/*
 * Copyright 2011 by Graz University of Technology, Austria
 * MOCCA has been developed by the E-Government Innovation Center EGIZ, a joint
 * initiative of the Federal Chancellery Austria and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */

package at.gv.egiz.bku.webstart.autostart;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.List;
import java.util.prefs.Preferences;

public class WinRegistry {
	public static final int HKEY_CURRENT_USER = 0x80000001;
	public static final int HKEY_LOCAL_MACHINE = 0x80000002;
	public static final int REG_SUCCESS = 0;
	public static final int REG_NOTFOUND = 2;
	public static final int REG_ACCESSDENIED = 5;

//	private static final int KEY_ALL_ACCESS = 0xf003f;
	private static final int KEY_READ = 0x20019;
	private static Preferences userRoot = Preferences.userRoot();
	private static Preferences systemRoot = Preferences.systemRoot();
	private static Class<? extends Preferences> userClass = userRoot.getClass();
	private static Method regOpenKey = null;
	private static Method regCloseKey = null;
	private static Method regQueryValueEx = null;
	private static Method regEnumValue = null;
	private static Method regQueryInfoKey = null;
	private static Method regEnumKeyEx = null;
//	private static Method regCreateKeyEx = null;
//	private static Method regSetValueEx = null;
//	private static Method regDeleteKey = null;
//	private static Method regDeleteValue = null;

	static {
		try {
			regOpenKey = userClass.getDeclaredMethod("WindowsRegOpenKey",
					new Class[] { int.class, byte[].class, int.class });
			regOpenKey.setAccessible(true);
			regCloseKey = userClass.getDeclaredMethod("WindowsRegCloseKey",
					new Class[] { int.class });
			regCloseKey.setAccessible(true);
			regQueryValueEx = userClass.getDeclaredMethod(
					"WindowsRegQueryValueEx", new Class[] { int.class,
							byte[].class });
			regQueryValueEx.setAccessible(true);
			regEnumValue = userClass.getDeclaredMethod("WindowsRegEnumValue",
					new Class[] { int.class, int.class, int.class });
			regEnumValue.setAccessible(true);
			regQueryInfoKey = userClass.getDeclaredMethod(
					"WindowsRegQueryInfoKey1", new Class[] { int.class });
			regQueryInfoKey.setAccessible(true);
			regEnumKeyEx = userClass.getDeclaredMethod("WindowsRegEnumKeyEx",
					new Class[] { int.class, int.class, int.class });
			regEnumKeyEx.setAccessible(true);
//			regCreateKeyEx = userClass.getDeclaredMethod(
//					"WindowsRegCreateKeyEx", new Class[] { int.class,
//							byte[].class });
//			regCreateKeyEx.setAccessible(true);
//			regSetValueEx = userClass.getDeclaredMethod("WindowsRegSetValueEx",
//					new Class[] { int.class, byte[].class, byte[].class });
//			regSetValueEx.setAccessible(true);
//			regDeleteValue = userClass.getDeclaredMethod(
//					"WindowsRegDeleteValue", new Class[] { int.class,
//							byte[].class });
//			regDeleteValue.setAccessible(true);
//			regDeleteKey = userClass.getDeclaredMethod("WindowsRegDeleteKey",
//					new Class[] { int.class, byte[].class });
//			regDeleteKey.setAccessible(true);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private WinRegistry() {
	}

	/**
	 * Read a value from key and value name
	 * 
	 * @param hkey
	 *            HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
	 * @param key
	 * @param valueName
	 * @return the value
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 * @throws InvocationTargetException
	 */
	public static String readString(int hkey, String key, String valueName)
			throws IllegalArgumentException, IllegalAccessException,
			InvocationTargetException {
		if (hkey == HKEY_LOCAL_MACHINE) {
			return readString(systemRoot, hkey, key, valueName);
		} else if (hkey == HKEY_CURRENT_USER) {
			return readString(userRoot, hkey, key, valueName);
		} else {
			throw new IllegalArgumentException("hkey=" + hkey);
		}
	}

	/**
	 * Read value(s) and value name(s) form given key
	 * 
	 * @param hkey
	 *            HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
	 * @param key
	 * @return the value name(s) plus the value(s)
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 * @throws InvocationTargetException
	 */
	public static Map<String, String> readStringValues(int hkey, String key)
			throws IllegalArgumentException, IllegalAccessException,
			InvocationTargetException {
		if (hkey == HKEY_LOCAL_MACHINE) {
			return readStringValues(systemRoot, hkey, key);
		} else if (hkey == HKEY_CURRENT_USER) {
			return readStringValues(userRoot, hkey, key);
		} else {
			throw new IllegalArgumentException("hkey=" + hkey);
		}
	}

	/**
	 * Read the value name(s) from a given key
	 * 
	 * @param hkey
	 *            HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
	 * @param key
	 * @return the value name(s)
	 * @throws IllegalArgumentException
	 * @throws IllegalAccessException
	 * @throws InvocationTargetException
	 */
	public static List<String> readStringSubKeys(int hkey, String key)
			throws IllegalArgumentException, IllegalAccessException,
			InvocationTargetException {
		if (hkey == HKEY_LOCAL_MACHINE) {
			return readStringSubKeys(systemRoot, hkey, key);
		} else if (hkey == HKEY_CURRENT_USER) {
			return readStringSubKeys(userRoot, hkey, key);
		} else {
			throw new IllegalArgumentException("hkey=" + hkey);
		}
	}

//	/**
//	 * Create a key
//	 * 
//	 * @param hkey
//	 *            HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE
//	 * @param key
//	 * @throws IllegalArgumentException
//	 * @throws IllegalAccessException
//	 * @throws InvocationTargetException
//	 */
//	public static void createKey(int hkey, String key)
//			throws IllegalArgumentException, IllegalAccessException,
//			InvocationTargetException {
//		int[] ret;
//		if (hkey == HKEY_LOCAL_MACHINE) {
//			ret = createKey(systemRoot, hkey, key);
//			regCloseKey
//					.invoke(systemRoot, new Object[] { new Integer(ret[0]) });
//		} else if (hkey == HKEY_CURRENT_USER) {
//			ret = createKey(userRoot, hkey, key);
//			regCloseKey.invoke(userRoot, new Object[] { new Integer(ret[0]) });
//		} else {
//			throw new IllegalArgumentException("hkey=" + hkey);
//		}
//		if (ret[1] != REG_SUCCESS) {
//			throw new IllegalArgumentException("rc=" + ret[1] + "  key=" + key);
//		}
//	}

//	/**
//	 * Write a value in a given key/value name
//	 * 
//	 * @param hkey
//	 * @param key
//	 * @param valueName
//	 * @param value
//	 * @throws IllegalArgumentException
//	 * @throws IllegalAccessException
//	 * @throws InvocationTargetException
//	 */
//	public static void writeStringValue(int hkey, String key, String valueName,
//			String value) throws IllegalArgumentException,
//			IllegalAccessException, InvocationTargetException {
//		if (hkey == HKEY_LOCAL_MACHINE) {
//			writeStringValue(systemRoot, hkey, key, valueName, value);
//		} else if (hkey == HKEY_CURRENT_USER) {
//			writeStringValue(userRoot, hkey, key, valueName, value);
//		} else {
//			throw new IllegalArgumentException("hkey=" + hkey);
//		}
//	}

//	/**
//	 * Delete a given key
//	 * 
//	 * @param hkey
//	 * @param key
//	 * @throws IllegalArgumentException
//	 * @throws IllegalAccessException
//	 * @throws InvocationTargetException
//	 */
//	public static void deleteKey(int hkey, String key)
//			throws IllegalArgumentException, IllegalAccessException,
//			InvocationTargetException {
//		int rc = -1;
//		if (hkey == HKEY_LOCAL_MACHINE) {
//			rc = deleteKey(systemRoot, hkey, key);
//		} else if (hkey == HKEY_CURRENT_USER) {
//			rc = deleteKey(userRoot, hkey, key);
//		}
//		if (rc != REG_SUCCESS) {
//			throw new IllegalArgumentException("rc=" + rc + "  key=" + key);
//		}
//	}

//	/**
//	 * delete a value from a given key/value name
//	 * 
//	 * @param hkey
//	 * @param key
//	 * @param value
//	 * @throws IllegalArgumentException
//	 * @throws IllegalAccessException
//	 * @throws InvocationTargetException
//	 */
//	public static void deleteValue(int hkey, String key, String value)
//			throws IllegalArgumentException, IllegalAccessException,
//			InvocationTargetException {
//		int rc = -1;
//		if (hkey == HKEY_LOCAL_MACHINE) {
//			rc = deleteValue(systemRoot, hkey, key, value);
//		} else if (hkey == HKEY_CURRENT_USER) {
//			rc = deleteValue(userRoot, hkey, key, value);
//		}
//		if (rc != REG_SUCCESS) {
//			throw new IllegalArgumentException("rc=" + rc + "  key=" + key
//					+ "  value=" + value);
//		}
//	}

	// =====================

//	private static int deleteValue(Preferences root, int hkey, String key,
//			String value) throws IllegalArgumentException,
//			IllegalAccessException, InvocationTargetException {
//		int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
//				new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS) });
//		if (handles[1] != REG_SUCCESS) {
//			return handles[1]; // can be REG_NOTFOUND, REG_ACCESSDENIED
//		}
//		int rc = ((Integer) regDeleteValue.invoke(root, new Object[] {
//				new Integer(handles[0]), toCstr(value) })).intValue();
//		regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
//		return rc;
//	}

//	private static int deleteKey(Preferences root, int hkey, String key)
//			throws IllegalArgumentException, IllegalAccessException,
//			InvocationTargetException {
//		int rc = ((Integer) regDeleteKey.invoke(root, new Object[] {
//				new Integer(hkey), toCstr(key) })).intValue();
//		return rc; // can REG_NOTFOUND, REG_ACCESSDENIED, REG_SUCCESS
//	}

	private static String readString(Preferences root, int hkey, String key,
			String value) throws IllegalArgumentException,
			IllegalAccessException, InvocationTargetException {
		int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
				new Integer(hkey), toCstr(key), new Integer(KEY_READ) });
		if (handles[1] != REG_SUCCESS) {
			return null;
		}
		byte[] valb = (byte[]) regQueryValueEx.invoke(root, new Object[] {
				new Integer(handles[0]), toCstr(value) });
		regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
		return (valb != null ? new String(valb).trim() : null);
	}

	private static Map<String, String> readStringValues(Preferences root,
			int hkey, String key) throws IllegalArgumentException,
			IllegalAccessException, InvocationTargetException {
		HashMap<String, String> results = new HashMap<String, String>();
		int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
				new Integer(hkey), toCstr(key), new Integer(KEY_READ) });
		if (handles[1] != REG_SUCCESS) {
			return null;
		}
		int[] info = (int[]) regQueryInfoKey.invoke(root,
				new Object[] { new Integer(handles[0]) });

		int count = info[2]; // count
		int maxlen = info[3]; // value length max
		for (int index = 0; index < count; index++) {
			byte[] name = (byte[]) regEnumValue.invoke(root, new Object[] {
					new Integer(handles[0]), new Integer(index),
					new Integer(maxlen + 1) });
			String value = readString(hkey, key, new String(name));
			results.put(new String(name).trim(), value);
		}
		regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
		return results;
	}

	private static List<String> readStringSubKeys(Preferences root, int hkey,
			String key) throws IllegalArgumentException,
			IllegalAccessException, InvocationTargetException {
		List<String> results = new ArrayList<String>();
		int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
				new Integer(hkey), toCstr(key), new Integer(KEY_READ) });
		if (handles[1] != REG_SUCCESS) {
			return null;
		}
		int[] info = (int[]) regQueryInfoKey.invoke(root,
				new Object[] { new Integer(handles[0]) });

		int count = info[2]; // count
		int maxlen = info[3]; // value length max
		for (int index = 0; index < count; index++) {
			byte[] name = (byte[]) regEnumKeyEx.invoke(root, new Object[] {
					new Integer(handles[0]), new Integer(index),
					new Integer(maxlen + 1) });
			results.add(new String(name).trim());
		}
		regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
		return results;
	}

//	private static int[] createKey(Preferences root, int hkey, String key)
//			throws IllegalArgumentException, IllegalAccessException,
//			InvocationTargetException {
//		return (int[]) regCreateKeyEx.invoke(root, new Object[] {
//				new Integer(hkey), toCstr(key) });
//	}

//	private static void writeStringValue(Preferences root, int hkey,
//			String key, String valueName, String value)
//			throws IllegalArgumentException, IllegalAccessException,
//			InvocationTargetException {
//		int[] handles = (int[]) regOpenKey.invoke(root, new Object[] {
//				new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS) });
//
//		regSetValueEx.invoke(root, new Object[] { new Integer(handles[0]),
//				toCstr(valueName), toCstr(value) });
//		regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) });
//	}

	// utility
	private static byte[] toCstr(String str) {
		byte[] result = new byte[str.length() + 1];

		for (int i = 0; i < str.length(); i++) {
			result[i] = (byte) str.charAt(i);
		}
		result[str.length()] = 0;
		return result;
	}
}