/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cards.pay.paycardsrecognizer.sdk.camera.gles;

import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.util.Log;

import java.nio.FloatBuffer;

import cards.pay.paycardsrecognizer.sdk.utils.Constants;

public class Texture2dProgram {
    private static final boolean DBG = Constants.DEBUG;
    private static final String TAG = GlUtil.TAG;

    // Simple vertex shader, used for all programs.
    private static final String VERTEX_SHADER =
            "uniform mat4 uMVPMatrix;\n" +
                    "uniform mat4 uTexMatrix;\n" +
                    "attribute vec4 aPosition;\n" +
                    "attribute vec4 aTextureCoord;\n" +
                    "varying vec2 vTextureCoord;\n" +
                    "void main() {\n" +
                    "    gl_Position = uMVPMatrix * aPosition;\n" +
                    "    vTextureCoord = (uTexMatrix * aTextureCoord).xy;\n" +
                    "}\n";

    // Simple fragment shader for use with external 2D textures (e.g. what we get from
    // SurfaceTexture).
    private static final String FRAGMENT_SHADER_EXT =
            "#extension GL_OES_EGL_image_external : require\n" +
                    "precision mediump float;\n" +
                    "varying vec2 vTextureCoord;\n" +
                    "uniform samplerExternalOES sTexture;\n" +
                    "void main() {\n" +
                    "    gl_FragColor = texture2D(sTexture, vTextureCoord);\n" +
                    "}\n";

    public static final int KERNEL_SIZE = 9;

    // Handles to the GL program and various components of it.
    private int mProgramHandle;
    private int muMVPMatrixLoc;
    private int muTexMatrixLoc;
    private int muKernelLoc;
    private int muTexOffsetLoc;
    private int muColorAdjustLoc;
    private int maPositionLoc;
    private int maTextureCoordLoc;

    private int mTextureTarget;

    private float[] mKernel = new float[KERNEL_SIZE];
    private float[] mTexOffset;
    private float mColorAdjust;

    /**
     * Prepares the program in the current EGL context.
     */
    public Texture2dProgram() {
        mTextureTarget = GLES11Ext.GL_TEXTURE_EXTERNAL_OES;
        mProgramHandle = GlUtil.createProgram(VERTEX_SHADER, FRAGMENT_SHADER_EXT);

        if (DBG) Log.d(TAG, "Created program " + mProgramHandle + " (TEXTURE_EXT)");

        // get locations of attributes and uniforms

        maPositionLoc = GLES20.glGetAttribLocation(mProgramHandle, "aPosition");
        GlUtil.checkLocation(maPositionLoc, "aPosition");
        maTextureCoordLoc = GLES20.glGetAttribLocation(mProgramHandle, "aTextureCoord");
        GlUtil.checkLocation(maTextureCoordLoc, "aTextureCoord");
        muMVPMatrixLoc = GLES20.glGetUniformLocation(mProgramHandle, "uMVPMatrix");
        GlUtil.checkLocation(muMVPMatrixLoc, "uMVPMatrix");
        muTexMatrixLoc = GLES20.glGetUniformLocation(mProgramHandle, "uTexMatrix");
        GlUtil.checkLocation(muTexMatrixLoc, "uTexMatrix");
        muKernelLoc = GLES20.glGetUniformLocation(mProgramHandle, "uKernel");
        if (muKernelLoc < 0) {
            // no kernel in this one
            muKernelLoc = -1;
            muTexOffsetLoc = -1;
            muColorAdjustLoc = -1;
        } else {
            // has kernel, must also have tex offset and color adj
            muTexOffsetLoc = GLES20.glGetUniformLocation(mProgramHandle, "uTexOffset");
            GlUtil.checkLocation(muTexOffsetLoc, "uTexOffset");
            muColorAdjustLoc = GLES20.glGetUniformLocation(mProgramHandle, "uColorAdjust");
            GlUtil.checkLocation(muColorAdjustLoc, "uColorAdjust");

            // initialize default values
            setKernel(new float[] {0f, 0f, 0f,  0f, 1f, 0f,  0f, 0f, 0f}, 0f);
            setTexSize(256, 256);
        }
    }

    /**
     * Releases the program.
     * <p>
     * The appropriate EGL context must be current (i.e. the one that was used to create
     * the program).
     */
    public void release() {
        if (DBG) Log.d(TAG, "deleting program " + mProgramHandle);
        GLES20.glDeleteProgram(mProgramHandle);
        mProgramHandle = -1;
    }

    /**
     * Creates a texture object suitable for use with this program.
     * <p>
     * On exit, the texture will be bound.
     */
    public int createTextureObject() {
        int[] textures = new int[1];
        GLES20.glGenTextures(1, textures, 0);
        GlUtil.checkGlError("glGenTextures");

        int texId = textures[0];
        GLES20.glBindTexture(mTextureTarget, texId);
        GlUtil.checkGlError("glBindTexture " + texId);

        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER,
                GLES20.GL_NEAREST);
        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER,
                GLES20.GL_LINEAR);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_S,
                GLES20.GL_CLAMP_TO_EDGE);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_T,
                GLES20.GL_CLAMP_TO_EDGE);
        GlUtil.checkGlError("glTexParameter");

        return texId;
    }

    /**
     * Configures the convolution filter values.
     *
     * @param values Normalized filter values; must be KERNEL_SIZE elements.
     */
    private void setKernel(float[] values, float colorAdj) {
        if (values.length != KERNEL_SIZE) {
            throw new IllegalArgumentException("Kernel size is " + values.length +
                    " vs. " + KERNEL_SIZE);
        }
        System.arraycopy(values, 0, mKernel, 0, KERNEL_SIZE);
        mColorAdjust = colorAdj;
    }

    /**
     * Sets the size of the texture.  This is used to find adjacent texels when filtering.
     */
    public void setTexSize(int width, int height) {
        float rw = 1.0f / width;
        float rh = 1.0f / height;

        // Don't need to create a new array here, but it's syntactically convenient.
        mTexOffset = new float[] {
                -rw, -rh,   0f, -rh,    rw, -rh,
                -rw, 0f,    0f, 0f,     rw, 0f,
                -rw, rh,    0f, rh,     rw, rh
        };
        //if (DBG) Log.d(TAG, "filt size: " + width + "x" + height + ": " + Arrays.toString(mTexOffset));
    }

    /**
     * Issues the draw call.  Does the full setup on every call.
     *
     * @param mvpMatrix The 4x4 projection matrix.
     * @param vertexBuffer Buffer with vertex position data.
     * @param firstVertex Index of first vertex to use in vertexBuffer.
     * @param vertexCount Number of vertices in vertexBuffer.
     * @param coordsPerVertex The number of coordinates per vertex (e.g. x,y is 2).
     * @param vertexStride Width, in bytes, of the position data for each vertex (often
     *        vertexCount * sizeof(float)).
     * @param texMatrix A 4x4 transformation matrix for texture coords.  (Primarily intended
     *        for use with SurfaceTexture.)
     * @param texBuffer Buffer with vertex texture data.
     * @param texStride Width, in bytes, of the texture data for each vertex.
     */
    public void draw(float[] mvpMatrix, FloatBuffer vertexBuffer, int firstVertex,
                     int vertexCount, int coordsPerVertex, int vertexStride,
                     float[] texMatrix, FloatBuffer texBuffer, int textureId, int texStride) {
        GlUtil.checkGlError("draw start");

        // Select the program.
        GLES20.glUseProgram(mProgramHandle);
        GlUtil.checkGlError("glUseProgram");

        // Set the texture.
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(mTextureTarget, textureId);

        // Copy the model / view / projection matrix over.
        GLES20.glUniformMatrix4fv(muMVPMatrixLoc, 1, false, mvpMatrix, 0);
        GlUtil.checkGlError("glUniformMatrix4fv");

        // Copy the texture transformation matrix over.
        GLES20.glUniformMatrix4fv(muTexMatrixLoc, 1, false, texMatrix, 0);
        GlUtil.checkGlError("glUniformMatrix4fv");

        // Enable the "aPosition" vertex attribute.
        GLES20.glEnableVertexAttribArray(maPositionLoc);
        GlUtil.checkGlError("glEnableVertexAttribArray");

        // Connect vertexBuffer to "aPosition".
        GLES20.glVertexAttribPointer(maPositionLoc, coordsPerVertex,
                GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
        GlUtil.checkGlError("glVertexAttribPointer");

        // Enable the "aTextureCoord" vertex attribute.
        GLES20.glEnableVertexAttribArray(maTextureCoordLoc);
        GlUtil.checkGlError("glEnableVertexAttribArray");

        // Connect texBuffer to "aTextureCoord".
        GLES20.glVertexAttribPointer(maTextureCoordLoc, 2,
                GLES20.GL_FLOAT, false, texStride, texBuffer);
        GlUtil.checkGlError("glVertexAttribPointer");

        // Populate the convolution kernel, if present.
        if (muKernelLoc >= 0) {
            GLES20.glUniform1fv(muKernelLoc, KERNEL_SIZE, mKernel, 0);
            GLES20.glUniform2fv(muTexOffsetLoc, KERNEL_SIZE, mTexOffset, 0);
            GLES20.glUniform1f(muColorAdjustLoc, mColorAdjust);
        }

        // Draw the rect.
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, firstVertex, vertexCount);
        GlUtil.checkGlError("glDrawArrays");

        // Done -- disable vertex array, texture, and program.
        GLES20.glDisableVertexAttribArray(maPositionLoc);
        GLES20.glDisableVertexAttribArray(maTextureCoordLoc);
        GLES20.glBindTexture(mTextureTarget, 0);
        GLES20.glUseProgram(0);
    }
}