//
// MessagePack for Java
//
// Copyright (C) 2009 - 2013 FURUHASHI Sadayuki
//
//    Licensed 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.msgpack.util;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Properties;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.tools.DiagnosticCollector;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.StandardLocation;
import javax.tools.ToolProvider;

import org.msgpack.template.TemplateRegistry;
import org.msgpack.template.builder.JavassistTemplateBuilder;

/**
 * This class is a template precompiler, which is used for saving templates that
 * <code>TemplateBuilder</code> generated. It saves templates as .class files.
 * Application enables to load the .class files and use templates.
 * 
 */
public class TemplatePrecompiler {

    private static final Logger LOG = Logger.getLogger(TemplatePrecompiler.class.getName());

    public static final String DEST = "msgpack.template.destdir";

    public static final String DEFAULT_DEST = ".";

    public static void saveTemplates(final String[] classNames)
            throws IOException, ClassNotFoundException {
        // TODO #MN
        TemplateRegistry registry = new TemplateRegistry(null);
        List<String> ret = new ArrayList<String>();
        for (String className : classNames) {
            matchClassNames(ret, className);
        }
        List<Class<?>> ret0 = toClass(ret);
        for (Class<?> c : ret0) {
            saveTemplateClass(registry, c);
        }
    }

    @SuppressWarnings("serial")
    private static void matchClassNames(List<String> ret, final String className)
            throws IOException {
        String packageName = className.substring(0, className.lastIndexOf('.'));
        String relativedName = className.substring(
                className.lastIndexOf('.') + 1, className.length());
        String patName = relativedName.replace("*", "(\\w+)");
        Pattern pat = Pattern.compile(patName);

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        JavaFileManager fm = compiler.getStandardFileManager(
                new DiagnosticCollector<JavaFileObject>(), null, null);
        HashSet<JavaFileObject.Kind> kind = new HashSet<JavaFileObject.Kind>() {
            {
                add(JavaFileObject.Kind.CLASS);
            }
        };

        for (JavaFileObject f : fm.list(StandardLocation.PLATFORM_CLASS_PATH, packageName, kind, false)) {
            String relatived0 = f.getName();
            String name0 = relatived0.substring(0, relatived0.length() - ".class".length());
            Matcher m = pat.matcher(name0);
            if (m.matches()) {
                String name = packageName + '.' + name0;
                if (!ret.contains(name)) {
                    ret.add(name);
                }
            }
        }
    }

    private static List<Class<?>> toClass(List<String> classNames)
            throws ClassNotFoundException {
        List<Class<?>> ret = new ArrayList<Class<?>>(classNames.size());
        ClassLoader cl = TemplatePrecompiler.class.getClassLoader();
        for (String className : classNames) {
            Class<?> c = cl.loadClass(className);
            ret.add(c);
        }
        return ret;
    }

    public static void saveTemplateClasses(TemplateRegistry registry, Class<?>[] targetClasses)
            throws IOException {
        for (Class<?> c : targetClasses) {
            saveTemplateClass(registry, c);
        }
    }

    public static void saveTemplateClass(TemplateRegistry registry, Class<?> targetClass) 
            throws IOException {
        LOG.info("Saving template of " + targetClass.getName() + "...");
        Properties props = System.getProperties();
        String distDirName = getDirName(props, DEST, DEFAULT_DEST);
        if (targetClass.isEnum()) {
            throw new UnsupportedOperationException(
                    "Not supported enum type yet: " + targetClass.getName());
        } else {
            new JavassistTemplateBuilder(registry).writeTemplate(targetClass,
                    distDirName);
        }
        LOG.info("Saved .class file of template class of " + targetClass.getName());
    }

    public static boolean deleteTemplateClass(Class<?> targetClass)
            throws IOException {
        LOG.info("Deleting template of " + targetClass.getName() + "...");
        Properties props = System.getProperties();
        String distDirName = getDirName(props, DEST, DEFAULT_DEST);
        String targetClassName = targetClass.getName();
        String targetClassFileName = targetClassName.replace('.',
                File.separatorChar) + "_$$_Template.class";
        File targetFile = new File(distDirName + File.separatorChar
                + targetClassFileName);
        boolean deleted = false;
        if (!targetFile.isDirectory() && targetFile.exists()) {
            deleted = targetFile.delete();
        }
        LOG.info("Deleted .class file of template class of " + targetClass.getName());
        return deleted;
    }

    private static String getDirName(Properties props, String dirName, String defaultDirName)
            throws IOException {
        String dName = props.getProperty(dirName, defaultDirName);
        File d = new File(dName);
        if (!d.isDirectory() && !d.exists()) {
            throw new IOException("Directory not exists: " + dName);
        }
        return d.getAbsolutePath();
    }

    public static void main(final String[] args) throws Exception {
        TemplatePrecompiler.saveTemplates(args);
    }
}