/*
 * Copyright 2019 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "bench/Benchmark.h"
#include "include/utils/SkRandom.h"
#include "src/sksl/SkSLByteCode.h"
#include "src/sksl/SkSLCompiler.h"
#include "src/sksl/SkSLInterpreter.h"

// Without this build flag, this bench isn't runnable.
#if defined(SK_ENABLE_SKSL_INTERPRETER)

// Benchmarks the interpreter with a function that has a color-filter style signature
class SkSLInterpreterCFBench : public Benchmark {
public:
    SkSLInterpreterCFBench(SkSL::String name, int pixels, const char* src)
        : fName(SkStringPrintf("sksl_interp_cf_%d_%s", pixels, name.c_str()))
        , fSrc(src)
        , fCount(pixels) {}

protected:
    static constexpr int VecWidth = 16;

    const char* onGetName() override {
        return fName.c_str();
    }

    bool isSuitableFor(Backend backend) override {
        return backend == kNonRendering_Backend;
    }

    void onDelayedSetup() override {
        SkSL::Compiler compiler;
        SkSL::Program::Settings settings;
        auto program = compiler.convertProgram(SkSL::Program::kGeneric_Kind, fSrc, settings);
        SkASSERT(compiler.errorCount() == 0);
        std::unique_ptr<SkSL::ByteCode> byteCode = compiler.toByteCode(*program);
        fMain = byteCode->getFunction("main");
        fInterpreter.reset(new SkSL::Interpreter<VecWidth>(std::move(byteCode)));
        SkASSERT(compiler.errorCount() == 0);

        SkRandom rnd;
        fPixels.resize(fCount * 4);
        for (float& c : fPixels) {
            c = rnd.nextF();
        }
    }

    void onDraw(int loops, SkCanvas*) override {
        for (int i = 0; i < loops; i++) {
            float* args[] = {
                fPixels.data() + 0 * fCount,
                fPixels.data() + 1 * fCount,
                fPixels.data() + 2 * fCount,
                fPixels.data() + 3 * fCount,
            };

            fInterpreter->runStriped(fMain, fCount, (float**) args);
        }
    }

private:
    SkString fName;
    SkSL::String fSrc;
    std::unique_ptr<SkSL::Interpreter<VecWidth>> fInterpreter;
    const SkSL::ByteCodeFunction* fMain;

    int fCount;
    std::vector<float> fPixels;

    typedef Benchmark INHERITED;
};

///////////////////////////////////////////////////////////////////////////////

const char* kLumaToAlphaSrc = R"(
    void main(inout float4 color) {
        color.a = color.r*0.3 + color.g*0.6 + color.b*0.1;
        color.r = 0;
        color.g = 0;
        color.b = 0;
    }
)";

const char* kHighContrastFilterSrc = R"(
    half ucontrast_Stage2;
    half hue2rgb_Stage2(half p, half q, half t) {
        if (t < 0)  t += 1;
        if (t > 1)  t -= 1;
        return (t < 1 / 6.) ? p + (q - p) * 6 * t
             : (t < 1 / 2.) ? q
             : (t < 2 / 3.) ? p + (q - p) * (2 / 3. - t) * 6
             : p;
    }
    half max(half a, half b) { return a > b ? a : b; }
    half min(half a, half b) { return a < b ? a : b; }
    void main(inout half4 color) {
        ucontrast_Stage2 = 0.2;

        // HighContrastFilter
        half nonZeroAlpha = max(color.a, 0.0001);
        color = half4(color.rgb / nonZeroAlpha, nonZeroAlpha);
        color.rgb = color.rgb * color.rgb;
        half fmax = max(color.r, max(color.g, color.b));
        half fmin = min(color.r, min(color.g, color.b));
        half l = (fmax + fmin) / 2;
        half h;
        half s;
        if (fmax == fmin) {
            h = 0;
            s = 0;
        } else {
            half d = fmax - fmin;
            s = l > 0.5 ? d / (2 - fmax - fmin) : d / (fmax + fmin);
            if (color.r >= color.g && color.r >= color.b) {
                h = (color.g - color.b) / d + (color.g < color.b ? 6 : 0);
            } else if (color.g >= color.b) {
                h = (color.b - color.r) / d + 2;
            } else {
                h = (color.r - color.g) / d + 4;
            }
        }
        h /= 6;
        l = 1.0 - l;
        if (s == 0) {
            color = half4(l, l, l, 0);
        } else {
            half q = l < 0.5 ? l * (1 + s) : l + s - l * s;
            half p = 2 * l - q;
            color.r = hue2rgb_Stage2(p, q, h + 1 / 3.);
            color.g = hue2rgb_Stage2(p, q, h);
            color.b = hue2rgb_Stage2(p, q, h - 1 / 3.);
        }
        if (ucontrast_Stage2 != 0) {
            half m = (1 + ucontrast_Stage2) / (1 - ucontrast_Stage2);
            half off = (-0.5 * m + 0.5);
            color = m * color + off;
        }
        // color = saturate(color);
        color.rgb = sqrt(color.rgb);
        color.rgb *= color.a;
    }
)";

DEF_BENCH(return new SkSLInterpreterCFBench("lumaToAlpha", 256, kLumaToAlphaSrc));
DEF_BENCH(return new SkSLInterpreterCFBench("hcf", 256, kHighContrastFilterSrc));
#endif // SK_ENABLE_SKSL_INTERPRETER