/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2008 Sun Microsystems, Inc.
 * Portions copyright 2013-2016 ForgeRock AS.
 */

package org.forgerock.opendj.config;

import org.forgerock.util.Reject;

import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedList;
import java.util.List;

/**
 * Class property definition.
 * <p>
 * A class property definition defines a property whose values represent a Java
 * class. It is possible to restrict the type of java class by specifying
 * "instance of" constraints.
 * <p>
 * Note that in a client/server environment, the client is probably not capable
 * of validating the Java class (e.g. it will not be able to load it nor have
 * access to the interfaces it is supposed to implement). For this reason,
 * validation is disabled in client applications.
 */
public final class ClassPropertyDefinition extends PropertyDefinition<String> {

    /** An interface for incrementally constructing class property definitions. */
    public static final class Builder extends AbstractBuilder<String, ClassPropertyDefinition> {

        /** List of interfaces which property values must implement. */
        private final List<String> instanceOfInterfaces = new LinkedList<>();

        /** Private constructor. */
        private Builder(AbstractManagedObjectDefinition<?, ?> d, String propertyName) {
            super(d, propertyName);
        }

        /**
         * Add an class name which property values must implement.
         *
         * @param className
         *            The name of a class which property values must implement.
         */
        public final void addInstanceOf(String className) {
            Reject.ifNull(className);

            /* Do some basic checks to make sure the string representation is valid. */
            String value = className.trim();
            if (!value.matches(CLASS_RE)) {
                throw new IllegalArgumentException("\"" + value + "\" is not a valid Java class name");
            }

            instanceOfInterfaces.add(value);
        }

        @Override
        protected ClassPropertyDefinition buildInstance(AbstractManagedObjectDefinition<?, ?> d, String propertyName,
            EnumSet<PropertyOption> options, AdministratorAction adminAction,
            DefaultBehaviorProvider<String> defaultBehavior) {
            return new ClassPropertyDefinition(d, propertyName, options, adminAction, defaultBehavior,
                instanceOfInterfaces);
        }

    }

    /** Regular expression for validating class names. */
    private static final String CLASS_RE = "^([A-Za-z][A-Za-z0-9_]*\\.)*[A-Za-z][A-Za-z0-9_]*(\\$[A-Za-z0-9_]+)*$";

    /**
     * Create a class property definition builder.
     *
     * @param d
     *            The managed object definition associated with this property
     *            definition.
     * @param propertyName
     *            The property name.
     * @return Returns the new class property definition builder.
     */
    public static Builder createBuilder(AbstractManagedObjectDefinition<?, ?> d, String propertyName) {
        return new Builder(d, propertyName);
    }

    /** Load a named class. */
    private static Class<?> loadClass(String className, boolean initialize) throws ClassNotFoundException {
        return Class.forName(className, initialize, ConfigurationFramework.getInstance().getClassLoader());
    }

    /** List of interfaces which property values must implement. */
    private final List<String> instanceOfInterfaces;

    /** Private constructor. */
    private ClassPropertyDefinition(AbstractManagedObjectDefinition<?, ?> d, String propertyName,
        EnumSet<PropertyOption> options, AdministratorAction adminAction,
        DefaultBehaviorProvider<String> defaultBehavior, List<String> instanceOfInterfaces) {
        super(d, String.class, propertyName, options, adminAction, defaultBehavior);

        this.instanceOfInterfaces = Collections.unmodifiableList(new LinkedList<String>(instanceOfInterfaces));
    }

    @Override
    public <R, P> R accept(PropertyDefinitionVisitor<R, P> v, P p) {
        return v.visitClass(this, p);
    }

    @Override
    public <R, P> R accept(PropertyValueVisitor<R, P> v, String value, P p) {
        return v.visitClass(this, value, p);
    }

    @Override
    public String decodeValue(String value) {
        Reject.ifNull(value);

        try {
            validateValue(value);
        } catch (PropertyException e) {
            throw PropertyException.illegalPropertyValueException(this, value, e.getCause());
        }

        return value;
    }

    /**
     * Get an unmodifiable list of classes which values of this property must
     * implement.
     *
     * @return Returns an unmodifiable list of classes which values of this
     *         property must implement.
     */
    public List<String> getInstanceOfInterface() {
        return instanceOfInterfaces;
    }

    /**
     * Validate and load the named class, and cast it to a subclass of the
     * specified class.
     *
     * @param <T>
     *            The requested type.
     * @param className
     *            The name of the class to validate and load.
     * @param instanceOf
     *            The class representing the requested type.
     * @return Returns the named class cast to a subclass of the specified
     *         class.
     * @throws PropertyException
     *             If the named class was invalid, could not be loaded, or did
     *             not implement the required interfaces.
     * @throws ClassCastException
     *             If the referenced class does not implement the requested
     *             type.
     */
    public <T> Class<? extends T> loadClass(String className, Class<T> instanceOf) {
        Reject.ifNull(className, instanceOf);

        // Make sure that the named class is valid.
        validateClassName(className);
        Class<?> theClass = validateClassInterfaces(className, true);

        // Cast it to the required type.
        return theClass.asSubclass(instanceOf);
    }

    @Override
    public String normalizeValue(String value) {
        Reject.ifNull(value);

        return value.trim();
    }

    @Override
    public void validateValue(String value) {
        Reject.ifNull(value);

        // Always make sure the name is a valid class name.
        validateClassName(value);

        /*
         * If additional validation is enabled then attempt to load the class
         * and check the interfaces that it implements/extends.
         */
        if (!ConfigurationFramework.getInstance().isClient()) {
            validateClassInterfaces(value, false);
        }
    }

    /** Do some basic checks to make sure the string representation is valid. */
    private void validateClassName(String className) {
        String nvalue = className.trim();
        if (!nvalue.matches(CLASS_RE)) {
            throw PropertyException.illegalPropertyValueException(this, className);
        }
    }

    /** Make sure that named class implements the interfaces named by this definition. */
    private Class<?> validateClassInterfaces(String className, boolean initialize) {
        Class<?> theClass = loadClassForValidation(className, className, initialize);
        for (String i : instanceOfInterfaces) {
            Class<?> instanceOfClass = loadClassForValidation(className, i, initialize);
            if (!instanceOfClass.isAssignableFrom(theClass)) {
                throw PropertyException.illegalPropertyValueException(this, className);
            }
        }
        return theClass;
    }

    private Class<?> loadClassForValidation(String componentClassName, String classToBeLoaded, boolean initialize) {
        try {
            return loadClass(classToBeLoaded.trim(), initialize);
        } catch (ClassNotFoundException | LinkageError e) {
            // If the class cannot be loaded / initialized then it is an invalid value.
            throw PropertyException.illegalPropertyValueException(this, componentClassName, e);
        }
    }
}