package java.security.cert;

import java.security.InvalidAlgorithmParameterException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

/**
 * Parameters used as input for the PKIX CertPathValidator  algorithm.<br />
 * <br />
 * A PKIX <code>CertPathValidator</code> uses these parameters to validate a
 * <code>CertPath</code> according to the PKIX certification path validation
 * algorithm.<br />
 * <br />
 * To instantiate a <code>PKIXParameters</code> object, an application must specify
 * one or more <i>most-trusted CAs</i> as defined by the PKIX certification
 * path validation algorithm. The most-trusted CAs can be specified
 * using one of two constructors. An application can call
 * {@link #PKIXParameters(Set)}, specifying a Set of <code>TrustAnchor</code> objects, each
 * of which identify a most-trusted CA. Alternatively, an application
 * can call {@link #PKIXParameters(KeyStore)}, specifying a <code>KeyStore</code> instance
 * containing trusted certificate entries, each of which will be
 * considered as a most-trusted CA.<br />
 * <br />
 * Once a <code>PKIXParameters</code> object has been created, other parameters can
 * be specified (by calling {@link #setInitialPolicies} or {@link #setDate}, for
 * instance) and then the <code>PKIXParameters</code> is passed along with the
 * <code>CertPath</code> to be validated to {@link CertPathValidator#validate}.<br />
 * <br />
 * Any parameter that is not set (or is set to null) will be set to the
 * default value for that parameter. The default value for the date
 * parameter is null, which indicates the current time when the path is
 * validated. The default for the remaining parameters is the least
 * constrained.<br />
 * <br />
 * <b>Concurrent Access</b><br />
 * <br />
 * Unless otherwise specified, the methods defined in this class are
 * not thread-safe. Multiple threads that need to access a single
 * object concurrently should synchronize amongst themselves and
 * provide the necessary locking. Multiple threads each manipulating
 * separate objects need not synchronize.
 *
 * @see CertPathValidator
 **/
public class PKIXParameters implements CertPathParameters {
    private Set trustAnchors;
    private Set initialPolicies = new HashSet();
    private List certStores = new ArrayList();
    private CertSelector certSelector;
    private List certPathCheckers = new ArrayList();
    private boolean revocationEnabled = true;
    private boolean explicitPolicyRequired = false;
    private boolean policyMappingInhibited = false;
    private boolean anyPolicyInhibited = false;
    private boolean policyQualifiersRejected = true;
    private Date date;
    private String sigProvider;

	/**
	 * Creates an instance of PKIXParameters with the specified
	 * Set of most-trusted CAs. Each element of the set is a
	 * TrustAnchor.<br />
	 * <br />
	 * Note that the Set is copied to protect against subsequent
	 * modifications.
	 *
	 * @param trustAnchors a Set of TrustAnchors
	 *
	 * @exception InvalidAlgorithmParameterException if the
	 * specified Set is empty <code>(trustAnchors.isEmpty() == true)</code>
	 * @exception NullPointerException if the specified Set is <code>null</code>
	 * @exception ClassCastException if any of the elements in the
	 * Set are not of type
	 * <code>java.security.cert.TrustAnchor</code>
	 **/
    public PKIXParameters(Set trustAnchors)
	throws InvalidAlgorithmParameterException
    {
	setTrustAnchors( trustAnchors );
    }

	/**
	 * Creates an instance of PKIXParameters that populates the
	 * set of most-trusted CAs from the trusted certificate
	 * entries contained in the specified KeyStore. Only keystore
	 * entries that contain trusted X509Certificates  are
	 * considered; all other certificate types are ignored.
	 *
	 * @param keystore a KeyStore from which the set of
	 * most-trusted CAs will be populated
	 *
	 * @exception KeyStoreException if the keystore has not been
	 * initialized
	 * @exception InvalidAlgorithmParameterException if the keystore
	 * does not contain at least one trusted certificate entry
	 * @exception NullPointerException if the keystore is null
	**/
    public PKIXParameters(KeyStore keystore)
	throws KeyStoreException,
	InvalidAlgorithmParameterException
    {
	if ( keystore == null )
	    throw new NullPointerException( "the keystore parameter must be non-null" );

	Set trustAnchors = new HashSet();
	String alias;
	Certificate cert;
	Enumeration enum = keystore.aliases();
	while ( enum.hasMoreElements() ) {
	    alias = (String)enum.nextElement();
	    if ( keystore.isCertificateEntry( alias ) ) {
		cert = keystore.getCertificate( alias );
		if ( cert instanceof X509Certificate )
		    trustAnchors.add( new TrustAnchor( (X509Certificate)cert, null ) );
	    }
	}
	setTrustAnchors( trustAnchors );
    }

	/**
	 * Returns an immutable Set of the most-trusted CAs.
	 *
	 * @return an immutable <code>Set</code> of
	 * <code>TrustAnchors</code> (never <code>null</code>)
	 *
	 * @see #setTrustAnchors
	 **/
    public Set getTrustAnchors()
    {
	return Collections.unmodifiableSet(trustAnchors);
    }

	/**
	 * Sets the Set of most-trusted CAs.<br />
	 * <br />
	 * Note that the Set is copied to protect against subsequent
	 * modifications.<br />
	 * <br />
	 * @param trustAnchors a Set of TrustAnchors
	 *
	 * @exception InvalidAlgorithmParameterException if the specified Set is empty <code>(trustAnchors.isEmpty() == true)</code>
	 * @exception NullPointerException if the specified Set is <code>null</code>
	 * @exception ClassCastException if any of the elements in
	 * the set are not of type java.security.cert.TrustAnchor
	 *
	 * @see #getTrustAnchors
	 **/
    public void setTrustAnchors(Set trustAnchors)
	throws InvalidAlgorithmParameterException
    {
	if ( trustAnchors == null )
	    throw new NullPointerException("the trustAnchors parameter must be non-null");
	if ( trustAnchors.isEmpty() )
	    throw new InvalidAlgorithmParameterException("the trustAnchors parameter must be non-empty");

	Iterator iter = trustAnchors.iterator();
	TrustAnchor obj;
	this.trustAnchors = new HashSet();
	while( iter.hasNext() ) {
	    obj = (TrustAnchor)iter.next();
	    if ( obj != null ) {
		this .trustAnchors.add( obj );
	    }
	}
    }

	/**
	 * Returns an immutable Set of initial policy identifiers (OID
	 * strings), indicating that any one of these policies would
	 * be acceptable to the certificate user for the purposes of
	 * certification path processing. The default return value is
	 * an empty <code>Set</code>, which is interpreted as meaning that any
	 * policy would be acceptable.
	 *
	 * @return an immutable <code>Set</code> of initial policy
	 * OIDs in String format, or an empty <code>Set</code> (implying any policy
	 * is acceptable). Never returns <code>null</code>.
	 *
	 * @see #setInitialPolicies(java.util.Set)
	 **/
    public Set getInitialPolicies()
    {
	Set returnSet = initialPolicies;
	if ( initialPolicies == null )
	    returnSet = new HashSet();

	return Collections.unmodifiableSet( returnSet );
    }

	/**
	 * Sets the <code>Set</code> of initial policy identifiers (OID strings),
	 * indicating that any one of these policies would be
	 * acceptable to the certificate user for the purposes of
	 * certification path processing. By default, any policy is
	 * acceptable (i.e. all policies), so a user that wants to
	 * allow any policy as acceptable does not need to call this
	 * method, or can call it with an empty <code>Set</code> (or <code>null</code>).<br />
	 * <br />
	 * Note that the Set is copied to protect against subsequent
	 * modifications.<br />
	 * <br />
	 * @param initialPolicies a Set of initial policy OIDs in String format (or <code>null</code>)
	 *
	 * @exception ClassCastException if any of the elements in the
	 * set are not of type String
	 *
	 * @see #getInitialPolicies()
	 **/
    public void setInitialPolicies(Set initialPolicies)
    {
	if ( initialPolicies == null || initialPolicies.isEmpty() )
	{
	    this.initialPolicies = null;
	}
	else
	{
	    Iterator iter = initialPolicies.iterator();
	    this.initialPolicies = new HashSet();
	    String obj;
	    while ( iter.hasNext() )
	    {
		obj = (String)iter.next();
		if ( obj != null ) {
		    this.initialPolicies.add( obj );
		}
	    }
	}
    }

	/**
	 * Sets the list of CertStores to be used in finding
	 * certificates and CRLs. May be null, in which case no
	 * CertStores will be used. The first CertStores in the list
	 * may be preferred to those that appear later.<br />
	 * <br />
	 * Note that the List is copied to protect against subsequent
	 * modifications.<br />
	 * <br />
	 * @param stores a List of CertStores (or <code>null</code>)
	 *
	 * @exception ClassCastException if any of the elements in the
	 * list are not of type <code>java.security.cert.CertStore</code>
	 *
	 * @see #getCertStores()
	 **/
    public void setCertStores(List stores)
    {
	certStores = new ArrayList();
	if ( stores != null && ! stores.isEmpty() )
	{
	    Iterator iter = stores.iterator();
	    CertStore obj;
	    while ( iter.hasNext() )
	    {
		obj = (CertStore)iter.next();
		if ( obj != null )
		{
		    certStores.add( obj );
		}
	    }
	}
    }

	/**
	 * Adds a CertStore to the end of the list of CertStores used
	 * in finding certificates and CRLs.
	 *
	 * @param store  the <code>CertStore</code> to add. If
	 * <code>null</code<, the store is ignored (not added to
	 * list).
	 **/
    public void addCertStore(CertStore store)
    {
	if ( store != null )
	    certStores.add( store );
    }

	/**
	 * Returns an immutable List of CertStores that are used to
	 * find certificates and CRLs.
	 *
	 * @return an immutable List of CertStores (may be empty, but never <code>null</code>)
	 *
	 * @see #setCertStores(java.util.List)
	 **/
    public List getCertStores()
    {
	return Collections.unmodifiableList(certStores);
    }

	/**
	* Sets the RevocationEnabled flag. If this flag is true, the default
	* revocation checking mechanism of the underlying PKIX service provider 
	* will be used. If this flag is false, the default revocation checking 
	* mechanism will be disabled (not used).<br />
	* <br />
	* When a <code>PKIXParameters</code> object is created, this flag is set
	* to true. This setting reflects the most common strategy for checking
	* revocation, since each service provider must support revocation 
	* checking to be PKIX compliant. Sophisticated applications should set
	* this flag to false when it is not practical to use a PKIX service 
	* provider's default revocation checking mechanism or when an alternative 
	* revocation checking mechanism is to be substituted (by also calling the 
	* {@link #addCertPathChecker addCertPathChecker} or {@link 
	* #setCertPathCheckers setCertPathCheckers} methods).
	*
	* @param val the new value of the RevocationEnabled flag
	**/
    public void setRevocationEnabled(boolean val)
    {
	revocationEnabled = val;
    }

	/** 
	 * Checks the RevocationEnabled flag. If this flag is true,
	 * the default revocation checking mechanism of the underlying
	 * PKIX service provider will be used. If this flag is false,
	 * the default revocation checking mechanism will be disabled
	 * (not used). See the setRevocationEnabled method for more
	 * details on setting the value of this flag.
	 *
	 * @return the current value of the RevocationEnabled flag
	**/
    public boolean isRevocationEnabled()
    {
	return revocationEnabled;
    }

	/**
	 * Sets the ExplicitPolicyRequired flag. If this flag is true,
	 * an acceptable policy needs to be explicitly identified in
	 * every certificate. By default, the ExplicitPolicyRequired
	 * flag is false.
	 *
	 * @param val true if explicit policy is to be required, false
	 * otherwise
	 **/
    public void setExplicitPolicyRequired(boolean val)
    {
	explicitPolicyRequired = val;
    }

	/**
	 * Checks if explicit policy is required. If this flag is
	 * true, an acceptable policy needs to be explicitly
	 * identified in every certificate. By default, the
	 * ExplicitPolicyRequired flag is false.
	 *
	 * @return true if explicit policy is required, false otherwise
	 **/
    public boolean isExplicitPolicyRequired()
    {
	return explicitPolicyRequired;
    }

	/**
	 * Sets the PolicyMappingInhibited flag. If this flag is true,
	 * policy mapping is inhibited. By default, policy mapping is
	 * not inhibited (the flag is false).
	 *
	 * @param val true if policy mapping is to be inhibited, false otherwise
	 **/
    public void setPolicyMappingInhibited(boolean val)
    {
	policyMappingInhibited = val;
    }

	/**
	 * Checks if policy mapping is inhibited. If this flag is
	 * true, policy mapping is inhibited. By default, policy
	 * mapping is not inhibited (the flag is false).
	 *
	 * @return true if policy mapping is inhibited, false otherwise
	 **/
    public boolean isPolicyMappingInhibited()
    {
	return policyMappingInhibited;
    }

	/**
	 * Sets state to determine if the any policy OID should be
	 * processed if it is included in a certificate. By default,
	 * the any policy OID is not inhibited ({@link #isAnyPolicyInhibited()}
	 * returns false).
	 *
	 * @return val - <code>true</code> if the any policy OID is to be inhibited, <code>false</code> otherwise
	 **/
    public void setAnyPolicyInhibited(boolean val)
    {
	anyPolicyInhibited = val;
    }

	/**
	 * Checks whether the any policy OID should be processed if it
	 * is included in a certificate.
	 *
	 * @return <code>true</code> if the any policy OID is inhibited, <code>false</code> otherwise
	 **/
    public boolean isAnyPolicyInhibited()
    {
	return anyPolicyInhibited;
    }

	/**
	 * Sets the PolicyQualifiersRejected flag. If this flag is
	 * true, certificates that include policy qualifiers in a
	 * certificate policies extension that is marked critical are
	 * rejected. If the flag is false, certificates are not
	 * rejected on this basis.<br />
	 * <br />
	 * When a <code>PKIXParameters</code> object is created, this flag is set
	 * to true. This setting reflects the most common (and
	 * simplest) strategy for processing policy
	 * qualifiers. Applications that want to use a more
	 * sophisticated policy must set this flag to false.<br />
	 * <br />
	 * Note that the PKIX certification path validation algorithm
	 * specifies that any policy qualifier in a certificate
	 * policies extension that is marked critical must be
	 * processed and validated. Otherwise the certification path
	 * must be rejected. If the policyQualifiersRejected flag is
	 * set to false, it is up to the application to validate all
	 * policy qualifiers in this manner in order to be PKIX
	 * compliant.
	 *
	 * @param qualifiersRejected the new value of the PolicyQualifiersRejected flag
	 *
	 * @see #getPolicyQualifiersRejected()
	 * @see PolicyQualifierInfo
	 **/
    public void setPolicyQualifiersRejected(boolean qualifiersRejected)
    {
	policyQualifiersRejected = qualifiersRejected;
    }

	/**
	 * Gets the PolicyQualifiersRejected flag. If this flag is
	 * true, certificates that include policy qualifiers in a
	 * certificate policies extension that is marked critical are
	 * rejected. If the flag is false, certificates are not
	 * rejected on this basis.<br />
	 * <br />
	 * When a PKIXParameters object is created, this flag is set to
	 * true. This setting reflects the most common (and simplest)
	 * strategy for processing policy qualifiers. Applications that
	 * want to use a more sophisticated policy must set this flag
	 * to false.
	 *
	 * @return the current value of the PolicyQualifiersRejected flag
	 *
	 * @see #setPolicyQualifiersRejected(boolean)
	 **/
    public boolean getPolicyQualifiersRejected()
    {
	return policyQualifiersRejected;
    }

        /**
	 * Returns the time for which the validity of the
	 * certification path should be determined. If null, the
	 * current time is used.<br />
	 * <br />
	 * Note that the Date returned is copied to protect against
	 * subsequent modifications.
	 *
	 * @return the Date, or <code>null</code> if not set
	 *
	 * @see #setDate(java.util.Date)
	 **/
    public Date getDate()
    {
	if ( date == null )
	    return null;

	return new Date( date.getTime() );
    }

	/**
	 * Sets the time for which the validity of the certification
	 * path should be determined. If null, the current time is
	 * used.<br />
	 * <br />
	 * Note that the Date supplied here is copied to protect
	 * against subsequent modifications.
	 *
	 * @param date the Date, or <code>null</code> for the current time
	 *
	 * @see #getDate()
	 **/
    public void setDate(Date date)
    {
	if ( date == null )
	    this.date = null;
	else
	    this.date = new Date( date.getTime() );
    }

	/**
	 * Sets a <code>List</code> of additional certification path checkers. If
	 * the specified List contains an object that is not a
	 * PKIXCertPathChecker, it is ignored.<br />
	 * <br />
	 * Each <code>PKIXCertPathChecker</code> specified implements additional
	 * checks on a certificate. Typically, these are checks to
	 * process and verify private extensions contained in
	 * certificates. Each <code>PKIXCertPathChecker</code> should be
	 * instantiated with any initialization parameters needed to
	 * execute the check.<br />
	 * <br />
	 * This method allows sophisticated applications to extend a
	 * PKIX <code>CertPathValidator</code> or <code>CertPathBuilder</code>. Each of the
	 * specified PKIXCertPathCheckers will be called, in turn, by
	 * a PKIX <code>CertPathValidator</code> or <code>CertPathBuilder</code> for each
	 * certificate processed or validated.<br />
	 * <br />
	 * Regardless of whether these additional PKIXCertPathCheckers
	 * are set, a PKIX <code>CertPathValidator</code> or <code>CertPathBuilder</code> must
	 * perform all of the required PKIX checks on each
	 * certificate. The one exception to this rule is if the
	 * RevocationEnabled flag is set to false (see the
	 * {@link #setRevocationEnabled(boolean) setRevocationEnabled} method).<br />
	 * <br />
	 * Note that the List supplied here is copied and each
	 * PKIXCertPathChecker in the list is cloned to protect against
	 * subsequent modifications.
	 *
	 * @param checkers a List of PKIXCertPathCheckers. May be
	 * null, in which case no additional checkers will be used.
	 * @exception ClassCastException if any of the elements in the
	 * list are not of type
	 * <code>java.security.cert.PKIXCertPathChecker</code>
	 * @see #getCertPathCheckers()
	 **/
    public void setCertPathCheckers(List checkers)
    {
	certPathCheckers = new ArrayList();
	if ( checkers == null )
	    return;
	Iterator iter = checkers.iterator();
	while ( iter.hasNext() )
	    certPathCheckers.add( (PKIXCertPathChecker)((PKIXCertPathChecker)iter.next()).clone() );
    }

	/**
	 * Returns the List of certification path checkers. The
	 * returned List is immutable, and each PKIXCertPathChecker in
	 * the List is cloned to protect against subsequent
	 * modifications.
	 *
	 * @return an immutable List of PKIXCertPathCheckers (may be empty, but not <code>null</code>)
	 *
	 * @see #setCertPathCheckers(java.util.List)
	 **/
    public List getCertPathCheckers()
    {
	List checkers = new ArrayList();
	Iterator iter = certPathCheckers.iterator();
	while ( iter.hasNext() )
	{    
	    checkers.add( (PKIXCertPathChecker)((PKIXCertPathChecker)iter.next()).clone() );
	}
	return Collections.unmodifiableList(checkers);
    }

	/**
	 * Adds a PKIXCertPathChecker to the list of certification
	 * path checkers. See the {@link #setCertPathCheckers} method for more
	 * details.<br />
	 * <br />
	 * Note that the <code>PKIXCertPathChecker</code> is cloned to protect
	 * against subsequent modifications.
	 *
	 * @param checker  a <code>PKIXCertPathChecker</code> to add
	 * to the list of checks. If <code>null</code>, the checker is
	 * ignored (not added to list).
	 **/
    public void addCertPathChecker( PKIXCertPathChecker checker )
    {
	if ( checker != null )
	{
	    certPathCheckers.add( checker.clone() );
	}
    }

	/**
	 * Returns the signature provider's name, or <code>null</code> if not set.
	 *
	 * @return the signature provider's name (or <code>null</code>)
	 *
	 * @see #setSigProvider(java.lang.String)
	 **/
    public String getSigProvider()
    {
	return sigProvider;
    }

	/**
	 * Sets the signature provider's name. The specified provider
	 * will be preferred when creating Signature objects. If null
	 * or not set, the first provider found supporting the
	 * algorithm will be used.
	 *
	 * @param sigProvider the signature provider's name (or <code>null</code>)
	 *
	 * @see #getSigProvider()
	 **/
    public void setSigProvider(String sigProvider)
    {
	this.sigProvider = sigProvider;
    }

	/**
	 * Returns the required constraints on the target
	 * certificate. The constraints are returned as an instance of
	 * CertSelector. If <code>null</code>, no constraints are defined.<br />
	 * <br />
	 * Note that the CertSelector returned is cloned to protect
	 * against subsequent modifications.
	 *
	 * @return a CertSelector specifying the constraints on the target certificate (or <code>null</code>)
	 *
	 * @see #setTargetCertConstraints(java.security.cert.CertSelector)
	 **/
    public CertSelector getTargetCertConstraints()
    {
	if ( certSelector == null )
	    return null;

	return (CertSelector)certSelector.clone();
    }

	/**
	 * Sets the required constraints on the target
	 * certificate. The constraints are specified as an instance
	 * of CertSelector. If null, no constraints are defined.<br />
	 * <br />
	 * Note that the CertSelector specified is cloned to protect
	 * against subsequent modifications.
	 *
	 * @param selector  a CertSelector specifying the constraints
	 * on the target certificate (or <code>null</code>)
	 *
	 * @see #getTargetCertConstraints()
	 **/
    public void setTargetCertConstraints(CertSelector selector)
    {
	if ( selector == null )
	    certSelector = null;
	else
	    certSelector = (CertSelector)selector.clone();
    }

	/**
	 * Makes a copy of this PKIXParameters object. Changes to the
	 * copy will not affect the original and vice versa.
	 *
	 * @return a copy of this <code>PKIXParameters</code> object
	 **/
    public Object clone()
    {
	try {
	    PKIXParameters obj = (PKIXParameters)super.clone();
	    obj.certStores = new ArrayList( certStores );
	    Iterator iter = certPathCheckers.iterator();
	    obj.certPathCheckers = new ArrayList();
	    while ( iter.hasNext() )
	    {
		obj.certPathCheckers.add( ((PKIXCertPathChecker)iter.next()).clone() );
	    }
	    if ( initialPolicies != null )
	    {
		obj.initialPolicies = new HashSet( initialPolicies );
	    }
	    if ( trustAnchors != null )
	    {
		obj.trustAnchors = new HashSet( trustAnchors );
	    }
	    if ( certSelector != null )
	    {
		obj.certSelector = (CertSelector)certSelector.clone();
	    }
	    return obj;
	} catch ( CloneNotSupportedException ex ) {
	    throw new InternalError();
	}
    }

	/**
	 * Returns a formatted string describing the parameters.
	 *
	 * @return a formatted string describing the parameters.
	 **/
    public String toString()
    {
	StringBuffer s = new StringBuffer();
	s.append("[\n");
	if ( trustAnchors != null )
	{
	    s.append("  Trust Anchors: " + trustAnchors.toString() + "\n");
	}
	if ( initialPolicies != null )
	{
	    if ( initialPolicies.isEmpty() )
	    {
		s.append("  Initial Policy OIDs: any\n" );
	    }
	    else
	    {
		s.append("  Initial Policy OIDs: [" + initialPolicies.toString() + "]\n");
	    }
	}
	s.append("  Validity Date: ");
	if ( date != null )
	    s.append(date);
	else
	    s.append("null");
	s.append("\n");

	s.append("  Signature Provider: ");
	if ( sigProvider != null )
	    s.append(sigProvider);
	else
	    s.append("null");
	s.append("\n");

	s.append("  Default Revocation Enabled: ");
	s.append(revocationEnabled);
	s.append("\n" );

	s.append("  Explicit Policy Required: ");
	s.append(explicitPolicyRequired);
	s.append("\n");

	s.append("  Policy Mapping Inhibited: ");
	s.append(policyMappingInhibited);
	s.append("\n");

	s.append("  Any Policy Inhibited: ");
	s.append(anyPolicyInhibited);
	s.append("\n");

	s.append("  Policy Qualifiers Rejected: ");
	s.append(policyQualifiersRejected);
	s.append("\n");

	s.append("  Target Cert Constraints: ");
	s.append(certSelector);
	s.append("\n");

	s.append("  Certification Path Checkers: [");
	s.append(certPathCheckers);
	s.append( "}\n");

	s.append("  CertStores: [");
	s.append(certStores);
	s.append("}\n");

	s.append("]\n");

	return s.toString();
    }
}
