using System;
using System.IO;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using ChaosBot.Models;
using Discord.Commands;

namespace ChaosBot.Services.ProgrammingLanguageInterpreter
{
    public static class ProgrammingLanguageInterpreterFacade
    {
        public static bool TryInterpret(SocketCommandContext context, CustomCommand customCommand, out string errorReason)
        {
            errorReason = "";
            IProgrammingLanguageInterpreter interpreter =
                ProgrammingLanguageInterpreterFactory.GetInterpreter(customCommand.Type);
            if (interpreter == null)
            {
                errorReason = "Could not set up an interpreter for the code";
                return false;
            }

            try
            {
                CancellationTokenSource tokenSource = new CancellationTokenSource();
                LimitedSocketCommandContext limitedContext = new LimitedSocketCommandContext(context);
                Task<string> task = Task.Run(() =>
                {
                    Thread.CurrentThread.Priority = ThreadPriority.Lowest;
                    return interpreter.Interpret(tokenSource.Token, limitedContext, customCommand.Content, customCommand.Command);
                }, tokenSource.Token);

                const int timeout = 250;
                bool isTaskCompleted = task.Wait(TimeSpan.FromMilliseconds(timeout));

                if (!isTaskCompleted)
                {
                    tokenSource.Cancel();
                    throw new TimeoutException($"Command '{customCommand.Command}' took more than {timeout}ms to run. It has been killed.");
                }

                string output = task.Result;

                if (output.Length > 2000)
                {
                    context.Channel.SendMessageAsync($"Command '{customCommand.Command}' has {output.Length} characters of output. That is more than the 2000 limit. Packaging into file...").GetAwaiter().GetResult();
                    Stream stream = new MemoryStream(Encoding.ASCII.GetBytes(output));
                    if (stream.Length > 8 * 1024 * 1024)
                        context.Channel.SendMessageAsync($"Packaged filesize of {stream.Length / 1024 / 1024} MB is too big.");
                    else
                        context.Channel.SendFileAsync(stream, "command-output.txt");
                }
                else if (output.Length > 0)
                    context.Channel.SendMessageAsync(output);
                else
                    context.Channel.SendMessageAsync($"Command '{customCommand.Command}' had no output.");
                return true;
            }
            catch (Exception ex)
            {
                LoggingFacade.Exception(ex);
                errorReason = $"There was an error with your code ({ex.GetType().Name}): {ex.Message}";
                return false;
            }
        }
    }
}