package br.gov.serpro.util;

public class Base64Utils {

    private static byte[] mBase64EncMap, mBase64DecMap;

    /**
     * Class initializer. Initializes the Base64 alphabet (specified in RFC-2045).
     */
    static {
        byte[] base64Map = {
            (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F',
            (byte)'G', (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L',
            (byte)'M', (byte)'N', (byte)'O', (byte)'P', (byte)'Q', (byte)'R',
            (byte)'S', (byte)'T', (byte)'U', (byte)'V', (byte)'W', (byte)'X',
            (byte)'Y', (byte)'Z',
            (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f',
            (byte)'g', (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l',
            (byte)'m', (byte)'n', (byte)'o', (byte)'p', (byte)'q', (byte)'r',
            (byte)'s', (byte)'t', (byte)'u', (byte)'v', (byte)'w', (byte)'x',
            (byte)'y', (byte)'z',
            (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5',
            (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'+', (byte)'/' };
        mBase64EncMap = base64Map;
        mBase64DecMap = new byte[128];
        for (int i=0; i<mBase64EncMap.length; i++)
            mBase64DecMap[mBase64EncMap[i]] = (byte) i;
    }

    /**
     * This class isn't meant to be instantiated.
     */
    private Base64Utils() {
    }

    /**
     * Encodes the given byte[] using the Base64-encoding,
     * as specified in RFC-2045 (Section 6.8).
     *
     * @param aData the data to be encoded
     * @return the Base64-encoded <var>aData</var>
     * @exception IllegalArgumentException if NULL or empty array is passed
     */
    public static String base64Encode(byte[] aData) {
        if ((aData == null) || (aData.length == 0))
            throw new IllegalArgumentException("Can not encode NULL or empty byte array.");

        byte encodedBuf[] = new byte[((aData.length+2)/3)*4];

        // 3-byte to 4-byte conversion
        int srcIndex, destIndex;
        for (srcIndex=0, destIndex=0; srcIndex < aData.length-2; srcIndex += 3) {
            encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex] >>> 2) & 077];
            encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex+1] >>> 4) & 017 |
                        (aData[srcIndex] << 4) & 077];
            encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex+2] >>> 6) & 003 |
                        (aData[srcIndex+1] << 2) & 077];
            encodedBuf[destIndex++] = mBase64EncMap[aData[srcIndex+2] & 077];
        }

        // Convert the last 1 or 2 bytes
        if (srcIndex < aData.length) {
            encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex] >>> 2) & 077];
            if (srcIndex < aData.length-1) {
                encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex+1] >>> 4) & 017 |
                    (aData[srcIndex] << 4) & 077];
                encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex+1] << 2) & 077];
            }
            else {
                encodedBuf[destIndex++] = mBase64EncMap[(aData[srcIndex] << 4) & 077];
            }
        }

        // Add padding to the end of encoded data
        while (destIndex < encodedBuf.length) {
            encodedBuf[destIndex] = (byte) '=';
            destIndex++;
        }

        String result = new String(encodedBuf);
        return result;
    }


    /**
     * Decodes the given Base64-encoded data,
     * as specified in RFC-2045 (Section 6.8).
     *
     * @param aData the Base64-encoded aData.
     * @return the decoded <var>aData</var>.
     * @exception IllegalArgumentException if NULL or empty data is passed
     */
    public static byte[] base64Decode(String aData) {
        if ((aData == null) || (aData.length() == 0))
            throw new IllegalArgumentException("Can not decode NULL or empty string.");

        byte[] data = aData.getBytes();

        // Skip padding from the end of encoded data
        int tail = data.length;
        while (data[tail-1] == '=')
            tail--;

        byte decodedBuf[] = new byte[tail - data.length/4];

        // ASCII-printable to 0-63 conversion
        for (int i = 0; i < data.length; i++)
            data[i] = mBase64DecMap[data[i]];

        // 4-byte to 3-byte conversion
        int srcIndex, destIndex;
        for (srcIndex = 0, destIndex=0; destIndex < decodedBuf.length-2;
                srcIndex += 4, destIndex += 3) {
            decodedBuf[destIndex] = (byte) ( ((data[srcIndex] << 2) & 255) |
                ((data[srcIndex+1] >>> 4) & 003) );
            decodedBuf[destIndex+1] = (byte) ( ((data[srcIndex+1] << 4) & 255) |
                ((data[srcIndex+2] >>> 2) & 017) );
            decodedBuf[destIndex+2] = (byte) ( ((data[srcIndex+2] << 6) & 255) |
                (data[srcIndex+3] & 077) );
        }

        // Handle last 1 or 2 bytes
        if (destIndex < decodedBuf.length)
            decodedBuf[destIndex] = (byte) ( ((data[srcIndex] << 2) & 255) |
                ((data[srcIndex+1] >>> 4) & 003) );
        if (++destIndex < decodedBuf.length)
            decodedBuf[destIndex] = (byte) ( ((data[srcIndex+1] << 4) & 255) |
                ((data[srcIndex+2] >>> 2) & 017) );

        return decodedBuf;
    }


    public static String der2pem(byte[] der, boolean isCert){

        int begin = 0;
    	int lineSize = isCert ? 64 : 76;
        int end = lineSize;
    	int bytesWriten = 0;

        String CRLF = "\r\n";
        String base64encoded = Base64Utils.base64Encode(der);
        StringBuilder sb = new StringBuilder();

        String beginCertificate = "-----BEGIN CERTIFICATE-----" +CRLF;
        String endCertificate = "-----END CERTIFICATE-----" +CRLF;

        if (isCert){
            sb.append(beginCertificate);
        }

    	do {

    		if (base64encoded.length() - begin < end - begin){
    			end = base64encoded.length();
    		}

    		String subs = base64encoded.substring(begin, end);
    		sb.append(subs + CRLF);
    		bytesWriten += end - begin;
    		begin = end;
    		end += lineSize;

    	} while (bytesWriten != base64encoded.length());

        if (isCert){
            sb.append(endCertificate);
        }

    	return sb.toString();

    }

    public static String der2pem(byte[] der){
        return Base64Utils.der2pem(der, false);
    }

}