/*
 * Copyright The WildFly Authors
 * SPDX-License-Identifier: Apache-2.0
 */

package org.jboss.as.jsf.injection;

import java.lang.annotation.Annotation;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import jakarta.faces.component.FacesComponent;
import jakarta.faces.component.behavior.FacesBehavior;
import jakarta.faces.context.ExternalContext;
import jakarta.faces.convert.FacesConverter;
import jakarta.faces.event.NamedEvent;
import jakarta.faces.render.FacesBehaviorRenderer;
import jakarta.faces.render.FacesRenderer;
import jakarta.faces.validator.FacesValidator;
import jakarta.servlet.ServletContext;

/**
 * This class retrieves the annotation map from application scope.  This map was placed there by the JSFAnnotationProcessor
 * in the Jakarta Server Faces subsystem.
 *
 * The class also reloads the map if needed.  The reason why the map must be reloaded is because the Jakarta Server Faces Annotation classes used as the map keys are always
 * loaded by the Jakarta Server Faces subsystem and thus always correspond to the default Jakarta Server Faces implementation.  If a different Jakarta Server Faces
 * implementation is used then the Jakarta Server Faces impl will be looking for the wrong version of the map keys.  So, we replace
 * the default implementations of the Jakarta Server Faces Annotation classes with whatever version the WAR is actually using.
 *
 * The reason this works is because we have a "slot" for jsf-injection for each Jakarta Server Faces implementation.  And jsf-injection
 * points to its corresponding Jakarta Server Faces impl/api slots.
 *
 * @author Stan Silvert ssilvert@redhat.com (C) 2012 Red Hat Inc.
 */
public class AnnotationMap {
    /**
     * @see org.jboss.as.jsf.deployment.JSFAnnotationProcessor#FACES_ANNOTATIONS_SC_ATTR
     */
    public static final String FACES_ANNOTATIONS_SC_ATTR =  "org.jboss.as.jsf.FACES_ANNOTATIONS";
    private static final String ANNOTATION_MAP_CONVERTED = "org.jboss.as.jsf.ANNOTATION_MAP_CONVERTED";

    private static final Map<String, Class<? extends Annotation>> stringToAnnoMap = new HashMap<String, Class<? extends Annotation>>();

    static {
        // These classes need to be loaded in order!  Some can't be loaded if the Jakarta Server Faces version is too old.

        try { // all of the following classes are available from Faces 2.0 and Faces 2.1
            stringToAnnoMap.put(FacesComponent.class.getName(), FacesComponent.class);
            stringToAnnoMap.put(FacesConverter.class.getName(), FacesConverter.class);
            stringToAnnoMap.put(FacesValidator.class.getName(), FacesValidator.class);
            stringToAnnoMap.put(FacesRenderer.class.getName(), FacesRenderer.class);
            stringToAnnoMap.put(NamedEvent.class.getName(), NamedEvent.class);
            stringToAnnoMap.put(FacesBehavior.class.getName(), FacesBehavior.class);
            stringToAnnoMap.put(FacesBehaviorRenderer.class.getName(), FacesBehaviorRenderer.class);

            // Put Jakarta Server Faces 2.2+ annotations below this line if any new ones are to be scanned.
            // Load the class to avoid a NoClassDefFoundError if it is not present in the impl
            ClassLoader loader = AnnotationMap.class.getClassLoader();
            addAnnotationIfPresent(loader, "jakarta.faces.view.facelets.FaceletsResourceResolver");
        } catch (Exception e) {
            // Ignore.  Whatever classes are available have been loaded into the map.
        }
    }

    // don't allow instance
    private AnnotationMap() {}

    private static void addAnnotationIfPresent(ClassLoader loader, String name) {
        try {
            Class clazz = loader.loadClass(name);
            if (Annotation.class.isAssignableFrom(clazz)) {
                stringToAnnoMap.put(name, clazz);
            }
        } catch(ClassNotFoundException e) {
            // ignore, annotation not found in the used Jakarta Server Faces version
        }
    }

    public static Map<Class<? extends Annotation>, Set<Class<?>>> get(final ExternalContext extContext) {
        Map<String, Object> appMap = extContext.getApplicationMap();
        if (appMap.get(ANNOTATION_MAP_CONVERTED) != null) {
            return (Map<Class<? extends Annotation>, Set<Class<?>>>)appMap.get(FACES_ANNOTATIONS_SC_ATTR);
        } else {
            appMap.put(ANNOTATION_MAP_CONVERTED, Boolean.TRUE);
            return convert((Map<Class<? extends Annotation>, Set<Class<?>>>)appMap.get(FACES_ANNOTATIONS_SC_ATTR));
        }
    }

    public static Map<Class<? extends Annotation>, Set<Class<?>>> get(final ServletContext servletContext) {
        Map<Class<? extends Annotation>, Set<Class<?>>> annotations = (Map<Class<? extends Annotation>, Set<Class<?>>>) servletContext.getAttribute(FACES_ANNOTATIONS_SC_ATTR);
        if (servletContext.getAttribute(ANNOTATION_MAP_CONVERTED) != null) {
            return annotations;
        } else {
            servletContext.setAttribute(ANNOTATION_MAP_CONVERTED, Boolean.TRUE);
            return convert(annotations);
        }
    }

    private static Map<Class<? extends Annotation>, Set<Class<?>>> convert(Map<Class<? extends Annotation>, Set<Class<?>>> annotations) {
        final Map<Class<? extends Annotation>, Set<Class<?>>> convertedAnnotatedClasses = new HashMap<Class<? extends Annotation>, Set<Class<?>>>();
        for (Map.Entry<Class<? extends Annotation>, Set<Class<?>>> entry : annotations.entrySet()) {
            final Class<? extends Annotation> annotation = entry.getKey();
            final Set<Class<?>> annotated = entry.getValue();
            final Class<? extends Annotation> knownAnnotation = stringToAnnoMap.get(annotation.getName());
            if (knownAnnotation != null) {
                convertedAnnotatedClasses.put(knownAnnotation, annotated); // put back in the map with the proper version of the class
            } else {
                // just copy over the original annotation to annotated classes mapping
                convertedAnnotatedClasses.put(annotation, annotated);
            }
        }

        return convertedAnnotatedClasses;
    }
}
