/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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 android.filterpacks.imageproc;

import android.filterfw.core.Filter;
import android.filterfw.core.FilterContext;
import android.filterfw.core.Frame;
import android.filterfw.core.FrameFormat;
import android.filterfw.core.GenerateFieldPort;
import android.filterfw.core.MutableFrameFormat;
import android.filterfw.core.Program;
import android.filterfw.core.ShaderProgram;
import android.filterfw.format.ImageFormat;

public class ImageSlicer extends Filter {

    @GenerateFieldPort(name = "xSlices")
    private int mXSlices;

    @GenerateFieldPort(name = "ySlices")
    private int mYSlices;

    @GenerateFieldPort(name = "padSize")
    private int mPadSize;

    // The current slice index from 0 to xSlices * ySlices
    private int mSliceIndex;

    private Frame mOriginalFrame;

    private Program mProgram;

    private int mInputWidth;
    private int mInputHeight;

    private int mSliceWidth;
    private int mSliceHeight;

    private int mOutputWidth;
    private int mOutputHeight;

    public ImageSlicer(String name) {
        super(name);
        mSliceIndex = 0;
    }

    @Override
    public void setupPorts() {
        addMaskedInputPort("image", ImageFormat.create(ImageFormat.COLORSPACE_RGBA,
                                                       FrameFormat.TARGET_GPU));
        addOutputBasedOnInput("image", "image");
    }

    @Override
    public FrameFormat getOutputFormat(String portName, FrameFormat inputFormat) {
        return inputFormat;
    }

    private void calcOutputFormatForInput(Frame frame) {

        // calculate the output size based on input size, xSlices, and ySlices
        mInputWidth = frame.getFormat().getWidth();
        mInputHeight = frame.getFormat().getHeight();

        mSliceWidth = (mInputWidth + mXSlices - 1) / mXSlices;
        mSliceHeight = (mInputHeight + mYSlices - 1)/ mYSlices;

        mOutputWidth = mSliceWidth + mPadSize * 2;
        mOutputHeight = mSliceHeight + mPadSize * 2;
    }


    @Override
    public void process(FilterContext context) {

        // Get input frame
        if (mSliceIndex == 0) {
            mOriginalFrame = pullInput("image");
            calcOutputFormatForInput(mOriginalFrame);
        }

        FrameFormat inputFormat = mOriginalFrame.getFormat();
        MutableFrameFormat outputFormat = inputFormat.mutableCopy();
        outputFormat.setDimensions(mOutputWidth, mOutputHeight);

        // Create output frame
        Frame output = context.getFrameManager().newFrame(outputFormat);

        // Create the program if not created already
        if (mProgram == null) {
            mProgram = ShaderProgram.createIdentity(context);
        }

        // Calculate the four corner of the source region
        int xSliceIndex = mSliceIndex % mXSlices;
        int ySliceIndex = mSliceIndex / mXSlices;

        // TODO(rslin) : not sure shifting by 0.5 is needed.
        float x0 = (xSliceIndex * mSliceWidth - mPadSize) / ((float) mInputWidth);
        float y0 = (ySliceIndex * mSliceHeight - mPadSize) / ((float) mInputHeight);

        ((ShaderProgram) mProgram).setSourceRect(x0, y0,
                                                 ((float) mOutputWidth) / mInputWidth,
                                                 ((float) mOutputHeight) / mInputHeight);

        // Process
        mProgram.process(mOriginalFrame, output);
        mSliceIndex++;

        if (mSliceIndex == mXSlices * mYSlices) {
            mSliceIndex = 0;
            mOriginalFrame.release();
            setWaitsOnInputPort("image", true);
        } else {
            // Retain the original frame so it can be used next time.
            mOriginalFrame.retain();
            setWaitsOnInputPort("image", false);
        }

        // Push output
        pushOutput("image", output);

        // Release pushed frame
        output.release();
    }
}