using Swan.Logging;
using System;

namespace Swan.Lite.Logging {
  /// <summary>
  /// Use this class for text-based logger.
  /// </summary>
  public abstract class TextLogger {
    /// <summary>
    /// Gets or sets the logging time format.
    /// set to null or empty to prevent output.
    /// </summary>
    /// <value>
    /// The logging time format.
    /// </value>
    public static String LoggingTimeFormat { get; set; } = "HH:mm:ss.fff";

    /// <summary>
    /// Gets the color of the output of the message (the output message has a new line char in the end).
    /// </summary>
    /// <param name="logEvent">The <see cref="LogMessageReceivedEventArgs" /> instance containing the event data.</param>
    /// <returns>
    /// The output message formatted and the color of the console to be used.
    /// </returns>
    protected (String outputMessage, ConsoleColor color) GetOutputAndColor(LogMessageReceivedEventArgs logEvent) {
      (String prefix, ConsoleColor color) = GetConsoleColorAndPrefix(logEvent.MessageType);

      String loggerMessage = String.IsNullOrWhiteSpace(logEvent.Message) ? String.Empty : logEvent.Message.RemoveControlCharsExcept('\n');

      String outputMessage = CreateOutputMessage(logEvent.Source, loggerMessage, prefix, logEvent.UtcDate);

      // Further format the output in the case there is an exception being logged
      if(logEvent.MessageType == LogLevel.Error && logEvent.Exception != null) {
        try {
          outputMessage += $"{logEvent.Exception.Stringify().Indent()}{Environment.NewLine}";
        } catch {
          // Ignore  
        }
      }

      return (outputMessage, color);
    }

    private static (String Prefix, ConsoleColor color) GetConsoleColorAndPrefix(LogLevel messageType) => messageType switch
    {
      LogLevel.Debug => (ConsoleLogger.DebugPrefix, ConsoleLogger.DebugColor),
      LogLevel.Error => (ConsoleLogger.ErrorPrefix, ConsoleLogger.ErrorColor),
      LogLevel.Info => (ConsoleLogger.InfoPrefix, ConsoleLogger.InfoColor),
      LogLevel.Trace => (ConsoleLogger.TracePrefix, ConsoleLogger.TraceColor),
      LogLevel.Warning => (ConsoleLogger.WarnPrefix, ConsoleLogger.WarnColor),
      LogLevel.Fatal => (ConsoleLogger.FatalPrefix, ConsoleLogger.FatalColor),
      _ => (new String(' ', ConsoleLogger.InfoPrefix.Length), Terminal.Settings.DefaultColor),
    };

    private static String CreateOutputMessage(String sourceName, String loggerMessage, String prefix, DateTime date) {
      String friendlySourceName = String.IsNullOrWhiteSpace(sourceName) ? String.Empty : sourceName.SliceLength(sourceName.LastIndexOf('.') + 1, sourceName.Length);

      String outputMessage = String.IsNullOrWhiteSpace(sourceName) ? loggerMessage : $"[{friendlySourceName}] {loggerMessage}";

      return String.IsNullOrWhiteSpace(LoggingTimeFormat) ? $" {prefix} >> {outputMessage}{Environment.NewLine}" : $" {date.ToLocalTime().ToString(LoggingTimeFormat)} {prefix} >> {outputMessage}{Environment.NewLine}";
    }
  }
}