using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
using System.Windows.Forms;
using DTS.Common.Utilities.Properties;

// ReSharper disable once CheckNamespace
namespace DTS.Common.Utilities.Logging
{
    /// <summary>
    /// this class encapsulating writing to the log
    /// 
    /// </summary>
    public static class APILogger
    {
        private static readonly object ProcessLock = new object();
        private static readonly Dictionary<string, Stack<Stopwatch>> _processes = new Dictionary<string, Stack<Stopwatch>>();

        public static void StartProcess(string name)
        {
            lock (ProcessLock)
            {
                if (!_processes.ContainsKey(name)) { _processes[name] = new Stack<Stopwatch>(); }
                var sw = new Stopwatch();
                sw.Start();
                _processes[name].Push(sw);
                Log($"Starting process: [{name}] ({_processes[name].Count})");
            }
        }

        public static void StopProcess(string name)
        {
            lock (ProcessLock)
            {
                if (!_processes.ContainsKey(name) || 0 == _processes[name].Count)
                {
                    Log($"Stopping process: [{name}] (0)");
                    return;
                }
                var sw = _processes[name].Pop();
                sw.Stop();
                var ts = new TimeSpan(sw.ElapsedTicks);
                Log($"Stopping process: [{name}], {TimespanToHumanReadable(ts)}");
            }
        }
        private static string TimespanToHumanReadable(TimeSpan ts)
        {
            var sb = new StringBuilder();
            if (ts.TotalDays > 1)
            {
                sb.Append($"{System.Math.Floor(ts.TotalDays):0} days, ");
            }
            sb.Append($"{ts.Hours:00}:{ts.Minutes:00}:{ts.Seconds}.{ts.Milliseconds:000}");
            return sb.ToString();
        }
        /// <summary>
        /// describes an event that should be raised when there's an error that needs to be handled by an application
        /// </summary>
        public delegate void ErrorRaisedEventDelegate(string msg);

        private static ErrorRaisedEventDelegate _OnErrorRaised;
        /// <summary>
		/// Error handler called when errors are raised
		/// </summary>
        public static ErrorRaisedEventDelegate OnErrorRaised
        {
            get => _OnErrorRaised;
            set => _OnErrorRaised = value;
        }

        /// <summary>
        /// raises an error, if an error handler is set, calls error handler
        /// </summary>
        public static void RaiseError(string error)
        {
            OnErrorRaised?.Invoke(error);
        }
        [MethodImpl(MethodImplOptions.NoInlining)]
        public static string GetCurrentMethod()
        {
            var st = new StackTrace();
            var sf = st.GetFrame(1);

            return sf.GetMethod().Name;
        }

        private static bool _bDoPerformanceLog;
        public static void SetDoPerformanceLog(bool bDoLog)
        {
            _bDoPerformanceLog = bDoLog;
        }
        private static readonly object MyLock = new object();
        public static void DoPerformanceLog(string msg)
        {
            if (!_bDoPerformanceLog) { return; }
            var dt = DateTime.Now;
            var s = string.Format("{0:0000}-{1:00}-{2:00} {3:00}:{4:00}:{5:00}.{6:0000} ***{7}\r\n", dt.Year, dt.Month, dt.Day, dt.Hour, dt.Minute, dt.Second, dt.Millisecond, msg);
            lock (MyLock)
            {
                try
                {
                    File.AppendAllText("PERFLOG.LOG", s);
                }
                catch (Exception)
                {
                    // ignored - performance logging is only for statistics, we fail then we fail, just keep going
                }
            }
        }
        /// <summary>
        /// a function capable of logging a message
        /// </summary>
        /// <param name="msg">message to log</param>
        public delegate void Sink(string msg);

        /// <summary>
        /// a consumer of log messages
        /// </summary>
        public static Sink Writer;

        public static Sink ConfigurationLogWriter;
        public static Sink ConfigReadErrorLogWriter;

        public static Sink StateWriter;

        private static string LogException(Exception ex, bool bPrepend, bool bNewLine)
        {
            if (Writer == null)
            {
                return "";
            }
            try
            {
                if (ex == null)
                {
                    Writer("LogException: called with null exception");
                }
                else
                {
                    var sb = new StringBuilder();
                    if (bPrepend) { sb.Append(string.Concat(DateTime.Now.ToString(Resources.APILogging_DateTime_Format), " ")); }
                    ExceptionFormater(ref sb, ex, 0);
                    sb = sb.Replace(Environment.NewLine, " ");
                    if (bNewLine) { sb.AppendLine(); }
                    return sb.ToString();
                }
            }
            catch (Exception ownEx)
            {
                // and to be really paranoid...
                string orgMsg;
                if (ex == null)
                {
                    orgMsg = "null exception";
                }
                else if (string.IsNullOrEmpty(ex.Message))
                {
                    orgMsg = "blank exception message";
                }
                else
                {
                    orgMsg = ex.Message;
                }
                try
                {
                    Writer("APILogger: LogException threw an expection: " + ownEx.Message + " when handling: " + orgMsg);
                }
                catch (Exception)
                {
                }
            }
            return "";
        }
        /// <summary>
        /// log an exception
        /// </summary>
        /// <param name="ex">exception to be logged</param>
        public static void LogException(Exception ex)
        {
            Writer(LogException(ex, true, true));
        }
        public const string EXCEPTIONSTART_STRING = "!!  ";
        private static void ExceptionFormater(ref StringBuilder sb, Exception ex, int level)
        {
            while (true)
            {
                if (ex == null)
                    return;
                var front = new string(' ', level);
                sb.Append(EXCEPTIONSTART_STRING);
                sb.AppendFormat(Resources.APILogging_ExceptionFormatter_ExceptionOfTypeOccurredString, front, level > 0 ? Resources.APILogging_ExceptionFormatter_InnerIndicationString : Resources.APILogging_ExceptionFormatter_NonInnerIndicationString, ex.GetType());
                if (null != ex.TargetSite)
                {
                    sb.AppendFormat(Resources.APILogging_ModuleNameDisplayString, front, NullGuard(ex.TargetSite.Module.Name), NullGuard(ex.TargetSite.Name));
                }
                sb.AppendFormat(Resources.APILogging_ExceptionMessageDisplayString, front, NullGuard(ex.Message));
                if (!string.IsNullOrEmpty(ex.StackTrace))
                {
                    // RW: It appears .NET 4.5 has a subtle difference in stack formatting.  I don't see it, but it's breaking the Regex.
                    // I'm not sure why it's using regex in the first place.  This should work for both, but has not been tested with .NET 2.0
                    string[] delimeters = { Environment.NewLine };
                    var lines = ex.StackTrace.Split(delimeters, 2, StringSplitOptions.None);
                    if (lines.Length > 0)
                    {
                        sb.AppendFormat(Resources.APILogging_StackTraceDisplayString, front, NullGuard(lines[0]));
                        if (lines.Length > 1)
                        {
                            sb.AppendFormat(Resources.APILogging_StackTraceDisplayString, front, NullGuard(lines[1]));
                        }
                    }
                }
                // now call ourself with inner
                ex = ex.InnerException;
                level = level + 1;
            }
        }

        private static string NullGuard(string s)
        {
            return s ?? Resources.Generic_NullIndicatorString;
        }

        private static readonly string DATE_FORMAT = Resources.APILogging_DateTime_Format;
        private static string LogString(string str, bool bPrepend, bool bNewLine, bool bReplaceNewLines = true)
        {
            if (Writer == null)
                throw new Exception(Resources.APILogging_NullWriterDelegateString);
            var sb = new StringBuilder();
            if (bPrepend) { sb.Append($"{DateTime.Now.ToString(DATE_FORMAT)} "); }

            if (bReplaceNewLines)
            {
                sb.Append(str.Replace(Environment.NewLine, " "));
            }
            else
            {
                sb.Append(str);
            }

            if (bNewLine) { sb.AppendLine(); }
            return sb.ToString();
        }
        /// <summary>
        /// logs a string
        /// </summary>
        /// <param name="str">string to be logged</param>
        public static void LogString(string str)
        {
            Writer?.Invoke(LogString(str, true, true));
        }
        private static readonly object PhaseShiftLogLock = new object();
        /// <summary>
        /// logs a phase shift into a table
        /// </summary>
        /// <param name="serial"></param>
        /// <param name="msPhaseShift">MICROSECONDS of shift</param>
        /// <param name="originalT0"></param>
        /// <param name="modifiedTo"></param>
        /// <param name="samples"></param>
        /// <param name="rule"></param>
        public static void LogPhaseShift(string serial, double msPhaseShift, ulong originalT0, ulong modifiedTo, ulong samples, string rule)
        {
            try
            {
                var now = DateTime.Now;
                var s = string.Format("{0:0000}-{1:00}-{2:00} {3:00}:{4:00}:{5:00}.{6:0000}\t{7}\t{8}\t{9}\t{10}\t{11}\t{12}\r\n",
                    now.Year,
                    now.Month,
                    now.Day,
                    now.Hour,
                    now.Minute,
                    now.Second,
                    now.Millisecond,
                    serial,
                    samples,
                    msPhaseShift,
                    originalT0,
                    modifiedTo,
                    rule
                    );
                lock (PhaseShiftLogLock)
                {

                    File.WriteAllLines("PHASE_SHIFT_LOG.txt", new[] { s });
                }
            }
            catch (Exception ex) { Log(ex); }
        }

        public static void StateLog(params object[] paramlist)
        {
            try
            {
                var sb = new StringBuilder();
                for (var i = 0; i < paramlist.Length; i++)
                {
                    if (i > 0) { sb.Append(" "); }
                    var s = paramlist[i] as string;
                    if (paramlist[i] is DialogResult) { s = string.Format(" User selected {0}", ((DialogResult)paramlist[i])); }
                    var ex = paramlist[i] as Exception;

                    if (null == s && null == ex && null != paramlist[i]) { s = paramlist[i].ToString(); }

                    var bPrepend = 0 == i;
                    var bNewLine = paramlist.Length == i + 1;
                    if (null != ex) { sb.Append(LogException(ex, bPrepend, bNewLine)); }
                    else if (null != s) { sb.Append(LogString(s, bPrepend, bNewLine, false)); }
                }
                var msg = sb.ToString();
                StateWriter(msg);
            }
            catch (Exception ex)
            {
                //if we fail to log there's not much more we can do ...
                Trace.WriteLine(ex);
            }
        }

        /// <summary>
        /// logs multiple parameters
        /// </summary>
        /// <param name="paramlist">
        /// collection of parameters, can be exceptions, strings, or an object with tostring
        /// </param>
        public static void Log(params object[] paramlist)
        {
            try
            {
                var sb = new StringBuilder();
                for (var i = 0; i < paramlist.Length; i++)
                {
                    var obj = paramlist[i];
                    if (i > 0) { sb.Append(" "); }
                    var s = obj as string;
                    if (obj is DialogResult) { s = $" User selected {(DialogResult)obj}"; }

                    if (obj is byte[])
                    {
                        s = BitConverter.ToString((byte[])obj).Replace("-", "");
                    }

                    var ex = obj as Exception;
                    if (null == s && null == ex && null != obj) { s = obj.ToString(); }

                    var bPrepend = 0 == i;
                    var bNewLine = paramlist.Length == i + 1;
                    if (null != ex) { sb.Append(LogException(ex, bPrepend, bNewLine)); }
                    else if (null != s) { sb.Append(LogString(s, bPrepend, bNewLine)); }
                }
                var msg = sb.ToString();
                //KeywordAlert.Instance.ProcessMsg(msg);
                Writer(msg);
            }
            catch (Exception ex)
            {
                //if we fail to log there's not much more we can do ...
                Trace.WriteLine(ex);
            }
        }
        /// <summary>
        /// logs multiple parameters
        /// </summary>
        /// <param name="paramlist">
        /// collection of parameters, can be exceptions, strings, or an object with tostring
        /// </param>
        public static void ConfLog(params object[] paramlist)
        {
            try
            {
                var sb = new StringBuilder();
                for (var i = 0; i < paramlist.Length; i++)
                {
                    if (i > 0)
                    {
                        sb.Append(" ");
                    }
                    var s = paramlist[i] as string;
                    if (paramlist[i] is DialogResult)
                    {
                        s = $" User selected {(DialogResult)paramlist[i]}";
                    }
                    var ex = paramlist[i] as Exception;

                    if (null == s && null == ex && null != paramlist[i])
                    {
                        s = paramlist[i].ToString();
                    }

                    var bPrepend = 0 == i;
                    var bNewLine = paramlist.Length == i + 1;
                    if (null != ex)
                    {
                        sb.Append(LogException(ex, bPrepend, bNewLine));
                    }
                    else if (null != s)
                    {
                        sb.Append(LogString(s, bPrepend, bNewLine));
                    }
                }
                var msg = sb.ToString();
                ConfigurationLogWriter(msg);
            }
            catch (Exception ex)
            {
                //as with the other log function, if we fail we don't have much backing we can do
                Trace.WriteLine(ex);
            }
        }
    }
}