package org.gametrack.util;

import java.io.PrintStream;

/**
 * <p>Title: Log class</p>
 * <p>Description: A nice throw-in Log class, with logging functions including std and err stream rerouting</p>
 * <p>Copyright: Copyright (c) 2002</p>
 * @author Brian Cairns
 * @version 0.1
 */

// logging functions
public class Log
{
  public static final PrintStream SYS_OUT = System.out;
  public static PrintStream SYS_ERR = System.err;

  static int DEBUG_TAB = 3;  // how many spaces to indent per priority level of message

  static char NORMAL_DELIM = ':';  // programmatically called Log output will have this
  static char REDIR_DELIM = '>';   // redirected out and err streams will have this

  static String ERROR_PREFIX = "[ERROR]";
  static String DEBUG_PREFIX = "[DEBUG]";

  /**
   * Determines what debug output to display.
   * 0 = none at all
   * -1 = ALL debug output
   * any other # = the highest level that will be outputted
   */
  public static int debugLevel = -1;

  /**
   * Logs the message to standard output.  Use this method to log stuff that
   * the application should ALWAYS log, no matter what.
   * @param message the message
   */
  public static void log( String message )
  {
    SYS_OUT.println( Formatting.timestamp() + NORMAL_DELIM + " " + message );
  }

  /**
   * Logs with print() instead of println(), allowing continuation of the line,
   * usually with logDirect()
   * @param message
   */
  public static void logCont( String message )
  {
    SYS_OUT.print( Formatting.timestamp() + NORMAL_DELIM + " " + message );
  }

  /**
   * Write directly to system out
   * @param output
   */
  public static void direct( String output )
  {
    SYS_OUT.print( output );
  }

  /**
   * Writes the message to standard error.  Use this message to log any error
   * conditions.
   * @param message
   */
  public static void err( String message )
  {
    err( NORMAL_DELIM, message );
  }

  /**
   * Conditionally logs the message to standard output.  Use this method for
   * debugging statements you want to be able to turn on and off.
   * @param message the message to display
   * @param priority the priority of this debug statement (priority 1 is highest)
   */
  public static void debug( int priority, String message )
  {
    debug( NORMAL_DELIM, priority, message );
  }

  /**
   * Convenience function.. debug at level 1 (highest priority)
   * Use this for quick and dirty debug output... add a priority number if
   * you're leaving the statement in though!
   * @param message the message
   */
  public static void debug( String message )
  {
    debug( 1, message );
  }

  /**
   * Set the debug level for the log (the higher the number, the more output)
   * @param level the debug level
   */
  public static void setDebugLevel( int level )
  {
    debugLevel = level;
  }

  /**
   * Instruct Log class to intercept System.out.println and treat as a debug statement
   */
  public static void interceptSystemOut()
  {
    System.setOut( new LoggingPrintStream( false ) );
  }

  /**
   * Instruct Log class to intercept System.err.println and treat as an err statement
   */
  public static void interceptSystemErr()
  {
    System.setErr( new LoggingPrintStream( true ) );
  }

  /**
   * Mix err in with standard output
   */
  public static void mixErr()
  {
    SYS_ERR = SYS_OUT;
  }

  // private /////////////////////////////////////////////////////////////////

  private static void err( char delim, String message )
  {
    SYS_ERR.println( Formatting.timestamp() + delim + " " + ERROR_PREFIX + " " + message );
  }

  private static void debug( char delim, int priority, String message )
  {
    if ( debugLevel == -1 || priority <= debugLevel )
    {
      SYS_OUT.println( Formatting.timestamp() + delim + " " + Formatting.repeat( " ", priority * DEBUG_TAB ) + DEBUG_PREFIX + " " +
                       message );
    }
  }

  // inner class /////////////////////////////////////////////////////////////

  private static class LoggingPrintStream
      extends PrintStream
  {
    boolean bError;

    public LoggingPrintStream( boolean error )
    {
      super( error ? System.err : System.out, true );
      bError = error;
    }

    public void println( String s )
    {
      if ( bError )
      {
        err( REDIR_DELIM, s );
      }
      else
      {
        debug( REDIR_DELIM, 0, s );
      }
    }
  }
}