/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache license, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the license for the specific language governing permissions and
   * limitations under the license.
   */
  package org.apache.logging.log4j.core.pattern;
  
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
  import org.apache.logging.log4j.core.config.plugins.util.PluginType;
  import org.apache.logging.log4j.core.util.NanoClockFactory;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * Most of the work of the {@link org.apache.logging.log4j.core.layout.PatternLayout} class is delegated to the
   * PatternParser class.
   * <p>
   * It is this class that parses conversion patterns and creates a chained list of {@link PatternConverter
   * PatternConverters}.
   */
  public final class PatternParser {
      static final String NO_CONSOLE_NO_ANSI = "noConsoleNoAnsi";
  
      /**
       * Escape character for format specifier.
       */
      private static final char ESCAPE_CHAR = '%';
  
      /**
       * The states the parser can be in while parsing the pattern.
       */
      private enum ParserState {
          /**
           * Literal state.
           */
          LITERAL_STATE,
  
          /**
           * In converter name state.
           */
          CONVERTER_STATE,
  
          /**
           * Dot state.
           */
          DOT_STATE,
  
          /**
           * Min state.
           */
          MIN_STATE,
  
          /**
           * Max state.
           */
          MAX_STATE;
      }
  
      private static final Logger LOGGER = StatusLogger.getLogger();
  
      private static final int BUF_SIZE = 32;
  
      private static final int DECIMAL = 10;
  
      private final Configuration config;
  
      private final Map<String, Class<PatternConverter>> converterRules;
  
      /**
       * Constructor.
       *
       * @param converterKey
       *            The type of converters that will be used.
       */
      public PatternParser(final String converterKey) {
          this(null, converterKey, null, null);
      }
 
     /**
      * Constructor.
      *
      * @param config
      *            The current Configuration.
      * @param converterKey
      *            The key to lookup the converters.
      * @param expected
      *            The expected base Class of each Converter.
      */
     public PatternParser(final Configuration config, final String converterKey, final Class<?> expected) {
         this(config, converterKey, expected, null);
     }
 
     /**
      * Constructor.
      *
      * @param config
      *            The current Configuration.
      * @param converterKey
      *            The key to lookup the converters.
      * @param expectedClass
      *            The expected base Class of each Converter.
      * @param filterClass
      *            Filter the returned plugins after calling the plugin manager.
      */
     public PatternParser(final Configuration config, final String converterKey, final Class<?> expectedClass,
             final Class<?> filterClass) {
         this.config = config;
         final PluginManager manager = new PluginManager(converterKey);
         manager.collectPlugins(config == null ? null : config.getPluginPackages());
         final Map<String, PluginType<?>> plugins = manager.getPlugins();
         final Map<String, Class<PatternConverter>> converters = new LinkedHashMap<>();
 
         for (final PluginType<?> type : plugins.values()) {
             try {
                 @SuppressWarnings("unchecked")
                 final Class<PatternConverter> clazz = (Class<PatternConverter>) type.getPluginClass();
                 if (filterClass != null && !filterClass.isAssignableFrom(clazz)) {
                     continue;
                 }
                 final ConverterKeys keys = clazz.getAnnotation(ConverterKeys.class);
                 if (keys != null) {
                     for (final String key : keys.value()) {
                         if (converters.containsKey(key)) {
                             LOGGER.warn("Converter key '{}' is already mapped to '{}'. " +
                                     "Sorry, Dave, I can't let you do that! Ignoring plugin [{}].",
                                 key, converters.get(key), clazz);
                         } else {
                             converters.put(key, clazz);
                         }
                     }
                 }
             } catch (final Exception ex) {
                 LOGGER.error("Error processing plugin " + type.getElementName(), ex);
             }
         }
         converterRules = converters;
     }
 
     public List<PatternFormatter> parse(final String pattern) {
         return parse(pattern, false, false);
     }
 
     public List<PatternFormatter> parse(final String pattern, final boolean alwaysWriteExceptions,
             final boolean noConsoleNoAnsi) {
         final List<PatternFormatter> list = new ArrayList<>();
         final List<PatternConverter> converters = new ArrayList<>();
         final List<FormattingInfo> fields = new ArrayList<>();
 
         parse(pattern, converters, fields, noConsoleNoAnsi, true);
 
         final Iterator<FormattingInfo> fieldIter = fields.iterator();
         boolean handlesThrowable = false;
 
         NanoClockFactory.setMode(NanoClockFactory.Mode.Dummy); // LOG4J2-1074 use dummy clock by default
         for (final PatternConverter converter : converters) {
             if (converter instanceof NanoTimePatternConverter) {
                 // LOG4J2-1074 Switch to actual clock if nanosecond timestamps are required in config.
                 // LoggerContext will notify known NanoClockFactory users that the configuration has changed.
                 NanoClockFactory.setMode(NanoClockFactory.Mode.System);
             }
             LogEventPatternConverter pc;
             if (converter instanceof LogEventPatternConverter) {
                 pc = (LogEventPatternConverter) converter;
                 handlesThrowable |= pc.handlesThrowable();
             } else {
                 pc = new LiteralPatternConverter(config, Strings.EMPTY, true);
             }
 
             FormattingInfo field;
             if (fieldIter.hasNext()) {
                 field = fieldIter.next();
             } else {
                 field = FormattingInfo.getDefault();
             }
             list.add(new PatternFormatter(pc, field));
         }
         if (alwaysWriteExceptions && !handlesThrowable) {
             final LogEventPatternConverter pc = ExtendedThrowablePatternConverter.newInstance(null);
             list.add(new PatternFormatter(pc, FormattingInfo.getDefault()));
         }
         return list;
     }
 
     /**
      * Extracts the converter identifier found at the given start position.
      * <p>
      * After this function returns, the variable i will point to the first char after the end of the converter
      * identifier.
      * </p>
      * <p>
      * If i points to a char which is not a character acceptable at the start of a unicode identifier, the value null is
      * returned.
      * </p>
      *
      * @param lastChar
      *        last processed character.
      * @param pattern
      *        format string.
      * @param i
      *        current index into pattern format.
      * @param convBuf
      *        buffer to receive conversion specifier.
      * @param currentLiteral
      *        literal to be output in case format specifier in unrecognized.
      * @return position in pattern after converter.
      */
     private static int extractConverter(final char lastChar, final String pattern, final int start,
             final StringBuilder convBuf, final StringBuilder currentLiteral) {
         int i = start;
         convBuf.setLength(0);
 
         // When this method is called, lastChar points to the first character of the
         // conversion word. For example:
         // For "%hello" lastChar = 'h'
         // For "%-5hello" lastChar = 'h'
         // System.out.println("lastchar is "+lastChar);
         if (!Character.isUnicodeIdentifierStart(lastChar)) {
             return i;
         }
 
         convBuf.append(lastChar);
 
         while (i < pattern.length() && Character.isUnicodeIdentifierPart(pattern.charAt(i))) {
             convBuf.append(pattern.charAt(i));
             currentLiteral.append(pattern.charAt(i));
             i++;
         }
 
         return i;
     }
 
     /**
      * Extract options.
      *
      * @param pattern
      *            conversion pattern.
      * @param i
      *            start of options.
      * @param options
      *            array to receive extracted options
      * @return position in pattern after options.
      */
     private static int extractOptions(final String pattern, final int start, final List<String> options) {
         int i = start;
         while (i < pattern.length() && pattern.charAt(i) == '{') {
             final int begin = i++;
             int end;
             int depth = 0;
             do {
                 end = pattern.indexOf('}', i);
                 if (end == -1) {
                     break;
                 }
                 final int next = pattern.indexOf("{", i);
                 if (next != -1 && next < end) {
                     i = end + 1;
                     ++depth;
                 } else if (depth > 0) {
                     --depth;
                 }
             } while (depth > 0);
 
             if (end == -1) {
                 break;
             }
 
             final String r = pattern.substring(begin + 1, end);
             options.add(r);
             i = end + 1;
         }
 
         return i;
     }
 
     /**
      * Parse a format specifier.
      *
      * @param pattern
      *            pattern to parse.
      * @param patternConverters
      *            list to receive pattern converters.
      * @param formattingInfos
      *            list to receive field specifiers corresponding to pattern converters.
      * @param noConsoleNoAnsi
      *            TODO
      * @param convertBackslashes if {@code true}, backslash characters are treated as escape characters and character
      *            sequences like "\" followed by "t" (backslash+t) are converted to special characters like '\t' (tab).
      */
     public void parse(final String pattern, final List<PatternConverter> patternConverters,
             final List<FormattingInfo> formattingInfos, final boolean noConsoleNoAnsi,
             final boolean convertBackslashes) {
         Objects.requireNonNull(pattern, "pattern");
 
         final StringBuilder currentLiteral = new StringBuilder(BUF_SIZE);
 
         final int patternLength = pattern.length();
         ParserState state = ParserState.LITERAL_STATE;
         char c;
         int i = 0;
         FormattingInfo formattingInfo = FormattingInfo.getDefault();
 
         while (i < patternLength) {
             c = pattern.charAt(i++);
 
             switch (state) {
             case LITERAL_STATE:
 
                 // In literal state, the last char is always a literal.
                 if (i == patternLength) {
                     currentLiteral.append(c);
 
                     continue;
                 }
 
                 if (c == ESCAPE_CHAR) {
                     // peek at the next char.
                     switch (pattern.charAt(i)) {
                     case ESCAPE_CHAR:
                         currentLiteral.append(c);
                         i++; // move pointer
 
                         break;
 
                     default:
 
                         if (currentLiteral.length() != 0) {
                             patternConverters.add(new LiteralPatternConverter(config, currentLiteral.toString(),
                                     convertBackslashes));
                             formattingInfos.add(FormattingInfo.getDefault());
                         }
 
                         currentLiteral.setLength(0);
                         currentLiteral.append(c); // append %
                         state = ParserState.CONVERTER_STATE;
                         formattingInfo = FormattingInfo.getDefault();
                     }
                 } else {
                     currentLiteral.append(c);
                 }
 
                 break;
 
             case CONVERTER_STATE:
                 currentLiteral.append(c);
 
                 switch (c) {
                 case '-':
                     formattingInfo = new FormattingInfo(true, formattingInfo.getMinLength(),
                             formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate());
                     break;
 
                 case '.':
                     state = ParserState.DOT_STATE;
                     break;
 
                 default:
 
                     if (c >= '0' && c <= '9') {
                         formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), c - '0',
                                 formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate());
                         state = ParserState.MIN_STATE;
                     } else {
                         i = finalizeConverter(c, pattern, i, currentLiteral, formattingInfo, converterRules,
                                 patternConverters, formattingInfos, noConsoleNoAnsi, convertBackslashes);
 
                         // Next pattern is assumed to be a literal.
                         state = ParserState.LITERAL_STATE;
                         formattingInfo = FormattingInfo.getDefault();
                         currentLiteral.setLength(0);
                     }
                 } // switch
 
                 break;
 
             case MIN_STATE:
                 currentLiteral.append(c);
 
                 if (c >= '0' && c <= '9') {
                     // Multiply the existing value and add the value of the number just encountered.
                     formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength()
                             * DECIMAL + c - '0', formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate());
                 } else if (c == '.') {
                     state = ParserState.DOT_STATE;
                 } else {
                     i = finalizeConverter(c, pattern, i, currentLiteral, formattingInfo, converterRules,
                             patternConverters, formattingInfos, noConsoleNoAnsi, convertBackslashes);
                     state = ParserState.LITERAL_STATE;
                     formattingInfo = FormattingInfo.getDefault();
                     currentLiteral.setLength(0);
                 }
 
                 break;
 
             case DOT_STATE:
                 currentLiteral.append(c);
                 switch (c) {
                 case '-':
                     formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
                             formattingInfo.getMaxLength(),false);
                     break;
 
                 default:
 
 	                if (c >= '0' && c <= '9') {
 	                    formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
 	                            c - '0', formattingInfo.isLeftTruncate());
 	                    state = ParserState.MAX_STATE;
 	                } else {
 	                    LOGGER.error("Error occurred in position " + i + ".\n Was expecting digit, instead got char \"" + c
 	                            + "\".");
 
 	                    state = ParserState.LITERAL_STATE;
 	                }
                 }
 
                 break;
 
             case MAX_STATE:
                 currentLiteral.append(c);
 
                 if (c >= '0' && c <= '9') {
                     // Multiply the existing value and add the value of the number just encountered.
                     formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
                             formattingInfo.getMaxLength() * DECIMAL + c - '0', formattingInfo.isLeftTruncate());
                 } else {
                     i = finalizeConverter(c, pattern, i, currentLiteral, formattingInfo, converterRules,
                             patternConverters, formattingInfos, noConsoleNoAnsi, convertBackslashes);
                     state = ParserState.LITERAL_STATE;
                     formattingInfo = FormattingInfo.getDefault();
                     currentLiteral.setLength(0);
                 }
 
                 break;
             } // switch
         }
 
         // while
         if (currentLiteral.length() != 0) {
             patternConverters.add(new LiteralPatternConverter(config, currentLiteral.toString(), convertBackslashes));
             formattingInfos.add(FormattingInfo.getDefault());
         }
     }
 
     /**
      * Creates a new PatternConverter.
      *
      * @param converterId
      *            converterId.
      * @param currentLiteral
      *            literal to be used if converter is unrecognized or following converter if converterId contains extra
      *            characters.
      * @param rules
      *            map of stock pattern converters keyed by format specifier.
      * @param options
      *            converter options.
      * @param noConsoleNoAnsi TODO
      * @return converter or null.
      */
     private PatternConverter createConverter(final String converterId, final StringBuilder currentLiteral,
             final Map<String, Class<PatternConverter>> rules, final List<String> options, final boolean noConsoleNoAnsi) {
         String converterName = converterId;
         Class<PatternConverter> converterClass = null;
 
         if (rules == null) {
             LOGGER.error("Null rules for [" + converterId + ']');
             return null;
         }
         for (int i = converterId.length(); i > 0 && converterClass == null; i--) {
             converterName = converterName.substring(0, i);
             converterClass = rules.get(converterName);
         }
 
         if (converterClass == null) {
             LOGGER.error("Unrecognized format specifier [" + converterId + ']');
             return null;
         }
 
         if (AnsiConverter.class.isAssignableFrom(converterClass)) {
             options.add(NO_CONSOLE_NO_ANSI + '=' + noConsoleNoAnsi);
         }
         // Work around the regression bug in Class.getDeclaredMethods() in Oracle Java in version > 1.6.0_17:
         // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6815786
         final Method[] methods = converterClass.getDeclaredMethods();
         Method newInstanceMethod = null;
         for (final Method method : methods) {
             if (Modifier.isStatic(method.getModifiers()) && method.getDeclaringClass().equals(converterClass)
                     && method.getName().equals("newInstance")) {
                 if (newInstanceMethod == null) {
                     newInstanceMethod = method;
                 } else if (method.getReturnType().equals(newInstanceMethod.getReturnType())) {
                     LOGGER.error("Class " + converterClass + " cannot contain multiple static newInstance methods");
                     return null;
                 }
             }
         }
         if (newInstanceMethod == null) {
             LOGGER.error("Class " + converterClass + " does not contain a static newInstance method");
             return null;
         }
 
         final Class<?>[] parmTypes = newInstanceMethod.getParameterTypes();
         final Object[] parms = parmTypes.length > 0 ? new Object[parmTypes.length] : null;
 
         if (parms != null) {
             int i = 0;
             boolean errors = false;
             for (final Class<?> clazz : parmTypes) {
                 if (clazz.isArray() && clazz.getName().equals("[Ljava.lang.String;")) {
                     final String[] optionsArray = options.toArray(new String[options.size()]);
                     parms[i] = optionsArray;
                 } else if (clazz.isAssignableFrom(Configuration.class)) {
                     parms[i] = config;
                 } else {
                     LOGGER.error("Unknown parameter type " + clazz.getName() + " for static newInstance method of "
                             + converterClass.getName());
                     errors = true;
                 }
                 ++i;
             }
             if (errors) {
                 return null;
             }
         }
 
         try {
             final Object newObj = newInstanceMethod.invoke(null, parms);
 
             if (newObj instanceof PatternConverter) {
                 currentLiteral.delete(0, currentLiteral.length() - (converterId.length() - converterName.length()));
 
                 return (PatternConverter) newObj;
             }
             LOGGER.warn("Class {} does not extend PatternConverter.", converterClass.getName());
         } catch (final Exception ex) {
             LOGGER.error("Error creating converter for " + converterId, ex);
         }
 
         return null;
     }
 
     /**
      * Processes a format specifier sequence.
      *
      * @param c
      *            initial character of format specifier.
      * @param pattern
      *            conversion pattern
      * @param i
      *            current position in conversion pattern.
      * @param currentLiteral
      *            current literal.
      * @param formattingInfo
      *            current field specifier.
      * @param rules
      *            map of stock pattern converters keyed by format specifier.
      * @param patternConverters
      *            list to receive parsed pattern converter.
      * @param formattingInfos
      *            list to receive corresponding field specifier.
      * @param noConsoleNoAnsi
      *            TODO
      * @param convertBackslashes if {@code true}, backslash characters are treated as escape characters and character
      *            sequences like "\" followed by "t" (backslash+t) are converted to special characters like '\t' (tab).
      * @return position after format specifier sequence.
      */
     private int finalizeConverter(final char c, final String pattern, final int start,
             final StringBuilder currentLiteral, final FormattingInfo formattingInfo,
             final Map<String, Class<PatternConverter>> rules, final List<PatternConverter> patternConverters,
             final List<FormattingInfo> formattingInfos, final boolean noConsoleNoAnsi, final boolean convertBackslashes) {
         int i = start;
         final StringBuilder convBuf = new StringBuilder();
         i = extractConverter(c, pattern, i, convBuf, currentLiteral);
 
         final String converterId = convBuf.toString();
 
         final List<String> options = new ArrayList<>();
         i = extractOptions(pattern, i, options);
 
         final PatternConverter pc = createConverter(converterId, currentLiteral, rules, options, noConsoleNoAnsi);
 
         if (pc == null) {
             StringBuilder msg;
 
             if (Strings.isEmpty(converterId)) {
                 msg = new StringBuilder("Empty conversion specifier starting at position ");
             } else {
                 msg = new StringBuilder("Unrecognized conversion specifier [");
                 msg.append(converterId);
                 msg.append("] starting at position ");
             }
 
             msg.append(Integer.toString(i));
             msg.append(" in conversion pattern.");
 
             LOGGER.error(msg.toString());
 
             patternConverters.add(new LiteralPatternConverter(config, currentLiteral.toString(), convertBackslashes));
             formattingInfos.add(FormattingInfo.getDefault());
         } else {
             patternConverters.add(pc);
             formattingInfos.add(formattingInfo);
 
             if (currentLiteral.length() > 0) {
                 patternConverters
                         .add(new LiteralPatternConverter(config, currentLiteral.toString(), convertBackslashes));
                 formattingInfos.add(FormattingInfo.getDefault());
             }
         }
 
         currentLiteral.setLength(0);
 
         return i;
     }
 }