/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package java.security.cert;

import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;
import org.apache.harmony.security.fortress.Engine;

/**
 * This class implements the functionality of a builder for an unverified
 * <i>Certification Path</i>s from a specified certificate to a trust anchor.
 */
public class CertPathBuilder {

    // Store CertPathBuilder service name
    private static final String SERVICE = "CertPathBuilder";

    // Used to access common engine functionality
    private static final Engine ENGINE = new Engine(SERVICE);

    // Store default property name
    private static final String PROPERTY_NAME = "certpathbuilder.type";

    // Default value of CertPathBuilder type.
    private static final String DEFAULT_PROPERTY = "PKIX";

    // Store used provider
    private final Provider provider;

    // Store spi implementation
    private final CertPathBuilderSpi spiImpl;

    // Store algorithm name
    private final String algorithm;

    /**
     * Creates a new {@code CertPathBuilder}.
     *
     * @param builderSpi
     *            the implementation delegate.
     * @param provider
     *            the provider.
     * @param algorithm
     *            the desired algorithm available at the provider.
     */
    protected CertPathBuilder(CertPathBuilderSpi builderSpi, Provider provider,
            String algorithm) {
        this.provider = provider;
        this.algorithm = algorithm;
        this.spiImpl = builderSpi;
    }

    /**
     * Returns the algorithm name of this instance.
     *
     * @return the algorithm name of this instance.
     */
    public final String getAlgorithm() {
        return algorithm;
    }

    /**
     * Returns the provider of this instance.
     *
     * @return the provider of this instance.
     */
    public final Provider getProvider() {
        return provider;
    }

    /**
     * Creates a new {@code CertPathBuilder} instance with the specified
     * algorithm.
     *
     * @param algorithm
     *            the name of the algorithm.
     * @return a builder for the requested algorithm.
     * @throws NullPointerException
     *             if the algorithm is {@code null}.
     * @throws NoSuchAlgorithmException
     *             if no installed provider can provide the algorithm.
     */
    public static CertPathBuilder getInstance(String algorithm)
            throws NoSuchAlgorithmException {
        if (algorithm == null) {
            throw new NullPointerException("algorithm == null");
        }
        Engine.SpiAndProvider sap = ENGINE.getInstance(algorithm, null);
        return new CertPathBuilder((CertPathBuilderSpi) sap.spi, sap.provider, algorithm);
    }

    /**
     * Creates a new {@code CertPathBuilder} instance from the specified
     * provider providing the specified algorithm.
     *
     * @param algorithm
     *            the name of the algorithm.
     * @param provider
     *            the name of the provider.
     * @return a builder for the requested algorithm.
     * @throws NoSuchAlgorithmException
     *             if the specified provider cannot provide the algorithm.
     * @throws NoSuchProviderException
     *             if no provider with the specified name can be found.
     * @throws NullPointerException
     *             if algorithm is {@code null}.
     * @throws IllegalArgumentException if {@code provider == null || provider.isEmpty()}
     */
    public static CertPathBuilder getInstance(String algorithm, String provider)
            throws NoSuchAlgorithmException, NoSuchProviderException {
        if (provider == null || provider.isEmpty()) {
            throw new IllegalArgumentException("provider == null || provider.isEmpty()");
        }
        Provider impProvider = Security.getProvider(provider);
        if (impProvider == null) {
            throw new NoSuchProviderException(provider);
        }
        return getInstance(algorithm, impProvider);

    }

    /**
     * Creates a new {@code CertPathBuilder} instance from the specified
     * provider providing the specified algorithm.
     *
     * @param algorithm
     *            the name of the algorithm.
     * @param provider
     *            the provider.
     * @return a builder for the requested algorithm
     * @throws NoSuchAlgorithmException
     *             if the specified provider cannot provide the algorithm.
     * @throws IllegalArgumentException if {@code provider == null}
     * @throws NullPointerException
     *             if algorithm is {@code null}.
     */
    public static CertPathBuilder getInstance(String algorithm,
            Provider provider) throws NoSuchAlgorithmException {
        if (provider == null) {
            throw new IllegalArgumentException("provider == null");
        }
        if (algorithm == null) {
            throw new NullPointerException("algorithm == null");
        }
        Object spi = ENGINE.getInstance(algorithm, provider, null);
        return new CertPathBuilder((CertPathBuilderSpi) spi, provider, algorithm);
    }

    /**
     * Builds a certification path with the specified algorithm parameters.
     *
     * @param params
     *            the algorithm parameters.
     * @return the built certification path.
     * @throws CertPathBuilderException
     *             if the build fails.
     * @throws InvalidAlgorithmParameterException
     *             if the specified parameters cannot be used to build with this
     *             builder.
     * @see CertPathBuilderResult
     */
    public final CertPathBuilderResult build(CertPathParameters params)
            throws CertPathBuilderException, InvalidAlgorithmParameterException {
        return spiImpl.engineBuild(params);
    }

    /**
     * Returns the default {@code CertPathBuilder} type from the <i>Security
     * Properties</i>.
     *
     * @return the default {@code CertPathBuilder} type from the <i>Security
     *         Properties</i>, or the string "{@code PKIX}" if it cannot be
     *         determined.
     */
    public static final String getDefaultType() {
        String defaultType = Security.getProperty(PROPERTY_NAME);
        return (defaultType != null ? defaultType : DEFAULT_PROPERTY);
    }
}