using System;
using System.Collections.Generic;
using System.Dynamic;
using System.Threading.Tasks;
using Discord;
using Discord.Commands;

namespace Geekbot.net.Commands
{
    public class ContextHandler : IContextHandler
    {
        private Dictionary<ulong, ContextStore> _store;
        private readonly IDiscordClient _client;
        private readonly CommandService _commandService;
        private readonly IServiceProvider _servicesProvider;

        public ContextHandler(IDiscordClient client, CommandService commandService, IServiceProvider servicesProvider)
        {
            _store = new Dictionary<ulong, ContextStore>();
            _commandService = commandService;
            _servicesProvider = servicesProvider;
            _client = client;
        }
        
        public ContextReference HasContext(IUserMessage message)
        {
            if (_store.ContainsKey(message.Author.Id)) return ContextReference.User;

            if (_store.ContainsKey(message.Channel.Id)) return ContextReference.Channel;
            
            return ContextReference.None;
        }

        public void SaveContext(ContextReference type, ICommandContext context, string commandName)
        {
            var contextStore = new ContextStore()
            {
                CommandName = commandName
            };
            var id = GetId(type, context.Message);
            _store.Add(id, contextStore);
        }

        public async void ExecuteOnContext(ContextReference type, IUserMessage message)
        {
            var id = GetId(type, message);
            var obj = _store[id];
            var context = new CommandContext(_client, message);
            var rest = await _commandService.ExecuteAsync(context, $"{obj.CommandSearch} {context.Message?.Content}", _servicesProvider);
            if (!rest.IsSuccess)
            {
                await context.Channel.SendMessageAsync(rest.ErrorReason);
            }
        }

        public void ClearContext(ulong id)
        {
            _store.Remove(id);
        }

        private ulong GetId(ContextReference type, IUserMessage message)
        {
            if (type == ContextReference.Channel)
            {
                return message.Author.Id;
            }

            if (type == ContextReference.User)
            {
                return message.Author.Id;
            }

            throw new Exception("No Context Object Found");
        }
        
        private class ContextStore
        {
            public string CommandName { get; set; }
            public string CommandSearch => $"{CommandName} ctx";
        }
    }

    public enum ContextReference
    {
        User,
        Channel,
        None
    }

    public interface IContextHandler
    {
        ContextReference HasContext(IUserMessage message);
        void SaveContext(ContextReference type, ICommandContext context, string commandName);
        void ExecuteOnContext(ContextReference type, IUserMessage message);
        void ClearContext(ulong id);
    }
}