/*
 * To change this template, choose Tools | Templates and open the template in
 * the editor.
 */
package fr.xephi.authme.security.crypts;

import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @author stefano
 */
public class PHPBB implements EncryptionMethod {

	private String itoa64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

	public static String md5(String data) {
		try {
			byte[] bytes = data.getBytes("ISO-8859-1");
			MessageDigest md5er = MessageDigest.getInstance("MD5");
			byte[] hash = md5er.digest(bytes);
			return bytes2hex(hash);
		} catch (GeneralSecurityException | UnsupportedEncodingException e) {
			throw new RuntimeException(e);
		}
	}

	private static String bytes2hex(byte[] bytes) {
		StringBuilder r = new StringBuilder(32);
		for (byte b : bytes) {
			String x = Integer.toHexString(b & 0xff);
			if (x.length() < 2)
				r.append("0");
			r.append(x);
		}
		return r.toString();
	}

	static int hexToInt(char ch) {
		if (ch >= '0' && ch <= '9')
			return ch - '0';
		ch = Character.toUpperCase(ch);
		if (ch >= 'A' && ch <= 'F')
			return ch - 'A' + 0xA;
		throw new IllegalArgumentException("Not a hex character: " + ch);
	}

	static String pack(String hex) {
		StringBuilder buf = new StringBuilder();
		for (int i = 0; i < hex.length(); i += 2) {
			char c1 = hex.charAt(i);
			char c2 = hex.charAt(i + 1);
			char packed = (char) (hexToInt(c1) * 16 + hexToInt(c2));
			buf.append(packed);
		}
		return buf.toString();
	}

	@Override
	public boolean comparePassword(String hash, String password, String playerName) throws NoSuchAlgorithmException {
		return phpbb_check_hash(password, hash);
	}

	@Override
	public String getHash(String password, String salt, String name) throws NoSuchAlgorithmException {
		return phpbb_hash(password, salt);
	}

	public boolean phpbb_check_hash(String password, String hash) {
		if (hash.length() == 34)
			return _hash_crypt_private(password, hash).equals(hash);
		else
			return md5(password).equals(hash);
	}

	public String phpbb_hash(String password, String salt) {
		String random_state = salt;
		StringBuilder random = new StringBuilder();
		int count = 6;
		for (int i = 0; i < count; i += 16) {
			random_state = md5(salt + random_state);
			random.append(pack(md5(random_state)));
		}
		String hash = _hash_crypt_private(password, _hash_gensalt_private(random.substring(0, count), itoa64));
		if (hash.length() == 34) {
			return hash;
		}
		return md5(password);
	}

	/**
	 * Encode hash
	 */
	private String _hash_encode64(String input, int count) {
		StringBuilder output = new StringBuilder();
		int i = 0;
		do {
			int value = input.charAt(i++);
			output.append(itoa64.charAt(value & 0x3f));
			if (i < count)
				value |= input.charAt(i) << 8;
			output.append(itoa64.charAt((value >> 6) & 0x3f));
			if (i++ >= count)
				break;
			if (i < count)
				value |= input.charAt(i) << 16;
			output.append(itoa64.charAt((value >> 12) & 0x3f));
			if (i++ >= count)
				break;
			output.append(itoa64.charAt((value >> 18) & 0x3f));
		} while (i < count);
		return output.toString();
	}

	private String _hash_gensalt_private(String input, String itoa64) {
		return _hash_gensalt_private(input, itoa64, 6);
	}

	private String _hash_gensalt_private(String input, String itoa64, int iteration_count_log2) {
		if (iteration_count_log2 < 4 || iteration_count_log2 > 31) {
			iteration_count_log2 = 8;
		}
		String output = "$H$";
		output += itoa64.charAt(Math.min(iteration_count_log2 + 3, 30)); // PHP_VERSION >= 5 ? 5 : 3
		output += _hash_encode64(input, 6);
		return output;
	}

	String _hash_crypt_private(String password, String setting) {
		String output = "*";
		if (!setting.substring(0, 3).equals("$H$"))
			return output;
		int count_log2 = itoa64.indexOf(setting.charAt(3));
		if (count_log2 < 7 || count_log2 > 30)
			return output;
		int count = 1 << count_log2;
		String salt = setting.substring(4, 12);
		if (salt.length() != 8)
			return output;
		String m1 = md5(salt + password);
		String hash = pack(m1);
		do {
			hash = pack(md5(hash + password));
		} while (--count > 0);
		output = setting.substring(0, 12);
		output += _hash_encode64(hash, 16);
		return output;
	}
}