ExtensionManagerGenerator.java

/*******************************************************************************
 * Copyright (c) 2012-2017 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.util;

import org.apache.commons.io.FileUtils;
import org.eclipse.che.ide.api.extension.Extension;
import org.reflections.Reflections;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.regex.Pattern;

import static org.eclipse.che.util.IgnoreUnExistedResourcesReflectionConfigurationBuilder.*;

/**
 * Generates {ExtensionManager} class source
 *
 * @author <a href="mailto:nzamosenchuk@exoplatform.com">Nikolay Zamosenchuk</a>
 */
public class ExtensionManagerGenerator {

    /** Annotation to look for. */
    protected static final String EXT_ANNOTATION = "@Extension";

    /** Reg Exp that matches the "@Extension  ( ... )" */
    protected static final Pattern EXT_PATTERN = Pattern.compile(".*@Extension\\s*\\(.*\\).*", Pattern.DOTALL);

    /**
     * Path of the output class, it definitely should already exits. To ensure proper config.
     * File content will be overridden.
     */
    protected static final String EXT_MANAGER_PATH =
            "/org/eclipse/che/ide/client/ExtensionManager.java";

    /** Map containing <FullFQN, ClassName> */
    protected static final Map<String, String> EXTENSIONS_FQN = new HashMap<String, String>();

    /**
     * Entry point. --rootDir is the optional parameter.
     *
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        File rootFolder = GeneratorUtils.getRootFolder(args);
        System.out.println(" ------------------------------------------------------------------------ ");
        System.out.println(String.format("Searching for Extensions in %s", rootFolder.getAbsolutePath()));
        System.out.println(" ------------------------------------------------------------------------ ");
        // find all Extension FQNs
        findExtensions();
        generateExtensionManager(rootFolder);
    }

    /**
     * Generate to source of the Class
     *
     * @param rootFolder
     */
    public static void generateExtensionManager(File rootFolder) throws IOException {
        File extManager = new File(rootFolder, EXT_MANAGER_PATH);
        StringBuilder builder = new StringBuilder();
        builder.append("package org.eclipse.che.ide.client;\n\n");
        generateImports(builder);
        generateClass(builder);
        // flush content
        FileUtils.writeStringToFile(extManager, builder.toString());
    }

    /**
     * Generate Class declarations
     *
     * @param builder
     */
    public static void generateClass(StringBuilder builder) {
        // generate class header
        builder.append("/**\n");
        builder.append(" * THIS CLASS WILL BE OVERRIDDEN BY MAVEN BUILD. DON'T EDIT CLASS, IT WILL HAVE NO EFFECT.\n");
        builder.append(" */\n");
        builder.append("@Singleton\n");
        builder.append("@SuppressWarnings(\"rawtypes\")\n");
        builder.append("public class ExtensionManager\n");
        builder.append("{\n");
        builder.append("\n");

        // field
        builder.append(GeneratorUtils.TAB)
               .append("/** Contains the map will all the Extension Providers <FullClassFQN, Provider>. */\n");
        builder.append(GeneratorUtils.TAB)
               .append("protected final Map<String, Provider> extensions = new HashMap<>();\n\n");

        // generate constructor
        builder.append(GeneratorUtils.TAB)
               .append("/** Constructor that accepts all the Extension found in IDE package */\n");
        builder.append(GeneratorUtils.TAB).append("@Inject\n");
        builder.append(GeneratorUtils.TAB).append("public ExtensionManager(\n");

        // paste args here
        Iterator<Entry<String, String>> entryIterator = EXTENSIONS_FQN.entrySet().iterator();
        while (entryIterator.hasNext()) {
            // <FullFQN, ClassName>
            Entry<String, String> extensionEntry = entryIterator.next();
            String hasComma = entryIterator.hasNext() ? "," : "";
            // add constructor argument like:
            // fullFQN classNameToLowerCase,
            String classFQN = String.format("Provider<%s>", extensionEntry.getKey());
            String variableName = extensionEntry.getValue().toLowerCase();
            builder.append(GeneratorUtils.TAB2).append(classFQN).append(" ").append(variableName).append(hasComma).append("\n");
        }

        builder.append(GeneratorUtils.TAB).append(")\n");
        builder.append(GeneratorUtils.TAB).append("{\n");

        // paste add here
        for (Entry<String, String> extension : EXTENSIONS_FQN.entrySet()) {
            String fullFqn = extension.getKey();
            String variableName = extension.getValue().toLowerCase();

            String putStatement = String.format("this.extensions.put(\"%s\",%s);%n", fullFqn, variableName);
            builder.append(GeneratorUtils.TAB2).append(putStatement);
        }

        // close constructor
        builder.append(GeneratorUtils.TAB).append("}\n\n");

        // generate getter
        builder.append(GeneratorUtils.TAB)
               .append("/** Returns  the map will all the Extension Providers <FullClassFQN, Provider>. */\n");
        builder.append(GeneratorUtils.TAB).append("public Map<String, Provider> getExtensions()\n");
        builder.append(GeneratorUtils.TAB).append("{\n");
        builder.append(GeneratorUtils.TAB2).append("return extensions;\n");
        builder.append(GeneratorUtils.TAB).append("}\n");

        // close class
        builder.append("}\n");

    }

    /**
     * Generate imports
     *
     * @param builder
     */
    public static void generateImports(StringBuilder builder) {

        builder.append("import com.google.inject.Inject;\n");
        builder.append("import com.google.inject.Provider;\n");
        builder.append("import com.google.inject.Singleton;\n");

        builder.append("import java.util.HashMap;\n");
        builder.append("import java.util.Map;\n");
    }

    /**
     * Find all the Java Classes that have proper @Extension declaration
     *
     * @throws IOException
     */
    @SuppressWarnings("unchecked")
    public static void findExtensions() throws IOException {
        Reflections reflection = new Reflections(getConfigurationBuilder());
        Set<Class<?>> classes = reflection.getTypesAnnotatedWith(Extension.class);
        for (Class clazz : classes) {
            EXTENSIONS_FQN.put(clazz.getCanonicalName(), clazz.getSimpleName());
            System.out.println(String.format("New Extension Found: %s", clazz.getCanonicalName()));
        }
        System.out.println(String.format("Found: %d extensions", EXTENSIONS_FQN.size()));
    }
}