/*
 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation. Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package java.lang;

import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Objects;

import jdk.internal.loader.BootLoader;
import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.Reflection;


/**
 * Represents metadata about a run-time package associated with a class loader.
 * Metadata includes annotations, versioning, and sealing.
 * <p>
 * Annotations for the run-time package are read from {@code package-info.class}
 * at the same code source as classes in the run-time package.
 * <p>
 * The set of classes that make up the run-time package may implement a
 * particular specification. The specification title, version, and vendor
 * (indicating the owner/maintainer of the specification) can be provided
 * when the {@code Package} is defined. An application can ask if the
 * {@code Package} is compatible with a particular specification version
 * by using the {@link #isCompatibleWith Package.isCompatibleWith(String)}
 * method. In addition, information about the actual classes that make up the
 * run-time package can be provided when the Package is defined.
 * This information consists of an implementation title, version, and vendor
 * (indicating the supplier of the classes).
 * <p>
 * A {@code Package} may be explicitly defined with
 * the {@link ClassLoader#definePackage(String, String, String, String,
 * String, String, String, URL)} method.
 * The caller supplies the specification and implementation titles, versions, and
 * vendors. The caller also indicates whether the package is
 * {@linkplain java.util.jar.Attributes.Name#SEALED sealed}.
 * If a {@code Package} is not explicitly defined for a run-time package when
 * a class in that run-time package is defined, then a {@code Package} is
 * automatically defined by the class's defining class loader, as follows.
 * <p>
 * A {@code Package} automatically defined for classes in a named module has
 * the following properties:
 * <ul>
 * <li>The name of the package is derived from the {@linkplain Class#getName() binary names}
 * of the classes. Since classes in a named module must be in a named package,
 * the derived name is never empty.</li>
 * <li>The package is sealed with the {@linkplain java.lang.module.ModuleReference#location()
 * module location} as the code source, if known.</li>
 * <li>The specification and implementation titles, versions, and vendors
 * are unspecified.</li>
 * <li>Any annotations on the package are read from {@code package-info.class}
 * as specified above.</li>
 * </ul>
 * <p>
 * A {@code Package} automatically defined for classes in an unnamed module
 * has the following properties:
 * <ul>
 * <li>The name of the package is either {@code ""} (for classes in an unnamed package)
 * or derived from the {@linkplain Class#getName() binary names} of the classes
 * (for classes in a named package).</li>
 * <li>The package is not sealed.</li>
 * <li>The specification and implementation titles, versions, and vendors
 * are unspecified.</li>
 * <li>Any annotations on the package are read from {@code package-info.class}
 * as specified above.</li>
 * </ul>
 *
 * <p>
 * A {@code Package} can be obtained with the {@link Package#getPackage
 * Package.getPackage(String)} and {@link ClassLoader#getDefinedPackage
 * ClassLoader.getDefinedPackage(String)} methods.
 * Every {@code Package} defined by a class loader can be obtained
 * with the {@link Package#getPackages Package.getPackages()} and
 * {@link ClassLoader#getDefinedPackages} methods.
 *
 * @implNote
 * The <a href="ClassLoader.html#builtinLoaders">builtin class loaders</a>
 * do not explicitly define {@code Package} objects for packages in
 * <em>named modules</em>. Instead those packages are automatically defined
 * and have no specification and implementation versioning information.
 *
 * @jvms 5.3 Run-time package
 * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
 * The JAR File Specification: Package Sealing</a>
 * @see ClassLoader#definePackage(String, String, String, String, String, String, String, URL)
 *
 * @since 1.2
 * @revised 9
 * @spec JPMS
 */
public class Package extends NamedPackage implements java.lang.reflect.AnnotatedElement {
 /**
 * Return the name of this package.
 *
 * @return The fully-qualified name of this package as defined in section 6.5.3 of
 * <cite>The Java&trade; Language Specification</cite>,
 * for example, {@code java.lang}
 */
 public String getName() {
 return packageName();
 }

 /**
 * Return the title of the specification that this package implements.
 * @return the specification title, {@code null} is returned if it is not known.
 */
 public String getSpecificationTitle() {
 return versionInfo.specTitle;
 }

 /**
 * Returns the version number of the specification
 * that this package implements.
 * This version string must be a sequence of non-negative decimal
 * integers separated by "."'s and may have leading zeros.
 * When version strings are compared the most significant
 * numbers are compared.
 *
 *
 * <p>Specification version numbers use a syntax that consists of non-negative
 * decimal integers separated by periods ".", for example "2.0" or
 * "1.2.3.4.5.6.7". This allows an extensible number to be used to represent
 * major, minor, micro, etc. versions. The version specification is described
 * by the following formal grammar:
 * <blockquote>
 * <dl>
 * <dt><i>SpecificationVersion:</i>
 * <dd><i>Digits RefinedVersion<sub>opt</sub></i>

 * <dt><i>RefinedVersion:</i>
 * <dd>{@code .} <i>Digits</i>
 * <dd>{@code .} <i>Digits RefinedVersion</i>
 *
 * <dt><i>Digits:</i>
 * <dd><i>Digit</i>
 * <dd><i>Digits</i>
 *
 * <dt><i>Digit:</i>
 * <dd>any character for which {@link Character#isDigit} returns {@code true},
 * e.g. 0, 1, 2, ...
 * </dl>
 * </blockquote>
 *
 * @return the specification version, {@code null} is returned if it is not known.
 */
 public String getSpecificationVersion() {
 return versionInfo.specVersion;
 }

 /**
 * Return the name of the organization, vendor,
 * or company that owns and maintains the specification
 * of the classes that implement this package.
 * @return the specification vendor, {@code null} is returned if it is not known.
 */
 public String getSpecificationVendor() {
 return versionInfo.specVendor;
 }

 /**
 * Return the title of this package.
 * @return the title of the implementation, {@code null} is returned if it is not known.
 */
 public String getImplementationTitle() {
 return versionInfo.implTitle;
 }

 /**
 * Return the version of this implementation. It consists of any string
 * assigned by the vendor of this implementation and does
 * not have any particular syntax specified or expected by the Java
 * runtime. It may be compared for equality with other
 * package version strings used for this implementation
 * by this vendor for this package.
 * @return the version of the implementation, {@code null} is returned if it is not known.
 */
 public String getImplementationVersion() {
 return versionInfo.implVersion;
 }

 /**
 * Returns the vendor that implemented this package, {@code null}
 * is returned if it is not known.
 * @return the vendor that implemented this package, {@code null}
 * is returned if it is not known.
 *
 * @revised 9
 * @spec JPMS
 */
 public String getImplementationVendor() {
 return versionInfo.implVendor;
 }

 /**
 * Returns true if this package is sealed.
 *
 * @return true if the package is sealed, false otherwise
 */
 public boolean isSealed() {
 return module().isNamed() || versionInfo.sealBase != null;
 }

 /**
 * Returns true if this package is sealed with respect to the specified
 * code source {@code url}.
 *
 * @param url the code source URL
 * @return true if this package is sealed with respect to the given {@code url}
 */
 public boolean isSealed(URL url) {
 Objects.requireNonNull(url);

 URL sealBase = null;
 if (versionInfo != VersionInfo.NULL_VERSION_INFO) {
 sealBase = versionInfo.sealBase;
 } else {
 try {
 URI uri = location();
 sealBase = uri != null ? uri.toURL() : null;
 } catch (MalformedURLException e) {
 }
 }
 return url.equals(sealBase);
 }

 /**
 * Compare this package's specification version with a
 * desired version. It returns true if
 * this packages specification version number is greater than or equal
 * to the desired version number. <p>
 *
 * Version numbers are compared by sequentially comparing corresponding
 * components of the desired and specification strings.
 * Each component is converted as a decimal integer and the values
 * compared.
 * If the specification value is greater than the desired
 * value true is returned. If the value is less false is returned.
 * If the values are equal the period is skipped and the next pair of
 * components is compared.
 *
 * @param desired the version string of the desired version.
 * @return true if this package's version number is greater
 * than or equal to the desired version number
 *
 * @exception NumberFormatException if the current version is not known or
 * the desired or current version is not of the correct dotted form.
 */
 public boolean isCompatibleWith(String desired)
 throws NumberFormatException
 {
 if (versionInfo.specVersion == null || versionInfo.specVersion.length() < 1) {
 throw new NumberFormatException("Empty version string");
 }

 String [] sa = versionInfo.specVersion.split("\\.", -1);
 int [] si = new int[sa.length];
 for (int i = 0; i < sa.length; i++) {
 si[i] = Integer.parseInt(sa[i]);
 if (si[i] < 0)
 throw NumberFormatException.forInputString("" + si[i], 10);
 }

 String [] da = desired.split("\\.", -1);
 int [] di = new int[da.length];
 for (int i = 0; i < da.length; i++) {
 di[i] = Integer.parseInt(da[i]);
 if (di[i] < 0)
 throw NumberFormatException.forInputString("" + di[i], 10);
 }

 int len = Math.max(di.length, si.length);
 for (int i = 0; i < len; i++) {
 int d = (i < di.length ? di[i] : 0);
 int s = (i < si.length ? si[i] : 0);
 if (s < d)
 return false;
 if (s > d)
 return true;
 }
 return true;
 }

 /**
 * Finds a package by name in the caller's class loader and its
 * ancestors.
 * <p>
 * If the caller's class loader defines a {@code Package} of the given name,
 * the {@code Package} is returned. Otherwise, the ancestors of the
 * caller's class loader are searched recursively (parent by parent)
 * for a {@code Package} of the given name.
 * <p>
 * Calling this method is equivalent to calling {@link ClassLoader#getPackage}
 * on a {@code ClassLoader} instance which is the caller's class loader.
 *
 * @param name A package name, such as "{@code java.lang}".
 * @return The {@code Package} of the given name defined by the caller's
 * class loader or its ancestors, or {@code null} if not found.
 *
 * @throws NullPointerException
 * if {@code name} is {@code null}.
 *
 * @deprecated
 * If multiple class loaders delegate to each other and define classes
 * with the same package name, and one such loader relies on the lookup
 * behavior of {@code getPackage} to return a {@code Package} from
 * a parent loader, then the properties exposed by the {@code Package}
 * may not be as expected in the rest of the program.
 * For example, the {@code Package} will only expose annotations from the
 * {@code package-info.class} file defined by the parent loader, even if
 * annotations exist in a {@code package-info.class} file defined by
 * a child loader. A more robust approach is to use the
 * {@link ClassLoader#getDefinedPackage} method which returns
 * a {@code Package} for the specified class loader.
 *
 * @see ClassLoader#getDefinedPackage
 *
 * @revised 9
 * @spec JPMS
 */
 @CallerSensitive
 @Deprecated(since="9")
 @SuppressWarnings("deprecation")
 public static Package getPackage(String name) {
 ClassLoader l = ClassLoader.getClassLoader(Reflection.getCallerClass());
 return l != null ? l.getPackage(name) : BootLoader.getDefinedPackage(name);
 }

 /**
 * Returns all of the {@code Package}s defined by the caller's class loader
 * and its ancestors. The returned array may contain more than one
 * {@code Package} object of the same package name, each defined by
 * a different class loader in the class loader hierarchy.
 * <p>
 * Calling this method is equivalent to calling {@link ClassLoader#getPackages}
 * on a {@code ClassLoader} instance which is the caller's class loader.
 *
 * @return The array of {@code Package} objects defined by this
 * class loader and its ancestors
 *
 * @see ClassLoader#getDefinedPackages
 *
 * @revised 9
 * @spec JPMS
 */
 @CallerSensitive
 public static Package[] getPackages() {
 ClassLoader cl = ClassLoader.getClassLoader(Reflection.getCallerClass());
 return cl != null ? cl.getPackages() : BootLoader.packages().toArray(Package[]::new);
 }

 /**
 * Return the hash code computed from the package name.
 * @return the hash code computed from the package name.
 */
 @Override
 public int hashCode(){
 return packageName().hashCode();
 }

 /**
 * Returns the string representation of this Package.
 * Its value is the string "package " and the package name.
 * If the package title is defined it is appended.
 * If the package version is defined it is appended.
 * @return the string representation of the package.
 */
 @Override
 public String toString() {
 String spec = versionInfo.specTitle;
 String ver = versionInfo.specVersion;
 if (spec != null && !spec.isEmpty())
 spec = ", " + spec;
 else
 spec = "";
 if (ver != null && !ver.isEmpty())
 ver = ", version " + ver;
 else
 ver = "";
 return "package " + packageName() + spec + ver;
 }

 private Class<?> getPackageInfo() {
 if (packageInfo == null) {
 // find package-info.class defined by loader
 String cn = packageName() + ".package-info";
 Module module = module();
 PrivilegedAction<ClassLoader> pa = module::getClassLoader;
 ClassLoader loader = AccessController.doPrivileged(pa);
 Class<?> c;
 if (loader != null) {
 c = loader.loadClass(module, cn);
 } else {
 c = BootLoader.loadClass(module, cn);
 }

 if (c != null) {
 packageInfo = c;
 } else {
 // store a proxy for the package info that has no annotations
 class PackageInfoProxy {}
 packageInfo = PackageInfoProxy.class;
 }
 }
 return packageInfo;
 }

 /**
 * @throws NullPointerException {@inheritDoc}
 * @since 1.5
 */
 public <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
 return getPackageInfo().getAnnotation(annotationClass);
 }

 /**
 * {@inheritDoc}
 * @throws NullPointerException {@inheritDoc}
 * @since 1.5
 */
 @Override
 public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
 return AnnotatedElement.super.isAnnotationPresent(annotationClass);
 }

 /**
 * @throws NullPointerException {@inheritDoc}
 * @since 1.8
 */
 @Override
 public <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationClass) {
 return getPackageInfo().getAnnotationsByType(annotationClass);
 }

 /**
 * @since 1.5
 */
 public Annotation[] getAnnotations() {
 return getPackageInfo().getAnnotations();
 }

 /**
 * @throws NullPointerException {@inheritDoc}
 * @since 1.8
 */
 @Override
 public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationClass) {
 return getPackageInfo().getDeclaredAnnotation(annotationClass);
 }

 /**
 * @throws NullPointerException {@inheritDoc}
 * @since 1.8
 */
 @Override
 public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationClass) {
 return getPackageInfo().getDeclaredAnnotationsByType(annotationClass);
 }

 /**
 * @since 1.5
 */
 public Annotation[] getDeclaredAnnotations() {
 return getPackageInfo().getDeclaredAnnotations();
 }

 /**
 * Construct a package instance for an unnamed module
 * with the specified version information.
 *
 * @apiNote
 * This method should not be called to define a Package for named module.
 *
 * @param name the name of the package
 * @param spectitle the title of the specification
 * @param specversion the version of the specification
 * @param specvendor the organization that maintains the specification
 * @param impltitle the title of the implementation
 * @param implversion the version of the implementation
 * @param implvendor the organization that maintains the implementation
 * @param sealbase code source where this Package comes from
 * @param loader defining class loader
 */
 Package(String name,
 String spectitle, String specversion, String specvendor,
 String impltitle, String implversion, String implvendor,
 URL sealbase, ClassLoader loader)
 {
 super(Objects.requireNonNull(name),
 loader != null ? loader.getUnnamedModule()
 : BootLoader.getUnnamedModule());

 this.versionInfo = VersionInfo.getInstance(spectitle, specversion,
 specvendor, impltitle,
 implversion, implvendor,
 sealbase);
 }

 Package(String name, Module module) {
 super(name, module);
 this.versionInfo = VersionInfo.NULL_VERSION_INFO;
 }

 /*
 * Versioning information. Only for packages in unnamed modules.
 */
 static class VersionInfo {
 static final VersionInfo NULL_VERSION_INFO
 = new VersionInfo(null, null, null, null, null, null, null);

 private final String specTitle;
 private final String specVersion;
 private final String specVendor;
 private final String implTitle;
 private final String implVersion;
 private final String implVendor;
 private final URL sealBase;

 static VersionInfo getInstance(String spectitle, String specversion,
 String specvendor, String impltitle,
 String implversion, String implvendor,
 URL sealbase) {
 if (spectitle == null && specversion == null &&
 specvendor == null && impltitle == null &&
 implversion == null && implvendor == null &&
 sealbase == null) {
 return NULL_VERSION_INFO;
 }
 return new VersionInfo(spectitle, specversion, specvendor,
 impltitle, implversion, implvendor,
 sealbase);
 }

 private VersionInfo(String spectitle, String specversion,
 String specvendor, String impltitle,
 String implversion, String implvendor,
 URL sealbase)
 {
 this.implTitle = impltitle;
 this.implVersion = implversion;
 this.implVendor = implvendor;
 this.specTitle = spectitle;
 this.specVersion = specversion;
 this.specVendor = specvendor;
 this.sealBase = sealbase;
 }
 }

 private final VersionInfo versionInfo;
 private Class<?> packageInfo;
}