content: /*
   *  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
   *
   *      https://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.tools.ant.taskdefs.optional.extension;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.StringTokenizer;
  import java.util.jar.Attributes;
  import java.util.jar.Manifest;
  import java.util.stream.Stream;
  
  import org.apache.tools.ant.util.DeweyDecimal;
  
  /**
   * <p>Utility class that represents either an available "Optional Package"
   * (formerly known as "Standard Extension") as described in the manifest
   * of a JAR file, or the requirement for such an optional package.</p>
   *
   * <p>For more information about optional packages, see the document
   * <em>Optional Package Versioning</em> in the documentation bundle for your
   * Java2 Standard Edition package, in file
   * <code>guide/extensions/versioning.html</code>.</p>
   *
   */
  public final class Extension {
      /**
       * Manifest Attribute Name object for EXTENSION_LIST.
       */
      public static final Attributes.Name EXTENSION_LIST
          = new Attributes.Name("Extension-List");
  
      /**
       * <code>Name</code> object for <code>Optional-Extension-List</code>
       * manifest attribute used for declaring optional dependencies on
       * installed extensions. Note that the dependencies declared by this method
       * are not required for the library to operate but if present will be used.
       * It is NOT part of the official "Optional Package" specification.
       *
       * @see <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/extensions/spec.html#dependency">
       *      Installed extension dependency</a>
       */
      public static final Attributes.Name OPTIONAL_EXTENSION_LIST
          = new Attributes.Name("Optional-Extension-List");
  
      /**
       * Manifest Attribute Name object for EXTENSION_NAME.
       */
      public static final Attributes.Name EXTENSION_NAME =
          new Attributes.Name("Extension-Name");
      /**
       * Manifest Attribute Name object for SPECIFICATION_VERSION.
       */
      public static final Attributes.Name SPECIFICATION_VERSION
          = Attributes.Name.SPECIFICATION_VERSION;
  
      /**
       * Manifest Attribute Name object for SPECIFICATION_VENDOR.
       */
      public static final Attributes.Name SPECIFICATION_VENDOR
          = Attributes.Name.SPECIFICATION_VENDOR;
  
      /**
       * Manifest Attribute Name object for IMPLEMENTATION_VERSION.
       */
      public static final Attributes.Name IMPLEMENTATION_VERSION
          = Attributes.Name.IMPLEMENTATION_VERSION;
  
      /**
       * Manifest Attribute Name object for IMPLEMENTATION_VENDOR.
       */
      public static final Attributes.Name IMPLEMENTATION_VENDOR
          = Attributes.Name.IMPLEMENTATION_VENDOR;
  
      /**
       * Manifest Attribute Name object for IMPLEMENTATION_URL.
       */
      public static final Attributes.Name IMPLEMENTATION_URL
          = new Attributes.Name("Implementation-URL");
  
      /**
       * Manifest Attribute Name object for IMPLEMENTATION_VENDOR_ID.
       */
      public static final Attributes.Name IMPLEMENTATION_VENDOR_ID
          = new Attributes.Name("Implementation-Vendor-Id");
  
      /**
       * Enum indicating that extension is compatible with other extension.
       */
      public static final Compatibility COMPATIBLE
          = new Compatibility("COMPATIBLE");
  
      /**
       * Enum indicating that extension requires an upgrade
       * of specification to be compatible with other extension.
       */
      public static final Compatibility REQUIRE_SPECIFICATION_UPGRADE
          = new Compatibility("REQUIRE_SPECIFICATION_UPGRADE");
  
      /**
       * Enum indicating that extension requires a vendor
       * switch to be compatible with other extension.
       */
      public static final Compatibility REQUIRE_VENDOR_SWITCH
          = new Compatibility("REQUIRE_VENDOR_SWITCH");
  
      /**
       * Enum indicating that extension requires an upgrade
       * of implementation to be compatible with other extension.
       */
      public static final Compatibility REQUIRE_IMPLEMENTATION_UPGRADE
          = new Compatibility("REQUIRE_IMPLEMENTATION_UPGRADE");
  
      /**
       * Enum indicating that extension is incompatible with
       * other extension in ways other than other enums
       * indicate). For example the other extension may have
       * a different ID.
       */
      public static final Compatibility INCOMPATIBLE
          = new Compatibility("INCOMPATIBLE");
  
      /**
       * The name of the optional package being made available, or required.
       */
      private String extensionName;
  
      /**
       * The version number (dotted decimal notation) of the specification
       * to which this optional package conforms.
       */
      private DeweyDecimal specificationVersion;
  
      /**
       * The name of the company or organization that originated the
       * specification to which this optional package conforms.
       */
      private String specificationVendor;
  
      /**
       * The unique identifier of the company that produced the optional
       * package contained in this JAR file.
       */
      private String implementationVendorID;
  
      /**
       * The name of the company or organization that produced this
       * implementation of this optional package.
       */
      private String implementationVendor;
  
      /**
       * The version number (dotted decimal notation) for this implementation
       * of the optional package.
       */
      private DeweyDecimal implementationVersion;
  
      /**
       * The URL from which the most recent version of this optional package
       * can be obtained if it is not already installed.
       */
      private String implementationURL;
  
      /**
       * Return an array of <code>Extension</code> objects representing optional
       * packages that are available in the JAR file associated with the
       * specified <code>Manifest</code>.  If there are no such optional
       * packages, a zero-length array is returned.
       *
       * @param manifest Manifest to be parsed
       * @return the "available" extensions in specified manifest
       */
      public static Extension[] getAvailable(final Manifest manifest) {
          if (null == manifest) {
              return new Extension[0];
          }
          return Stream
              .concat(Optional.ofNullable(manifest.getMainAttributes())
                      .map(Stream::of).orElse(Stream.empty()),
                  manifest.getEntries().values().stream())
              .map(attrs -> getExtension("", attrs)).filter(Objects::nonNull)
              .toArray(Extension[]::new);
      }
  
      /**
       * Return the set of <code>Extension</code> objects representing optional
       * packages that are required by the application contained in the JAR
       * file associated with the specified <code>Manifest</code>.  If there
       * are no such optional packages, a zero-length list is returned.
       *
       * @param manifest Manifest to be parsed
       * @return the dependencies that are specified in manifest
       */
      public static Extension[] getRequired(final Manifest manifest) {
          return getListed(manifest, Attributes.Name.EXTENSION_LIST);
      }
  
      /**
       * Return the set of <code>Extension</code> objects representing "Optional
       * Packages" that the application declares they will use if present. If
       * there are no such optional packages, a zero-length list is returned.
       *
       * @param manifest Manifest to be parsed
       * @return the optional dependencies that are specified in manifest
       */
      public static Extension[] getOptions(final Manifest manifest) {
          return getListed(manifest, OPTIONAL_EXTENSION_LIST);
      }
  
      /**
       * Add Extension to the specified manifest Attributes.
       *
       * @param attributes the attributes of manifest to add to
       * @param extension the extension
       */
      public static void addExtension(final Extension extension,
                                       final Attributes attributes) {
          addExtension(extension, "", attributes);
      }
  
      /**
       * Add Extension to the specified manifest Attributes.
       * Use the specified prefix so that dependencies can added
       * with a prefix such as "java3d-" etc.
       *
       * @param attributes the attributes of manifest to add to
       * @param extension the extension
       * @param prefix the name to prefix to extension
       */
      public static void addExtension(final Extension extension,
                                       final String prefix,
                                       final Attributes attributes) {
          attributes.putValue(prefix + EXTENSION_NAME,
                               extension.getExtensionName());
  
          final String specificationVendor = extension.getSpecificationVendor();
          if (null != specificationVendor) {
              attributes.putValue(prefix + SPECIFICATION_VENDOR,
                                   specificationVendor);
          }
  
          final DeweyDecimal specificationVersion
              = extension.getSpecificationVersion();
          if (null != specificationVersion) {
              attributes.putValue(prefix + SPECIFICATION_VERSION,
                                   specificationVersion.toString());
          }
  
          final String implementationVendorID
              = extension.getImplementationVendorID();
          if (null != implementationVendorID) {
              attributes.putValue(prefix + IMPLEMENTATION_VENDOR_ID,
                                   implementationVendorID);
          }
  
          final String implementationVendor = extension.getImplementationVendor();
          if (null != implementationVendor) {
              attributes.putValue(prefix + IMPLEMENTATION_VENDOR,
                                   implementationVendor);
          }
  
          final DeweyDecimal implementationVersion
              = extension.getImplementationVersion();
          if (null != implementationVersion) {
              attributes.putValue(prefix + IMPLEMENTATION_VERSION,
                                   implementationVersion.toString());
          }
  
          final String implementationURL = extension.getImplementationURL();
          if (null != implementationURL) {
              attributes.putValue(prefix + IMPLEMENTATION_URL,
                                   implementationURL);
          }
      }
  
      /**
       * The constructor to create Extension object.
       * Note that every component is allowed to be specified
       * but only the extensionName is mandatory.
       *
       * @param extensionName the name of extension.
       * @param specificationVersion the specification Version of extension.
       * @param specificationVendor the specification Vendor of extension.
       * @param implementationVersion the implementation Version of extension.
       * @param implementationVendor the implementation Vendor of extension.
       * @param implementationVendorId the implementation VendorId of extension.
       * @param implementationURL the implementation URL of extension.
       */
      public Extension(final String extensionName,
                        final String specificationVersion,
                        final String specificationVendor,
                        final String implementationVersion,
                        final String implementationVendor,
                        final String implementationVendorId,
                        final String implementationURL) {
          this.extensionName = extensionName;
          this.specificationVendor = specificationVendor;
  
          if (null != specificationVersion) {
              try {
                  this.specificationVersion
                      = new DeweyDecimal(specificationVersion);
              } catch (final NumberFormatException nfe) {
                  final String error = "Bad specification version format '"
                      + specificationVersion + "' in '" + extensionName
                      + "'. (Reason: " + nfe + ")";
                  throw new IllegalArgumentException(error);
              }
          }
  
          this.implementationURL = implementationURL;
          this.implementationVendor = implementationVendor;
          this.implementationVendorID = implementationVendorId;
  
          if (null != implementationVersion) {
              try {
                  this.implementationVersion
                      = new DeweyDecimal(implementationVersion);
              } catch (final NumberFormatException nfe) {
                  final String error = "Bad implementation version format '"
                      + implementationVersion + "' in '" + extensionName
                      + "'. (Reason: " + nfe + ")";
                  throw new IllegalArgumentException(error);
              }
          }
  
          if (null == this.extensionName) {
              throw new NullPointerException("extensionName property is null");
          }
      }
  
      /**
       * Get the name of the extension.
       *
       * @return the name of the extension
       */
      public String getExtensionName() {
          return extensionName;
      }
  
      /**
       * Get the vendor of the extensions specification.
       *
       * @return the vendor of the extensions specification.
       */
      public String getSpecificationVendor() {
          return specificationVendor;
      }
  
      /**
       * Get the version of the extensions specification.
       *
       * @return the version of the extensions specification.
       */
      public DeweyDecimal getSpecificationVersion() {
          return specificationVersion;
      }
  
      /**
       * Get the url of the extensions implementation.
       *
       * @return the url of the extensions implementation.
       */
      public String getImplementationURL() {
          return implementationURL;
      }
  
      /**
       * Get the vendor of the extensions implementation.
       *
       * @return the vendor of the extensions implementation.
       */
      public String getImplementationVendor() {
          return implementationVendor;
      }
  
      /**
       * Get the vendorID of the extensions implementation.
       *
       * @return the vendorID of the extensions implementation.
       */
      public String getImplementationVendorID() {
          return implementationVendorID;
      }
  
      /**
       * Get the version of the extensions implementation.
       *
       * @return the version of the extensions implementation.
       */
      public DeweyDecimal getImplementationVersion() {
          return implementationVersion;
      }
  
      /**
       * Return a Compatibility enum indicating the relationship of this
       * <code>Extension</code> with the specified <code>Extension</code>.
       *
       * @param required Description of the required optional package
       * @return the enum indicating the compatibility (or lack thereof)
       *         of specified extension
       */
      public Compatibility getCompatibilityWith(final Extension required) {
          // Extension Name must match
          if (!extensionName.equals(required.getExtensionName())) {
              return INCOMPATIBLE;
          }
  
          // Available specification version must be >= required
          final DeweyDecimal requiredSpecificationVersion
              = required.getSpecificationVersion();
          if (null != requiredSpecificationVersion) {
              if (null == specificationVersion
                  || !isCompatible(specificationVersion, requiredSpecificationVersion)) {
                  return REQUIRE_SPECIFICATION_UPGRADE;
              }
          }
  
          // Implementation Vendor ID must match
          final String requiredImplementationVendorID
              = required.getImplementationVendorID();
          if (null != requiredImplementationVendorID) {
              if (null == implementationVendorID
                  || !implementationVendorID.equals(requiredImplementationVendorID)) {
                  return REQUIRE_VENDOR_SWITCH;
              }
          }
  
          // Implementation version must be >= required
          final DeweyDecimal requiredImplementationVersion
              = required.getImplementationVersion();
          if (null != requiredImplementationVersion) {
              if (null == implementationVersion
                  || !isCompatible(implementationVersion, requiredImplementationVersion)) {
                  return REQUIRE_IMPLEMENTATION_UPGRADE;
              }
          }
  
          // This available optional package satisfies the requirements
          return COMPATIBLE;
      }
  
      /**
       * Return <code>true</code> if the specified <code>Extension</code>
       * (which represents an optional package required by an application)
       * is satisfied by this <code>Extension</code> (which represents an
       * optional package that is already installed.  Otherwise, return
       * <code>false</code>.
       *
       * @param required Description of the required optional package
       * @return true if the specified extension is compatible with this extension
       */
      public boolean isCompatibleWith(final Extension required) {
          return (COMPATIBLE == getCompatibilityWith(required));
      }
  
      /**
       * Return a String representation of this object.
       *
       * @return string representation of object.
       */
      @Override
      public String toString() {
          final String format = "%s: %s%n";
  
          final StringBuilder sb = new StringBuilder(String.format(format,
                  EXTENSION_NAME, extensionName));
  
          if (null != specificationVersion) {
              sb.append(String.format(format, SPECIFICATION_VERSION, specificationVersion));
          }
  
          if (null != specificationVendor) {
              sb.append(String.format(format, SPECIFICATION_VENDOR, specificationVendor));
          }
  
          if (null != implementationVersion) {
              sb.append(String.format(format, IMPLEMENTATION_VERSION, implementationVersion));
          }
  
          if (null != implementationVendorID) {
              sb.append(String.format(format, IMPLEMENTATION_VENDOR_ID, implementationVendorID));
          }
  
          if (null != implementationVendor) {
              sb.append(String.format(format, IMPLEMENTATION_VENDOR, implementationVendor));
          }
  
          if (null != implementationURL) {
              sb.append(String.format(format, IMPLEMENTATION_URL, implementationURL));
          }
  
          return sb.toString();
      }
  
      /**
       * Return <code>true</code> if the first version number is greater than
       * or equal to the second; otherwise return <code>false</code>.
       *
       * @param first First version number (dotted decimal)
       * @param second Second version number (dotted decimal)
       */
      private boolean isCompatible(final DeweyDecimal first,
                                   final DeweyDecimal second) {
          return first.isGreaterThanOrEqual(second);
      }
  
      /**
       * Retrieve all the extensions listed under a particular key
       * (Usually EXTENSION_LIST or OPTIONAL_EXTENSION_LIST).
       *
       * @param manifest the manifest to extract extensions from
       * @param listKey the key used to get list (Usually
       *        EXTENSION_LIST or OPTIONAL_EXTENSION_LIST)
       * @return the list of listed extensions
       */
      private static Extension[] getListed(final Manifest manifest,
                                            final Attributes.Name listKey) {
          final List<Extension> results = new ArrayList<>();
          final Attributes mainAttributes = manifest.getMainAttributes();
  
          if (null != mainAttributes) {
              getExtension(mainAttributes, results, listKey);
          }
  
          manifest.getEntries().values()
              .forEach(attributes -> getExtension(attributes, results, listKey));
  
          return results.toArray(new Extension[0]);
      }
  
      /**
       * Add required optional packages defined in the specified
       * attributes entry, if any.
       *
       * @param attributes Attributes to be parsed
       * @param required list to add required optional packages to
       * @param listKey the key to use to lookup list, usually EXTENSION_LIST
       *    or OPTIONAL_EXTENSION_LIST
       */
      private static void getExtension(final Attributes attributes,
                                       final List<Extension> required,
                                       final Attributes.Name listKey) {
          final String names = attributes.getValue(listKey);
          if (null == names) {
              return;
          }
          for (final String prefix : split(names, " ")) {
              final Extension extension = getExtension(prefix + "-", attributes);
              if (null != extension) {
                  required.add(extension);
              }
          }
      }
  
      /**
       * Splits the string on every token into an array of strings.
       *
       * @param string the string
       * @param onToken the token
       * @return the resultant array
       */
      private static String[] split(final String string,
                                          final String onToken) {
          final StringTokenizer tokenizer = new StringTokenizer(string, onToken);
          final String[] result = new String[tokenizer.countTokens()];
  
          for (int i = 0; i < result.length; i++) {
              result[i] = tokenizer.nextToken();
          }
  
          return result;
      }
  
      /**
       * Extract an Extension from Attributes.
       * Prefix indicates the prefix checked for each string.
       * Usually the prefix is <em>"&lt;extension&gt;-"</em> if looking for a
       * <b>Required</b> extension. If you are looking for an
       * <b>Available</b> extension
       * then the prefix is <em>""</em>.
       *
       * @param prefix the prefix for each attribute name
       * @param attributes Attributes to searched
       * @return the new Extension object, or null
       */
      private static Extension getExtension(final String prefix,
                                            final Attributes attributes) {
          //WARNING: We trim the values of all the attributes because
          //Some extension declarations are badly defined (ie have spaces
          //after version or vendorID)
          final String nameKey = prefix + EXTENSION_NAME;
          final String name = getTrimmedString(attributes.getValue(nameKey));
          if (null == name) {
              return null;
          }
  
          final String specVendorKey = prefix + SPECIFICATION_VENDOR;
          final String specVendor
              = getTrimmedString(attributes.getValue(specVendorKey));
          final String specVersionKey = prefix + SPECIFICATION_VERSION;
          final String specVersion
              = getTrimmedString(attributes.getValue(specVersionKey));
  
          final String impVersionKey = prefix + IMPLEMENTATION_VERSION;
          final String impVersion
              = getTrimmedString(attributes.getValue(impVersionKey));
          final String impVendorKey = prefix + IMPLEMENTATION_VENDOR;
          final String impVendor
              = getTrimmedString(attributes.getValue(impVendorKey));
          final String impVendorIDKey = prefix + IMPLEMENTATION_VENDOR_ID;
          final String impVendorId
              = getTrimmedString(attributes.getValue(impVendorIDKey));
          final String impURLKey = prefix + IMPLEMENTATION_URL;
          final String impURL = getTrimmedString(attributes.getValue(impURLKey));
  
          return new Extension(name, specVersion, specVendor, impVersion,
                                impVendor, impVendorId, impURL);
      }
  
      /**
       * Trim the supplied string if the string is non-null
       *
       * @param value the string to trim or null
       * @return the trimmed string or null
       */
      private static String getTrimmedString(final String value) {
          return null == value ? null : value.trim();
      }
  }
  