/*
 * Copyright 2019 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.graphics;

import android.annotation.NonNull;
import android.annotation.Nullable;

import libcore.util.NativeAllocationRegistry;

/**
 * Shader that calculates pixel output with a program (fragment shader) running on a GPU.
 * @hide
 */
public class RuntimeShader extends Shader {

    private static class NoImagePreloadHolder {
        public static final NativeAllocationRegistry sRegistry =
                NativeAllocationRegistry.createMalloced(
                RuntimeShader.class.getClassLoader(), nativeGetFinalizer());
    }

    private byte[] mUniforms;
    private boolean mIsOpaque;

    /**
     * Current native shader factory instance.
     */
    private long mNativeInstanceRuntimeShaderFactory;

    /**
     * Creates a new RuntimeShader.
     *
     * @param sksl The text of SKSL program to run on the GPU.
     * @param uniforms Array of parameters passed by the SKSL shader. Array size depends
     *                 on number of uniforms declared by sksl.
     * @param isOpaque True if all pixels have alpha 1.0f.
     */
    public RuntimeShader(@NonNull String sksl, @Nullable byte[] uniforms, boolean isOpaque) {
        this(sksl, uniforms, isOpaque, ColorSpace.get(ColorSpace.Named.SRGB));
    }

    private RuntimeShader(@NonNull String sksl, @Nullable byte[] uniforms, boolean isOpaque,
            ColorSpace colorSpace) {
        super(colorSpace);
        mUniforms = uniforms;
        mIsOpaque = isOpaque;
        mNativeInstanceRuntimeShaderFactory = nativeCreateShaderFactory(sksl);
        NoImagePreloadHolder.sRegistry.registerNativeAllocation(this,
                mNativeInstanceRuntimeShaderFactory);
    }

    /**
     * Sets new value for shader parameters.
     *
     * @param uniforms Array of parameters passed by the SKSL shader. Array size depends
     *                 on number of uniforms declared by mSksl.
     */
    public void updateUniforms(@Nullable byte[] uniforms) {
        mUniforms = uniforms;
        discardNativeInstance();
    }

    @Override
    long createNativeInstance(long nativeMatrix) {
        return nativeCreate(mNativeInstanceRuntimeShaderFactory, nativeMatrix, mUniforms,
                colorSpace().getNativeInstance(), mIsOpaque);
    }

    private static native long nativeCreate(long shaderFactory, long matrix, byte[] inputs,
            long colorSpaceHandle, boolean isOpaque);

    private static native long nativeCreateShaderFactory(String sksl);

    private static native long nativeGetFinalizer();
}