// --- BEGIN COPYRIGHT BLOCK ---
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; version 2 of the License.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// (C) 2007 Red Hat, Inc.
// All rights reserved.
// --- END COPYRIGHT BLOCK ---
package netscape.security.x509;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Array;
import java.util.Enumeration;
import java.util.Vector;

import netscape.security.util.BitArray;
import netscape.security.util.DerOutputStream;
import netscape.security.util.DerValue;

/**
 * Represent the Key Usage Extension.
 *
 * <p>
 * This extension, if present, defines the purpose (e.g., encipherment, signature, certificate signing) of the key
 * contained in the certificate. The usage restriction might be employed when a multipurpose key is to be restricted
 * (e.g., when an RSA key should be used only for signing or only for key encipherment).
 *
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 * @version 1.9
 * @see Extension
 * @see CertAttrSet
 */
public class KeyUsageExtension extends Extension
        implements CertAttrSet {

    /**
     *
     */
    private static final long serialVersionUID = 2899719374157256708L;
    /**
     * Identifier for this attribute, to be used with the
     * get, set, delete methods of Certificate, x509 type.
     */
    public static final String IDENT = "x509.info.extensions.KeyUsage";
    /**
     * Attribute names.
     */
    public static final String NAME = "KeyUsage";
    public static final String DIGITAL_SIGNATURE = "digital_signature";
    public static final String NON_REPUDIATION = "non_repudiation";
    public static final String KEY_ENCIPHERMENT = "key_encipherment";
    public static final String DATA_ENCIPHERMENT = "data_encipherment";
    public static final String KEY_AGREEMENT = "key_agreement";
    public static final String KEY_CERTSIGN = "key_certsign";
    public static final String CRL_SIGN = "crl_sign";
    public static final String ENCIPHER_ONLY = "encipher_only";
    public static final String DECIPHER_ONLY = "decipher_only";

    public static final int DIGITAL_SIGNATURE_BIT = 0;
    public static final int NON_REPUDIATION_BIT = 1;
    public static final int KEY_ENCIPHERMENT_BIT = 2;
    public static final int DATA_ENCIPHERMENT_BIT = 3;
    public static final int KEY_AGREEMENT_BIT = 4;
    public static final int KEY_CERTSIGN_BIT = 5;
    public static final int CRL_SIGN_BIT = 6;
    public static final int ENCIPHER_ONLY_BIT = 7;
    public static final int DECIPHER_ONLY_BIT = 8;

    public static final int NBITS = 9;

    public static String[] names = new String[NBITS];

    static {
        names[DIGITAL_SIGNATURE_BIT] = DIGITAL_SIGNATURE;
        names[NON_REPUDIATION_BIT] = NON_REPUDIATION;
        names[KEY_ENCIPHERMENT_BIT] = KEY_ENCIPHERMENT;
        names[DATA_ENCIPHERMENT_BIT] = DATA_ENCIPHERMENT;
        names[KEY_AGREEMENT_BIT] = KEY_AGREEMENT;
        names[KEY_CERTSIGN_BIT] = KEY_CERTSIGN;
        names[CRL_SIGN_BIT] = CRL_SIGN;
        names[ENCIPHER_ONLY_BIT] = ENCIPHER_ONLY;
        names[DECIPHER_ONLY_BIT] = DECIPHER_ONLY;
    }

    // Private data members
    private boolean[] bitString;

    // Encode this extension value
    private void encodeThis() throws IOException {
        DerOutputStream os = new DerOutputStream();
        os.putUnalignedBitString(this.bitString);
        this.extensionValue = os.toByteArray();
    }

    /**
     * Check if bit is set.
     *
     * @param position the position in the bit string to check.
     */
    private boolean isSet(int position) {
        if (bitString.length <= position)
            return false;
        return bitString[position];
    }

    /**
     * Set the bit at the specified position.
     */
    private void set(int position, boolean val) {
        // enlarge bitString if necessary
        if (position >= bitString.length) {
            boolean[] tmp = new boolean[position + 1];
            System.arraycopy(bitString, 0, tmp, 0, bitString.length);
            bitString = tmp;
        }
        bitString[position] = val;
    }

    /**
     * Create a KeyUsageExtension with the passed bit settings. The criticality
     * is set to true.
     *
     * @param bitString the bits to be set for the extension.
     */
    public KeyUsageExtension(boolean critical, byte[] bitString) throws IOException {
        this.bitString =
                new BitArray(bitString.length * 8, bitString).toBooleanArray();
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = critical;
        encodeThis();
    }

    public KeyUsageExtension(byte[] bitString) throws IOException {
        this.bitString =
                new BitArray(bitString.length * 8, bitString).toBooleanArray();
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = true;
        encodeThis();
    }

    /**
     * Create a KeyUsageExtension with the passed bit settings. The criticality
     * is set to true.
     *
     * @param bitString the bits to be set for the extension.
     */
    public KeyUsageExtension(boolean critical, boolean[] bitString) throws IOException {
        this.bitString = bitString;
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = critical;
        encodeThis();
    }

    public KeyUsageExtension(boolean[] bitString) throws IOException {
        this.bitString = bitString;
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = true;
        encodeThis();
    }

    /**
     * Create a KeyUsageExtension with the passed bit settings. The criticality
     * is set to true.
     *
     * @param bitString the bits to be set for the extension.
     */
    public KeyUsageExtension(BitArray bitString) throws IOException {
        this.bitString = bitString.toBooleanArray();
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = true;
        encodeThis();
    }

    /**
     * Create the extension from the passed DER encoded value of the same.
     *
     * @param critical true if the extension is to be treated as critical.
     * @param value Array of DER encoded bytes of the actual value.
     * @exception IOException on error.
     */
    public KeyUsageExtension(Boolean critical, Object value)
            throws IOException {
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = critical.booleanValue();
        /*
         * The following check should be activated again after
         * the PKIX profiling work becomes standard and the check
         * is not a barrier to interoperability !
         * if (!this.critical) {
         *   throw new IOException("KeyUsageExtension not marked critical,"
         *                         + " invalid profile.");
         * }
         */
        int len = Array.getLength(value);
        byte[] extValue = new byte[len];
        for (int i = 0; i < len; i++) {
            extValue[i] = Array.getByte(value, i);
        }
        this.extensionValue = extValue;
        DerValue val = new DerValue(extValue);
        this.bitString = val.getUnalignedBitString().toBooleanArray();
    }

    /**
     * Create a default key usage.
     */
    public KeyUsageExtension() {
        extensionId = PKIXExtensions.KeyUsage_Id;
        critical = true;
        bitString = new boolean[0];
    }

    /**
     * Set the attribute value.
     */
    public void set(String name, Object obj) throws IOException {
        clearValue();
        if (!(obj instanceof Boolean)) {
            throw new IOException("Attribute must be of type Boolean.");
        }
        boolean val = ((Boolean) obj).booleanValue();
        if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {
            set(0, val);
        } else if (name.equalsIgnoreCase(NON_REPUDIATION)) {
            set(1, val);
        } else if (name.equalsIgnoreCase(KEY_ENCIPHERMENT)) {
            set(2, val);
        } else if (name.equalsIgnoreCase(DATA_ENCIPHERMENT)) {
            set(3, val);
        } else if (name.equalsIgnoreCase(KEY_AGREEMENT)) {
            set(4, val);
        } else if (name.equalsIgnoreCase(KEY_CERTSIGN)) {
            set(5, val);
        } else if (name.equalsIgnoreCase(CRL_SIGN)) {
            set(6, val);
        } else if (name.equalsIgnoreCase(ENCIPHER_ONLY)) {
            set(7, val);
        } else if (name.equalsIgnoreCase(DECIPHER_ONLY)) {
            set(8, val);
        } else {
            throw new IOException("Attribute name not recognized by"
                                + " CertAttrSet:KeyUsage.");
        }
        encodeThis();
    }

    /**
     * Get the attribute value.
     */
    public Object get(String name) throws IOException {
        if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {
            return new Boolean(isSet(0));
        } else if (name.equalsIgnoreCase(NON_REPUDIATION)) {
            return new Boolean(isSet(1));
        } else if (name.equalsIgnoreCase(KEY_ENCIPHERMENT)) {
            return new Boolean(isSet(2));
        } else if (name.equalsIgnoreCase(DATA_ENCIPHERMENT)) {
            return new Boolean(isSet(3));
        } else if (name.equalsIgnoreCase(KEY_AGREEMENT)) {
            return new Boolean(isSet(4));
        } else if (name.equalsIgnoreCase(KEY_CERTSIGN)) {
            return new Boolean(isSet(5));
        } else if (name.equalsIgnoreCase(CRL_SIGN)) {
            return new Boolean(isSet(6));
        } else if (name.equalsIgnoreCase(ENCIPHER_ONLY)) {
            return new Boolean(isSet(7));
        } else if (name.equalsIgnoreCase(DECIPHER_ONLY)) {
            return new Boolean(isSet(8));
        } else {
            throw new IOException("Attribute name not recognized by"
                                + " CertAttrSet:KeyUsage.");
        }
    }

    /**
     * Delete the attribute value.
     */
    public void delete(String name) throws IOException {
        if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {
            set(0, false);
        } else if (name.equalsIgnoreCase(NON_REPUDIATION)) {
            set(1, false);
        } else if (name.equalsIgnoreCase(KEY_ENCIPHERMENT)) {
            set(2, false);
        } else if (name.equalsIgnoreCase(DATA_ENCIPHERMENT)) {
            set(3, false);
        } else if (name.equalsIgnoreCase(KEY_AGREEMENT)) {
            set(4, false);
        } else if (name.equalsIgnoreCase(KEY_CERTSIGN)) {
            set(5, false);
        } else if (name.equalsIgnoreCase(CRL_SIGN)) {
            set(6, false);
        } else if (name.equalsIgnoreCase(ENCIPHER_ONLY)) {
            set(7, false);
        } else if (name.equalsIgnoreCase(DECIPHER_ONLY)) {
            set(8, false);
        } else {
            throw new IOException("Attribute name not recognized by"
                                + " CertAttrSet:KeyUsage.");
        }
    }

    /**
     * Returns a printable representation of the KeyUsage.
     */
    public String toString() {
        String s = super.toString() + "KeyUsage [\n";

        try {
            if (isSet(0)) {
                s += "  DigitalSignature\n";
            }
            if (isSet(1)) {
                s += "  Non_repudiation\n";
            }
            if (isSet(2)) {
                s += "  Key_Encipherment\n";
            }
            if (isSet(3)) {
                s += "  Data_Encipherment\n";
            }
            if (isSet(4)) {
                s += "  Key_Agreement\n";
            }
            if (isSet(5)) {
                s += "  Key_CertSign\n";
            }
            if (isSet(6)) {
                s += "  Crl_Sign\n";
            }
            if (isSet(7)) {
                s += "  Encipher_Only\n";
            }
            if (isSet(8)) {
                s += "  Decipher_Only\n";
            }
        } catch (ArrayIndexOutOfBoundsException ex) {
        }

        s += "]\n";

        return (s);
    }

    /**
     * Decode the extension from the InputStream.
     *
     * @param in the InputStream to unmarshal the contents from.
     * @exception IOException on decoding or validity errors.
     */
    public void decode(InputStream in) throws IOException {
        throw new IOException("Method not to be called directly.");
    }

    /**
     * Write the extension to the DerOutputStream.
     *
     * @param out the DerOutputStream to write the extension to.
     * @exception IOException on encoding errors.
     */
    public void encode(OutputStream out) throws IOException {
        DerOutputStream tmp = new DerOutputStream();

        if (this.extensionValue == null) {
            this.extensionId = PKIXExtensions.KeyUsage_Id;
            this.critical = true;
            encodeThis();
        }
        super.encode(tmp);
        out.write(tmp.toByteArray());
    }

    /**
     * Return an enumeration of names of attributes existing within this
     * attribute.
     */
    public Enumeration<String> getAttributeNames() {
        Vector<String> elements = new Vector<String>();
        elements.addElement(DIGITAL_SIGNATURE);
        elements.addElement(NON_REPUDIATION);
        elements.addElement(KEY_ENCIPHERMENT);
        elements.addElement(DATA_ENCIPHERMENT);
        elements.addElement(KEY_AGREEMENT);
        elements.addElement(KEY_CERTSIGN);
        elements.addElement(CRL_SIGN);
        elements.addElement(ENCIPHER_ONLY);
        elements.addElement(DECIPHER_ONLY);

        return (elements.elements());
    }

    public boolean[] getBits() {
        return bitString.clone();
    }

    /**
     * Return the name of this attribute.
     */
    public String getName() {
        return (NAME);
    }
}