/* 
 * Copyright (c) 2002-2004 LWJGL Project
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are 
 * met:
 * 
 * * Redistributions of source code must retain the above copyright 
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'LWJGL' nor the names of 
 *   its contributors may be used to endorse or promote products derived 
 *   from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.lwjgl.openal;

import java.io.File;
import java.lang.reflect.Method;
import java.util.StringTokenizer;

import java.util.List;
import java.util.ArrayList;

import org.lwjgl.LWJGLException;
import org.lwjgl.Sys;

/**
 * $Id$
 * <br>
 * This is the OpenAL class. It extends the latest core.
 *
 * @author Brian Matzon <brian@matzon.dk>
 * @version $Revision$
 */
public final class AL {

	/** ALC instance. */
	protected static ALC alc;

	/** ALCdevice instance. */
	protected static ALCdevice device;

	/** Current ALCcontext. */
	protected static ALCcontext context;

	/** 
	 * String that requests a certain device or device configuration. 
	 * If null is specified, the implementation will provide an 
	 * implementation specific default. 
	 */
	protected static String deviceArguments;

	/** Frequency for mixing output buffer, in units of Hz. */
	protected static int contextFrequency = -1;

	/** Refresh intervalls, in units of Hz. */
	protected static int contextRefresh = -1;

	/** Flag, indicating a synchronous context. */
	protected static int contextSynchronized = ALC.ALC_FALSE;

	/** Have we been created? */
	protected static boolean created;

	static {
		Sys.initialize();
	}

	private AL() {
	}

	/**
	 * Native method to create AL instance
	 * 
	 * @param oalPaths Array of strings containing paths to search for OpenAL library
	 */
	protected static native void nCreate(String[] oalPaths) throws LWJGLException;

	/**
	 * Native method the destroy the AL
	 */
	protected static native void nDestroy();
	
	/**
	 * @return true if AL has been created
	 */
	public static boolean isCreated() {
		return created;
	}	
	
	/**
	 * Creates an OpenAL instance. Using this constructor will cause OpenAL to
	 * open the device using supplied device argument, and create a context using the context values
	 * supplied. 
	 * 
	 * @param deviceArguments Arguments supplied to native device
	 * @param contextFrequency Frequency for mixing output buffer, in units of Hz (Common values include 11025, 22050, and 44100).
	 * @param contextRefresh Refresh intervalls, in units of Hz.
	 * @param contextSynchronized Flag, indicating a synchronous context.* 
	 */
	public static void create(String deviceArguments, int contextFrequency, int contextRefresh, boolean contextSynchronized)
		throws LWJGLException {
			
		if (created) {
			return;
		}
			
			
		AL.deviceArguments = deviceArguments;
		AL.contextFrequency = contextFrequency;
		AL.contextRefresh = contextRefresh;
		AL.contextSynchronized = contextSynchronized ? ALC.ALC_TRUE : ALC.ALC_FALSE;

		create();
	}

	private static String[] getOALPaths() throws LWJGLException {
		// need to pass path of possible locations of OAL to native side
		List possible_paths = new ArrayList();
		
		String osName = System.getProperty("os.name");

		String libname;
		String platform_lib_name;
		if (osName.startsWith("Win")) {
			libname = "lwjglaudio";
			platform_lib_name = "lwjglaudio.dll";
		} else if (osName.startsWith("Lin")) {
			libname = "openal";
			platform_lib_name = "libopenal.so";
		} else if (osName.startsWith("Mac")) {
			libname = "openal";
			platform_lib_name = "openal.dylib";
		} else {
			throw new LWJGLException("Unknown platform: "+osName);
		}
		
		// Add all possible paths from java.library.path
		String java_library_path = System.getProperty("java.library.path");
		StringTokenizer st = new StringTokenizer(System.getProperty("java.library.path"), File.pathSeparator);
		while (st.hasMoreTokens()) {
			String path = st.nextToken();
			possible_paths.add(path + File.separator + platform_lib_name);
		}
		
		String classloader_path = getPathFromClassLoader(libname);
		if (classloader_path != null) {
			Sys.log("getPathFromClassLoader: Path found: " + classloader_path);
			possible_paths.add(classloader_path);
		}
		String lwjgl_classloader_path = getPathFromClassLoader("lwjgl");
		if (lwjgl_classloader_path != null) {
			Sys.log("getPathFromClassLoader: Path found: " + lwjgl_classloader_path);
			possible_paths.add(lwjgl_classloader_path.substring(0, lwjgl_classloader_path.lastIndexOf(File.separator))
				+ File.separator + platform_lib_name);
		}

		//add cwd path
		possible_paths.add(platform_lib_name);
		//create needed string array
		String[] oalPaths = new String[possible_paths.size()];
		possible_paths.toArray(oalPaths);

		return oalPaths;
	}

	/**
	 * Creates an OpenAL instance. The empty create will cause OpenAL to
	 * open the default device, and create a context using default values. 
	 */
	public static void create() throws LWJGLException {
		if (created) {
			return;
		}
		String[] oalPaths = getOALPaths();
		nCreate(oalPaths);
		created = true;

		try {
			AL10.initNativeStubs();
			ALC.initNativeStubs();

			device = ALC.alcOpenDevice(deviceArguments);
			if (device == null)
				throw new LWJGLException("Could not open ALC device");
			//check if doing default values or not
			if (contextFrequency == -1) {
				context = ALC.alcCreateContext(device.device, null);
			} else {
				context = ALC.alcCreateContext(device.device,
						ALCcontext.createAttributeList(contextFrequency, contextRefresh, contextSynchronized));
			}
			ALC.alcMakeContextCurrent(context.context);
			created = true;
		} catch (LWJGLException e) {
			destroy();
			throw e;
		}
	}

	/**
	 * Exit cleanly by calling destroy.
	 */
	public static void destroy() {
		if (context != null) {
			ALC.alcDestroyContext(context.context);
			context = null;
		}
		if (device != null) {
			ALC.alcCloseDevice(device.device);
			device = null;
		}
		resetNativeStubs(AL10.class);
		resetNativeStubs(ALC.class);

		deviceArguments = null;

		contextFrequency = -1;
		contextRefresh = -1;
		contextSynchronized = ALC.ALC_FALSE;
		
		if (created)
			nDestroy();
		created = false;
	}
	
	/**
	 * Tries to locate OpenAL from the current ClassLoader
	 * This method exists because OpenAL is loaded from native code, and as such
	 * is exempt from ClassLoader library loading rutines. OpenAL therefore always fails.
	 * We therefore invoke the protected method of the ClassLoader to see if it can
	 * locate it. 
	 * 
	 * @param libname Name of library to search for
	 * @return Absolute path to library if found, otherwise null
	 */
	private static String getPathFromClassLoader(String libname) {
		try {		 
			Sys.log("getPathFromClassLoader: searching for: " + libname);
			Object o = AL.class.getClassLoader();
			Class c = o.getClass();
			while (c != null) {
				try {
					Method findLibrary = c.getDeclaredMethod("findLibrary", new Class[] { String.class });
					findLibrary.setAccessible(true);
					Object[] arguments = new Object[] { libname };
					return (String)findLibrary.invoke(o, arguments);
				} catch (NoSuchMethodException e) {
					c = c.getSuperclass();
				}
			}
		} catch (Exception e) {
			Sys.log("Failure locating OpenAL using classloader:" + e);
		}
		return null;
	}

	private static native void resetNativeStubs(Class clazz);
	
	/**
	 * Gets a handle to the current openAL context. The handle is "opaque" right now
	 * because, realistically, there is nothing you can actually do with it. If it turns
	 * out that there are useful things you can do with it then it'll return an instance
	 * of ALCcontext (which will have to become a public class)
	 * @return an opaque handle to the AL context.
	 */
	public static Object getContext() {
		return context;
	}
}