// Copyright 2008-present Contributors to the OpenImageIO project.
// SPDX-License-Identifier: BSD-3-Clause
// https://github.com/OpenImageIO/oiio/blob/master/LICENSE.md


#include <OpenImageIO/argparse.h>
#include <OpenImageIO/benchmark.h>
#include <OpenImageIO/fmath.h>
#include <OpenImageIO/imageio.h>
#include <OpenImageIO/simd.h>
#include <OpenImageIO/strutil.h>
#include <OpenImageIO/sysutil.h>
#include <OpenImageIO/timer.h>
#include <OpenImageIO/unittest.h>

#include <iostream>

using namespace OIIO;



int
main(int argc, char** argv)
{
    ArgParse ap;
    // clang-format off
    ap.intro("timer_test\n" OIIO_INTRO_STRING)
      .usage("timer_test [options]");
    // clang-format on

    ap.parse(argc, (const char**)argv);

    // First, just compute and print how expensive a Timer begin/end is,
    // in cycles per second.
    {
        Timer timer;
        int n                  = 10000000;
        int zeroes             = 0;
        Timer::ticks_t biggest = 0;
        for (int i = 0; i < n; ++i) {
            Timer t;
            Timer::ticks_t ticks = t.ticks();  // force getting the time
            if (!ticks)
                ++zeroes;
            if (ticks > biggest)
                biggest = ticks;
        }
        std::cout << "Timer begin/end cost is " << double(n) / timer()
                  << " /sec\n";
        std::cout << "Out of " << n << " queries, " << zeroes
                  << " had no time\n";
        std::cout << "Longest was " << Timer::seconds(biggest) << " s.\n";
    }

    const int interval = 100000;  // 1/10 sec
    double eps         = 0.01;    // slop we allow in our timings
#ifdef __APPLE__
    eps = 0.03;
    // On some Apple OSX systems (especially >= 10.10 Yosemite), a feature
    // called "timer coalescing" causes sleep/wake events to merge in order
    // to produce longer idle periods for the CPU to go into a lower power
    // state. This tends to make usleep() less reliable in its timing.
    //
    // One (permanent) fix is to disable timer coalescing with this command:
    //     $ sudo sysctl -w kern.timer.coalescing_enabled=0
    // But you want better power use, so instead we just increase the timing
    // tolereance on Apple to make this test pass.
#    if defined(OIIO_CI) || defined(OIIO_CODE_COVERAGE)
    // It seems especially bad on CI runs, so give extra time slop.
    eps = 1.0;
#    endif
#elif defined(OIIO_CI)
    // Also on GitHub Actions CI, timing seems a little imprecise. Give it
    // some extra room to avoid spurious CI failures on this test.
    eps = 0.25;
#endif

    // Verify that Timer(false) doesn't start
    Timer all(Timer::StartNow);
    Timer selective(Timer::DontStartNow);
    Sysutil::usleep(interval);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.0, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.1, eps);

    // Make sure start/stop work
    selective.start();
    Sysutil::usleep(interval);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.1, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.2, eps);
    selective.stop();
    Sysutil::usleep(interval);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.1, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.3, eps);
    std::cout << "Checkpoint: All " << all() << " selective " << selective()
              << "\n";

    // Test reset() -- should set selective to 0 and turn it off
    selective.reset();
    Sysutil::usleep(interval);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.0, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.4, eps);
    selective.start();
    Sysutil::usleep(interval);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.1, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.5, eps);

    // Test lap()
    double lap = selective.lap();  // lap=.1, select.time_since_start
    OIIO_CHECK_EQUAL_THRESH(lap, 0.1, eps);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.1, eps);
    OIIO_CHECK_EQUAL_THRESH(selective.time_since_start(), 0.0, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.5, eps);
    Sysutil::usleep(interval);
    OIIO_CHECK_EQUAL_THRESH(selective(), 0.2, eps);
    OIIO_CHECK_EQUAL_THRESH(selective.time_since_start(), 0.1, eps);
    OIIO_CHECK_EQUAL_THRESH(all(), 0.6, eps);
    std::cout << "Checkpoint2: All " << all() << " selective " << selective()
              << "\n";


    // Test Benchmarker
    Benchmarker bench;
    bench("string ctr", [&]() { std::string x("foo"); });
    bench("usleep(1000)", [&]() { Sysutil::usleep(1000); });

    float val = 0.5;
    clobber(val);
    simd::float4 val4 = val;
    clobber(val4);

    bench("add", [&]() { DoNotOptimize(val + 1.5); });
    bench("cos", [&]() { DoNotOptimize(std::cos(val)); });
    bench("acos", [&]() { DoNotOptimize(std::acos(val)); });
    bench("fast_acos", [&]() { DoNotOptimize(OIIO::fast_acos(val)); });

    bench("sqrt", [&]() { DoNotOptimize(std::sqrt(val)); });
    bench.work(4);
    bench("simd sqrt", [&]() { DoNotOptimize(sqrt(val4)); });
    return unit_test_failures;
}
