/*
 * Copyright (C) 2023 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 com.android.wallpaper.picker.customization.animation.shader

import android.graphics.RuntimeShader
import com.android.systemui.surfaceeffects.shaderutil.ShaderUtilLibrary

/** Shader that renders sparkles in [CompositeLoadingShader]. */
// TODO (b/281878827): remove this and use loading animation in SystemUIShaderLib when available
class SparkleShader : RuntimeShader(SPARKLE_SHADER) {
    // language=AGSL
    companion object {
        private const val UNIFORMS =
            """
            uniform float in_gridNum;
            uniform vec3 in_noiseMove;
            uniform vec2 in_size;
            uniform float in_aspectRatio;
            uniform half in_time;
            uniform half in_pixelDensity;
            layout(color) uniform vec4 in_color;
        """
        private const val MAIN_SHADER =
            """vec4 main(vec2 p) {
            vec2 uv = p / in_size.xy;
            uv.x *= in_aspectRatio;
            vec3 noiseP = vec3(uv + in_noiseMove.xy, in_noiseMove.z) * in_gridNum;
            // Inverse luminosity per spec.
            half luma = 1.0 - getLuminosity(vec3(simplex3d(noiseP)));
            luma = max(/* intensity= */ 1.75 * luma - /* dim= */ 1.3, 0.);
            float sparkle = sparkles(p - mod(p, in_pixelDensity * 0.8), in_time);

            return vec4(maskLuminosity(in_color.rgb * sparkle, luma) * in_color.a, in_color.a);
        }
        """
        private const val SPARKLE_SHADER = UNIFORMS + ShaderUtilLibrary.SHADER_LIB + MAIN_SHADER
    }

    /** Sets noise move offset in x, y, and z direction. */
    fun setNoiseMove(x: Float, y: Float, z: Float) {
        setFloatUniform("in_noiseMove", x, y, z)
    }

    /** Sets the number of grid for generating noise. */
    fun setGridCount(gridNumber: Float = 1.0f) {
        setFloatUniform("in_gridNum", gridNumber)
    }

    /** Sets the size of the shader. */
    fun setSize(width: Float, height: Float) {
        setFloatUniform("in_size", width, height)
        setFloatUniform("in_aspectRatio", width / java.lang.Float.max(height, 0.001f))
    }

    /** Sets the pixel density of the screen. */
    fun setPixelDensity(pixelDensity: Float) {
        setFloatUniform("in_pixelDensity", pixelDensity)
    }

    fun setColor(color: Int) {
        setColorUniform("in_color", color)
    }

    fun setTime(time: Float) {
        setFloatUniform("in_time", time)
    }
}