/**
 * @file logger.h
 * Header for Base class for 'loggers' that write text messages to log files
 * (see \ref textlogs and class \link Cantera::Logger Logger\endlink).
 */
#ifndef CT_LOGGER_H
#define CT_LOGGER_H

#include <iostream>

#include <cstdlib>

namespace Cantera {

    ///
    /// Base class for 'loggers' that write text messages to log files.
    ///
    /// This class is used to direct log messages to application- or
    /// environment-specific output. The default is to simply print
    /// the messages to the standard output stream or standard error
    /// stream, but classes may be derived from Logger that implement
    /// other output options. This is important when Cantera is used
    /// in applications that do not display the standard output, such
    /// as MATLAB.  The Cantera MATLAB interface derives a class from
    /// Logger that implements these methods with MATLAB-specific
    /// procedures, insuring that the messages will be passed through
    /// to the user. It would also be possible to derive a class that
    /// displayed the messages in a pop-up window, or redirected them
    /// to a file, etc.
    ///  
    /// To install a logger, call function setLogger (global.h / misc.cpp).
    ///
    /// See the files Cantera/python/src/pylogger.h and
    /// Cantera/matlab/cantera/private/mllogger.h for examples of
    /// deriving logger classes.
    /// @ingroup textlogs
    ///
    class Logger {
    public:

      //! Constructor - empty
      Logger() {}

      //! Destructor - empty
      virtual ~Logger() {}

      //! Write a log message.
      /*!
       *  The default behavior is to write to
       *  the standard output. Note that no end-of-line character is
       *  appended to the message, and so if one is desired it must
       *  be included in the string.
       *
       * @param msg      String message to be written to cout
       */
      virtual void write(const std::string& msg) {
	std::cout << msg;
      }

      //! Write an end of line character and flush output.
      /*!
       *  Some systems treat endl and \n differently. The endl
       *  statement causes a flushing of stdout to the screen.
       */
      virtual void writeendl() {
        std::cout << std::endl;
      }

      //! Write an error message and quit. 
      /*! 
       *  The default behavior is
       *  to write to the standard eror stream, and then call
       *  exit(). Note that no end-of-line character is appended to
       *  the message, and so if one is desired it must be included
       *  in the string. Note that this default behavior will
       *  terminate the application Cantera is invoked from (MATLAB,
       *  Excel, etc.) If this is not desired, then derive a class
       *  and reimplement this method.
       *
       * @param msg    Error message to be written to cerr.
       */
      virtual void error(const std::string& msg) {
	std::cerr << msg << std::endl;
        exit(EXIT_FAILURE);
      }

      /// Return an integer specifying the application environment.
      virtual int env() { return 0; }
    };

}
#endif