/**
 * 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.
 */
/*
 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
 */
/*
 * $Id: KeyInfoFactory.java 1203722 2011-11-18 16:27:37Z mullan $
 */
package javax.xml.crypto.dsig.keyinfo;

import java.math.BigInteger;
import java.security.KeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.PublicKey;
import java.security.Security;
import java.security.cert.X509CRL;
import java.util.List;
import javax.xml.crypto.MarshalException;
import javax.xml.crypto.NoSuchMechanismException;
import javax.xml.crypto.URIDereferencer;
import javax.xml.crypto.XMLStructure;
import javax.xml.crypto.dom.DOMStructure;
import javax.xml.crypto.dsig.*;

/**
 * A factory for creating {@link KeyInfo} objects from scratch or for
 * unmarshalling a <code>KeyInfo</code> object from a corresponding XML 
 * representation.
 *
 * <p>Each instance of <code>KeyInfoFactory</code> supports a specific
 * XML mechanism type. To create a <code>KeyInfoFactory</code>, call one of the
 * static {@link #getInstance getInstance} methods, passing in the XML 
 * mechanism type desired, for example:
 *
 * <blockquote><code>
 *   KeyInfoFactory factory = KeyInfoFactory.getInstance("DOM");
 * </code></blockquote>
 *
 * <p>The objects that this factory produces will be based
 * on DOM and abide by the DOM interoperability requirements as defined in the
 * <a href="../../../../../overview-summary.html#DOM Mechanism Requirements">
 * DOM Mechanism Requirements</a> section of the API overview. See the
 * <a href="../../../../../overview-summary.html#Service Provider">Service 
 * Providers</a> section of the API overview for a list of standard mechanism 
 * types.
 *
 * <p><code>KeyInfoFactory</code> implementations are registered and loaded
 * using the {@link java.security.Provider} mechanism.
 * For example, a service provider that supports the
 * DOM mechanism would be specified in the <code>Provider</code> subclass as:
 * <pre>
 *     put("KeyInfoFactory.DOM", "org.example.DOMKeyInfoFactory");
 * </pre>
 *
 * <p>Also, the <code>XMLStructure</code>s that are created by this factory
 * may contain state specific to the <code>KeyInfo</code> and are not
 * intended to be reusable.
 *
 * <p>An implementation MUST minimally support the default mechanism type: DOM.
 *
 * <p>Note that a caller must use the same <code>KeyInfoFactory</code>
 * instance to create the <code>XMLStructure</code>s of a particular
 * <code>KeyInfo</code> object. The behavior is undefined if 
 * <code>XMLStructure</code>s from different providers or different mechanism 
 * types are used together.
 *
 * <p><b>Concurrent Access</b>
 * <p>The static methods of this class are guaranteed to be thread-safe. 
 * Multiple threads may concurrently invoke the static methods defined in this 
 * class with no ill effects.
 *
 * <p>However, this is not true for the non-static methods defined by this 
 * class. Unless otherwise documented by a specific provider, threads that 
 * need to access a single <code>KeyInfoFactory</code> instance concurrently 
 * should synchronize amongst themselves and provide the necessary locking. 
 * Multiple threads each manipulating a different <code>KeyInfoFactory</code> 
 * instance need not synchronize.
 *
 * @author Sean Mullan
 * @author JSR 105 Expert Group
 */
public abstract class KeyInfoFactory {

    private String mechanismType;
    private Provider provider;

    /**
     * Default constructor, for invocation by subclasses.
     */
    protected KeyInfoFactory() {}

    /**
     * Returns a <code>KeyInfoFactory</code> that supports the
     * specified XML processing mechanism and representation type (ex: "DOM").
     *
     * <p>This method uses the standard JCA provider lookup mechanism to 
     * locate and instantiate a <code>KeyInfoFactory</code> implementation of 
     * the desired mechanism type. It traverses the list of registered security 
     * <code>Provider</code>s, starting with the most preferred 
     * <code>Provider</code>. A new <code>KeyInfoFactory</code> object 
     * from the first <code>Provider</code> that supports the specified 
     * mechanism is returned. 
     * 
     * <p> Note that the list of registered providers may be retrieved via 
     * the {@link Security#getProviders() Security.getProviders()} method. 
     *
     * @param mechanismType the type of the XML processing mechanism and
     *    representation. See the <a 
     *    href="../../../../../overview-summary.html#Service Provider">Service 
     *    Providers</a> section of the API overview for a list of standard 
     *    mechanism types.
     * @return a new <code>KeyInfoFactory</code>
     * @throws NullPointerException if <code>mechanismType</code> is
     *    <code>null</code>
     * @throws NoSuchMechanismException if no <code>Provider</code> supports a
     *    <code>KeyInfoFactory</code> implementation for the specified mechanism
     * @see Provider
     */
    public static KeyInfoFactory getInstance(String mechanismType) {
        if (mechanismType == null) {
            throw new NullPointerException("mechanismType cannot be null");
        }

        return findInstance(mechanismType, null);
    }

    private static KeyInfoFactory findInstance(String mechanismType, 
        Provider provider) {

        if (provider == null) {
            provider = getProvider("KeyInfoFactory", mechanismType);
        }
        Provider.Service ps = provider.getService("KeyInfoFactory",
                                                  mechanismType);
        if (ps == null) {
            throw new NoSuchMechanismException("Cannot find " + mechanismType +
                                               " mechanism type");
        }
        try {
            KeyInfoFactory fac = (KeyInfoFactory)ps.newInstance(null);
            fac.mechanismType = mechanismType;
            fac.provider = provider;
            return fac;
        } catch (NoSuchAlgorithmException nsae) {
            throw new NoSuchMechanismException("Cannot find " + mechanismType +
                                               " mechanism type", nsae);
        }
    }

    private static Provider getProvider(String engine, String mech) {
        Provider[] providers = Security.getProviders(engine + "." + mech);
        if (providers == null) {
            throw new NoSuchMechanismException("Mechanism type " + mech +
                                               " not available");
        }
        return providers[0];
    }

    /**
     * Returns a <code>KeyInfoFactory</code> that supports the
     * requested XML processing mechanism and representation type (ex: "DOM"),
     * as supplied by the specified provider. Note that the specified 
     * <code>Provider</code> object does not have to be registered in the 
     * provider list. 
     *
     * @param mechanismType the type of the XML processing mechanism and
     *    representation. See the <a 
     *    href="../../../../../overview-summary.html#Service Provider">Service 
     *    Providers</a> section of the API overview for a list of standard 
     *    mechanism types.
     * @param provider the <code>Provider</code> object
     * @return a new <code>KeyInfoFactory</code>
     * @throws NullPointerException if <code>mechanismType</code> or
     *    <code>provider</code> are <code>null</code>
     * @throws NoSuchMechanismException if a <code>KeyInfoFactory</code> 
     *    implementation for the specified mechanism is not available from the 
     *    specified <code>Provider</code> object
     * @see Provider
     */
    public static KeyInfoFactory getInstance(String mechanismType,
        Provider provider) {
        if (mechanismType == null) {
            throw new NullPointerException("mechanismType cannot be null");
        } else if (provider == null) {
            throw new NullPointerException("provider cannot be null");
        }

        return findInstance(mechanismType, provider);
    }

    /**
     * Returns a <code>KeyInfoFactory</code> that supports the
     * requested XML processing mechanism and representation type (ex: "DOM"),
     * as supplied by the specified provider. The specified provider must be 
     * registered in the security provider list. 
     *
     * <p>Note that the list of registered providers may be retrieved via 
     * the {@link Security#getProviders() Security.getProviders()} method. 
     *
     * @param mechanismType the type of the XML processing mechanism and
     *    representation. See the <a 
     *    href="../../../../../overview-summary.html#Service Provider">Service 
     *    Providers</a> section of the API overview for a list of standard 
     *    mechanism types.
     * @param provider the string name of the provider
     * @return a new <code>KeyInfoFactory</code>
     * @throws NoSuchProviderException if the specified provider is not 
     *    registered in the security provider list
     * @throws NullPointerException if <code>mechanismType</code> or
     *    <code>provider</code> are <code>null</code>
     * @throws NoSuchMechanismException if a <code>KeyInfoFactory</code> 
     *    implementation for the specified mechanism is not available from the 
     *    specified provider
     * @see Provider
     */
    public static KeyInfoFactory getInstance(String mechanismType,
        String provider) throws NoSuchProviderException {
        if (mechanismType == null) {
            throw new NullPointerException("mechanismType cannot be null");
        } else if (provider == null) {
            throw new NullPointerException("provider cannot be null");
        }

        Provider prov = Security.getProvider(provider);
        if (prov == null) {
            throw new NoSuchProviderException("cannot find provider named " 
                + provider);
        }

        return findInstance(mechanismType, prov);
    }

    /**
     * Returns a <code>KeyInfoFactory</code> that supports the
     * default XML processing mechanism and representation type ("DOM").
     *
     * <p>This method uses the standard JCA provider lookup mechanism to 
     * locate and instantiate a <code>KeyInfoFactory</code> implementation of 
     * the default mechanism type. It traverses the list of registered security 
     * <code>Provider</code>s, starting with the most preferred
     * <code>Provider</code>.  A new <code>KeyInfoFactory</code> object
     * from the first <code>Provider</code> that supports the DOM mechanism is 
     * returned. 
     * 
     * <p> Note that the list of registered providers may be retrieved via 
     * the {@link Security#getProviders() Security.getProviders()} method. 
     *
     * @return a new <code>KeyInfoFactory</code>
     * @throws NoSuchMechanismException if no <code>Provider</code> supports a 
     *    <code>KeyInfoFactory</code> implementation for the DOM mechanism
     * @see Provider
     */
    public static KeyInfoFactory getInstance() {
        return getInstance("DOM");
    }

    /**
     * Returns the type of the XML processing mechanism and representation
     * supported by this <code>KeyInfoFactory</code> (ex: "DOM")
     *
     * @return the XML processing mechanism type supported by this
     *    <code>KeyInfoFactory</code>
     */
    public final String getMechanismType() {
        return mechanismType;
    }

    /**
     * Returns the provider of this <code>KeyInfoFactory</code>.
     *
     * @return the provider of this <code>KeyInfoFactory</code>
     */
    public final Provider getProvider() {
        return provider;
    }

    /**
     * Creates a <code>KeyInfo</code> containing the specified list of
     * key information types.
     *
     * @param content a list of one or more {@link XMLStructure}s representing 
     *    key information types. The list is defensively copied to protect
     *    against subsequent modification.
     * @return a <code>KeyInfo</code>
     * @throws NullPointerException if <code>content</code> is <code>null</code>
     * @throws IllegalArgumentException if <code>content</code> is empty
     * @throws ClassCastException if <code>content</code> contains any entries
     *    that are not of type {@link XMLStructure}
     */
    public abstract KeyInfo newKeyInfo(List content);

    /**
     * Creates a <code>KeyInfo</code> containing the specified list of key
     * information types and optional id. The
     * <code>id</code> parameter represents the value of an XML
     * <code>ID</code> attribute and is useful for referencing
     * the <code>KeyInfo</code> from other XML structures. 
     *
     * @param content a list of one or more {@link XMLStructure}s representing 
     *    key information types. The list is defensively copied to protect
     *    against subsequent modification.
     * @param id the value of an XML <code>ID</code> (may be <code>null</code>)
     * @return a <code>KeyInfo</code>
     * @throws NullPointerException if <code>content</code> is <code>null</code>
     * @throws IllegalArgumentException if <code>content</code> is empty
     * @throws ClassCastException if <code>content</code> contains any entries
     *    that are not of type {@link XMLStructure}
     */
    public abstract KeyInfo newKeyInfo(List content, String id);

    /**
     * Creates a <code>KeyName</code> from the specified name.
     *
     * @param name the name that identifies the key
     * @return a <code>KeyName</code>
     * @throws NullPointerException if <code>name</code> is <code>null</code>
     */
    public abstract KeyName newKeyName(String name);

    /**
     * Creates a <code>KeyValue</code> from the specified public key.
     *
     * @param key the public key
     * @return a <code>KeyValue</code>
     * @throws KeyException if the <code>key</code>'s algorithm is not 
     *    recognized or supported by this <code>KeyInfoFactory</code>
     * @throws NullPointerException if <code>key</code> is <code>null</code>
     */
    public abstract KeyValue newKeyValue(PublicKey key) throws KeyException;

    /**
     * Creates a <code>PGPData</code> from the specified PGP public key
     * identifier.
     *
     * @param keyId a PGP public key identifier as defined in <a href=
     *    "http://www.ietf.org/rfc/rfc2440.txt">RFC 2440</a>, section 11.2.
     *    The array is cloned to protect against subsequent modification.
     * @return a <code>PGPData</code>
     * @throws NullPointerException if <code>keyId</code> is <code>null</code>
     * @throws IllegalArgumentException if the key id is not in the correct
     *    format
     */
    public abstract PGPData newPGPData(byte[] keyId);

    /**
     * Creates a <code>PGPData</code> from the specified PGP public key
     * identifier, and optional key material packet and list of external 
     * elements.
     *
     * @param keyId a PGP public key identifier as defined in <a href=
     *    "http://www.ietf.org/rfc/rfc2440.txt">RFC 2440</a>, section 11.2.
     *    The array is cloned to protect against subsequent modification.
     * @param keyPacket a PGP key material packet as defined in <a href=
     *    "http://www.ietf.org/rfc/rfc2440.txt">RFC 2440</a>, section 5.5.
     *    The array is cloned to protect against subsequent modification. May 
     *    be <code>null</code>.
     * @param other a list of {@link XMLStructure}s representing elements from
     *    an external namespace. The list is defensively copied to protect
     *    against subsequent modification. May be <code>null</code> or empty.
     * @return a <code>PGPData</code>
     * @throws NullPointerException if <code>keyId</code> is <code>null</code>
     * @throws IllegalArgumentException if the <code>keyId</code> or 
     *    <code>keyPacket</code> is not in the correct format. For 
     *    <code>keyPacket</code>, the format of the packet header is 
     *    checked and the tag is verified that it is of type key material. The
     *    contents and format of the packet body are not checked.
     * @throws ClassCastException if <code>other</code> contains any
     *    entries that are not of type {@link XMLStructure}
     */
    public abstract PGPData newPGPData(byte[] keyId, byte[] keyPacket,
        List other);

    /**
     * Creates a <code>PGPData</code> from the specified PGP key material
     * packet and optional list of external elements.
     *
     * @param keyPacket a PGP key material packet as defined in <a href=
     *    "http://www.ietf.org/rfc/rfc2440.txt">RFC 2440</a>, section 5.5.
     *    The array is cloned to protect against subsequent modification.
     * @param other a list of {@link XMLStructure}s representing elements from
     *    an external namespace. The list is defensively copied to protect 
     *    against subsequent modification. May be <code>null</code> or empty.
     * @return a <code>PGPData</code>
     * @throws NullPointerException if <code>keyPacket</code> is 
     *    <code>null</code>
     * @throws IllegalArgumentException if <code>keyPacket</code> is not in the 
     *    correct format. For <code>keyPacket</code>, the format of the packet 
     *    header is checked and the tag is verified that it is of type key 
     *    material. The contents and format of the packet body are not checked.
     * @throws ClassCastException if <code>other</code> contains any
     *    entries that are not of type {@link XMLStructure}
     */
    public abstract PGPData newPGPData(byte[] keyPacket, List other);

    /**
     * Creates a <code>RetrievalMethod</code> from the specified URI.
     *
     * @param uri the URI that identifies the <code>KeyInfo</code> information 
     *    to be retrieved
     * @return a <code>RetrievalMethod</code>
     * @throws NullPointerException if <code>uri</code> is <code>null</code>
     * @throws IllegalArgumentException if <code>uri</code> is not RFC 2396
     *    compliant
     */
    public abstract RetrievalMethod newRetrievalMethod(String uri);

    /**
     * Creates a <code>RetrievalMethod</code> from the specified parameters.
     *
     * @param uri the URI that identifies the <code>KeyInfo</code> information 
     *    to be retrieved
     * @param type a URI that identifies the type of <code>KeyInfo</code> 
     *    information to be retrieved (may be <code>null</code>)
     * @param transforms a list of {@link Transform}s. The list is defensively
     *    copied to protect against subsequent modification. May be 
     *    <code>null</code> or empty.
     * @return a <code>RetrievalMethod</code>
     * @throws NullPointerException if <code>uri</code> is <code>null</code>
     * @throws IllegalArgumentException if <code>uri</code> is not RFC 2396
     *    compliant
     * @throws ClassCastException if <code>transforms</code> contains any
     *    entries that are not of type {@link Transform}
     */
    public abstract RetrievalMethod newRetrievalMethod(String uri, String type,
        List transforms);

    /**
     * Creates a <code>X509Data</code> containing the specified list of
     * X.509 content.
     *
     * @param content a list of one or more X.509 content types. Valid types are
     *    {@link String} (subject names), <code>byte[]</code> (subject key ids),
     *    {@link java.security.cert.X509Certificate}, {@link X509CRL},
     *    or {@link XMLStructure} ({@link X509IssuerSerial}
     *    objects or elements from an external namespace). Subject names are 
     *    distinguished names in RFC 2253 String format. Implementations MUST 
     *    support the attribute type keywords defined in RFC 2253 (CN, L, ST, 
     *    O, OU, C, STREET, DC and UID). Implementations MAY support additional 
     *    keywords. The list is defensively copied to protect against 
     *    subsequent modification.
     * @return a <code>X509Data</code>
     * @throws NullPointerException if <code>content</code> is <code>null</code>
     * @throws IllegalArgumentException if <code>content</code> is empty, or
     *    if a subject name is not RFC 2253 compliant or one of the attribute 
     *    type keywords is not recognized.
     * @throws ClassCastException if <code>content</code> contains any entries
     *    that are not of one of the valid types mentioned above
     */
    public abstract X509Data newX509Data(List content);

    /**
     * Creates an <code>X509IssuerSerial</code> from the specified X.500 issuer
     * distinguished name and serial number.
     *
     * @param issuerName the issuer's distinguished name in RFC 2253 String
     *    format. Implementations MUST support the attribute type keywords 
     *    defined in RFC 2253 (CN, L, ST, O, OU, C, STREET, DC and UID). 
     *    Implementations MAY support additional keywords.
     * @param serialNumber the serial number
     * @return an <code>X509IssuerSerial</code>
     * @throws NullPointerException if <code>issuerName</code> or 
     *    <code>serialNumber</code> are <code>null</code>
     * @throws IllegalArgumentException if the issuer name is not RFC 2253
     *    compliant or one of the attribute type keywords is not recognized.
     */
    public abstract X509IssuerSerial newX509IssuerSerial
        (String issuerName, BigInteger serialNumber);

    /**
     * Indicates whether a specified feature is supported.
     *
     * @param feature the feature name (as an absolute URI)
     * @return <code>true</code> if the specified feature is supported,
     *    <code>false</code> otherwise
     * @throws NullPointerException if <code>feature</code> is <code>null</code>
     */
    public abstract boolean isFeatureSupported(String feature);

    /**
     * Returns a reference to the <code>URIDereferencer</code> that is used by 
     * default to dereference URIs in {@link RetrievalMethod} objects.
     *
     * @return a reference to the default <code>URIDereferencer</code>
     */
    public abstract URIDereferencer getURIDereferencer();

    /**
     * Unmarshals a new <code>KeyInfo</code> instance from a 
     * mechanism-specific <code>XMLStructure</code> (ex: {@link DOMStructure}) 
     * instance.
     *
     * @param xmlStructure a mechanism-specific XML structure from which to 
     *   unmarshal the keyinfo from
     * @return the <code>KeyInfo</code>
     * @throws NullPointerException if <code>xmlStructure</code> is 
     *   <code>null</code>
     * @throws ClassCastException if the type of <code>xmlStructure</code> is
     *   inappropriate for this factory
     * @throws MarshalException if an unrecoverable exception occurs during 
     *   unmarshalling
     */
    public abstract KeyInfo unmarshalKeyInfo(XMLStructure xmlStructure)
        throws MarshalException;
}
