package impaspav.glsl;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import javax.media.opengl.GL3;
import javax.media.opengl.GLCapabilities;
import javax.media.opengl.GLContext;
import javax.media.opengl.GLDrawable;
import javax.media.opengl.GLDrawableFactory;
import javax.media.opengl.GLProfile;

import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import com.jogamp.newt.Display;
import com.jogamp.newt.NewtFactory;
import com.jogamp.newt.Screen;
import com.jogamp.newt.Window;
import com.jogamp.opengl.util.glsl.ShaderUtil;

public class TransformFeedbackVeryingsBugTest {

	static {
		 //NativeUtil.preloadNativeLibs(); // internal method
		GLProfile.initSingleton();
	}

	private GLContext context;
	private String VERTEX_SHADER_TEXT;

	@Before
	public void setUp() {
		VERTEX_SHADER_TEXT = 
				  "#version 330                           \n"
				+ "                                       \n"
				+ "out vec4 Position;                     \n"
				+ "                                       \n"
				+ "void main() {                          \n"
				+ "  Position = vec4(1.0, 1.0, 1.0, 1.0); \n"
				+ "}                                      \n";
		
		GLCapabilities caps;
		Window window;
		GLDrawable drawable;

		GLProfile glp = GLProfile.get(GLProfile.GL3);
		caps = new GLCapabilities(glp);

		caps.setOnscreen(true);
		caps.setDoubleBuffered(true);

		Display display = NewtFactory.createDisplay(null); // local display
		Screen screen = NewtFactory.createScreen(display, 0); // screen 0

		window = NewtFactory.createWindow(screen, caps, true);
		window.setSize(800, 600);
		window.setVisible(true);

		drawable = GLDrawableFactory.getFactory(glp).createGLDrawable(window);
		drawable.setRealized(true);

		context = drawable.createContext(null);

		context.makeCurrent();
	}

	@After
	public void tearDown() {
		context.release();
	}
	
	private int getShader(GL3 gl, String text, int type) {
		int shaderProgram = gl.glCreateProgram();
		
		int vertShader = gl.glCreateShader(type);
		
		String[] lines = new String[] { text };
		int[] lengths = new int[] { lines[0].length() };
		gl.glShaderSource(vertShader, lines.length, lines, lengths, 0);
		gl.glCompileShader(vertShader);
		gl.glAttachShader(shaderProgram, vertShader);
		
		return shaderProgram;
	}

	@Test
	public void testGlTransformFeedbackVaryings_WhenVarNameOK() {
		// given
		
		GL3 gl = context.getGL().getGL3();
		int shaderProgram = getShader(gl, VERTEX_SHADER_TEXT, GL3.GL_VERTEX_SHADER);
		String[] vars = new String[] { "Position" };

		// when

		gl.glTransformFeedbackVaryings(shaderProgram, 1, vars, GL3.GL_SEPARATE_ATTRIBS);
		gl.glLinkProgram(shaderProgram);

		// then

		Assert.assertTrue(ShaderUtil.isProgramValid(gl, shaderProgram, System.out));
		Assert.assertEquals(GL3.GL_NO_ERROR, gl.glGetError());
	}

	@Test
	public void testGlTransformFeedbackVaryings_WhenVarNameWrong() {
		// given
		
		GL3 gl = context.getGL().getGL3();
		int shaderProgram = getShader(gl, VERTEX_SHADER_TEXT, GL3.GL_VERTEX_SHADER);
		String[] vars = new String[] { "PPPosition" };
		
		// when

		gl.glTransformFeedbackVaryings(shaderProgram, 1, vars, GL3.GL_SEPARATE_ATTRIBS);
		gl.glLinkProgram(shaderProgram);

		// then

		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		Assert.assertFalse(ShaderUtil.isProgramValid(gl, shaderProgram, new PrintStream(baos)));
		Assert.assertEquals(GL3.GL_NO_ERROR, gl.glGetError());
		Assert.assertTrue(baos.toString().contains("(named PPPosition)"));
	}
}