/**

  * Back 2 Browser Bytecode Translator

  * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, version 2 of the License.

  *

  * This program 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 for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. Look for COPYING file in the top folder.

  * If not, see http://opensource.org/licenses/GPL-2.0.

  */

 package org.apidesign.bck2brwsr.htmlpage;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.OutputStreamWriter;

 import java.io.Writer;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 import java.util.Locale;

 import java.util.Set;

 import javax.annotation.processing.AbstractProcessor;

 import javax.annotation.processing.Completion;

 import javax.annotation.processing.Completions;

 import javax.annotation.processing.Processor;

 import javax.annotation.processing.RoundEnvironment;

 import javax.annotation.processing.SupportedAnnotationTypes;

 import javax.lang.model.element.AnnotationMirror;

 import javax.lang.model.element.Element;

 import javax.lang.model.element.ElementKind;

 import javax.lang.model.element.ExecutableElement;

 import javax.lang.model.element.Modifier;

 import javax.lang.model.element.PackageElement;

 import javax.lang.model.element.TypeElement;

 import javax.lang.model.type.TypeMirror;

 import javax.tools.Diagnostic;

 import javax.tools.FileObject;

 import javax.tools.StandardLocation;

 import org.apidesign.bck2brwsr.htmlpage.api.On;

 import org.apidesign.bck2brwsr.htmlpage.api.Page;

 import org.openide.util.lookup.ServiceProvider;

 /** Annotation processor to process an XHTML page and generate appropriate 

  * "id" file.

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  */

 @ServiceProvider(service=Processor.class)

 @SupportedAnnotationTypes({

     "org.apidesign.bck2brwsr.htmlpage.api.Page",

     "org.apidesign.bck2brwsr.htmlpage.api.On"

 })

 public final class PageProcessor extends AbstractProcessor {

     @Override

     public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {

         for (Element e : roundEnv.getElementsAnnotatedWith(Page.class)) {

             Page p = e.getAnnotation(Page.class);

             if (p == null) {

                 continue;

             }

             PackageElement pe = (PackageElement)e.getEnclosingElement();

             String pkg = pe.getQualifiedName().toString();

             ProcessPage pp;

             try {

                 InputStream is = openStream(pkg, p.xhtml());

                 pp = ProcessPage.readPage(is);

                 is.close();

             } catch (IOException iOException) {

                 processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "Can't read " + p.xhtml(), e);

                 return false;

             }

             Writer w;

             String className = p.className();

             if (className.isEmpty()) {

                 int indx = p.xhtml().indexOf('.');

                 className = p.xhtml().substring(0, indx);

             }

             try {

                 FileObject java = processingEnv.getFiler().createSourceFile(pkg + '.' + className, e);

                 w = new OutputStreamWriter(java.openOutputStream());

                 try {

                     w.append("package " + pkg + ";\n");

                     w.append("import org.apidesign.bck2brwsr.htmlpage.api.*;\n");

                     w.append("class ").append(className).append(" {\n");

                     for (String id : pp.ids()) {

                         String tag = pp.tagNameForId(id);

                         String type = type(tag);

                         w.append("  ").append("public static final ").

                             append(type).append(' ').append(cnstnt(id)).append(" = new ").

                             append(type).append("(\"").append(id).append("\");\n");

                     }

                     w.append("  static {\n");

                     if (!initializeOnClick(pe, w, pp)) {

                         return false;

                     }

                     w.append("  }\n");

                     w.append("}\n");

                 } finally {

                     w.close();

                 }

             } catch (IOException ex) {

                 processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "Can't create " + className + ".java", e);

                 return false;

             }

         }

         return true;

     }

     private InputStream openStream(String pkg, String name) throws IOException {

         try {

             FileObject fo = processingEnv.getFiler().getResource(

                 StandardLocation.SOURCE_PATH, pkg, name);

             return fo.openInputStream();

         } catch (IOException ex) {

             return processingEnv.getFiler().getResource(StandardLocation.CLASS_OUTPUT, pkg, name).openInputStream();

         }

     }

     private static String type(String tag) {

         if (tag.equals("title")) {

             return "Title";

         }

         if (tag.equals("button")) {

             return "Button";

         }

         if (tag.equals("input")) {

             return "Input";

         }

         return "Element";

     }

     private static String cnstnt(String id) {

         return id.toUpperCase(Locale.ENGLISH).replace('.', '_');

     }

     private boolean initializeOnClick(PackageElement pe, Writer w, ProcessPage pp) throws IOException {

         TypeMirror stringType = processingEnv.getElementUtils().getTypeElement("java.lang.String").asType();

         for (Element clazz : pe.getEnclosedElements()) {

             if (clazz.getKind() != ElementKind.CLASS) {

                 continue;

             }

             TypeElement type = (TypeElement)clazz;

             for (Element method : clazz.getEnclosedElements()) {

                 On oc = method.getAnnotation(On.class);

                 if (oc != null) {

                     for (String id : oc.id()) {

                         if (pp.tagNameForId(id) == null) {

                             processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "id = " + id + " does not exist in the HTML page. Found only " + pp.ids(), method);

                             return false;

                         }

                         ExecutableElement ee = (ExecutableElement)method;

                         boolean hasParam;

                         if (ee.getParameters().isEmpty()) {

                             hasParam = false;

                         } else {

                             if (ee.getParameters().size() != 1 || ee.getParameters().get(0).asType() != stringType) {

                                 processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "@On method should either have no arguments or one String argument", ee);

                                 return false;

                             }

                             hasParam = true;

                         }

                         if (!ee.getModifiers().contains(Modifier.STATIC)) {

                             processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "@On method has to be static", ee);

                             return false;

                         }

                         if (ee.getModifiers().contains(Modifier.PRIVATE)) {

                             processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, "@On method can't be private", ee);

                             return false;

                         }

                         w.append("  OnEvent." + oc.event()).append(".of(").append(cnstnt(id)).

                             append(").perform(new Runnable() { public void run() {\n");

                         w.append("    ").append(type.getSimpleName().toString()).

                             append('.').append(ee.getSimpleName()).append("(");

                         if (hasParam) {

                             w.append("\"").append(id).append("\"");

                         }

                         w.append(");\n");

                         w.append("  }});\n");

                     }           

                 }

             }

         }

         return true;

     }

     @Override

     public Iterable<? extends Completion> getCompletions(

         Element element, AnnotationMirror annotation, 

         ExecutableElement member, String userText

     ) {

         if (!userText.startsWith("\"")) {

             return Collections.emptyList();

         }

         Element cls = findClass(element);

         Page p = cls.getAnnotation(Page.class);

         PackageElement pe = (PackageElement) cls.getEnclosingElement();

         String pkg = pe.getQualifiedName().toString();

         ProcessPage pp;

         try {

             InputStream is = openStream(pkg, p.xhtml());

             pp = ProcessPage.readPage(is);

             is.close();

         } catch (IOException iOException) {

             return Collections.emptyList();

         }

         List<Completion> cc = new ArrayList<Completion>();

         userText = userText.substring(1);

         for (String id : pp.ids()) {

             if (id.startsWith(userText)) {

                 cc.add(Completions.of("\"" + id + "\"", id));

             }

         }

         return cc;

     }

     private static Element findClass(Element e) {

         if (e == null) {

             return null;

         }

         Page p = e.getAnnotation(Page.class);

         if (p != null) {

             return e;

         }

         return e.getEnclosingElement();

     }

 }