using System;
using System.Text;
using System.Diagnostics;

//NOTE: *** methods without 'Safe' postfix ARE NOT thread safe, 
//      use them only from the Unity main thread ***
public static class Log 
{
  public static int frame_count = 0;
  public static int tick_count = 0;

  public static string CLIENT_VERSION = "1";
  public static string CLIENT_ERR_URL = "";

  public static System.Func<string, string> PreprocessRemoteLog;

  static StringBuilder history = new StringBuilder();

  public static System.Action<string> on_info = null;
  public static System.Action<string> on_debug = null;
  public static System.Action<string> on_error = null;
  public static System.Action<string> on_warn = null;
  public static System.Action<string> on_fatal = null;
  
#if UNITY_EDITOR
  static int main_thread_id;
#endif

  static StringBuilder MakeMsg(object message)
  {                        
    var now = DateTime.Now;
    StringBuilder sb = new StringBuilder(64);
    sb.Append(now.Hour);
    sb.Append(":");
    sb.Append(now.Minute);
    sb.Append(":");
    sb.Append(now.Second);
    sb.Append(".");
    sb.Append(now.Millisecond);
    sb.Append(" ");
    sb.Append(frame_count);
    sb.Append("(");
    sb.Append(tick_count);
    sb.Append(") ");
    sb.Append(message?.ToString());
    sb.Append("\n");
    return sb;
  }

  static string MakeMsgAndAddToHistory(object message)
  {
    var txt = MakeMsg(message); 
    
#if UNITY_EDITOR
    CheckThreadId(message);
#endif
    
    history.Append(txt);
    return txt.ToString();
  }
  
#if UNITY_EDITOR
  static void CheckThreadId(object message)
  {
    int current_id = System.Threading.Thread.CurrentThread.ManagedThreadId;
    if(main_thread_id != 0 && current_id != main_thread_id)
    {
      UnityEngine.Debug.LogError($"Unsafe log method called from a background thread - use log method with *Safe suffix here. Message: '{message}'");
      return;
    }

    main_thread_id = current_id;
  }
#endif

  public static string GetHistory()
  {
    return history.ToString();
  }

  public static void Info(object message)
  {
    var res = MakeMsgAndAddToHistory(message);
    UnityEngine.Debug.Log(res);

    if(on_info != null)
      on_info(res);
  }

  //NOTE: thread safe
  public static void InfoSafe(object message)
  {
    var res = MakeMsg(message).ToString();
    UnityEngine.Debug.Log(res);
  }

#if STRIP_LOGS
  [Conditional("COND_STRIP_LOGS")]
  public static void Debug(object message) {}
#else
  public static void Debug(object message)
  {
    var res = MakeMsgAndAddToHistory(message);
    UnityEngine.Debug.Log(res);

    if(on_debug != null)
      on_debug(res);
  }
#endif

#if STRIP_LOGS
  [Conditional("COND_STRIP_LOGS")]
  public static void DebugSafe(object message) {}
#else
  //NOTE: thread safe
  public static void DebugSafe(object message)
  {
    var res = MakeMsg(message).ToString();
    UnityEngine.Debug.Log(res);
  }
#endif

  public static void Error(object message)
  {
    var res = MakeMsgAndAddToHistory(message);
    UnityEngine.Debug.LogError(res);

    on_error?.Invoke(res);
  }

  //NOTE: thread safe
  public static void ErrorSafe(object message)
  {
    var res = MakeMsg(message).ToString(); 
    UnityEngine.Debug.LogError(res);
  }
  
#if STRIP_LOGS
  [Conditional("COND_STRIP_LOGS")]
  public static void Warn(object message) {}
#else
  public static void Warn(object message)
  {
    var res = MakeMsgAndAddToHistory(message);
    UnityEngine.Debug.LogWarning(res);

    if(on_warn != null)
      on_warn(res);
  }
#endif

#if STRIP_LOGS
  [Conditional("COND_STRIP_LOGS")]
  public static void WarnSafe(object message) {}
#else
  //NOTE: thread safe
  public static void WarnSafe(object message)
  {
    var res = MakeMsg(message).ToString();
    UnityEngine.Debug.LogWarning(res);
  }
#endif
}