package com.codigoparallevar.minicards.rendering;

import android.opengl.GLES20;
import android.util.Log;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

public class Triangle {

    private final String vertexShaderCode =
            "attribute vec4 vPosition;" +
            "void main(){" +
                "gl_Position = vPosition;" +
            "}";

    private final String fragmentShaderCode =
            "precision mediump float;" +
            "uniform vec4 vColor;" +
            "void main(){" +
                "gl_FragColor = vColor;" +
            "}";

    private FloatBuffer vertexBuffer;
    private final int mProgram;

    static final int COORDS_PER_VERTEX = 3;
    static float triangleCoords[] = {
             0.0f,  0.622008459f, 0.0f, // top
            -0.5f, -0.311004243f, 0.0f, // bottom left
             0.5f, -0.311004243f, 0.0f  // bottom right
    };

    // Set color with red, green, blue and alpha (opacity) values
    float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f };
    private int mPositionHandle;
    private int mColorHandle;

    private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX;
    private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex

    public Triangle(){
        ByteBuffer bb = ByteBuffer.allocateDirect(triangleCoords.length * 4);
        bb.order(ByteOrder.nativeOrder());

        vertexBuffer = bb.asFloatBuffer();
        vertexBuffer.put(triangleCoords);
        vertexBuffer.position(0);

        int vertexShader = MyGlRenderer.loadShader(GLES20.GL_VERTEX_SHADER,
                                                   vertexShaderCode);
        int fragmentShader = MyGlRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER,
                                                     fragmentShaderCode);

        mProgram = GLES20.glCreateProgram();
        GLES20.glAttachShader(mProgram, vertexShader);
        GLES20.glAttachShader(mProgram, fragmentShader);

        GLES20.glLinkProgram(mProgram);
    }

    public void draw(){
        GLES20.glUseProgram(mProgram);

        mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
        GLES20.glEnableVertexAttribArray(mPositionHandle);

        GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,
                                     GLES20.GL_FLOAT, false,
                                     vertexStride, vertexBuffer);

        mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");

        GLES20.glUniform4fv(mColorHandle, 1, color, 0);
        Log.d("Triangle", "VB "+ vertexBuffer.get(1));
        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);
        GLES20.glDisableVertexAttribArray(mPositionHandle);
    }
}