/*

 * Copyright (c) 1998, 2016, 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

 * or visit www.oracle.com if you need additional information or have any

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 */

package jdk.javadoc.internal.doclets.toolkit.util;

import java.io.*;

import java.net.*;

import java.util.HashMap;

import java.util.Map;

import javax.lang.model.element.Element;

import javax.lang.model.element.PackageElement;

import javax.tools.Diagnostic;

import javax.tools.DocumentationTool;

import jdk.javadoc.doclet.Reporter;

import jdk.javadoc.internal.doclets.toolkit.Configuration;

/**

 * Process and manage "-link" and "-linkoffline" to external packages. The

 * options "-link" and "-linkoffline" both depend on the fact that Javadoc now

 * generates "package-list"(lists all the packages which are getting

 * documented) file in the current or the destination directory, while

 * generating the documentation.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 *

 * @author Atul M Dambalkar

 * @author Robert Field

 */

public class Extern {

    /**

     * Map package names onto Extern Item objects.

     * Lazily initialized.

     */

    private Map<String, Item> packageToItemMap;

    /**

     * The global configuration information for this run.

     */

    private final Configuration configuration;

    /**

     * True if we are using -linkoffline and false if -link is used instead.

     */

    private boolean linkoffline = false;

    /**

     * Stores the info for one external doc set

     */

    private class Item {

        /**

         * Package name, found in the "package-list" file in the {@link path}.

         */

        final String packageName;

        /**

         * The URL or the directory path at which the package documentation will be

         * avaliable.

         */

        final String path;

        /**

         * If given path is directory path then true else if it is a URL then false.

         */

        final boolean relative;

        /**

         * Constructor to build a Extern Item object and map it with the package name.

         * If the same package name is found in the map, then the first mapped

         * Item object or offline location will be retained.

         *

         * @param packageName Package name found in the "package-list" file.

         * @param path        URL or Directory path from where the "package-list"

         * file is picked.

         * @param relative    True if path is URL, false if directory path.

         */

        Item(String packageName, String path, boolean relative) {

            this.packageName = packageName;

            this.path = path;

            this.relative = relative;

            if (packageToItemMap == null) {

                packageToItemMap = new HashMap<>();

            }

            if (!packageToItemMap.containsKey(packageName)) { // save the previous

                packageToItemMap.put(packageName, this);        // mapped location

            }

        }

        /**

         * String representation of "this" with packagename and the path.

         */

        public String toString() {

            return packageName + (relative? " -> " : " => ") + path;

        }

    }

    public Extern(Configuration configuration) {

        this.configuration = configuration;

    }

    /**

     * Determine if a element item is externally documented.

     *

     * @param element an Element.

     */

    public boolean isExternal(Element element) {

        if (packageToItemMap == null) {

            return false;

        }

        PackageElement pe = configuration.utils.containingPackage(element);

        if (pe.isUnnamed()) {

            return false;

        }

        return packageToItemMap.get(configuration.utils.getPackageName(pe)) != null;

    }

    /**

     * Convert a link to be an external link if appropriate.

     *

     * @param pkgName The package name.

     * @param relativepath    The relative path.

     * @param filename    The link to convert.

     * @return if external return converted link else return null

     */

    public DocLink getExternalLink(String pkgName, DocPath relativepath, String filename) {

        return getExternalLink(pkgName, relativepath, filename, null);

    }

    public DocLink getExternalLink(String pkgName, DocPath relativepath, String filename,

            String memberName) {

        Item fnd = findPackageItem(pkgName);

        if (fnd == null)

            return null;

        DocPath p = fnd.relative ?

                relativepath.resolve(fnd.path).resolve(filename) :

                DocPath.create(fnd.path).resolve(filename);

        return new DocLink(p, "is-external=true", memberName);

    }

    /**

     * Build the extern package list from given URL or the directory path.

     * Flag error if the "-link" or "-linkoffline" option is already used.

     *

     * @param url        URL or Directory path.

     * @param pkglisturl This can be another URL for "package-list" or ordinary

     *                   file.

     * @param reporter   The <code>DocErrorReporter</code> used to report errors.

     * @param linkoffline True if -linkoffline is used and false if -link is used.

     */

    public boolean link(String url, String pkglisturl, Reporter reporter, boolean linkoffline) {

        this.linkoffline = linkoffline;

        try {

            url = adjustEndFileSeparator(url);

            if (isUrl(pkglisturl)) {

                readPackageListFromURL(url, toURL(adjustEndFileSeparator(pkglisturl)));

            } else {

                readPackageListFromFile(url, DocFile.createFileForInput(configuration, pkglisturl));

            }

            return true;

        } catch (Fault f) {

            reporter.print(Diagnostic.Kind.WARNING, f.getMessage());

            return false;

        }

    }

    private URL toURL(String url) throws Fault {

        try {

            return new URL(url);

        } catch (MalformedURLException e) {

            throw new Fault(configuration.getText("doclet.MalformedURL", url), e);

        }

    }

    private class Fault extends Exception {

        private static final long serialVersionUID = 0;

        Fault(String msg, Exception cause) {

            super(msg, cause);

        }

    }

    /**

     * Get the Extern Item object associated with this package name.

     *

     * @param pkgName Package name.

     */

    private Item findPackageItem(String pkgName) {

        if (packageToItemMap == null) {

            return null;

        }

        return packageToItemMap.get(pkgName);

    }

    /**

     * If the URL or Directory path is missing end file separator, add that.

     */

    private String adjustEndFileSeparator(String url) {

        return url.endsWith("/") ? url : url + '/';

    }

    /**

     * Fetch the URL and read the "package-list" file.

     *

     * @param urlpath        Path to the packages.

     * @param pkglisturlpath URL or the path to the "package-list" file.

     */

    private void readPackageListFromURL(String urlpath, URL pkglisturlpath) throws Fault {

        try {

            URL link = pkglisturlpath.toURI().resolve(DocPaths.PACKAGE_LIST.getPath()).toURL();

            readPackageList(link.openStream(), urlpath, false);

        } catch (URISyntaxException | MalformedURLException exc) {

            throw new Fault(configuration.getText("doclet.MalformedURL", pkglisturlpath.toString()), exc);

        }

        catch (IOException exc) {

            throw new Fault(configuration.getText("doclet.URL_error", pkglisturlpath.toString()), exc);

        }

    }

    /**

     * Read the "package-list" file which is available locally.

     *

     * @param path URL or directory path to the packages.

     * @param pkgListPath Path to the local "package-list" file.

     */

    private void readPackageListFromFile(String path, DocFile pkgListPath)

            throws Fault {

        DocFile file = pkgListPath.resolve(DocPaths.PACKAGE_LIST);

        if (! (file.isAbsolute() || linkoffline)){

            file = file.resolveAgainst(DocumentationTool.Location.DOCUMENTATION_OUTPUT);

        }

        try {

            if (file.exists() && file.canRead()) {

                boolean pathIsRelative =

                readPackageList(file.openInputStream(), path, pathIsRelative);

            } else {

                throw new Fault(configuration.getText("doclet.File_error", file.getPath()), null);

            }

        } catch (IOException exc) {

           throw new Fault(configuration.getText("doclet.File_error", file.getPath()), exc);

        }

    }

    /**

     * Read the file "package-list" and for each package name found, create

     * Extern object and associate it with the package name in the map.

     *

     * @param input    InputStream from the "package-list" file.

     * @param path     URL or the directory path to the packages.

     * @param relative Is path relative?

     */

    private void readPackageList(InputStream input, String path, boolean relative)

                         throws IOException {

        BufferedReader in = new BufferedReader(new InputStreamReader(input));

        StringBuilder strbuf = new StringBuilder();

        try {

            int c;

            while ((c = in.read()) >= 0) {

                char ch = (char)c;

                if (ch == '\n' || ch == '\r') {

                    if (strbuf.length() > 0) {

                        String packname = strbuf.toString();

                        String packpath = path +

                                      packname.replace('.', '/') + '/';

                        new Item(packname, packpath, relative);

                        strbuf.setLength(0);

                    }

                } else {

                    strbuf.append(ch);

                }

            }

        } finally {

            input.close();

        }

    }

    public boolean isUrl (String urlCandidate) {

        try {

            new URL(urlCandidate);

            //No exception was thrown, so this must really be a URL.

            return true;

        } catch (MalformedURLException e) {

            //Since exception is thrown, this must be a directory path.

            return false;

        }

    }

}