import Base32;

import java.security.MessageDigest;

public class Sha1HashExtension implements AdcHashExtension {

	public String getExtensionName() {
		return "SHA1";
	}

	public byte[] hash(byte[] bytes) {
		byte[] result = null;
		try {
			MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
			messageDigest.update(bytes);
			result = messageDigest.digest();
		} catch (Exception exception) {
			exception.printStackTrace();
		}
		return result;
	}

	public String hash(String baseEncodedData) {
		return Base32.encode(hash(Base32.decode(baseEncodedData)));
	}

	public String password(String baseEncodedCid, String password, String baseEncodedKey) {
		String result = null;
		try {
			MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
			messageDigest.update(Base32.decode(baseEncodedCid));
			messageDigest.update(password.getBytes());
			messageDigest.update(Base32.decode(baseEncodedKey));
			result = Base32.encode(messageDigest.digest());
		} catch (Exception exception) {
			exception.printStackTrace();
		}
		return result;
	}
}

public class Base32 {
	private static final String base32Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
	private static final int[] base32Lookup = { 0xFF, 0xFF, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, // '0',
	// '1',
	// '2',
	// '3',
	// '4', '5', '6', '7'
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // '8', '9', ':',
	// ';', '<', '=',
	// '>', '?'
	0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, // '@', 'A', 'B',
	// 'C', 'D', 'E',
	// 'F', 'G'
	0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, // 'H', 'I', 'J',
	// 'K', 'L', 'M',
	// 'N', 'O'
	0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, // 'P', 'Q', 'R',
	// 'S', 'T', 'U',
	// 'V', 'W'
	0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 'X', 'Y', 'Z',
	// '[', '\', ']',
	// '^', '_'
	0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, // '`', 'a', 'b',
	// 'c', 'd', 'e',
	// 'f', 'g'
	0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, // 'h', 'i', 'j',
	// 'k', 'l', 'm',
	// 'n', 'o'
	0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, // 'p', 'q', 'r',
	// 's', 't', 'u',
	// 'v', 'w'
	0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF // 'x', 'y', 'z',
	// '{', '|', '}',
	// '~', 'DEL'
	};

	static public byte[] decode(final String base32) {
		int i, index, lookup, offset, digit;
		byte[] bytes = new byte[base32.length() * 5 / 8];

		for (i = 0, index = 0, offset = 0; i < base32.length(); i++) {
			lookup = base32.charAt(i) - '0';

			/* Skip chars outside the lookup table */
			if (lookup < 0 || lookup >= base32Lookup.length) {
				continue;
			}

			digit = base32Lookup[lookup];

			/* If this digit is not in the table, ignore it */
			if (digit == 0xFF) {
				continue;
			}

			if (index <= 3) {
				index = (index + 5) % 8;
				if (index == 0) {
					bytes[offset] |= digit;
					offset++;
					if (offset >= bytes.length) {
						break;
					}
				} else {
					bytes[offset] |= digit << 8 - index;
				}
			} else {
				index = (index + 5) % 8;
				bytes[offset] |= digit >>> index;
				offset++;

				if (offset >= bytes.length) {
					break;
				}
				bytes[offset] |= digit << 8 - index;
			}
		}
		return bytes;
	}

	static public String encode(final byte[] bytes) {
		int i = 0, index = 0, digit = 0;
		int currByte, nextByte;
		StringBuffer base32 = new StringBuffer((bytes.length + 7) * 8 / 5);

		while (i < bytes.length) {
			currByte = bytes[i] >= 0 ? bytes[i] : bytes[i] + 256; // unsign

			/* Is the current digit going to span a byte boundary? */
			if (index > 3) {
				if (i + 1 < bytes.length) {
					nextByte = bytes[i + 1] >= 0 ? bytes[i + 1] : bytes[i + 1] + 256;
				} else {
					nextByte = 0;
				}

				digit = currByte & 0xFF >> index;
				index = (index + 5) % 8;
				digit <<= index;
				digit |= nextByte >> 8 - index;
				i++;
			} else {
				digit = currByte >> 8 - (index + 5) & 0x1F;
				index = (index + 5) % 8;
				if (index == 0) {
					i++;
				}
			}
			base32.append(base32Chars.charAt(digit));
		}

		return base32.toString();
	}
}