package com.android.rs.refocus;

import android.support.v8.renderscript.RenderScript;
import android.support.v8.renderscript.Allocation;
import android.support.v8.renderscript.Element;

import com.android.rs.refocus.renderscript.ScriptField_KernelInfo;

/**
 * A class that manages the blur kernel matrices of a blending layer that
 * interface between Java and Render Script. This class will be specialized for
 * float in f32 package and for byte in u8 package.
 *
 * @author zhl@google.com (Li Zhang)
 */
public class KernelDataForRenderScript {
	/**
	 *	A flag to turn on using optimized RenderScript. 
	 *  False means using original version; true means using the new version.
	 */
	private static boolean UseNewRS = false;

  /**
   * Number of sub-pixels that is used to generate anti-aliased blur kernel
   * matrix. That is, we divide one pixel into
   * {@code NUM_SUB_PIXELS * NUM_SUB_PIXELS} sub-pixels to test whether or not a
   * pixel is in the blur disk.
   */
  protected static final int NUM_SUB_PIXELS = 5;

  /**
   * The width of the pixels that are used to pad the image boundary to avoid
   * boundary checking in filtering operation.
   */
  private static final int MAX_KERNEL_RADIUS =
      computeKernelRadiusFromDiskRadius(BlurStack.getMaxDiskRadius());

  /**
   * The length of an array that concatenates all (vectorized) kernel matrices.
   */
  protected int stackLength;

  /**
   * A class automatically generated by Render Script compiler, which contains
   * required auxiliary information to parse {@code kernelStack}, including the
   * starting position of each kernel matrix in a memory buffer and the radius
   * (radius_x,radius_y) of each kernel matrix. The names radius_x and radius_y
   * follow C++ style because render script is C language.
   */
  protected ScriptField_KernelInfo kernelInfo;

	/** Java array version of the current kernel info. Used when UseNewRS is true.
	 * 4*m: offset; 4*m + 1: radius_x; 4*m + 2: radius_y
	 */
	protected float[] infoArray;

	/** An allocation used to store global allocation of stack info. Used when UseNewRS is true.
	 *
	 */
    public Allocation infoAllocation;

  public static int getNumSubPixels() {
    return NUM_SUB_PIXELS;
  }

  public static int getMaxKernelRadius() {
    return MAX_KERNEL_RADIUS;
  }

    public static void setUseNewRS(boolean choice) {UseNewRS = choice;}

  /**
   * Computes the kernel matrix radius from the blur disk radius.
   *
   * @param diskRadius blur disk radius
   * @return kernel matrix radius
   */
  public static int computeKernelRadiusFromDiskRadius(float diskRadius) {
    return (int) (diskRadius) + 1;
  }

  public ScriptField_KernelInfo getKernelInfo() {
    return kernelInfo;
  }

  /**
   * Initializes {@code kernelInfo}.
   *
   * @param targetLayer the index of a target layer
   * @param blurStack an instance of {@code BlurStack}
   * @param renderScript an instance of {@code RenderScript}
   */
  protected KernelDataForRenderScript(int targetLayer, BlurStack blurStack,
      RenderScript renderScript) {
		if (UseNewRS) {
			// Use the new version of renderscript files.
 			int numDepths = blurStack.getNumDepths(targetLayer);
			infoAllocation = Allocation.createSized(
        	renderScript, Element.F32_4(renderScript),
        	numDepths);

			infoArray = new float[4*numDepths];
    		// Generates information for each blur kernel matrix.
    		int offset = 0;
    		for (int m = 0; m < numDepths; ++m) {
      			int depth = blurStack.getDepth(targetLayer, m);
      			float diskRadius = blurStack.getDiskRadius(depth);
      			int kernelRadius = computeKernelRadiusFromDiskRadius(diskRadius);

				infoArray[m*4] = offset;
				infoArray[m*4 + 1] = kernelRadius;
				infoArray[m*4 + 2] = kernelRadius;
	
      			// Updates offset variable.
      			int kernelLength = (2 * kernelRadius + 1) * (2 * kernelRadius + 1);
      			offset += kernelLength;
    		}
			infoAllocation.copyFrom(infoArray);
    		stackLength = offset;
		} else {
			// Use original version of renderscript files.
    		int numDepths = blurStack.getNumDepths(targetLayer);
    		kernelInfo = new ScriptField_KernelInfo(renderScript, numDepths);

    		// Generates information for each blur kernel matrix.
    		int offset = 0;
    		for (int m = 0; m < numDepths; ++m) {
      			int depth = blurStack.getDepth(targetLayer, m);
      			float diskRadius = blurStack.getDiskRadius(depth);
      			int kernelRadius = computeKernelRadiusFromDiskRadius(diskRadius);
      			// Sets information for the {@code m}'th kernel matrix.
      			kernelInfo.set_offset(m, offset, true);
      			kernelInfo.set_radius_x(m, kernelRadius, true);
      			kernelInfo.set_radius_y(m, kernelRadius, true);
      			// Updates offset variable.
      			int kernelLength = (2 * kernelRadius + 1) * (2 * kernelRadius + 1);
      			offset += kernelLength;
    		}
    		stackLength = offset;
		}
  }
}