using System;
using System.Collections.Concurrent;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace StardewModdingAPI
{
    public static class Log
    {
        private static readonly LogWriter _writer;

        static Log()
        {
            _writer = LogWriter.Instance;
        }

        private static void PrintLog(LogInfo li)
        {
            _writer.WriteToLog(li);
        }

        #region Exception Logging

        /// <summary>
        ///     Catch unhandled exception from the application
        /// </summary>
        /// <remarks>Should be moved out of here if we do more than just log the exception.</remarks>
        public static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
        {
            Console.WriteLine("An exception has been caught");
            File.WriteAllText(Path.Combine(Constants.LogDir, $"MODDED_ErrorLog.Log_{DateTime.UtcNow.Ticks}.txt"), e.ExceptionObject.ToString());
        }

        /// <summary>
        ///     Catch thread exception from the application
        /// </summary>
        /// <remarks>Should be moved out of here if we do more than just log the exception.</remarks>
        public static void Application_ThreadException(object sender, ThreadExceptionEventArgs e)
        {
            Console.WriteLine("A thread exception has been caught");
            File.WriteAllText(Path.Combine(Constants.LogDir, $"MODDED_ErrorLog.Log_{Extensions.Random.Next(100000000, 999999999)}.txt"), e.Exception.ToString());
        }

        #endregion

        #region Sync Logging

        /// <summary>
        ///     NOTICE: Sync logging is discouraged. Please use Async instead.
        /// </summary>
        /// <param name="message">Message to log</param>
        /// <param name="colour">Colour of message</param>
        public static void SyncColour(object message, ConsoleColor colour)
        {
            PrintLog(new LogInfo(message?.ToString(), colour));
        }

        #endregion

        #region Async Logging

        public static void AsyncColour(object message, ConsoleColor colour)
        {
            Task.Run(() => { PrintLog(new LogInfo(message?.ToString(), colour)); });
        }

        public static void Async(object message)
        {
            AsyncColour(message?.ToString(), ConsoleColor.Gray);
        }

        public static void AsyncR(object message)
        {
            AsyncColour(message?.ToString(), ConsoleColor.Red);
        }

        public static void AsyncO(object message)
        {
            AsyncColour(message.ToString(), ConsoleColor.DarkYellow);
        }

        public static void AsyncY(object message)
        {
            AsyncColour(message?.ToString(), ConsoleColor.Yellow);
        }

        public static void AsyncG(object message)
        {
            AsyncColour(message?.ToString(), ConsoleColor.Green);
        }

        public static void AsyncC(object message)
        {
            AsyncColour(message?.ToString(), ConsoleColor.Cyan);
        }

        public static void AsyncM(object message)
        {
            AsyncColour(message?.ToString(), ConsoleColor.Magenta);
        }

        public static void Error(object message)
        {
            AsyncR("[ERROR] " + message);
        }

        public static void Success(object message)
        {
            AsyncG("[SUCCESS] " + message);
        }

        public static void Info(object message)
        {
            AsyncY("[INFO] " + message);
        }

        public static void Out(object message)
        {
            Async("[OUT] " + message);
        }

        public static void Debug(object message)
        {
            AsyncO("[DEBUG] " + message);
        }

        #endregion

        #region ToRemove

        public static void LogValueNotSpecified()
        {
            AsyncR("<value> must be specified");
        }

        public static void LogObjectValueNotSpecified()
        {
            AsyncR("<object> and <value> must be specified");
        }

        public static void LogValueInvalid()
        {
            AsyncR("<value> is invalid");
        }

        public static void LogObjectInvalid()
        {
            AsyncR("<object> is invalid");
        }

        public static void LogValueNotInt32()
        {
            AsyncR("<value> must be a whole number (Int32)");
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        private static void PrintLog(object message, bool disableLogging, params object[] values)
        {
            PrintLog(new LogInfo(message?.ToString()));
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        public static void Success(object message, params object[] values)
        {
            Success(message);
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        public static void Verbose(object message, params object[] values)
        {
            Out(message);
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        public static void Comment(object message, params object[] values)
        {
            AsyncC(message);
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        public static void Info(object message, params object[] values)
        {
            Info(message);
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        public static void Error(object message, params object[] values)
        {
            Error(message);
        }

        [Obsolete("Parameter 'values' is no longer supported. Format before logging.")]
        public static void Debug(object message, params object[] values)
        {
            Debug(message);
        }

        #endregion
    }

    /// <summary>
    ///     A Logging class implementing the Singleton pattern and an internal Queue to be flushed perdiodically
    /// </summary>
    public class LogWriter
    {
        private static LogWriter _instance;
        private static ConcurrentQueue<LogInfo> _logQueue;
        private static DateTime _lastFlushTime = DateTime.Now;
        private static StreamWriter _stream;

        /// <summary>
        ///     Private to prevent creation of other instances
        /// </summary>
        private LogWriter()
        {
        }

        /// <summary>
        ///     Exposes _instace and creates a new one if it is null
        /// </summary>
        internal static LogWriter Instance
        {
            get
            {
                if (_instance == null)
                {
                    _instance = new LogWriter();
                    // Field cannot be used by anything else regardless, do not surround with lock { }
                    // ReSharper disable once InconsistentlySynchronizedField
                    _logQueue = new ConcurrentQueue<LogInfo>();
                    Console.WriteLine(Constants.LogPath);

                    // If the ErrorLogs dir doesn't exist StreamWriter will throw an exception.
                    if (!Directory.Exists(Constants.LogDir))
                    {
                        Directory.CreateDirectory(Constants.LogDir);
                    }

                    _stream = new StreamWriter(Constants.LogPath, false);
                    Console.WriteLine("Created log instance");
                }
                return _instance;
            }
        }

        /// <summary>
        ///     Writes into the ConcurrentQueue the Message specified
        /// </summary>
        /// <param name="message">The message to write to the log</param>
        public void WriteToLog(string message)
        {
            lock (_logQueue)
            {
                var logEntry = new LogInfo(message);
                _logQueue.Enqueue(logEntry);

                if (_logQueue.Any())
                {
                    FlushLog();
                }
            }
        }

        /// <summary>
        ///     Writes into the ConcurrentQueue the Entry specified
        /// </summary>
        /// <param name="logEntry">The logEntry to write to the log</param>
        public void WriteToLog(LogInfo logEntry)
        {
            lock (_logQueue)
            {
                _logQueue.Enqueue(logEntry);

                if (_logQueue.Any())
                {
                    FlushLog();
                }
            }
        }

        /// <summary>
        ///     Flushes the ConcurrentQueue to the log file specified in Constants
        /// </summary>
        private void FlushLog()
        {
            lock (_stream)
            {
                LogInfo entry;
                while (_logQueue.TryDequeue(out entry))
                {
                    string m = $"[{entry.LogTime}] {entry.Message}";

                    Console.ForegroundColor = entry.Colour;
                    Console.WriteLine(m);
                    Console.ForegroundColor = ConsoleColor.Gray;

                    _stream.WriteLine(m);
                }
                _stream.Flush();
            }
        }
    }

    /// <summary>
    ///     A struct to store the message and the Date and Time the log entry was created
    /// </summary>
    public struct LogInfo
    {
        public string Message { get; set; }
        public string LogTime { get; set; }
        public string LogDate { get; set; }
        public ConsoleColor Colour { get; set; }

        public LogInfo(string message, ConsoleColor colour = ConsoleColor.Gray)
        {
            if (string.IsNullOrEmpty(message))
                message = "[null]";
            Message = message;
            LogDate = DateTime.Now.ToString("yyyy-MM-dd");
            LogTime = DateTime.Now.ToString("hh:mm:ss.fff tt");
            Colour = colour;
        }
    }
}