package org.bouncycastle.asn1;

import java.io.IOException;

/**
 * DER IA5String object - this is an ascii string.
 */
public class DERIA5String
    extends ASN1Object
    implements DERString
{
    String  string;

    /**
     * return a IA5 string from the passed in object
     *
     * @exception IllegalArgumentException if the object cannot be converted.
     */
    public static DERIA5String getInstance(
        Object  obj)
    {
        if (obj == null || obj instanceof DERIA5String)
        {
            return (DERIA5String)obj;
        }

        if (obj instanceof ASN1OctetString)
        {
            return new DERIA5String(((ASN1OctetString)obj).getOctets());
        }

        if (obj instanceof ASN1TaggedObject)
        {
            return getInstance(((ASN1TaggedObject)obj).getObject());
        }

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

    /**
     * return an IA5 String 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.
     * @exception IllegalArgumentException if the tagged object cannot
     *               be converted.
     */
    public static DERIA5String getInstance(
        ASN1TaggedObject obj,
        boolean          explicit)
    {
        return getInstance(obj.getObject());
    }

    /**
     * basic constructor - with bytes.
     */
    public DERIA5String(
        byte[]   string)
    {
        char[]  cs = new char[string.length];

        for (int i = 0; i != cs.length; i++)
        {
            cs[i] = (char)(string[i] & 0xff);
        }

        this.string = new String(cs);
    }

    /**
     * basic constructor - without validation.
     */
    public DERIA5String(
        String   string)
    {
        this(string, false);
    }

    /**
     * Constructor with optional validation.
     *
     * @param string the base string to wrap.
     * @param validate whether or not to check the string.
     * @throws IllegalArgumentException if validate is true and the string
     * contains characters that should not be in an IA5String.
     */
    public DERIA5String(
        String   string,
        boolean  validate)
    {
        if (validate && !isIA5String(string))
        {
            throw new IllegalArgumentException("string contains illegal characters");
        }

        this.string = string;
    }

    public String getString()
    {
        return string;
    }

    public byte[] getOctets()
    {
        char[]  cs = string.toCharArray();
        byte[]  bs = new byte[cs.length];

        for (int i = 0; i != cs.length; i++)
        {
            bs[i] = (byte)cs[i];
        }

        return bs; 
    }

    void encode(
        DEROutputStream  out)
        throws IOException
    {
        out.writeEncoded(IA5_STRING, this.getOctets());
    }

    public int hashCode()
    {
        return this.getString().hashCode();
    }

    boolean asn1Equals(
        DERObject  o)
    {
        if (!(o instanceof DERIA5String))
        {
            return false;
        }

        DERIA5String  s = (DERIA5String)o;

        return this.getString().equals(s.getString());
    }

    /**
     * return true if the passed in String can be represented without
     * loss as an IA5String, false otherwise.
     *
     * @return true if in printable set, false otherwise.
     */
    public static boolean isIA5String(
        String  str)
    {
        for (int i = str.length() - 1; i >= 0; i--)
        {
            char    ch = str.charAt(i);

            if (ch > 0x007f)
            {
                return false;
            }
        }

        return true;
    }
}
