/**

  * 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.Collection;

 import java.util.Collections;

 import java.util.HashMap;

 import java.util.LinkedHashSet;

 import java.util.List;

 import java.util.Locale;

 import java.util.Map;

 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.element.VariableElement;

 import javax.lang.model.type.MirroredTypeException;

 import javax.lang.model.type.TypeMirror;

 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.On;

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

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

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

                         return false;

                     }

                     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");

                     }

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

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

                     generateComputedProperties(w, e.getEnclosedElements(), propsGetSet, propsDeps);

                     generateProperties(w, p.properties(), propsGetSet, propsDeps);

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

                     if (!propsGetSet.isEmpty()) {

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

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

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

                         w.write("new String[] {\n");

                         String sep = "";

                         for (String n : propsGetSet) {

                             w.write(sep);

                             if (n == null) {

                                 w.write("    null");

                             } else {

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

                             }

                             sep = ",\n";

                         }

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

                 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";

         }

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

             return "Canvas";

         }

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

             return "Image";

         }

         return "Element";

     }

     private static String cnstnt(String id) {

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

     }

     private boolean initializeOnClick(

         String className, TypeElement type, 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;

            // }

             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.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;

                         StringBuilder params = new StringBuilder();

                         {

                             boolean first = true;

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

                                 if (!first) {

                                     params.append(", ");

                                 }

                                 first = false;

                                 if (ve.asType() == stringType) {

                                     params.append('"').append(id).append('"');

                                     continue;

                                 }

                                 String rn = ve.asType().toString();

                                 int last = rn.lastIndexOf('.');

                                 if (last >= 0) {

                                     rn = rn.substring(last + 1);

                                 }

                                 if (rn.equals(className)) {

                                     params.append(className).append(".this");

                                     continue;

                                 }

                                 processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, 

                                     "@On method can only accept String or " + className + " arguments",

                                     ee

                                 );

                                 return false;

                             }

                         }

                         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 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 Runnable {\n");

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

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

                 w.append("  public void run() {\n");

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

                 w.append(dispatch);

                 w.append("    }\n");

                 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();

     }

     private static void generateProperties(

         Writer w, Property[] properties, Collection<String> props,

         Map<String,Collection<String>> deps

     ) throws IOException {

         for (Property p : properties) {

             final String tn = typeName(p);

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

             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");

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

             if (dependants != null) {

                 for (String depProp : dependants) {

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

                 }

             }

             w.write("  }\n");

             w.write("}\n");

             props.add(p.name());

             props.add(gs[2]);

             props.add(gs[3]);

             props.add(gs[0]);

         }

     }

     private boolean generateComputedProperties(

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

         Map<String,Collection<String>> deps

     ) throws IOException {

         for (Element e : arr) {

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

                 continue;

             }

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

                 continue;

             }

             ExecutableElement ee = (ExecutableElement)e;

             final String tn = ee.getReturnType().toString();

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

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

             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();

                 final String dt = pe.asType().toString();

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

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

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

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

                 if (depends == null) {

                     depends = new LinkedHashSet<String>();

                     deps.put(dn, depends);

                 }

                 depends.add(sn);

             }

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

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

             w.write("    return " + e.getEnclosingElement().getSimpleName() + '.' + 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 true;

     }

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

         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('.', '_');

         return new String[]{

             pref + n, 

             "set" + n, 

             pref + nu + "__" + bck2brwsrType,

             "set" + nu + "__V" + bck2brwsrType

         };

     }

     private static String typeName(Property p) {

         try {

             return p.type().getName();

         } catch (MirroredTypeException ex) {

             return ex.getTypeMirror().toString();

         }

     }

 }