//
//  ========================================================================
//  Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util.log;

import java.io.PrintStream;
import java.security.AccessControlException;
import java.util.Properties;

import org.eclipse.jetty.util.DateCache;
import org.eclipse.jetty.util.annotation.ManagedAttribute;
import org.eclipse.jetty.util.annotation.ManagedObject;

/**
 * StdErr Logging implementation. 
 * <p>
 * A Jetty {@link Logger} that sends all logs to STDERR ({@link System#err}) with basic formatting.
 * <p>
 * Supports named loggers, and properties based configuration. 
 * <p>
 * Configuration Properties:
 * <dl>
 *   <dt>${name|hierarchy}.LEVEL=(ALL|DEBUG|INFO|WARN|OFF)</dt>
 *   <dd>
 *   Sets the level that the Logger should log at.<br/>
 *   Names can be a package name, or a fully qualified class name.<br/>
 *   Default: INFO<br/>
 *   <br/>
 *   Examples:
 *   <dl>
 *   <dt>org.eclipse.jetty.LEVEL=WARN</dt>
 *   <dd>indicates that all of the jetty specific classes, in any package that 
 *   starts with <code>org.eclipse.jetty</code> should log at level WARN.</dd>
 *   <dt>org.eclipse.jetty.io.ChannelEndPoint.LEVEL=ALL</dt>
 *   <dd>indicates that the specific class, ChannelEndPoint, should log all
 *   logging events that it can generate, including DEBUG, INFO, WARN (and even special
 *   internally ignored exception cases).</dd>
 *   </dl>  
 *   </dd>
 *   
 *   <dt>${name}.SOURCE=(true|false)</dt>
 *   <dd>
 *   Logger specific, attempt to print the java source file name and line number
 *   where the logging event originated from.<br/>
 *   Name must be a fully qualified class name (package name hierarchy is not supported
 *   by this configurable)<br/>
 *   Warning: this is a slow operation and will have an impact on performance!<br/>
 *   Default: false
 *   </dd>
 *   
 *   <dt>${name}.STACKS=(true|false)</dt>
 *   <dd>
 *   Logger specific, control the display of stacktraces.<br/>
 *   Name must be a fully qualified class name (package name hierarchy is not supported
 *   by this configurable)<br/>
 *   Default: true
 *   </dd>
 *   
 *   <dt>org.eclipse.jetty.util.log.stderr.SOURCE=(true|false)</dt>
 *   <dd>Special Global Configuration, attempt to print the java source file name and line number
 *   where the logging event originated from.<br/>
 *   Default: false
 *   </dd>
 *   
 *   <dt>org.eclipse.jetty.util.log.stderr.LONG=(true|false)</dt>
 *   <dd>Special Global Configuration, when true, output logging events to STDERR using
 *   long form, fully qualified class names.  when false, use abbreviated package names<br/>
 *   Default: false
 *   </dd>
 *   <dt>org.eclipse.jetty.util.log.stderr.ESCAPE=(true|false)</dt>
 *   <dd>Global Configuration, when true output logging events to STDERR are always
 *   escaped so that control characters are replaced with '?";  '\r' with '<' and '\n' replaced '|'<br/>
 *   Default: true
 *   </dd>
 * </dl>
 */
@ManagedObject("Jetty StdErr Logging Implementation")
public class StdErrLog extends AbstractLogger
{
    private static final String EOL = System.getProperty("line.separator");
    private static DateCache _dateCache;
    private static final Properties __props = new Properties();

    private final static boolean __source = Boolean.parseBoolean(Log.__props.getProperty("org.eclipse.jetty.util.log.SOURCE",
            Log.__props.getProperty("org.eclipse.jetty.util.log.stderr.SOURCE","false")));
    private final static boolean __long = Boolean.parseBoolean(Log.__props.getProperty("org.eclipse.jetty.util.log.stderr.LONG","false"));
    private final static boolean __escape = Boolean.parseBoolean(Log.__props.getProperty("org.eclipse.jetty.util.log.stderr.ESCAPE","true"));

    static
    {
        __props.putAll(Log.__props);

        String deprecatedProperties[] =
        { "DEBUG", "org.eclipse.jetty.util.log.DEBUG", "org.eclipse.jetty.util.log.stderr.DEBUG" };

        // Toss a message to users about deprecated system properties
        for (String deprecatedProp : deprecatedProperties)
        {
            if (System.getProperty(deprecatedProp) != null)
            {
                System.err.printf("System Property [%s] has been deprecated! (Use org.eclipse.jetty.LEVEL=DEBUG instead)%n",deprecatedProp);
            }
        }

        try
        {
            _dateCache = new DateCache("yyyy-MM-dd HH:mm:ss");
        }
        catch (Exception x)
        {
            x.printStackTrace(System.err);
        }
    }

    public static final int LEVEL_ALL = 0;
    public static final int LEVEL_DEBUG = 1;
    public static final int LEVEL_INFO = 2;
    public static final int LEVEL_WARN = 3;
    public static final int LEVEL_OFF = 10;

    private int _level = LEVEL_INFO;
    // Level that this Logger was configured as (remembered in special case of .setDebugEnabled())
    private int _configuredLevel;
    private PrintStream _stderr = null;
    private boolean _source = __source;
    // Print the long form names, otherwise use abbreviated
    private boolean _printLongNames = __long;
    // The full log name, as provided by the system.
    private final String _name;
    // The abbreviated log name (used by default, unless _long is specified)
    private final String _abbrevname;
    private boolean _hideStacks = false;

    /**
     * Obtain a StdErrLog reference for the specified class, a convenience method used most often during testing to allow for control over a specific logger.
     * <p>
     * Must be actively using StdErrLog as the Logger implementation.
     * 
     * @param clazz
     *            the Class reference for the logger to use.
     * @return the StdErrLog logger
     * @throws RuntimeException
     *             if StdErrLog is not the active Logger implementation.
     */
    public static StdErrLog getLogger(Class<?> clazz)
    {
        Logger log = Log.getLogger(clazz);
        if (log instanceof StdErrLog)
        {
            return (StdErrLog)log;
        }
        throw new RuntimeException("Logger for " + clazz + " is not of type StdErrLog");
    }

    /**
     * Construct an anonymous StdErrLog (no name).
     * <p>
     * NOTE: Discouraged usage!
     */
    public StdErrLog()
    {
        this(null);
    }

    /**
     * Construct a named StdErrLog using the {@link Log} defined properties
     * 
     * @param name
     *            the name of the logger
     */
    public StdErrLog(String name)
    {
        this(name,__props);
    }

    /**
     * Construct a named Logger using the provided properties to configure logger.
     * 
     * @param name
     *            the name of the logger
     * @param props
     *            the configuration properties
     */
    public StdErrLog(String name, Properties props)
    {
        if (props!=null && props!=__props)
            __props.putAll(props);
        this._name = name == null?"":name;
        this._abbrevname = condensePackageString(this._name);
        this._level = getLoggingLevel(props,this._name);
        this._configuredLevel = this._level;

        try
        {
            String source = getLoggingProperty(props,_name,"SOURCE");
            _source = source==null?__source:Boolean.parseBoolean(source);
        }
        catch (AccessControlException ace)
        {
            _source = __source;
        }

        try
        {
            // allow stacktrace display to be controlled by properties as well
            String stacks = getLoggingProperty(props,_name,"STACKS");
            _hideStacks = stacks==null?false:!Boolean.parseBoolean(stacks);
        }
        catch (AccessControlException ignore)
        {
            /* ignore */
        }        
    }

    /**
     * Get the Logging Level for the provided log name. Using the FQCN first, then each package segment from longest to
     * shortest.
     *
     * @param props
     *            the properties to check
     * @param name
     *            the name to get log for
     * @return the logging level
     */
    public static int getLoggingLevel(Properties props, final String name)
    {
        if ((props == null) || (props.isEmpty()))
        {
            // Default Logging Level
            return getLevelId("log.LEVEL","INFO");
        }
        
        // Calculate the level this named logger should operate under.
        // Checking with FQCN first, then each package segment from longest to shortest.
        String nameSegment = name;

        while ((nameSegment != null) && (nameSegment.length() > 0))
        {
            String levelStr = props.getProperty(nameSegment + ".LEVEL");
            // System.err.printf("[StdErrLog.CONFIG] Checking for property [%s.LEVEL] = %s%n",nameSegment,levelStr);
            int level = getLevelId(nameSegment + ".LEVEL",levelStr);
            if (level != (-1))
            {
                return level;
            }

            // Trim and try again.
            int idx = nameSegment.lastIndexOf('.');
            if (idx >= 0)
            {
                nameSegment = nameSegment.substring(0,idx);
            }
            else
            {
                nameSegment = null;
            }
        }

        // Default Logging Level
        return getLevelId("log.LEVEL",props.getProperty("log.LEVEL","INFO"));
    }
    
    public static String getLoggingProperty(Properties props, String name, String property)
    {
        // Calculate the level this named logger should operate under.
        // Checking with FQCN first, then each package segment from longest to shortest.
        String nameSegment = name;

        while ((nameSegment != null) && (nameSegment.length() > 0))
        {
            String s = props.getProperty(nameSegment+"."+property);
            if (s!=null)
                return s;

            // Trim and try again.
            int idx = nameSegment.lastIndexOf('.');
            nameSegment = (idx >= 0)?nameSegment.substring(0,idx):null;
        }

        return null;
    }

    protected static int getLevelId(String levelSegment, String levelName)
    {
        if (levelName == null)
        {
            return -1;
        }
        String levelStr = levelName.trim();
        if ("ALL".equalsIgnoreCase(levelStr))
        {
            return LEVEL_ALL;
        }
        else if ("DEBUG".equalsIgnoreCase(levelStr))
        {
            return LEVEL_DEBUG;
        }
        else if ("INFO".equalsIgnoreCase(levelStr))
        {
            return LEVEL_INFO;
        }
        else if ("WARN".equalsIgnoreCase(levelStr))
        {
            return LEVEL_WARN;
        }
        else if ("OFF".equalsIgnoreCase(levelStr))
        {
            return LEVEL_OFF;
        }

        System.err.println("Unknown StdErrLog level [" + levelSegment + "]=[" + levelStr + "], expecting only [ALL, DEBUG, INFO, WARN, OFF] as values.");
        return -1;
    }

    /**
     * Condenses a classname by stripping down the package name to just the first character of each package name
     * segment.Configured
     * <p>
     *
     * <pre>
     * Examples:
     * "org.eclipse.jetty.test.FooTest"           = "oejt.FooTest"
     * "org.eclipse.jetty.server.logging.LogTest" = "orjsl.LogTest"
     * </pre>
     *
     * @param classname
     *            the fully qualified class name
     * @return the condensed name
     */
    protected static String condensePackageString(String classname)
    {
        String parts[] = classname.split("\\.");
        StringBuilder dense = new StringBuilder();
        for (int i = 0; i < (parts.length - 1); i++)
        {
            dense.append(parts[i].charAt(0));
        }
        if (dense.length() > 0)
        {
            dense.append('.');
        }
        dense.append(parts[parts.length - 1]);
        return dense.toString();
    }

    public String getName()
    {
        return _name;
    }

    public void setPrintLongNames(boolean printLongNames)
    {
        this._printLongNames = printLongNames;
    }

    public boolean isPrintLongNames()
    {
        return this._printLongNames;
    }

    public boolean isHideStacks()
    {
        return _hideStacks;
    }

    public void setHideStacks(boolean hideStacks)
    {
        _hideStacks = hideStacks;
    }

    /* ------------------------------------------------------------ */
    /**
     * Is the source of a log, logged
     *
     * @return true if the class, method, file and line number of a log is logged.
     */
    public boolean isSource()
    {
        return _source;
    }

    /* ------------------------------------------------------------ */
    /**
     * Set if a log source is logged.
     *
     * @param source
     *            true if the class, method, file and line number of a log is logged.
     */
    public void setSource(boolean source)
    {
        _source = source;
    }

    public void warn(String msg, Object... args)
    {
        if (_level <= LEVEL_WARN)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":WARN:",msg,args);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }

    public void warn(Throwable thrown)
    {
        warn("",thrown);
    }

    public void warn(String msg, Throwable thrown)
    {
        if (_level <= LEVEL_WARN)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":WARN:",msg,thrown);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }

    public void info(String msg, Object... args)
    {
        if (_level <= LEVEL_INFO)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":INFO:",msg,args);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }

    public void info(Throwable thrown)
    {
        info("",thrown);
    }

    public void info(String msg, Throwable thrown)
    {
        if (_level <= LEVEL_INFO)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":INFO:",msg,thrown);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }

    @ManagedAttribute("is debug enabled for root logger Log.LOG")
    public boolean isDebugEnabled()
    {
        return (_level <= LEVEL_DEBUG);
    }

    /**
     * Legacy interface where a programmatic configuration of the logger level
     * is done as a wholesale approach.
     */
    @Override
    public void setDebugEnabled(boolean enabled)
    {
        if (enabled)
        {
            this._level = LEVEL_DEBUG;

            for (Logger log : Log.getLoggers().values())
            {                
                if (log.getName().startsWith(getName()) && log instanceof StdErrLog)
                    ((StdErrLog)log).setLevel(LEVEL_DEBUG);
            }
        }
        else
        {
            this._level = this._configuredLevel;

            for (Logger log : Log.getLoggers().values())
            {
                if (log.getName().startsWith(getName()) && log instanceof StdErrLog)
                    ((StdErrLog)log).setLevel(((StdErrLog)log)._configuredLevel);
            }
        }
    }

    public int getLevel()
    {
        return _level;
    }

    /**
     * Set the level for this logger.
     * <p>
     * Available values ({@link StdErrLog#LEVEL_ALL}, {@link StdErrLog#LEVEL_DEBUG}, {@link StdErrLog#LEVEL_INFO},
     * {@link StdErrLog#LEVEL_WARN})
     *
     * @param level
     *            the level to set the logger to
     */
    public void setLevel(int level)
    {
        this._level = level;
    }

    public void setStdErrStream(PrintStream stream)
    {
        this._stderr = stream==System.err?null:stream;
    }

    public void debug(String msg, Object... args)
    {
        if (_level <= LEVEL_DEBUG)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":DBUG:",msg,args);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }

    public void debug(String msg, long arg)
    {
        if (isDebugEnabled())
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":DBUG:",msg,arg);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }
    
    public void debug(Throwable thrown)
    {
        debug("",thrown);
    }

    public void debug(String msg, Throwable thrown)
    {
        if (_level <= LEVEL_DEBUG)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":DBUG:",msg,thrown);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }

    private void format(StringBuilder buffer, String level, String msg, Object... args)
    {
        long now = System.currentTimeMillis();
        int ms=(int)(now%1000);
        String d = _dateCache.formatNow(now);
        tag(buffer,d,ms,level);
        format(buffer,msg,args);
    }

    private void format(StringBuilder buffer, String level, String msg, Throwable thrown)
    {
        format(buffer,level,msg);
        if (isHideStacks())
        {
            format(buffer,": "+String.valueOf(thrown));
        }
        else
        {
            format(buffer,thrown);
        }
    }

    private void tag(StringBuilder buffer, String d, int ms, String tag)
    {
        buffer.setLength(0);
        buffer.append(d);
        if (ms > 99)
        {
            buffer.append('.');
        }
        else if (ms > 9)
        {
            buffer.append(".0");
        }
        else
        {
            buffer.append(".00");
        }
        buffer.append(ms).append(tag);
        if (_printLongNames)
        {
            buffer.append(_name);
        }
        else
        {
            buffer.append(_abbrevname);
        }
        buffer.append(':');
        buffer.append(Thread.currentThread().getName()).append(": ");
        if (_source)
        {
            Throwable source = new Throwable();
            StackTraceElement[] frames = source.getStackTrace();
            for (int i = 0; i < frames.length; i++)
            {
                final StackTraceElement frame = frames[i];
                String clazz = frame.getClassName();
                if (clazz.equals(StdErrLog.class.getName()) || clazz.equals(Log.class.getName()))
                {
                    continue;
                }
                if (!_printLongNames && clazz.startsWith("org.eclipse.jetty."))
                {
                    buffer.append(condensePackageString(clazz));
                }
                else
                {
                    buffer.append(clazz);
                }
                buffer.append('#').append(frame.getMethodName());
                if (frame.getFileName() != null)
                {
                    buffer.append('(').append(frame.getFileName()).append(':').append(frame.getLineNumber()).append(')');
                }
                buffer.append(':');
                break;
            }
        }
    }

    private void format(StringBuilder builder, String msg, Object... args)
    {
        if (msg == null)
        {
            msg = "";
            for (int i = 0; i < args.length; i++)
            {
                msg += "{} ";
            }
        }
        String braces = "{}";
        int start = 0;
        for (Object arg : args)
        {
            int bracesIndex = msg.indexOf(braces,start);
            if (bracesIndex < 0)
            {
                escape(builder,msg.substring(start));
                builder.append(" ");
                builder.append(arg);
                start = msg.length();
            }
            else
            {
                escape(builder,msg.substring(start,bracesIndex));
                builder.append(String.valueOf(arg));
                start = bracesIndex + braces.length();
            }
        }
        escape(builder,msg.substring(start));
    }

    private void escape(StringBuilder builder, String string)
    {
        if (__escape)
        {
            for (int i = 0; i < string.length(); ++i)
            {
                char c = string.charAt(i);
                if (Character.isISOControl(c))
                {
                    if (c == '\n')
                    {
                        builder.append('|');
                    }
                    else if (c == '\r')
                    {
                        builder.append('<');
                    }
                    else
                    {
                        builder.append('?');
                    }
                }
                else
                {
                    builder.append(c);
                }
            }
        }
        else
            builder.append(string);
    }

    protected void format(StringBuilder buffer, Throwable thrown)
    {
        format(buffer,thrown,"");
    }
    
    protected void format(StringBuilder buffer, Throwable thrown, String indent)
    {
        if (thrown == null)
        {
            buffer.append("null");
        }
        else
        {
            buffer.append(EOL).append(indent);
            format(buffer,thrown.toString());
            StackTraceElement[] elements = thrown.getStackTrace();
            for (int i = 0; elements != null && i < elements.length; i++)
            {
                buffer.append(EOL).append(indent).append("\tat ");
                format(buffer,elements[i].toString());
            }

            for (Throwable suppressed:thrown.getSuppressed())
            {
                buffer.append(EOL).append(indent).append("Suppressed: ");
                format(buffer,suppressed,"\t|"+indent);
            }
            
            Throwable cause = thrown.getCause();
            if (cause != null && cause != thrown)
            {
                buffer.append(EOL).append(indent).append("Caused by: ");
                format(buffer,cause,indent);
            }
        }
    }


    /**
     * Create a Child Logger of this Logger.
     */
    @Override
    protected Logger newLogger(String fullname)
    {
        StdErrLog logger = new StdErrLog(fullname);
        // Preserve configuration for new loggers configuration
        logger.setPrintLongNames(_printLongNames);
        logger._stderr = this._stderr;

        // Force the child to have any programmatic configuration
        if (_level!=_configuredLevel)
            logger._level=_level;

        return logger;
    }

    @Override
    public String toString()
    {
        StringBuilder s = new StringBuilder();
        s.append("StdErrLog:");
        s.append(_name);
        s.append(":LEVEL=");
        switch (_level)
        {
            case LEVEL_ALL:
                s.append("ALL");
                break;
            case LEVEL_DEBUG:
                s.append("DEBUG");
                break;
            case LEVEL_INFO:
                s.append("INFO");
                break;
            case LEVEL_WARN:
                s.append("WARN");
                break;
            default:
                s.append("?");
                break;
        }
        return s.toString();
    }

    public static void setProperties(Properties props)
    {
        __props.clear();
        __props.putAll(props);
    }

    public void ignore(Throwable ignored)
    {
        if (_level <= LEVEL_ALL)
        {
            StringBuilder buffer = new StringBuilder(64);
            format(buffer,":IGNORED:","",ignored);
            (_stderr==null?System.err:_stderr).println(buffer);
        }
    }
}
