/*
 * 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.generator;

import javax.swing.text.MutableAttributeSet;
import javax.swing.text.html.HTML;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.parser.ParserDelegator;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Stack;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.maven.artifact.Artifact;
import org.apache.maven.artifact.DependencyResolutionRequiredException;
import org.apache.maven.plugin.descriptor.MojoDescriptor;
import org.apache.maven.plugin.descriptor.PluginDescriptor;
import org.apache.maven.project.MavenProject;
import org.apache.maven.reporting.MavenReport;
import org.codehaus.plexus.component.repository.ComponentDependency;
import org.codehaus.plexus.util.StringUtils;
import org.codehaus.plexus.util.xml.XMLWriter;
import org.w3c.tidy.Tidy;

/**
 * Convenience methods to play with Maven plugins.
 *
 * @author jdcasey
 */
public final class GeneratorUtils {
    private GeneratorUtils() {
        // nop
    }

    /**
     * @param w not null writer
     * @param pluginDescriptor not null
     */
    public static void writeDependencies(XMLWriter w, PluginDescriptor pluginDescriptor) {
        w.startElement("dependencies");

        List<ComponentDependency> deps = pluginDescriptor.getDependencies();
        for (ComponentDependency dep : deps) {
            w.startElement("dependency");

            element(w, "groupId", dep.getGroupId());

            element(w, "artifactId", dep.getArtifactId());

            element(w, "type", dep.getType());

            element(w, "version", dep.getVersion());

            w.endElement();
        }

        w.endElement();
    }

    /**
     * @param w not null writer
     * @param name  not null
     * @param value could be null
     */
    public static void element(XMLWriter w, String name, String value) {
        w.startElement(name);

        if (value == null) {
            value = "";
        }

        w.writeText(value);

        w.endElement();
    }

    /**
     * @param artifacts not null collection of <code>Artifact</code>
     * @return list of component dependencies, without in provided scope
     */
    public static List<ComponentDependency> toComponentDependencies(Collection<Artifact> artifacts) {
        List<ComponentDependency> componentDeps = new LinkedList<>();

        for (Artifact artifact : artifacts) {
            if (Artifact.SCOPE_PROVIDED.equals(artifact.getScope())) {
                continue;
            }

            ComponentDependency cd = new ComponentDependency();

            cd.setArtifactId(artifact.getArtifactId());
            cd.setGroupId(artifact.getGroupId());
            cd.setVersion(artifact.getVersion());
            cd.setType(artifact.getType());

            componentDeps.add(cd);
        }

        return componentDeps;
    }

    /**
     * Returns a literal replacement <code>String</code> for the specified <code>String</code>. This method
     * produces a <code>String</code> that will work as a literal replacement <code>s</code> in the
     * <code>appendReplacement</code> method of the {@link Matcher} class. The <code>String</code> produced will
     * match the sequence of characters in <code>s</code> treated as a literal sequence. Slashes ('\') and dollar
     * signs ('$') will be given no special meaning. TODO: copied from Matcher class of Java 1.5, remove once target
     * platform can be upgraded
     *
     * @see <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/regex/Matcher.html">java.util.regex.Matcher</a>
     * @param s The string to be literalized
     * @return A literal string replacement
     */
    private static String quoteReplacement(String s) {
        if ((s.indexOf('\\') == -1) && (s.indexOf('$') == -1)) {
            return s;
        }

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == '\\') {
                sb.append('\\');
                sb.append('\\');
            } else if (c == '$') {
                sb.append('\\');
                sb.append('$');
            } else {
                sb.append(c);
            }
        }

        return sb.toString();
    }

    /**
     * Decodes javadoc inline tags into equivalent HTML tags. For instance, the inline tag "{@code <A&B>}" should be
     * rendered as "<code>&lt;A&amp;B&gt;</code>".
     *
     * @param description The javadoc description to decode, may be <code>null</code>.
     * @return The decoded description, never <code>null</code>.
     * @deprecated Only used for non java extractor
     */
    @Deprecated
    static String decodeJavadocTags(String description) {
        if (StringUtils.isEmpty(description)) {
            return "";
        }

        StringBuffer decoded = new StringBuffer(description.length() + 1024);

        Matcher matcher = Pattern.compile("\\{@(\\w+)\\s*([^\\}]*)\\}").matcher(description);
        while (matcher.find()) {
            String tag = matcher.group(1);
            String text = matcher.group(2);
            text = StringUtils.replace(text, "&", "&amp;");
            text = StringUtils.replace(text, "<", "&lt;");
            text = StringUtils.replace(text, ">", "&gt;");
            if ("code".equals(tag)) {
                text = "<code>" + text + "</code>";
            } else if ("link".equals(tag) || "linkplain".equals(tag) || "value".equals(tag)) {
                String pattern = "(([^#\\.\\s]+\\.)*([^#\\.\\s]+))?" + "(#([^\\(\\s]*)(\\([^\\)]*\\))?\\s*(\\S.*)?)?";
                final int label = 7;
                final int clazz = 3;
                final int member = 5;
                final int args = 6;
                Matcher link = Pattern.compile(pattern).matcher(text);
                if (link.matches()) {
                    text = link.group(label);
                    if (StringUtils.isEmpty(text)) {
                        text = link.group(clazz);
                        if (StringUtils.isEmpty(text)) {
                            text = "";
                        }
                        if (StringUtils.isNotEmpty(link.group(member))) {
                            if (StringUtils.isNotEmpty(text)) {
                                text += '.';
                            }
                            text += link.group(member);
                            if (StringUtils.isNotEmpty(link.group(args))) {
                                text += "()";
                            }
                        }
                    }
                }
                if (!"linkplain".equals(tag)) {
                    text = "<code>" + text + "</code>";
                }
            }
            matcher.appendReplacement(decoded, (text != null) ? quoteReplacement(text) : "");
        }
        matcher.appendTail(decoded);

        return decoded.toString();
    }

    /**
     * Fixes some javadoc comment to become a valid XHTML snippet.
     *
     * @param description Javadoc description with HTML tags, may be <code>null</code>.
     * @return The description with valid XHTML tags, never <code>null</code>.
     * @deprecated Redundant for java extractor
     */
    @Deprecated
    public static String makeHtmlValid(String description) {

        if (StringUtils.isEmpty(description)) {
            return "";
        }

        String commentCleaned = decodeJavadocTags(description);

        // Using jTidy to clean comment
        Tidy tidy = new Tidy();
        tidy.setDocType("loose");
        tidy.setXHTML(true);
        tidy.setXmlOut(true);
        tidy.setInputEncoding("UTF-8");
        tidy.setOutputEncoding("UTF-8");
        tidy.setMakeClean(true);
        tidy.setNumEntities(true);
        tidy.setQuoteNbsp(false);
        tidy.setQuiet(true);
        tidy.setShowWarnings(true);

        ByteArrayOutputStream out = new ByteArrayOutputStream(commentCleaned.length() + 256);
        tidy.parse(new ByteArrayInputStream(commentCleaned.getBytes(StandardCharsets.UTF_8)), out);
        commentCleaned = new String(out.toByteArray(), StandardCharsets.UTF_8);

        if (StringUtils.isEmpty(commentCleaned)) {
            return "";
        }

        // strip the header/body stuff
        String ls = System.getProperty("line.separator");
        int startPos = commentCleaned.indexOf("<body>" + ls) + 6 + ls.length();
        int endPos = commentCleaned.indexOf(ls + "</body>");
        commentCleaned = commentCleaned.substring(startPos, endPos);

        return commentCleaned;
    }

    /**
     * Converts a HTML fragment as extracted from a javadoc comment to a plain text string. This method tries to retain
     * as much of the text formatting as possible by means of the following transformations:
     * <ul>
     * <li>List items are converted to leading tabs (U+0009), followed by the item number/bullet, another tab and
     * finally the item contents. Each tab denotes an increase of indentation.</li>
     * <li>Flow breaking elements as well as literal line terminators in preformatted text are converted to a newline
     * (U+000A) to denote a mandatory line break.</li>
     * <li>Consecutive spaces and line terminators from character data outside of preformatted text will be normalized
     * to a single space. The resulting space denotes a possible point for line wrapping.</li>
     * <li>Each space in preformatted text will be converted to a non-breaking space (U+00A0).</li>
     * </ul>
     *
     * @param html The HTML fragment to convert to plain text, may be <code>null</code>.
     * @return A string with HTML tags converted into pure text, never <code>null</code>.
     * @since 2.4.3
     * @deprecated Replaced by {@link HtmlToPlainTextConverter}
     */
    @Deprecated
    public static String toText(String html) {
        if (StringUtils.isEmpty(html)) {
            return "";
        }

        final StringBuilder sb = new StringBuilder();

        HTMLEditorKit.Parser parser = new ParserDelegator();
        HTMLEditorKit.ParserCallback htmlCallback = new MojoParserCallback(sb);

        try {
            parser.parse(new StringReader(makeHtmlValid(html)), htmlCallback, true);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        return sb.toString().replace('\"', '\''); // for CDATA
    }

    /**
     * ParserCallback implementation.
     */
    private static class MojoParserCallback extends HTMLEditorKit.ParserCallback {
        /**
         * Holds the index of the current item in a numbered list.
         */
        class Counter {
            int value;
        }

        /**
         * A flag whether the parser is currently in the body element.
         */
        private boolean body;

        /**
         * A flag whether the parser is currently processing preformatted text, actually a counter to track nesting.
         */
        private int preformatted;

        /**
         * The current indentation depth for the output.
         */
        private int depth;

        /**
         * A stack of {@link Counter} objects corresponding to the nesting of (un-)ordered lists. A
         * <code>null</code> element denotes an unordered list.
         */
        private Stack<Counter> numbering = new Stack<>();

        /**
         * A flag whether an implicit line break is pending in the output buffer. This flag is used to postpone the
         * output of implicit line breaks until we are sure that are not to be merged with other implicit line
         * breaks.
         */
        private boolean pendingNewline;

        /**
         * A flag whether we have just parsed a simple tag.
         */
        private boolean simpleTag;

        /**
         * The current buffer.
         */
        private final StringBuilder sb;

        /**
         * @param sb not null
         */
        MojoParserCallback(StringBuilder sb) {
            this.sb = sb;
        }

        /** {@inheritDoc} */
        @Override
        public void handleSimpleTag(HTML.Tag t, MutableAttributeSet a, int pos) {
            simpleTag = true;
            if (body && HTML.Tag.BR.equals(t)) {
                newline(false);
            }
        }

        /** {@inheritDoc} */
        @Override
        public void handleStartTag(HTML.Tag t, MutableAttributeSet a, int pos) {
            simpleTag = false;
            if (body && (t.breaksFlow() || t.isBlock())) {
                newline(true);
            }
            if (HTML.Tag.OL.equals(t)) {
                numbering.push(new Counter());
            } else if (HTML.Tag.UL.equals(t)) {
                numbering.push(null);
            } else if (HTML.Tag.LI.equals(t)) {
                Counter counter = numbering.peek();
                if (counter == null) {
                    text("-\t");
                } else {
                    text(++counter.value + ".\t");
                }
                depth++;
            } else if (HTML.Tag.DD.equals(t)) {
                depth++;
            } else if (t.isPreformatted()) {
                preformatted++;
            } else if (HTML.Tag.BODY.equals(t)) {
                body = true;
            }
        }

        /** {@inheritDoc} */
        @Override
        public void handleEndTag(HTML.Tag t, int pos) {
            if (HTML.Tag.OL.equals(t) || HTML.Tag.UL.equals(t)) {
                numbering.pop();
            } else if (HTML.Tag.LI.equals(t) || HTML.Tag.DD.equals(t)) {
                depth--;
            } else if (t.isPreformatted()) {
                preformatted--;
            } else if (HTML.Tag.BODY.equals(t)) {
                body = false;
            }
            if (body && (t.breaksFlow() || t.isBlock()) && !HTML.Tag.LI.equals(t)) {
                if ((HTML.Tag.P.equals(t)
                                || HTML.Tag.PRE.equals(t)
                                || HTML.Tag.OL.equals(t)
                                || HTML.Tag.UL.equals(t)
                                || HTML.Tag.DL.equals(t))
                        && numbering.isEmpty()) {
                    pendingNewline = false;
                    newline(pendingNewline);
                } else {
                    newline(true);
                }
            }
        }

        /** {@inheritDoc} */
        @Override
        public void handleText(char[] data, int pos) {
            /*
             * NOTE: Parsers before JRE 1.6 will parse XML-conform simple tags like <br/> as "<br>" followed by
             * the text event ">..." so we need to watch out for the closing angle bracket.
             */
            int offset = 0;
            if (simpleTag && data[0] == '>') {
                simpleTag = false;
                for (++offset; offset < data.length && data[offset] <= ' '; ) {
                    offset++;
                }
            }
            if (offset < data.length) {
                String text = new String(data, offset, data.length - offset);
                text(text);
            }
        }

        /** {@inheritDoc} */
        @Override
        public void flush() {
            flushPendingNewline();
        }

        /**
         * Writes a line break to the plain text output.
         *
         * @param implicit A flag whether this is an explicit or implicit line break. Explicit line breaks are
         *            always written to the output whereas consecutive implicit line breaks are merged into a single
         *            line break.
         */
        private void newline(boolean implicit) {
            if (implicit) {
                pendingNewline = true;
            } else {
                flushPendingNewline();
                sb.append('\n');
            }
        }

        /**
         * Flushes a pending newline (if any).
         */
        private void flushPendingNewline() {
            if (pendingNewline) {
                pendingNewline = false;
                if (sb.length() > 0) {
                    sb.append('\n');
                }
            }
        }

        /**
         * Writes the specified character data to the plain text output. If the last output was a line break, the
         * character data will automatically be prefixed with the current indent.
         *
         * @param data The character data, must not be <code>null</code>.
         */
        private void text(String data) {
            flushPendingNewline();
            if (sb.length() <= 0 || sb.charAt(sb.length() - 1) == '\n') {
                for (int i = 0; i < depth; i++) {
                    sb.append('\t');
                }
            }
            String text;
            if (preformatted > 0) {
                text = data;
            } else {
                text = data.replace('\n', ' ');
            }
            sb.append(text);
        }
    }

    /**
     * Find the best package name, based on the number of hits of actual Mojo classes.
     *
     * @param pluginDescriptor not null
     * @return the best name of the package for the generated mojo
     */
    public static String discoverPackageName(PluginDescriptor pluginDescriptor) {
        Map<String, Integer> packageNames = new HashMap<>();

        List<MojoDescriptor> mojoDescriptors = pluginDescriptor.getMojos();
        if (mojoDescriptors == null) {
            return "";
        }
        for (MojoDescriptor descriptor : mojoDescriptors) {

            String impl = descriptor.getImplementation();
            if (StringUtils.equals(descriptor.getGoal(), "help") && StringUtils.equals("HelpMojo", impl)) {
                continue;
            }
            if (impl.lastIndexOf('.') != -1) {
                String name = impl.substring(0, impl.lastIndexOf('.'));
                if (packageNames.get(name) != null) {
                    int next = (packageNames.get(name)).intValue() + 1;
                    packageNames.put(name, Integer.valueOf(next));
                } else {
                    packageNames.put(name, Integer.valueOf(1));
                }
            } else {
                packageNames.put("", Integer.valueOf(1));
            }
        }

        String packageName = "";
        int max = 0;
        for (Map.Entry<String, Integer> entry : packageNames.entrySet()) {
            int value = entry.getValue().intValue();
            if (value > max) {
                max = value;
                packageName = entry.getKey();
            }
        }

        return packageName;
    }

    /**
     * @param impl a Mojo implementation, not null
     * @param project a MavenProject instance, could be null
     * @return <code>true</code> is the Mojo implementation implements <code>MavenReport</code>,
     * <code>false</code> otherwise.
     * @throws IllegalArgumentException if any
     */
    @SuppressWarnings("unchecked")
    public static boolean isMavenReport(String impl, MavenProject project) throws IllegalArgumentException {
        if (impl == null) {
            throw new IllegalArgumentException("mojo implementation should be declared");
        }

        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        if (project != null) {
            List<String> classPathStrings;
            try {
                classPathStrings = project.getCompileClasspathElements();
                if (project.getExecutionProject() != null) {
                    classPathStrings.addAll(project.getExecutionProject().getCompileClasspathElements());
                }
            } catch (DependencyResolutionRequiredException e) {
                throw new IllegalArgumentException(e);
            }

            List<URL> urls = new ArrayList<>(classPathStrings.size());
            for (String classPathString : classPathStrings) {
                try {
                    urls.add(new File(classPathString).toURL());
                } catch (MalformedURLException e) {
                    throw new IllegalArgumentException(e);
                }
            }

            classLoader = new URLClassLoader(urls.toArray(new URL[urls.size()]), classLoader);
        }

        try {
            Class<?> clazz = Class.forName(impl, false, classLoader);

            return MavenReport.class.isAssignableFrom(clazz);
        } catch (ClassNotFoundException e) {
            return false;
        }
    }
}