessages.ContainsKey(message.GetType())) { messageTypeToMessages.Add(message.GetType(), new List<IMessage>()); }

            delayedMessages.Add((message, time));
        }

        internal void AddMessageDelayedIgnoringTimeDilation(IMessage message, double time)
        {
            if (!messageTypeToMessages.ContainsKey(message.GetType())) { messageTypeToMessages.Add(message.GetType(), new List<IMessage>()); }

            delayedMessagesIgnoringTimeDilation.Add((message, time));
        }

        internal void ClearMessages()
        {
            foreach (var entry in messageTypeToMessages)
            {
                entry.Value.Clear();
            }
        }

        internal void ProcessDelayedMessages(double dt)
        {
            for (int i = delayedMessages.Count - 1; i >= 0; i--)
            {
                var (message, time) = delayedMessages[i];

                var updatedTime = time - (dt * timeManager.TimeDilationFactor);

                if (updatedTime <= 0)
                {
                    AddMessage(message);
                    delayedMessages.RemoveAt(i);
                }
                else
                {
                    delayedMessages[i] = (message, updatedTime);
                }
            }

            for (int i = delayedMessagesIgnoringTimeDilation.Count - 1; i >= 0; i--)
            {
                var (message, time) = delayedMessagesIgnoringTimeDilation[i];

                var updatedTime = time - dt;

                if (updatedTime <= 0)
                {
                    AddMessage(message);
                    delayedMessagesIgnoringTimeDilation.RemoveAt(i);
                }
                else
                {
                    delayedMessagesIgnoringTimeDilation[i] = (message, updatedTime);
                }
            }
        }

        internal IEnumerable<TMessage> GetMessagesByType<TMessage>() where TMessage : struct, IMessage
        {
            return messageTypeToMessages.ContainsKey(typeof(TMessage)) ?
                messageTypeToMessages[typeof(TMessage)].Cast<TMessage>() :
                Enumerable.Empty<TMessage>();
        }
    }
}