/**

 * 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();

    }

}