/**

 * 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.StringWriter;

import java.io.Writer;

import java.lang.annotation.AnnotationTypeMismatchException;

import java.lang.annotation.IncompleteAnnotationException;

import java.lang.reflect.Method;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.WeakHashMap;

import javax.annotation.processing.AbstractProcessor;

import javax.annotation.processing.Completion;

import javax.annotation.processing.Completions;

import javax.annotation.processing.ProcessingEnvironment;

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.AnnotationValue;

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.ArrayType;

import javax.lang.model.type.MirroredTypeException;

import javax.lang.model.type.TypeKind;

import javax.lang.model.type.TypeMirror;

import javax.lang.model.util.Elements;

import javax.lang.model.util.Types;

import javax.tools.Diagnostic;

import javax.tools.FileObject;

import javax.tools.StandardLocation;

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

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

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

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

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

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

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

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

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.Model",

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

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

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

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

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

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

})

public final class PageProcessor extends AbstractProcessor {

    private final Map<Element,String> models = new WeakHashMap<>();

    private final Map<Element,Prprt[]> verify = new WeakHashMap<>();

    @Override

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

        boolean ok = true;

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

            if (!processModel(e)) {

                ok = false;

            }

        }

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

            if (!processPage(e)) {

                ok = false;

            }

        }

        if (roundEnv.processingOver()) {

            models.clear();

            for (Map.Entry<Element, Prprt[]> entry : verify.entrySet()) {

                TypeElement te = (TypeElement)entry.getKey();

                String fqn = processingEnv.getElementUtils().getBinaryName(te).toString();

                Element finalElem = processingEnv.getElementUtils().getTypeElement(fqn);

                if (finalElem == null) {

                    continue;

                }

                Prprt[] props;

                Model m = finalElem.getAnnotation(Model.class);

                if (m != null) {

                    props = Prprt.wrap(processingEnv, finalElem, m.properties());

                } else {

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

                    props = Prprt.wrap(processingEnv, finalElem, p.properties());

                }

                for (Prprt p : props) {

                    boolean[] isModel = { false };

                    boolean[] isEnum = { false };

                    boolean[] isPrimitive = { false };

                    String t = checkType(p, isModel, isEnum, isPrimitive);

                    if (isEnum[0]) {

                        continue;

                    }

                    if (isPrimitive[0]) {

                        continue;

                    }

                    if (isModel[0]) {

                        continue;

                    }

                    if ("java.lang.String".equals(t)) {

                        continue;

                    }

                    error("The type " + t + " should be defined by @Model annotation", entry.getKey());

                }

            }

            verify.clear();

        }

        return ok;

    }

    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 void error(String msg, Element e) {

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

    }

    private boolean processModel(Element e) {

        boolean ok = true;

        Model m = e.getAnnotation(Model.class);

        if (m == null) {

            return true;

        }

        String pkg = findPkgName(e);

        Writer w;

        String className = m.className();

        models.put(e, className);

        try {

            StringWriter body = new StringWriter();

            List<String> propsGetSet = new ArrayList<>();

            List<String> functions = new ArrayList<>();

            Map<String, Collection<String>> propsDeps = new HashMap<>();

            Map<String, Collection<String>> functionDeps = new HashMap<>();

            Prprt[] props = createProps(e, m.properties());

            if (!generateComputedProperties(body, props, e.getEnclosedElements(), propsGetSet, propsDeps)) {

                ok = false;

            }

            if (!generateOnChange(e, propsDeps, props, className, functionDeps)) {

                ok = false;

            }

            if (!generateProperties(e, body, props, propsGetSet, propsDeps, functionDeps)) {

                ok = false;

            }

            if (!generateFunctions(e, body, className, e.getEnclosedElements(), functions)) {

                ok = false;

            }

            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("import org.apidesign.bck2brwsr.htmlpage.KOList;\n");

                w.append("import org.apidesign.bck2brwsr.core.JavaScriptOnly;\n");

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

                w.append("  private boolean locked;\n");

                w.append("  private org.apidesign.bck2brwsr.htmlpage.Knockout ko;\n");

                w.append(body.toString());

                w.append("  private static Class<" + inPckName(e) + "> modelFor() { return null; }\n");

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

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

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

                w.append("  private void intKnckt() {\n");

                w.append("    ko = org.apidesign.bck2brwsr.htmlpage.Knockout.applyBindings(this, ");

                writeStringArray(propsGetSet, w);

                w.append(", ");

                writeStringArray(functions, w);

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

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

                w.append("  ").append(className).append("(Object json) {\n");

                int values = 0;

                for (int i = 0; i < propsGetSet.size(); i += 4) {

                    Prprt p = findPrprt(props, propsGetSet.get(i));

                    if (p == null) {

                        continue;

                    }

                    values++;

                }

                w.append("    Object[] ret = new Object[" + values + "];\n");

                w.append("    org.apidesign.bck2brwsr.htmlpage.ConvertTypes.extractJSON(json, new String[] {\n");

                for (int i = 0; i < propsGetSet.size(); i += 4) {

                    Prprt p = findPrprt(props, propsGetSet.get(i));

                    if (p == null) {

                        continue;

                    }

                    w.append("      \"").append(propsGetSet.get(i)).append("\",\n");

                }

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

                for (int i = 0, cnt = 0, prop = 0; i < propsGetSet.size(); i += 4) {

                    final String pn = propsGetSet.get(i);

                    Prprt p = findPrprt(props, pn);

                    if (p == null) {

                        continue;

                    }

                    boolean[] isModel = { false };

                    boolean[] isEnum = { false };

                    boolean isPrimitive[] = { false };

                    String type = checkType(props[prop++], isModel, isEnum, isPrimitive);

                    if (p.array()) {

                        w.append("if (ret[" + cnt + "] instanceof Object[]) {\n");

                        w.append("  for (Object e : ((Object[])ret[" + cnt + "])) {\n");

                        if (isModel[0]) {

                            w.append("    this.prop_").append(pn).append(".add(new ");

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

                        } else if (isEnum[0]) {

                            w.append("    this.prop_").append(pn);

                            w.append(".add(");

                            w.append(type).append(".valueOf((String)e));\n");

                        } else {

                            if (isPrimitive(type)) {

                                w.append("    this.prop_").append(pn).append(".add(((Number)e).");

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

                            } else {

                                w.append("    this.prop_").append(pn).append(".add((");

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

                            }

                        }

                        w.append("  }\n");

                        w.append("}\n");

                    } else {

                        if (isEnum[0]) {

                            w.append("    this.prop_").append(pn);

                            w.append(" = ");

                            w.append(type).append(".valueOf((String)ret[" + cnt + "]);\n");

                        } else if (isPrimitive(type)) {

                            w.append("    this.prop_").append(pn);

                            w.append(" = ((Number)").append("ret[" + cnt + "]).");

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

                        } else {

                            w.append("    this.prop_").append(pn);

                            w.append(" = (").append(type).append(')');

                            w.append("ret[" + cnt + "];\n");

                        }

                    }

                    cnt++;

                }

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

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

                writeToString(props, w);

                writeClone(className, props, w);

                w.append("}\n");

            } finally {

                w.close();

            }

        } catch (IOException ex) {

            error("Can't create " + className + ".java", e);

            return false;

        }

        return ok;

    }

    private boolean processPage(Element e) {

        boolean ok = true;

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

        if (p == null) {

            return true;

        }

        String pkg = findPkgName(e);

        ProcessPage pp;

        try (InputStream is = openStream(pkg, p.xhtml())) {

            pp = ProcessPage.readPage(is);

            is.close();

        } catch (IOException iOException) {

            error("Can't read " + p.xhtml() + " as " + iOException.getMessage(), e);

            ok = false;

            pp = null;

        }

        Writer w;

        String className = p.className();

        if (className.isEmpty()) {

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

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

        }

        try {

            StringWriter body = new StringWriter();

            List<String> propsGetSet = new ArrayList<>();

            List<String> functions = new ArrayList<>();

            Map<String, Collection<String>> propsDeps = new HashMap<>();

            Map<String, Collection<String>> functionDeps = new HashMap<>();

            Prprt[] props = createProps(e, p.properties());

            if (!generateComputedProperties(body, props, e.getEnclosedElements(), propsGetSet, propsDeps)) {

                ok = false;

            }

            if (!generateOnChange(e, propsDeps, props, className, functionDeps)) {

                ok = false;

            }

            if (!generateProperties(e, body, props, propsGetSet, propsDeps, functionDeps)) {

                ok = false;

            }

            if (!generateFunctions(e, body, className, e.getEnclosedElements(), functions)) {

                ok = false;

            }

            if (!generateReceive(e, body, className, e.getEnclosedElements(), functions)) {

                ok = false;

            }

            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("import org.apidesign.bck2brwsr.htmlpage.KOList;\n");

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

                w.append("  private boolean locked;\n");

                if (!initializeOnClick(className, (TypeElement) e, w, pp)) {

                    ok = false;

                } else {

                    if (pp != null) for (String id : pp.ids()) {

                        String tag = pp.tagNameForId(id);

                        String type = type(tag);

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

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

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

                    }

                }

                w.append("  private org.apidesign.bck2brwsr.htmlpage.Knockout ko;\n");

                w.append(body.toString());

                if (!propsGetSet.isEmpty()) {

                    w.write("public " + className + " applyBindings() {\n");

                    w.write("  ko = org.apidesign.bck2brwsr.htmlpage.Knockout.applyBindings(");

                    w.write(className + ".class, this, ");

                    writeStringArray(propsGetSet, w);

                    w.append(", ");

                    writeStringArray(functions, w);

                    w.write(");\n  return this;\n}\n");

                    w.write("public void triggerEvent(Element e, OnEvent ev) {\n");

                    w.write("  org.apidesign.bck2brwsr.htmlpage.Knockout.triggerEvent(e.getId(), ev.getElementPropertyName());\n");

                    w.write("}\n");

                }

                w.append("}\n");

            } finally {

                w.close();

            }

        } catch (IOException ex) {

            error("Can't create " + className + ".java", e);

            return false;

        }

        return ok;

    }

    private static String type(String tag) {

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

            return "Title";

        }

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

            return "Button";

        }

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

            return "Input";

        }

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

            return "Canvas";

        }

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

            return "Image";

        }

        return "Element";

    }

    private static String cnstnt(String id) {

        return id.replace('.', '_').replace('-', '_');

    }

    private boolean initializeOnClick(

        String className, TypeElement type, Writer w, ProcessPage pp

    ) throws IOException {

        boolean ok = true;

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

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

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

            //    continue;

           // }

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

            StringBuilder dispatch = new StringBuilder();

            int dispatchCnt = 0;

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

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

                if (oc != null) {

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

                        if (pp == null) {

                            error("id = " + id + " not found in HTML page.", method);

                            ok = false;

                            continue;

                        }

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

                            error("id = " + id + " does not exist in the HTML page. Found only " + pp.ids(), method);

                            ok = false;

                            continue;

                        }

                        ExecutableElement ee = (ExecutableElement)method;

                        CharSequence params = wrapParams(ee, id, className, "ev", null);

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

                            error("@On method has to be static", ee);

                            ok = false;

                            continue;

                        }

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

                            error("@On method can't be private", ee);

                            ok = false;

                            continue;

                        }

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

                            append(").perform(new OnDispatch(" + dispatchCnt + "));\n");

                        dispatch.

                            append("      case ").append(dispatchCnt).append(": ").

                            append(type.getSimpleName().toString()).

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

                            append(params).

                            append("); break;\n");

                        dispatchCnt++;

                    }

                }

            }

            w.append("  }\n");

            if (dispatchCnt > 0) {

                w.append("class OnDispatch implements OnHandler {\n");

                w.append("  private final int dispatch;\n");

                w.append("  OnDispatch(int d) { dispatch = d; }\n");

                w.append("  public void onEvent(Object ev) {\n");

                w.append("    switch (dispatch) {\n");

                w.append(dispatch);

                w.append("    }\n");

                w.append("  }\n");

                w.append("}\n");

            }

        }

        return ok;

    }

    @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);

        String pkg = findPkgName(cls);

        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<>();

        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();

    }

    private boolean generateProperties(

        Element where,

        Writer w, Prprt[] properties,

        Collection<String> props, 

        Map<String,Collection<String>> deps,

        Map<String,Collection<String>> functionDeps

    ) throws IOException {

        boolean ok = true;

        for (Prprt p : properties) {

            final String tn;

            tn = typeName(where, p);

            String[] gs = toGetSet(p.name(), tn, p.array());

            if (p.array()) {

                w.write("private KOList<" + tn + "> prop_" + p.name() + " = new KOList<" + tn + ">(\""

                    + p.name() + "\"");

                Collection<String> dependants = deps.get(p.name());

                if (dependants != null) {

                    for (String depProp : dependants) {

                        w.write(", ");

                        w.write('\"');

                        w.write(depProp);

                        w.write('\"');

                    }

                }

                w.write(")");

                dependants = functionDeps.get(p.name());

                if (dependants != null) {

                    w.write(".onChange(new Runnable() { public void run() {\n");

                    for (String call : dependants) {

                        w.append(call);

                    }

                    w.write("}})");

                }

                w.write(";\n");

                w.write("public java.util.List<" + tn + "> " + gs[0] + "() {\n");

                w.write("  if (locked) throw new IllegalStateException();\n");

                w.write("  prop_" + p.name() + ".assign(ko);\n");

                w.write("  return prop_" + p.name() + ";\n");

                w.write("}\n");

            } else {

                w.write("private " + tn + " prop_" + p.name() + ";\n");

                w.write("public " + tn + " " + gs[0] + "() {\n");

                w.write("  if (locked) throw new IllegalStateException();\n");

                w.write("  return prop_" + p.name() + ";\n");

                w.write("}\n");

                w.write("public void " + gs[1] + "(" + tn + " v) {\n");

                w.write("  if (locked) throw new IllegalStateException();\n");

                w.write("  prop_" + p.name() + " = v;\n");

                w.write("  if (ko != null) {\n");

                w.write("    ko.valueHasMutated(\"" + p.name() + "\");\n");

                Collection<String> dependants = deps.get(p.name());

                if (dependants != null) {

                    for (String depProp : dependants) {

                        w.write("    ko.valueHasMutated(\"" + depProp + "\");\n");

                    }

                }

                w.write("  }\n");

                dependants = functionDeps.get(p.name());

                if (dependants != null) {

                    for (String call : dependants) {

                        w.append(call);

                    }

                }

                w.write("}\n");

            }

            props.add(p.name());

            props.add(gs[2]);

            props.add(gs[3]);

            props.add(gs[0]);

        }

        return ok;

    }

    private boolean generateComputedProperties(

        Writer w, Prprt[] fixedProps,

        Collection<? extends Element> arr, Collection<String> props,

        Map<String,Collection<String>> deps

    ) throws IOException {

        boolean ok = true;

        for (Element e : arr) {

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

                continue;

            }

            if (e.getAnnotation(ComputedProperty.class) == null) {

                continue;

            }

            ExecutableElement ee = (ExecutableElement)e;

            final TypeMirror rt = ee.getReturnType();

            final Types tu = processingEnv.getTypeUtils();

            TypeMirror ert = tu.erasure(rt);

            String tn = fqn(ert, ee);

            boolean array = false;

            if (tn.equals("java.util.List")) {

                array = true;

            }

            final String sn = ee.getSimpleName().toString();

            String[] gs = toGetSet(sn, tn, array);

            w.write("public " + tn + " " + gs[0] + "() {\n");

            w.write("  if (locked) throw new IllegalStateException();\n");

            int arg = 0;

            for (VariableElement pe : ee.getParameters()) {

                final String dn = pe.getSimpleName().toString();

                if (!verifyPropName(pe, dn, fixedProps)) {

                    ok = false;

                }

                final String dt = fqn(pe.asType(), ee);

                String[] call = toGetSet(dn, dt, false);

                w.write("  " + dt + " arg" + (++arg) + " = ");

                w.write(call[0] + "();\n");

                Collection<String> depends = deps.get(dn);

                if (depends == null) {

                    depends = new LinkedHashSet<>();

                    deps.put(dn, depends);

                }

                depends.add(sn);

            }

            w.write("  try {\n");

            w.write("    locked = true;\n");

            w.write("    return " + fqn(ee.getEnclosingElement().asType(), ee) + '.' + e.getSimpleName() + "(");

            String sep = "";

            for (int i = 1; i <= arg; i++) {

                w.write(sep);

                w.write("arg" + i);

                sep = ", ";

            }

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

            w.write("  } finally {\n");

            w.write("    locked = false;\n");

            w.write("  }\n");

            w.write("}\n");

            props.add(e.getSimpleName().toString());

            props.add(gs[2]);

            props.add(null);

            props.add(gs[0]);

        }

        return ok;

    }

    private static String[] toGetSet(String name, String type, boolean array) {

        String n = Character.toUpperCase(name.charAt(0)) + name.substring(1);

        String bck2brwsrType = "L" + type.replace('.', '_') + "_2";

        if ("int".equals(type)) {

            bck2brwsrType = "I";

        }

        if ("double".equals(type)) {

            bck2brwsrType = "D";

        }

        String pref = "get";

        if ("boolean".equals(type)) {

            pref = "is";

            bck2brwsrType = "Z";

        }

        final String nu = n.replace('.', '_');

        if (array) {

            return new String[] { 

                "get" + n,

                null,

                "get" + nu + "__Ljava_util_List_2",

                null

            };

        }

        return new String[]{

            pref + n, 

            "set" + n, 

            pref + nu + "__" + bck2brwsrType,

            "set" + nu + "__V" + bck2brwsrType

        };

    }

    private String typeName(Element where, Prprt p) {

        String ret;

        boolean[] isModel = { false };

        boolean[] isEnum = { false };

        boolean isPrimitive[] = { false };

        ret = checkType(p, isModel, isEnum, isPrimitive);

        if (p.array()) {

            String bt = findBoxedType(ret);

            if (bt != null) {

                return bt;

            }

        }

        return ret;

    }

    private static String findBoxedType(String ret) {

        if (ret.equals("boolean")) {

            return Boolean.class.getName();

        }

        if (ret.equals("byte")) {

            return Byte.class.getName();

        }

        if (ret.equals("short")) {

            return Short.class.getName();

        }

        if (ret.equals("char")) {

            return Character.class.getName();

        }

        if (ret.equals("int")) {

            return Integer.class.getName();

        }

        if (ret.equals("long")) {

            return Long.class.getName();

        }

        if (ret.equals("float")) {

            return Float.class.getName();

        }

        if (ret.equals("double")) {

            return Double.class.getName();

        }

        return null;

    }

    private boolean verifyPropName(Element e, String propName, Prprt[] existingProps) {

        StringBuilder sb = new StringBuilder();

        String sep = "";

        for (Prprt Prprt : existingProps) {

            if (Prprt.name().equals(propName)) {

                return true;

            }

            sb.append(sep);

            sb.append('"');

            sb.append(Prprt.name());

            sb.append('"');

            sep = ", ";

        }

        error(

            propName + " is not one of known properties: " + sb

            , e

        );

        return false;

    }

    private static String findPkgName(Element e) {

        for (;;) {

            if (e.getKind() == ElementKind.PACKAGE) {

                return ((PackageElement)e).getQualifiedName().toString();

            }

            e = e.getEnclosingElement();

        }

    }

    private boolean generateFunctions(

        Element clazz, StringWriter body, String className, 

        List<? extends Element> enclosedElements, List<String> functions

    ) {

        for (Element m : enclosedElements) {

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

                continue;

            }

            ExecutableElement e = (ExecutableElement)m;

            OnFunction onF = e.getAnnotation(OnFunction.class);

            if (onF == null) {

                continue;

            }

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

                error("@OnFunction method needs to be static", e);

                return false;

            }

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

                error("@OnFunction method cannot be private", e);

                return false;

            }

            if (e.getReturnType().getKind() != TypeKind.VOID) {

                error("@OnFunction method should return void", e);

                return false;

            }

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

            body.append("private void ").append(n).append("(Object data, Object ev) {\n");

            body.append("  ").append(clazz.getSimpleName()).append(".").append(n).append("(");

            body.append(wrapParams(e, null, className, "ev", "data"));

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

            body.append("}\n");

            functions.add(n);

            functions.add(n + "__VLjava_lang_Object_2Ljava_lang_Object_2");

        }

        return true;

    }

    private boolean generateOnChange(Element clazz, Map<String,Collection<String>> propDeps,

        Prprt[] properties, String className, 

        Map<String, Collection<String>> functionDeps

    ) {

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

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

                continue;

            }

            ExecutableElement e = (ExecutableElement) m;

            OnPropertyChange onPC = e.getAnnotation(OnPropertyChange.class);

            if (onPC == null) {

                continue;

            }

            for (String pn : onPC.value()) {

                if (findPrprt(properties, pn) == null && findDerivedFrom(propDeps, pn).isEmpty()) {

                    error("No Prprt named '" + pn + "' in the model", clazz);

                    return false;

                }

            }

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

                error("@OnPrprtChange method needs to be static", e);

                return false;

            }

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

                error("@OnPrprtChange method cannot be private", e);

                return false;

            }

            if (e.getReturnType().getKind() != TypeKind.VOID) {

                error("@OnPrprtChange method should return void", e);

                return false;

            }

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

            for (String pn : onPC.value()) {

                StringBuilder call = new StringBuilder();

                call.append("  ").append(clazz.getSimpleName()).append(".").append(n).append("(");

                call.append(wrapPropName(e, className, "name", pn));

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

                Collection<String> change = functionDeps.get(pn);

                if (change == null) {

                    change = new ArrayList<>();

                    functionDeps.put(pn, change);

                }

                change.add(call.toString());

                for (String dpn : findDerivedFrom(propDeps, pn)) {

                    change = functionDeps.get(dpn);

                    if (change == null) {

                        change = new ArrayList<>();

                        functionDeps.put(dpn, change);

                    }

                    change.add(call.toString());

                }

            }

        }

        return true;

    }

    private boolean generateReceive(

        Element clazz, StringWriter body, String className, 

        List<? extends Element> enclosedElements, List<String> functions

    ) {

        for (Element m : enclosedElements) {

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

                continue;

            }

            ExecutableElement e = (ExecutableElement)m;

            OnReceive onR = e.getAnnotation(OnReceive.class);

            if (onR == null) {

                continue;

            }

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

                error("@OnReceive method needs to be static", e);

                return false;

            }

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

                error("@OnReceive method cannot be private", e);

                return false;

            }

            if (e.getReturnType().getKind() != TypeKind.VOID) {

                error("@OnReceive method should return void", e);

                return false;

            }

            String modelClass = null;

            boolean expectsList = false;

            List<String> args = new ArrayList<>();

            {

                for (VariableElement ve : e.getParameters()) {

                    TypeMirror modelType = null;

                    if (ve.asType().toString().equals(className)) {

                        args.add(className + ".this");

                    } else if (isModel(ve.asType())) {

                        modelType = ve.asType();

                    } else if (ve.asType().getKind() == TypeKind.ARRAY) {

                        modelType = ((ArrayType)ve.asType()).getComponentType();

                        expectsList = true;

                    }

                    if (modelType != null) {

                        if (modelClass != null) {

                            error("There can be only one model class among arguments", e);

                        } else {

                            modelClass = modelType.toString();

                            if (expectsList) {

                                args.add("arr");

                            } else {

                                args.add("arr[0]");

                            }

                        }

                    }

                }

            }

            if (modelClass == null) {

                error("The method needs to have one @Model class as parameter", e);

            }

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

            body.append("public void ").append(n).append("(");

            StringBuilder assembleURL = new StringBuilder();

            String jsonpVarName = null;

            {

                String sep = "";

                boolean skipJSONP = onR.jsonp().isEmpty();

                for (String p : findParamNames(e, onR.url(), assembleURL)) {

                    if (!skipJSONP && p.equals(onR.jsonp())) {

                        skipJSONP = true;

                        jsonpVarName = p;

                        continue;

                    }

                    body.append(sep);

                    body.append("String ").append(p);

                    sep = ", ";

                }

                if (!skipJSONP) {

                    error(

                        "Name of jsonp attribute ('" + onR.jsonp() + 

                        "') is not used in url attribute '" + onR.url() + "'", e

                    );

                }

            }

            body.append(") {\n");

            body.append("  final Object[] result = { null };\n");

            body.append(

                "  class ProcessResult implements Runnable {\n" +

                "    @Override\n" +

                "    public void run() {\n" +

                "      Object value = result[0];\n");

            body.append(

                "      " + modelClass + "[] arr;\n");

            body.append(

                "      if (value instanceof Object[]) {\n" +

                "        Object[] data = ((Object[])value);\n" +

                "        arr = new " + modelClass + "[data.length];\n" +

                "        for (int i = 0; i < data.length; i++) {\n" +

                "          arr[i] = new " + modelClass + "(data[i]);\n" +

                "        }\n" +

                "      } else {\n" +

                "        arr = new " + modelClass + "[1];\n" +

                "        arr[0] = new " + modelClass + "(value);\n" +

                "      }\n"

            );

            {

                body.append(clazz.getSimpleName()).append(".").append(n).append("(");

                String sep = "";

                for (String arg : args) {

                    body.append(sep);

                    body.append(arg);

                    sep = ", ";

                }

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

            }

            body.append(

                "    }\n" +

                "  }\n"

            );

            body.append("  ProcessResult pr = new ProcessResult();\n");

            if (jsonpVarName != null) {

                body.append("  String ").append(jsonpVarName).

                    append(" = org.apidesign.bck2brwsr.htmlpage.ConvertTypes.createJSONP(result, pr);\n");

            }

            body.append("  org.apidesign.bck2brwsr.htmlpage.ConvertTypes.loadJSON(\n      ");

            body.append(assembleURL);

            body.append(", result, pr, ").append(jsonpVarName).append("\n  );\n");

//            body.append("  ").append(clazz.getSimpleName()).append(".").append(n).append("(");