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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

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 * The contents of this file are subject to the terms of either the GNU

 * General Public License Version 2 only ("GPL") or the Common

 * Development and Distribution License("CDDL") (collectively, the

 * "License"). You may not use this file except in compliance with the

 * License. You can obtain a copy of the License at

 * http://www.netbeans.org/cddl-gplv2.html

 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

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 * The Original Software is NetBeans. The Initial Developer of the Original

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 * If you wish your version of this file to be governed by only the CDDL

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package org.netbeans.html.geo.impl;

import java.io.IOException;

import java.io.Writer;

import java.util.List;

import java.util.Locale;

import java.util.Set;

import java.util.logging.Level;

import java.util.logging.Logger;

import javax.annotation.processing.AbstractProcessor;

import javax.annotation.processing.Processor;

import javax.annotation.processing.RoundEnvironment;

import javax.annotation.processing.SupportedAnnotationTypes;

import javax.annotation.processing.SupportedSourceVersion;

import javax.lang.model.SourceVersion;

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.element.VariableElement;

import javax.lang.model.type.TypeMirror;

import javax.tools.Diagnostic;

import javax.tools.JavaFileObject;

import net.java.html.geo.OnLocation;

import net.java.html.geo.Position;

import net.java.html.geo.Position.Handle;

import org.openide.util.lookup.ServiceProvider;

/** Annotation processor to generate callbacks from {@link Handle} class.

 *

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

 */

@ServiceProvider(service=Processor.class)

@SupportedSourceVersion(SourceVersion.RELEASE_6)

@SupportedAnnotationTypes({

    "net.java.html.geo.OnLocation"

})

public final class GeoProcessor extends AbstractProcessor {

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

    @Override

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

        boolean ok = true;

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

            if (!processLocation(e)) {

                ok = false;

            }

        }

        return ok;

    }

    private void error(String msg, Element e) {

        processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, msg, e);

    }

    private boolean processLocation(Element e) {

        if (e.getKind() != ElementKind.METHOD) {

            return false;

        }

        ExecutableElement me = (ExecutableElement) e;

        OnLocation ol = e.getAnnotation(OnLocation.class);

        if (ol == null) {

            return true;

        }

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

            error("Method annotated by @OnLocation cannot be private", e);

            return false;

        }

        TypeMirror positionClass = processingEnv.getElementUtils().getTypeElement(Position.class.getName()).asType();

        final List<? extends VariableElement> params = me.getParameters();

        if (params.size() < 1 || !params.get(0).asType().equals(positionClass)) {

            error("Method annotated by @OnLocation first argument must be net.java.html.geo.Position!", e);

            return false;

        }

        String className = ol.className();

        if (className.isEmpty()) {

            String n = e.getSimpleName().toString();

            if (n.isEmpty()) {

                error("Empty method name", e);

                return false;

            }

            final String firstLetter = n.substring(0, 1).toUpperCase(Locale.ENGLISH);

            className = firstLetter + n.substring(1) + "Handle";

        }

        TypeElement te = (TypeElement)e.getEnclosingElement();

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

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

        final String fqn = pkg + "." + className;

        final boolean isStatic = me.getModifiers().contains(Modifier.STATIC);

        String sep;

        try {

            JavaFileObject fo = processingEnv.getFiler().createSourceFile(fqn, e);

            Writer w = fo.openWriter();

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

            w.append("class ").append(className).append(" extends net.java.html.geo.Position.Handle {\n");

            if (!isStatic) {

                w.append("  private final ").append(te.getSimpleName()).append(" $i;\n");

            }

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append("  private final ").append(p.asType().toString()).append(" ").append(p.getSimpleName()).append(";\n");

            }

            w.append("  private ").append(className).append("(boolean oneTime");

            w.append(", ").append(te.getSimpleName()).append(" i");

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append(", ").append(p.asType().toString()).append(" ").append(p.getSimpleName());

            }

            w.append(") {\n    super(oneTime);\n");

            if (!isStatic) {

                w.append("    this.$i = i;\n");

            }

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append("  this.").append(p.getSimpleName()).append(" = ").append(p.getSimpleName()).append(";\n");

            }

            w.append("}\n");

            w.append("  static net.java.html.geo.Position.Handle createQuery(");

            String inst;

            if (!isStatic) {

                w.append(te.getSimpleName()).append(" instance");

                inst = "instance";

                sep = ", ";

            } else {

                inst = "null";

                sep = "";

            }

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append(sep).append(p.asType().toString()).append(" ").append(p.getSimpleName());

                sep = ", ";

            }

            w.append(") { return new ").append(className).append("(true, ").append(inst);

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append(", ").append(p.getSimpleName());

            }

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

            w.append("  static net.java.html.geo.Position.Handle createWatch(");

            if (!isStatic) {

                w.append(te.getSimpleName()).append(" instance");

                sep = ", ";

            } else {

                sep = "";

            }

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append(sep).append(p.asType().toString()).append(" ").append(p.getSimpleName());

            }

            w.append(") { return new ").append(className).append("(false, ").append(inst);

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append(", ").append(p.getSimpleName());

            }

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

            w.append("  @Override protected void onError(Exception t) throws Throwable {\n");

            if (ol.onError().isEmpty()) {

                w.append("    t.printStackTrace();");

            } else {

                if (!findOnError(me, te, ol.onError(), isStatic)) {

                    return false;

                }

                if (isStatic) {

                    w.append("    ").append(te.getSimpleName()).append(".");

                } else {

                    w.append("    $i.");

                }

                w.append(ol.onError()).append("(t");

                for (int i = 1; i < params.size(); i++) {

                    final VariableElement p = params.get(i);

                    w.append(", ").append(p.getSimpleName());

                }

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

            }

            w.append("  }\n");

            w.append("  @Override protected void onLocation(net.java.html.geo.Position p) throws Throwable {\n");

            if (isStatic) {

                w.append("    ").append(te.getSimpleName()).append(".");

            } else {

                w.append("    $i.");

            }

            w.append(me.getSimpleName()).append("(p");

            for (int i = 1; i < params.size(); i++) {

                final VariableElement p = params.get(i);

                w.append(", ").append(p.getSimpleName());

            }

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

            w.append("  }\n");

            w.append("}\n");

            w.close();

        } catch (IOException ex) {

            Logger.getLogger(GeoProcessor.class.getName()).log(Level.SEVERE, null, ex);

            error("Can't write handler class: " + ex.getMessage(), e);

            return false;

        }

        return true;

    }

    private boolean findOnError(ExecutableElement errElem, TypeElement te, String name, boolean onlyStatic) {

        String err = null;

        METHODS: for (Element e : te.getEnclosedElements()) {

            if (e.getKind() != ElementKind.METHOD) {

                continue;

            }

            if (!e.getSimpleName().contentEquals(name)) {

                continue;

            }

            if (onlyStatic && !e.getModifiers().contains(Modifier.STATIC)) {

                errElem = (ExecutableElement) e;

                err = "Would have to be static";

                continue;

            }

            ExecutableElement ee = (ExecutableElement) e;

            TypeMirror excType = processingEnv.getElementUtils().getTypeElement(Exception.class.getName()).asType();

            final List<? extends VariableElement> params = ee.getParameters(); 

            if (params.size() < 1 || 

                !processingEnv.getTypeUtils().isAssignable(excType, ee.getParameters().get(0).asType())

            ) {

                errElem = (ExecutableElement) e;

                err = "Error method first argument needs to be Exception";

                continue;

            }

            final List<? extends Element> origParams = errElem.getParameters();

            if (params.size() != origParams.size()) {

                errElem = (ExecutableElement) e;

                err = "Error method must have the same parameters as @OnLocation one";

                continue;

            }

            for (int i = 1; i < origParams.size(); i++) {

                final TypeMirror t1 = params.get(i).asType();

                final TypeMirror t2 = origParams.get(i).asType();

                if (!processingEnv.getTypeUtils().isSameType(t1, t2)) {

                    errElem = (ExecutableElement) e;

                    err = "Error method must have the same parameters as @OnLocation one";

                    continue METHODS;

                }

            }

            return true;

        }

        if (err == null) {

            err = "Cannot find " + name + "(Exception) method in this class";

        }

        error(err, errElem);

        return false;

    }

}