/*
    * 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.tools.plugin.javadoc;
  
  import java.util.Objects;
  import java.util.Optional;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Describes a code reference used in javadoc tags {@code see}, {@code link} and {@code linkplain}.
   * The format of the reference given as string is {@code module/package.class#member label}.
   * Members must be separated with a {@code #} to be detected.
   * Targets either module, package, class or field/method/constructor in class.
   * This class does not know whether the second part part refers to a package, class or both,
   * as they use the same alphabet and separators.
   * @see <a href="https://docs.oracle.com/en/java/javase/17/docs/specs/javadoc/doc-comment-spec.html#link">link tag specification</a>
   */
  public class JavadocReference {
      private final Optional<String> moduleName;
  
      private final Optional<String> packageNameClassName;
  
      private final Optional<String> member; // optional, but may appear with both className and packageName being null
  
      private final Optional<String> label;
  
      /*
       * Test at https://regex101.com/r/eDzWNx
       * Captures several groups: module name (1), package name and/or class name (2), member (3), label (4)
       */
      private static final Pattern REFERENCE_VALUE_PATTERN =
              Pattern.compile("^\\s*(?:(.+)/)??([^#\\s/]+)?(?:#([^\\s\\(]+(?:\\([^\\)]*\\))?))?(?: +(.*))?$");
  
      private static final int GROUP_INDEX_MODULE = 1;
  
      private static final int GROUP_INDEX_PACKAGECLASS = 2;
  
      private static final int GROUP_INDEX_MEMBER = 3;
  
      private static final int GROUP_INDEX_LABEL = 4;
  
      /**
       *
       * @param reference the reference value to parse
       * @return the created {@link JavadocReference}
       * @throws IllegalArgumentException in case the reference has an invalid format
       */
      public static JavadocReference parse(String reference) {
          Matcher matcher = REFERENCE_VALUE_PATTERN.matcher(reference);
          if (!matcher.matches()) {
              throw new IllegalArgumentException("Invalid format of javadoc reference: " + reference);
          }
          final Optional<String> moduleName = getOptionalGroup(matcher, GROUP_INDEX_MODULE);
          final Optional<String> packageNameClassName = getOptionalGroup(matcher, GROUP_INDEX_PACKAGECLASS);
          final Optional<String> member = getOptionalGroup(matcher, GROUP_INDEX_MEMBER);
          final Optional<String> label = getOptionalGroup(matcher, GROUP_INDEX_LABEL);
          return new JavadocReference(moduleName, packageNameClassName, member, label);
      }
  
      private static Optional<String> getOptionalGroup(Matcher matcher, int index) {
          String group = matcher.group(index);
          if (group != null && !group.isEmpty()) {
              return Optional.of(group);
          } else {
              return Optional.empty();
          }
      }
  
      JavadocReference(
              Optional<String> moduleName,
              Optional<String> packageNameClassName,
              Optional<String> member,
              Optional<String> label) {
          this.moduleName = moduleName;
          this.packageNameClassName = packageNameClassName;
          this.member = member;
          this.label = label;
      }
  
      public Optional<String> getModuleName() {
          return moduleName;
      }
 
     /**
      *
      * @return a package name, a class name or a package name followed by a class name
      */
     public Optional<String> getPackageNameClassName() {
         return packageNameClassName;
     }
 
     public Optional<String> getMember() {
         return member;
     }
 
     public Optional<String> getLabel() {
         return label;
     }
 
     @Override
     public String toString() {
         return "JavadocReference [moduleName=" + moduleName + ", packageNameClassName=" + packageNameClassName
                 + ", member=" + member + ", label=" + label + "]";
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(label, member, packageNameClassName, moduleName);
     }
 
     @Override
     public boolean equals(Object obj) {
         if (this == obj) {
             return true;
         }
         if (obj == null) {
             return false;
         }
         if (getClass() != obj.getClass()) {
             return false;
         }
         JavadocReference other = (JavadocReference) obj;
         return Objects.equals(label, other.label)
                 && Objects.equals(member, other.member)
                 && Objects.equals(packageNameClassName, other.packageNameClassName)
                 && Objects.equals(moduleName, other.moduleName);
     }
 }