package com.gensi.manage.utils;

public class Base64Util {
	private static final char[] intToBase64 = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
			'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
			'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
			'4', '5', '6', '7', '8', '9', '+', '/' };

	private static final char[] intToAltBase64 = { '!', '"', '#', '$', '%', '&', '\'', '(', ')', ',', '-', '.', ':',
			';', '<', '>', '@', '[', ']', '^', '`', '_', '{', '|', '}', '~', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
			'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2',
			'3', '4', '5', '6', '7', '8', '9', '+', '?' };

	private static final byte[] base64ToInt = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1,
			-1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8,
			9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,
			30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 };

	private static final byte[] altBase64ToInt = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, -1, 62, 9, 10,
			11, -1, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 12, 13, 14, -1, 15, 63, 16, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 17, -1, 18, 19, 21, 20, 26, 27, 28,
			29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 22, 23, 24,
			25 };

	public static String byteArrayToBase64(byte[] a) {
		return byteArrayToBase64(a, false);
	}

	private static String byteArrayToBase64(byte[] a, boolean alternate) {
		int aLen = a.length;
		int numFullGroups = aLen / 3;
		int numBytesInPartialGroup = aLen - 3 * numFullGroups;
		int resultLen = 4 * ((aLen + 2) / 3);
		StringBuffer result = new StringBuffer(resultLen);
		char[] intToAlpha = alternate ? intToAltBase64 : intToBase64;

		int inCursor = 0;
		for (int i = 0; i < numFullGroups; i++) {
			int byte0 = a[(inCursor++)] & 0xFF;
			int byte1 = a[(inCursor++)] & 0xFF;
			int byte2 = a[(inCursor++)] & 0xFF;
			result.append(intToAlpha[(byte0 >> 2)]);
			result.append(intToAlpha[(byte0 << 4 & 0x3F | byte1 >> 4)]);
			result.append(intToAlpha[(byte1 << 2 & 0x3F | byte2 >> 6)]);
			result.append(intToAlpha[(byte2 & 0x3F)]);
		}

		if (numBytesInPartialGroup != 0) {
			int byte0 = a[(inCursor++)] & 0xFF;
			result.append(intToAlpha[(byte0 >> 2)]);
			if (numBytesInPartialGroup == 1) {
				result.append(intToAlpha[(byte0 << 4 & 0x3F)]);
				result.append("==");
			} else {
				int byte1 = a[(inCursor++)] & 0xFF;
				result.append(intToAlpha[(byte0 << 4 & 0x3F | byte1 >> 4)]);
				result.append(intToAlpha[(byte1 << 2 & 0x3F)]);
				result.append('=');
			}
		}
		return result.toString();
	}

	public static byte[] base64ToByteArray(String s) {
		return base64ToByteArray(s, false);
	}

	private static byte[] base64ToByteArray(String s, boolean alternate) {
		byte[] alphaToInt = alternate ? altBase64ToInt : base64ToInt;
		int sLen = s.length();
		int numGroups = sLen / 4;
		if (4 * numGroups != sLen) {
			throw new IllegalArgumentException("String length must be a multiple of four.");
		}
		int missingBytesInLastGroup = 0;
		int numFullGroups = numGroups;
		if (sLen != 0) {
			if (s.charAt(sLen - 1) == '=') {
				missingBytesInLastGroup++;
				numFullGroups--;
			}
			if (s.charAt(sLen - 2) == '=') {
				missingBytesInLastGroup++;
			}
		}
		byte[] result = new byte[3 * numGroups - missingBytesInLastGroup];

		int inCursor = 0;
		int outCursor = 0;
		for (int i = 0; i < numFullGroups; i++) {
			int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
			int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
			int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
			int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt);
			result[(outCursor++)] = ((byte) (ch0 << 2 | ch1 >> 4));
			result[(outCursor++)] = ((byte) (ch1 << 4 | ch2 >> 2));
			result[(outCursor++)] = ((byte) (ch2 << 6 | ch3));
		}

		if (missingBytesInLastGroup != 0) {
			int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
			int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
			result[(outCursor++)] = ((byte) (ch0 << 2 | ch1 >> 4));

			if (missingBytesInLastGroup == 1) {
				int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
				result[(outCursor++)] = ((byte) (ch1 << 4 | ch2 >> 2));
			}
		}
		return result;
	}

	private static int base64toInt(char c, byte[] alphaToInt) {
		int result = alphaToInt[c];
		if (result < 0) {
			throw new IllegalArgumentException("Illegal character " + c);
		}
		return result;
	}
}
