package org.bouncycastle.asn1;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.math.BigInteger;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.bouncycastle.util.Arrays;

Class representing the ASN.1 OBJECT IDENTIFIER type.
/**
 * Class representing the ASN.1 OBJECT IDENTIFIER type.
 */
public class ASN1ObjectIdentifier
    extends ASN1Primitive
{
    private final String identifier;

    private byte[] body;

    
Return an OID from the passed in object
Params:
obj – an ASN1ObjectIdentifier or an object that can be converted into one.
Throws:
IllegalArgumentException – if the object cannot be converted.
Returns:
an ASN1ObjectIdentifier instance, or null./**
     * Return an OID from the passed in object
     *
     * @param obj an ASN1ObjectIdentifier or an object that can be converted into one.
     * @return an ASN1ObjectIdentifier instance, or null.
     * @throws IllegalArgumentException if the object cannot be converted.
     */
    public static ASN1ObjectIdentifier getInstance(
        Object obj)
    {
        if (obj == null || obj instanceof ASN1ObjectIdentifier)
        {
            return (ASN1ObjectIdentifier)obj;
        }

        if (obj instanceof ASN1Encodable)
        {
            ASN1Primitive primitive = ((ASN1Encodable)obj).toASN1Primitive();

            if (primitive instanceof ASN1ObjectIdentifier)
            {
                return (ASN1ObjectIdentifier)primitive;
            }
        }

        if (obj instanceof byte[])
        {
            byte[] enc = (byte[])obj;
            try
            {
                return (ASN1ObjectIdentifier)fromByteArray(enc);
            }
            catch (IOException e)
            {
                throw new IllegalArgumentException("failed to construct object identifier from byte[]: " + e.getMessage());
            }
        }

        throw new IllegalArgumentException("illegal object in getInstance: " + obj.getClass().getName());
    }

    
Return an OBJECT IDENTIFIER from a tagged object.
Params:
obj –      the tagged object holding the object we want
explicit – true if the object is meant to be explicitly
                tagged false otherwise.
Throws:
IllegalArgumentException – if the tagged object cannot
be converted.
Returns:
an ASN1ObjectIdentifier instance, or null./**
     * Return an OBJECT IDENTIFIER from a tagged object.
     *
     * @param obj      the tagged object holding the object we want
     * @param explicit true if the object is meant to be explicitly
     *                 tagged false otherwise.
     * @return an ASN1ObjectIdentifier instance, or null.
     * @throws IllegalArgumentException if the tagged object cannot
     * be converted.
     */
    public static ASN1ObjectIdentifier getInstance(
        ASN1TaggedObject obj,
        boolean explicit)
    {
        ASN1Primitive o = obj.getObject();

        if (explicit || o instanceof ASN1ObjectIdentifier)
        {
            return getInstance(o);
        }
        else
        {
            return ASN1ObjectIdentifier.fromOctetString(ASN1OctetString.getInstance(o).getOctets());
        }
    }

    private static final long LONG_LIMIT = (Long.MAX_VALUE >> 7) - 0x7f;

    ASN1ObjectIdentifier(
        byte[] bytes)
    {
        StringBuffer objId = new StringBuffer();
        long value = 0;
        BigInteger bigValue = null;
        boolean first = true;

        for (int i = 0; i != bytes.length; i++)
        {
            int b = bytes[i] & 0xff;

            if (value <= LONG_LIMIT)
            {
                value += (b & 0x7f);
                if ((b & 0x80) == 0)             // end of number reached
                {
                    if (first)
                    {
                        if (value < 40)
                        {
                            objId.append('0');
                        }
                        else if (value < 80)
                        {
                            objId.append('1');
                            value -= 40;
                        }
                        else
                        {
                            objId.append('2');
                            value -= 80;
                        }
                        first = false;
                    }

                    objId.append('.');
                    objId.append(value);
                    value = 0;
                }
                else
                {
                    value <<= 7;
                }
            }
            else
            {
                if (bigValue == null)
                {
                    bigValue = BigInteger.valueOf(value);
                }
                bigValue = bigValue.or(BigInteger.valueOf(b & 0x7f));
                if ((b & 0x80) == 0)
                {
                    if (first)
                    {
                        objId.append('2');
                        bigValue = bigValue.subtract(BigInteger.valueOf(80));
                        first = false;
                    }

                    objId.append('.');
                    objId.append(bigValue);
                    bigValue = null;
                    value = 0;
                }
                else
                {
                    bigValue = bigValue.shiftLeft(7);
                }
            }
        }

        this.identifier = objId.toString();
        this.body = Arrays.clone(bytes);
    }

    
Create an OID based on the passed in String.
Params:
identifier – a string representation of an OID./**
     * Create an OID based on the passed in String.
     *
     * @param identifier a string representation of an OID.
     */
    public ASN1ObjectIdentifier(
        String identifier)
    {
        if (identifier == null)
        {
            throw new IllegalArgumentException("'identifier' cannot be null");
        }
        if (!isValidIdentifier(identifier))
        {
            throw new IllegalArgumentException("string " + identifier + " not an OID");
        }

        this.identifier = identifier;
    }

    
Create an OID that creates a branch under the current one.
Params:
branchID – node numbers for the new branch.
Returns:
the OID for the new created branch./**
     * Create an OID that creates a branch under the current one.
     *
     * @param branchID node numbers for the new branch.
     * @return the OID for the new created branch.
     */
    ASN1ObjectIdentifier(ASN1ObjectIdentifier oid, String branchID)
    {
        if (!isValidBranchID(branchID, 0))
        {
            throw new IllegalArgumentException("string " + branchID + " not a valid OID branch");
        }

        this.identifier = oid.getId() + "." + branchID;
    }

    
Return the OID as a string.
Returns:
the string representation of the OID carried by this object./**
     * Return the OID as a string.
     *
     * @return the string representation of the OID carried by this object.
     */
    public String getId()
    {
        return identifier;
    }

    
Return an OID that creates a branch under the current one.
Params:
branchID – node numbers for the new branch.
Returns:
the OID for the new created branch./**
     * Return an OID that creates a branch under the current one.
     *
     * @param branchID node numbers for the new branch.
     * @return the OID for the new created branch.
     */
    public ASN1ObjectIdentifier branch(String branchID)
    {
        return new ASN1ObjectIdentifier(this, branchID);
    }

    
Return true if this oid is an extension of the passed in branch - stem.
Params:
stem – the arc or branch that is a possible parent.
Returns:
true if the branch is on the passed in stem, false otherwise./**
     * Return true if this oid is an extension of the passed in branch - stem.
     *
     * @param stem the arc or branch that is a possible parent.
     * @return true if the branch is on the passed in stem, false otherwise.
     */
    public boolean on(ASN1ObjectIdentifier stem)
    {
        String id = getId(), stemId = stem.getId();
        return id.length() > stemId.length() && id.charAt(stemId.length()) == '.' && id.startsWith(stemId);
    }

    private void writeField(
        ByteArrayOutputStream out,
        long fieldValue)
    {
        byte[] result = new byte[9];
        int pos = 8;
        result[pos] = (byte)((int)fieldValue & 0x7f);
        while (fieldValue >= (1L << 7))
        {
            fieldValue >>= 7;
            result[--pos] = (byte)((int)fieldValue & 0x7f | 0x80);
        }
        out.write(result, pos, 9 - pos);
    }

    private void writeField(
        ByteArrayOutputStream out,
        BigInteger fieldValue)
    {
        int byteCount = (fieldValue.bitLength() + 6) / 7;
        if (byteCount == 0)
        {
            out.write(0);
        }
        else
        {
            BigInteger tmpValue = fieldValue;
            byte[] tmp = new byte[byteCount];
            for (int i = byteCount - 1; i >= 0; i--)
            {
                tmp[i] = (byte)((tmpValue.intValue() & 0x7f) | 0x80);
                tmpValue = tmpValue.shiftRight(7);
            }
            tmp[byteCount - 1] &= 0x7f;
            out.write(tmp, 0, tmp.length);
        }
    }

    private void doOutput(ByteArrayOutputStream aOut)
    {
        OIDTokenizer tok = new OIDTokenizer(identifier);
        int first = Integer.parseInt(tok.nextToken()) * 40;

        String secondToken = tok.nextToken();
        if (secondToken.length() <= 18)
        {
            writeField(aOut, first + Long.parseLong(secondToken));
        }
        else
        {
            writeField(aOut, new BigInteger(secondToken).add(BigInteger.valueOf(first)));
        }

        while (tok.hasMoreTokens())
        {
            String token = tok.nextToken();
            if (token.length() <= 18)
            {
                writeField(aOut, Long.parseLong(token));
            }
            else
            {
                writeField(aOut, new BigInteger(token));
            }
        }
    }

    private synchronized byte[] getBody()
    {
        if (body == null)
        {
            ByteArrayOutputStream bOut = new ByteArrayOutputStream();

            doOutput(bOut);

            body = bOut.toByteArray();
        }

        return body;
    }

    boolean isConstructed()
    {
        return false;
    }

    int encodedLength()
        throws IOException
    {
        int length = getBody().length;

        return 1 + StreamUtil.calculateBodyLength(length) + length;
    }

    void encode(
        ASN1OutputStream out)
        throws IOException
    {
        byte[] enc = getBody();

        out.write(BERTags.OBJECT_IDENTIFIER);
        out.writeLength(enc.length);
        out.write(enc);
    }

    public int hashCode()
    {
        return identifier.hashCode();
    }

    boolean asn1Equals(
        ASN1Primitive o)
    {
        if (o == this)
        {
            return true;
        }

        if (!(o instanceof ASN1ObjectIdentifier))
        {
            return false;
        }

        return identifier.equals(((ASN1ObjectIdentifier)o).identifier);
    }

    public String toString()
    {
        return getId();
    }

    private static boolean isValidBranchID(
        String branchID, int start)
    {
        boolean periodAllowed = false;

        int pos = branchID.length();
        while (--pos >= start)
        {
            char ch = branchID.charAt(pos);

            // TODO Leading zeroes?
            if ('0' <= ch && ch <= '9')
            {
                periodAllowed = true;
                continue;
            }

            if (ch == '.')
            {
                if (!periodAllowed)
                {
                    return false;
                }

                periodAllowed = false;
                continue;
            }

            return false;
        }

        return periodAllowed;
    }

    private static boolean isValidIdentifier(
        String identifier)
    {
        if (identifier.length() < 3 || identifier.charAt(1) != '.')
        {
            return false;
        }

        char first = identifier.charAt(0);
        if (first < '0' || first > '2')
        {
            return false;
        }

        return isValidBranchID(identifier, 2);
    }

    
Intern will return a reference to a pooled version of this object, unless it
is not present in which case intern will add it.

The pool is also used by the ASN.1 parsers to limit the number of duplicated OID
objects in circulation.

Returns:
a reference to the identifier in the pool./**
     * Intern will return a reference to a pooled version of this object, unless it
     * is not present in which case intern will add it.
     * <p>
     * The pool is also used by the ASN.1 parsers to limit the number of duplicated OID
     * objects in circulation.
     * </p>
     *
     * @return a reference to the identifier in the pool.
     */
    public ASN1ObjectIdentifier intern()
    {
        final OidHandle hdl = new OidHandle(getBody());
        ASN1ObjectIdentifier oid = pool.get(hdl);
        if (oid == null)
        {
            oid = pool.putIfAbsent(hdl, this);
            if (oid == null)
            {
                oid = this;
            }
        }
        return oid;
    }

    private static final ConcurrentMap<OidHandle, ASN1ObjectIdentifier> pool = new ConcurrentHashMap<OidHandle, ASN1ObjectIdentifier>();

    private static class OidHandle
    {
        private final int key;
        private final byte[] enc;

        OidHandle(byte[] enc)
        {
            this.key = Arrays.hashCode(enc);
            this.enc = enc;
        }

        public int hashCode()
        {
            return key;
        }

        public boolean equals(Object o)
        {
            if (o instanceof OidHandle)
            {
                return Arrays.areEqual(enc, ((OidHandle)o).enc);
            }

            return false;
        }
    }

    static ASN1ObjectIdentifier fromOctetString(byte[] enc)
    {
        final OidHandle hdl = new OidHandle(enc);
        ASN1ObjectIdentifier oid = pool.get(hdl);
        if (oid == null)
        {
            return new ASN1ObjectIdentifier(enc);
        }
        return oid;
    }
}