/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Android code.
 *
 * The Initial Developer of the Original Code is Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2009-2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   James Willcox <jwillcox@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

package org.mozilla.gecko.gfx;

import android.util.Log;
import android.opengl.GLES20;
import java.util.concurrent.ArrayBlockingQueue;
import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLContext;

public class TextureGenerator {
    private static final String LOGTAG = "TextureGenerator";
    private static final int POOL_SIZE = 5;

    private static TextureGenerator sSharedInstance;

    private ArrayBlockingQueue<Integer> mTextureIds;
    private EGLContext mContext;

    private TextureGenerator() { mTextureIds = new ArrayBlockingQueue<Integer>(POOL_SIZE); }

    public static TextureGenerator get() {
        if (sSharedInstance == null)
            sSharedInstance = new TextureGenerator();
        return sSharedInstance;
    }

    public synchronized int take() {
        try {
            // Will block until one becomes available
            return (int)mTextureIds.take();
        } catch (InterruptedException e) {
            return 0;
        }
    }

    public synchronized void fill() {
        EGL10 egl = (EGL10)EGLContext.getEGL();
        EGLContext context = egl.eglGetCurrentContext();

        if (mContext != null && mContext != context) {
            mTextureIds.clear();
        }

        mContext = context;

        int numNeeded = mTextureIds.remainingCapacity();
        if (numNeeded == 0)
            return;

        // Clear existing GL errors
        int error;
        while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
            Log.w(LOGTAG, String.format("Clearing GL error: %#x", error));
        }

        int[] textures = new int[numNeeded];
        GLES20.glGenTextures(numNeeded, textures, 0);

        error = GLES20.glGetError();
        if (error != GLES20.GL_NO_ERROR) {
            Log.e(LOGTAG, String.format("Failed to generate textures: %#x", error), new Exception());
            return;
        }
        
        for (int i = 0; i < numNeeded; i++) {
            mTextureIds.offer(textures[i]);
        }
    }
}