// © 2018 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
 * ******************************************************************************
 * Copyright (C) 2007, International Business Machines Corporation and others.
 * All Rights Reserved.
 * ******************************************************************************
 */
package com.ibm.icu.dev.tool.tzu;

import java.awt.Component;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;
import java.util.Date;

import javax.swing.JOptionPane;

/**
 * A singleton object that handles output to the screen and to a log file. Get the current instance
 * of the logger with <code>getInstance</code> and use the output functions to output to the
 * screen, the log file, the status bar, and in dialog messages.
 */
public class Logger {

    /**
     * A default name to use for creating a log file.
     */
    public static final String DEFAULT_FILENAME = "icutzu.log";

    /**
     * The single instance of the logger.
     */
    private static Logger logger = null;

    /**
     * Normal mode.
     */
    public static final int NORMAL = 0;

    /**
     * Quiet mode.
     */
    public static final int QUIET = -1;

    /**
     * Verbose mode.
     */
    public static final int VERBOSE = 1;

    /**
     * Gets the instance of the logger, constructing a new one with <code>filename</code> and
     * <code>verbosity</code> if one is not already constructed.
     * 
     * @param logFile
     *            The file to use for logging output.
     * @param verbosity
     *            The verbosity for output to the screen. Should be one of the following:
     *            <ul>
     *            <li>QUIET</li>
     *            <li>NORMAL</li>
     *            <li>VERBOSE</li>
     *            </ul>
     * @return The instance of the logger.
     * @throws FileNotFoundException
     */
    public static synchronized Logger getInstance(File logFile, int verbosity)
            throws FileNotFoundException {
        if (logger == null) {
            logger = new Logger(logFile, verbosity, null, null);
        }
        return logger;
    }

    /**
     * Gets the instance of the logger, constructing a new one with <code>filename</code> and
     * <code>verbosity</code> if one is not already constructed. If a statusbar is given, status
     * messages will be sent to it. If a dialogParent is specified, dialog messages will be
     * displayed.
     * 
     * @param logFile
     *            The file to use for logging output.
     * @param verbosity
     *            The verbosity for output to the screen. Should be one of the following:
     *            <ul>
     *            <li>QUIET</li>
     *            <li>NORMAL</li>
     *            <li>VERBOSE</li>
     *            </ul>
     * @param statusBar
     *            The status bar for status-bar messages, or null if none is present.
     * @param dialogParent
     *            The parent for dialog messages, or null if no dialog messages are wanted.
     * @return The instance of the logger.
     * @throws FileNotFoundException
     */
    public static synchronized Logger getInstance(File logFile, int verbosity,
            ResultComponent statusComponent, Component dialogParent) throws FileNotFoundException {
        if (logger == null) {
            logger = new Logger(logFile, verbosity, statusComponent, dialogParent);
        }
        return logger;
    }

    /**
     * The parent to use when displaying a dialog.
     */
    private Component dialogParent = null;

    /**
     * The means of output to the log file.
     */
    private PrintStream fileStream = null;

    /**
     * The status bar to display status messages.
     */
    private ResultComponent statusComponent = null;

    /**
     * The verbosity of the logger.
     */
    private int verbosity = NORMAL;

    /**
     * Constructs a logger that outputs to the filename specified and outputs to the screen with the
     * specified verbosity. Used internally.
     * 
     * @param filename
     *            The filename to use for logging output.
     * @param verbosity
     *            The verbosity for output to the screen.
     * @param statusBar
     *            The status bar for status-bar messages, or null if none is present.
     * @param dialogParent
     *            The parent for dialog messages, or null if no dialog messages are wanted.
     * @throws FileNotFoundException
     */
    private Logger(File logFile, int verbosity, ResultComponent statusComponent,
            Component dialogParent) throws FileNotFoundException {
        if (this.fileStream != null)
            this.fileStream.close();
        this.fileStream = new PrintStream(new FileOutputStream(logFile.toString(), true));
        this.verbosity = verbosity;
        this.statusComponent = statusComponent;
        this.dialogParent = dialogParent;

        this.fileStream.println();
        this.fileStream.println("##### " + new Date() + " #####");
        this.fileStream.println();
    }

    /**
     * Prints an error message to the screen and to the log.
     * 
     * @param message
     *            The message to print.
     */
    public void error(String message) {
        if (statusComponent != null)
            statusComponent.addStatusMessage(message);
        System.err.print(message);
        if (fileStream != null)
            fileStream.print(message);
    }

    /**
     * Prints an error message to the screen and to the log, and terminates the line.
     * 
     * @param message
     *            The message to print.
     */
    public void errorln(String message) {
        if (statusComponent != null)
            statusComponent.addStatusMessage(message);
        System.err.println(message);
        if (fileStream != null)
            fileStream.println(message);
    }

    /**
     * Returns the current allowed verbosity.
     * 
     * @return The current allowed verbosity for output to the screen. Should be one of the
     *         following:
     *         <ul>
     *         <li>QUIET</li>
     *         <li>NORMAL</li>
     *         <li>VERBOSE</li>
     *         </ul>
     */
    public int getVerbosity() {
        return verbosity;
    }

    /**
     * Sets the allowed verbosity.
     * 
     * @param verbosity
     *            The desired allowed verbosity for output to the screen. Should be one of the
     *            following:
     *            <ul>
     *            <li>QUIET</li>
     *            <li>NORMAL</li>
     *            <li>VERBOSE</li>
     *            </ul>
     */
    public void setVerbosity(int verbosity) {
        this.verbosity = verbosity;
    }

    /**
     * Logs a message to the screen if the logger is in a mode higher than normal mode (ie.
     * VERBOSE), and always logs the message to the file.
     * 
     * @param message
     *            The message to print.
     */
    public void loglnToBoth(String message) {
        loglnToScreen(message);
        loglnToFile(message);
    }

    /**
     * Logs a message to the file used by this logger, and terminates the line.
     * 
     * @param message
     *            The message to print.
     */
    public void loglnToFile(String message) {
        if (fileStream != null)
            fileStream.println(message);
    }

    /**
     * Logs a message to the screen if the logger is in a mode higher than normal mode (ie.
     * VERBOSE), and terminates the line.
     * 
     * @param message
     *            The message to print.
     */
    public void loglnToScreen(String message) {
        if (verbosity > NORMAL) {
            if (statusComponent != null)
                statusComponent.addStatusMessage(message);
            System.out.println(message);
        }
    }

    /**
     * Prints a message to the screen and to the log.
     * 
     * @param message
     *            The message to print.
     */
    public void logStackTraceToBoth(Exception ex) {
        logStackTraceToScreen(ex);
        logStackTraceToFile(ex);
    }

    /**
     * Logs the stack trace to the file.
     * 
     * @param ex
     *            The exception
     */
    public void logStackTraceToFile(Exception ex) {
        if (fileStream != null)
            ex.printStackTrace(fileStream);
    }

    /**
     * Logs the stack trace to the file.
     * 
     * @param ex
     *            The exception
     */
    public void logStackTraceToScreen(Exception ex) {
        if (verbosity > NORMAL)
            ex.printStackTrace(System.out);
    }

    /**
     * Prints a message to the screen and to the log, and terminates the line.
     * 
     * @param message
     *            The message to print.
     */
    public void printlnToBoth(String message) {
        printlnToScreen(message);
        loglnToFile(message);
    }

    /**
     * Prints a message to the screen, and terminates the line.
     * 
     * @param message
     *            The message to print.
     */
    public void printlnToScreen(String message) {
        if (verbosity >= NORMAL) {
            if (statusComponent != null)
                statusComponent.addStatusMessage(message);
            System.out.println(message);
        }
    }

    /**
     * If dialogParent is not null, brings up an informative dialog about something the user should
     * be aware of.
     * 
     * @param message
     *            The message to the user.
     */
    public void showInformationDialog(String message) {
        if (dialogParent != null)
            JOptionPane.showMessageDialog(dialogParent, message, "INFORMATION MESSAGE",
                    JOptionPane.INFORMATION_MESSAGE);
    }
}