/*
    * 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.maven.plugin.compiler;
  
  import javax.tools.Diagnostic;
  import javax.tools.DiagnosticListener;
  import javax.tools.JavaFileObject;
  
  import java.nio.file.Path;
  import java.util.Arrays;
  import java.util.LinkedHashMap;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Optional;
  
  import org.apache.maven.api.plugin.Log;
  import org.apache.maven.api.services.MessageBuilder;
  import org.apache.maven.api.services.MessageBuilderFactory;
  
  /**
   * A Java compiler diagnostic listener which send the messages to the Maven logger.
   *
   * @author Martin Desruisseaux
   */
  final class DiagnosticLogger implements DiagnosticListener<JavaFileObject> {
      /**
       * The logger where to send diagnostics.
       */
      private final Log logger;
  
      /**
       * The factory for creating message builders.
       */
      private final MessageBuilderFactory messageBuilderFactory;
  
      /**
       * The locale for compiler message.
       */
      private final Locale locale;
  
      /**
       * The base directory with which to relativize the paths to source files.
       */
      private final Path directory;
  
      /**
       * Number of errors or warnings.
       */
      private int numErrors, numWarnings;
  
      /**
       * Number of messages received for each code.
       */
      private final Map<String, Integer> codeCount;
  
      /**
       * The first error, or {@code null} if none.
       */
      private String firstError;
  
      /**
       * Creates a listener which will send the diagnostics to the given logger.
       *
       * @param logger the logger where to send diagnostics
       * @param messageBuilderFactory the factory for creating message builders
       * @param locale the locale for compiler message
       * @param directory the base directory with which to relativize the paths to source files
       */
      DiagnosticLogger(Log logger, MessageBuilderFactory messageBuilderFactory, Locale locale, Path directory) {
          this.logger = logger;
          this.messageBuilderFactory = messageBuilderFactory;
          this.locale = locale;
          this.directory = directory;
          codeCount = new LinkedHashMap<>();
      }
  
      /**
       * Makes the given file relative to the base directory.
       *
       * @param  file  the path to make relative to the base directory
       * @return the given path, potentially relative to the base directory
       */
      private String relativize(String file) {
         if (directory != null) {
             try {
                 return directory.relativize(Path.of(file)).toString();
             } catch (IllegalArgumentException e) {
                 // Ignore, keep the absolute path.
             }
         }
         return file;
     }
 
     /**
      * Invoked when the compiler emitted a warning.
      *
      * @param diagnostic the warning emitted by the Java compiler
      */
     @Override
     public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
         String message = diagnostic.getMessage(locale);
         if (message == null || message.isBlank()) {
             return;
         }
         MessageBuilder record = messageBuilderFactory.builder();
         record.a(message);
         JavaFileObject source = diagnostic.getSource();
         Diagnostic.Kind kind = diagnostic.getKind();
         String style;
         switch (kind) {
             case ERROR:
                 style = ".error:-bold,f:red";
                 break;
             case MANDATORY_WARNING:
             case WARNING:
                 style = ".warning:-bold,f:yellow";
                 break;
             default:
                 style = ".info:-bold,f:blue";
                 if (diagnostic.getLineNumber() == Diagnostic.NOPOS) {
                     source = null; // Some messages are generic, e.g. "Recompile with -Xlint:deprecation".
                 }
                 break;
         }
         if (source != null) {
             record.newline().a("    at ").a(relativize(source.getName()));
             long line = diagnostic.getLineNumber();
             long column = diagnostic.getColumnNumber();
             if (line != Diagnostic.NOPOS || column != Diagnostic.NOPOS) {
                 record.style(style).a('[');
                 if (line != Diagnostic.NOPOS) {
                     record.a(line);
                 }
                 if (column != Diagnostic.NOPOS) {
                     record.a(',').a(column);
                 }
                 record.a(']').resetStyle();
             }
         }
         String log = record.toString();
         switch (kind) {
             case ERROR:
                 if (firstError == null) {
                     firstError = message;
                 }
                 logger.error(log);
                 numErrors++;
                 break;
             case MANDATORY_WARNING:
             case WARNING:
                 logger.warn(log);
                 numWarnings++;
                 break;
             default:
                 logger.info(log);
                 break;
         }
         // Statistics
         String code = diagnostic.getCode();
         if (code != null) {
             codeCount.merge(code, 1, (old, initial) -> old + 1);
         }
     }
 
     /**
      * Returns the first error, if any.
      *
      * @param cause if compilation failed with an exception, the cause
      */
     Optional<String> firstError(Throwable cause) {
         return Optional.ofNullable(cause != null && firstError == null ? cause.getMessage() : firstError);
     }
 
     /**
      * Reports summary after the compilation finished.
      */
     void logSummary() {
         MessageBuilder message = messageBuilderFactory.builder();
         final String patternForCount;
         if (!codeCount.isEmpty()) {
             @SuppressWarnings("unchecked")
             Map.Entry<String, Integer>[] entries = codeCount.entrySet().toArray(Map.Entry[]::new);
             Arrays.sort(entries, (a, b) -> Integer.compare(b.getValue(), a.getValue()));
             patternForCount = patternForCount(Math.max(entries[0].getValue(), Math.max(numWarnings, numErrors)));
             message.strong("Summary of compiler messages:").newline();
             for (Map.Entry<String, Integer> entry : entries) {
                 int count = entry.getValue();
                 message.format(patternForCount, count, entry.getKey()).newline();
             }
         } else {
             patternForCount = patternForCount(Math.max(numWarnings, numErrors));
         }
         if ((numWarnings | numErrors) != 0) {
             message.strong("Total:");
         }
         if (numWarnings != 0) {
             writeCount(message, patternForCount, numWarnings, "warning");
         }
         if (numErrors != 0) {
             writeCount(message, patternForCount, numErrors, "error");
         }
         logger.info(message.toString());
     }
 
     /**
      * {@return the pattern for formatting the specified number followed by a label}
      * The given number should be the widest number to format.
      * A margin of 4 spaces is added at the beginning of the line.
      */
     private static String patternForCount(int n) {
         return "    %" + Integer.toString(n).length() + "d %s";
     }
 
     /**
      * Appends the count of warnings or errors, making them plural if needed.
      */
     private static void writeCount(MessageBuilder message, String patternForCount, int count, String name) {
         message.newline();
         message.format(patternForCount, count, name);
         if (count > 1) {
             message.append('s');
         }
     }
 }