// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <perftest/results.h>

#include <errno.h>
#include <inttypes.h>
#include <math.h>

#include <fbl/algorithm.h>
#include <zircon/assert.h>

#include <utility>

namespace perftest {
namespace {

double Mean(const fbl::Vector<double>& values) {
    double sum = fbl::accumulate(values.begin(), values.end(), 0.0);
    return sum / static_cast<double>(values.size());
}

double Min(const fbl::Vector<double>& values) {
    return *fbl::min_element(values.begin(), values.end());
}

double Max(const fbl::Vector<double>& values) {
    return *fbl::max_element(values.begin(), values.end());
}

double StdDev(const fbl::Vector<double>& values, double mean) {
    double sum_of_squared_diffs = 0.0;
    for (double value : values) {
        double diff = value - mean;
        sum_of_squared_diffs += diff * diff;
    }
    return sqrt(sum_of_squared_diffs / static_cast<double>(values.size()));
}

// Comparison function for use with qsort().
int CompareDoubles(const void* ptr1, const void* ptr2) {
    double val1 = *reinterpret_cast<const double*>(ptr1);
    double val2 = *reinterpret_cast<const double*>(ptr2);
    if (val1 < val2) {
        return -1;
    }
    if (val1 > val2) {
        return 1;
    }
    return 0;
}

double Median(const fbl::Vector<double>& values) {
    // Make a sorted copy of the vector.
    fbl::Vector<double> copy;
    copy.reserve(values.size());
    for (double value : values) {
        copy.push_back(value);
    }
    qsort(copy.get(), copy.size(), sizeof(copy[0]), CompareDoubles);

    size_t index = copy.size() / 2;
    // Interpolate two values if necessary.
    if (copy.size() % 2 == 0) {
        return (copy[index - 1] + copy[index]) / 2;
    }
    return copy[index];
}

} // namespace

SummaryStatistics TestCaseResults::GetSummaryStatistics() const {
    ZX_ASSERT(values.size() > 0);
    double mean = Mean(values);
    return SummaryStatistics{
        .min = Min(values),
        .max = Max(values),
        .mean = mean,
        .std_dev = StdDev(values, mean),
        .median = Median(values),
    };
}

void WriteJSONString(FILE* out_file, const char* string) {
    fputc('"', out_file);
    for (const char* ptr = string; *ptr; ptr++) {
        uint8_t c = *ptr;
        if (c == '"') {
            fputs("\\\"", out_file);
        } else if (c == '\\') {
            fputs("\\\\", out_file);
        } else if (c < 32 || c >= 128) {
            // Escape non-printable characters (<32) and top-bit-set
            // characters (>=128).
            //
            // TODO(TO-824): Handle top-bit-set characters better.  Ideally
            // we should treat the input string as UTF-8 and preserve the
            // encoded Unicode in the JSON.  We could interpret the UTF-8
            // sequences and convert them to \uXXXX escape sequences.
            // Alternatively we could pass through UTF-8, but if we do
            // that, we ought to block overlong UTF-8 sequences to prevent
            // closing quotes from being encoded as overlong UTF-8
            // sequences.
            //
            // The current code treats the input string as a byte array
            // rather than UTF-8, which isn't *necessarily* what we want,
            // but will at least result in valid JSON and make the data
            // recoverable.
            fprintf(out_file, "\\u%04x", c);
        } else {
            fputc(c, out_file);
        }
    }
    fputc('"', out_file);
}

void TestCaseResults::WriteJSON(FILE* out_file) const {
    fprintf(out_file, "{\"label\":");
    WriteJSONString(out_file, label.c_str());
    fprintf(out_file, ",\"test_suite\":");
    WriteJSONString(out_file, test_suite.c_str());
    fprintf(out_file, ",\"unit\":");
    WriteJSONString(out_file, unit.c_str());
    if (bytes_processed_per_run) {
        fprintf(out_file, ",\"bytes_processed_per_run\":%" PRIu64,
                bytes_processed_per_run);
    }
    fprintf(out_file, ",\"values\":[");
    bool first = true;
    for (const auto value : values) {
        if (!first) {
            fprintf(out_file, ",");
        }
        fprintf(out_file, "%f", value);
        first = false;
    }
    fprintf(out_file, "]}");
}

TestCaseResults* ResultsSet::AddTestCase(const fbl::String& test_suite,
                                         const fbl::String& label,
                                         const fbl::String& unit) {
    TestCaseResults test_case(test_suite, label, unit);
    results_.push_back(std::move(test_case));
    return &results_[results_.size() - 1];
}

void ResultsSet::WriteJSON(FILE* out_file) const {
    fprintf(out_file, "[");
    bool first = true;
    for (const auto& test_case_results : results_) {
        if (!first) {
            fprintf(out_file, ",\n");
        }
        test_case_results.WriteJSON(out_file);
        first = false;
    }
    fprintf(out_file, "]");
}

bool ResultsSet::WriteJSONFile(const char* output_filename) const {
    FILE* fh = fopen(output_filename, "w");
    if (!fh) {
        fprintf(stderr, "Failed to open output file \"%s\": %s\n",
                output_filename, strerror(errno));
        return false;
    }
    WriteJSON(fh);
    fclose(fh);
    return true;
}

void ResultsSet::PrintSummaryStatistics(FILE* out_file) const {
    // Print table headings row.
    fprintf(out_file, "%10s %10s %10s %10s %10s %-12s %15s %s\n",
            "Mean", "Std dev", "Min", "Max", "Median", "Unit",
            "Mean Mbytes/sec", "Test case");
    if (results_.size() == 0) {
        fprintf(out_file, "(No test results)\n");
    }
    for (const auto& test : results_) {
        SummaryStatistics stats = test.GetSummaryStatistics();
        fprintf(out_file, "%10.0f %10.0f %10.0f %10.0f %10.0f %-12s",
                stats.mean, stats.std_dev, stats.min, stats.max, stats.median,
                test.unit.c_str());
        // Output the throughput column.
        if (test.bytes_processed_per_run != 0 && test.unit == "nanoseconds") {
            double bytes_per_second =
                static_cast<double>(test.bytes_processed_per_run)
                / stats.mean * 1e9;
            double mbytes_per_second = bytes_per_second / (1024 * 1024);
            fprintf(out_file, " %15.3f", mbytes_per_second);
        } else {
            fprintf(out_file, " %15s", "N/A");
        }
        fprintf(out_file, " %s\n", test.label.c_str());
    }
}

} // namespace perftest