#include "fesa/analysis/newton_iteration_log.h"

#include <algorithm>
#include <charconv>
#include <chrono>
#include <cmath>
#include <filesystem>
#include <fstream>
#include <functional>
#include <limits>
#include <iterator>
#include <stdexcept>
#include <string>
#include <string_view>
#include <vector>

#include <gtest/gtest.h>

namespace {

class TempDirectory {
 public:
  explicit TempDirectory(const std::string& label) {
    const auto tick =
        std::chrono::steady_clock::now().time_since_epoch().count();
    path_ = std::filesystem::temp_directory_path() /
            ("fesa-newton-log-" + label + "-" + std::to_string(tick));
    std::error_code error;
    if (!std::filesystem::create_directory(path_, error) || error) {
      throw std::runtime_error{"Unable to create Newton log test fixture."};
    }
  }

  TempDirectory(const TempDirectory&) = delete;
  TempDirectory& operator=(const TempDirectory&) = delete;

  ~TempDirectory() {
    std::error_code ignored;
    std::filesystem::remove_all(path_, ignored);
  }

  const std::filesystem::path& Path() const noexcept { return path_; }

 private:
  std::filesystem::path path_;
};

void ExpectLogOutputFailure(const fesa::Status& status) {
  ASSERT_FALSE(status.IsOk());
  ASSERT_EQ(status.Category(), fesa::FailureCategory::kOutput);
  ASSERT_EQ(status.Diagnostics().size(), 1U);
  EXPECT_EQ(status.Diagnostics().front().code, "log-output-failure");
}

std::vector<std::string> SplitTabs(const std::string& line) {
  std::vector<std::string> fields;
  std::size_t start = 0U;
  while (start <= line.size()) {
    const std::size_t end = line.find('\t', start);
    if (end == std::string::npos) {
      fields.push_back(line.substr(start));
      return fields;
    }
    fields.push_back(line.substr(start, end - start));
    start = end + 1U;
  }
  return fields;
}

const std::string& FieldValue(const std::vector<std::string>& fields,
                              const std::string_view label) {
  const std::string prefix = std::string{label} + "=";
  for (const std::string& field : fields) {
    if (field.compare(0U, prefix.size(), prefix) == 0) {
      return field;
    }
  }
  throw std::runtime_error{"Newton log field is missing."};
}

std::string ValueAfterEquals(const std::string& field) {
  return field.substr(field.find('=') + 1U);
}

fesa::Vector VectorFrom(const std::vector<double>& values) {
  fesa::Vector result{values.size()};
  for (std::size_t index = 0U; index < values.size(); ++index) {
    result[index] = values[index];
  }
  return result;
}

fesa::NewtonChannelDecision MakeDecision(const std::string& identity) {
  return {identity,
          0.0012345678901234567,
          1.2345678901234567,
          fesa::NewtonConvergenceBranch::kRelative,
          fesa::kNewtonRelativeThreshold,
          fesa::NewtonChannelUnit::kDimensionless,
          true};
}

fesa::NewtonIterationLogRecord CompleteRecord() {
  return {"Step-1",
          3U,
          0.12345678901234567,
          2U,
          fesa::NewtonIterationStage::kConvergenceEvaluated,
          {false, fesa::NewtonIterationStage::kFailed, "", ""},
          "accept",
          "accepted",
          "none",
          MakeDecision("residual_force"),
          MakeDecision("residual_moment"),
          MakeDecision("correction_translation"),
          MakeDecision("correction_rotation"),
          true};
}

std::vector<std::string> WriteAndRead(
    const std::filesystem::path& path,
    const fesa::NewtonIterationLogRecord& record) {
  fesa::NewtonIterationLogWriter writer;
  if (!writer.Open(path).IsOk() || !writer.Write(record).IsOk() ||
      !writer.Flush().IsOk() || !writer.Close().IsOk()) {
    throw std::runtime_error{"Unable to write Newton log test record."};
  }

  std::ifstream input{path, std::ios::binary};
  if (!input.is_open()) {
    throw std::runtime_error{"Unable to read Newton log test record."};
  }
  const std::string contents{std::istreambuf_iterator<char>{input},
                             std::istreambuf_iterator<char>{}};
  if (contents.empty()) {
    throw std::runtime_error{"Newton log test record is empty."};
  }
  EXPECT_EQ(contents.back(), '\n');
  EXPECT_EQ(std::count(contents.begin(), contents.end(), '\n'), 1);
  EXPECT_EQ(contents.find('\r'), std::string::npos);
  EXPECT_FALSE(contents.size() >= 3U &&
               static_cast<unsigned char>(contents[0U]) == 0xEFU &&
               static_cast<unsigned char>(contents[1U]) == 0xBBU &&
               static_cast<unsigned char>(contents[2U]) == 0xBFU);
  return SplitTabs(contents.substr(0U, contents.size() - 1U));
}

// NSNR-LOG-001, NSNR-LOG-002, and NSNR-LOG-003
TEST(NewtonIterationLog, WritesOneLfTerminated39FieldRecordInApprovedOrder) {
  TempDirectory directory{"complete"};
  const auto fields =
      WriteAndRead(directory.Path() / "model_log.txt", CompleteRecord());

  const std::vector<std::string> labels{
      "record", "schema", "increment", "target_factor", "iteration",
      "last_completed_stage", "failing_stage", "residual_force_channel",
      "residual_force_numerator_norm", "residual_force_denominator_scale",
      "residual_force_branch", "residual_force_threshold",
      "residual_force_threshold_unit", "residual_force_pass",
      "residual_moment_channel", "residual_moment_numerator_norm",
      "residual_moment_denominator_scale", "residual_moment_branch",
      "residual_moment_threshold", "residual_moment_threshold_unit",
      "residual_moment_pass", "correction_translation_channel",
      "correction_translation_numerator_norm",
      "correction_translation_denominator_scale",
      "correction_translation_branch", "correction_translation_threshold",
      "correction_translation_threshold_unit", "correction_translation_pass",
      "correction_rotation_channel", "correction_rotation_numerator_norm",
      "correction_rotation_denominator_scale", "correction_rotation_branch",
      "correction_rotation_threshold", "correction_rotation_threshold_unit",
      "correction_rotation_pass", "combined_pass", "transition", "outcome",
      "diagnostic_code"};

  ASSERT_EQ(fields.size(), labels.size());
  for (std::size_t index = 0U; index < labels.size(); ++index) {
    EXPECT_EQ(fields[index].substr(0U, fields[index].find('=')), labels[index]);
  }
  EXPECT_EQ(FieldValue(fields, "record"), "record=newton-iteration");
  EXPECT_EQ(FieldValue(fields, "schema"), "schema=nsnr-log-v1");
}

// NSNR-LOG-004
TEST(NewtonIterationLog, FormatsFiniteNumbersForLocaleIndependentRoundTrip) {
  TempDirectory directory{"numbers"};
  const auto fields =
      WriteAndRead(directory.Path() / "model_log.txt", CompleteRecord());
  const std::string value = ValueAfterEquals(FieldValue(fields, "target_factor"));

  double parsed = 0.0;
  const auto result = std::from_chars(value.data(), value.data() + value.size(),
                                      parsed, std::chars_format::general);
  EXPECT_EQ(result.ec, std::errc{});
  EXPECT_EQ(result.ptr, value.data() + value.size());
  EXPECT_DOUBLE_EQ(parsed, 0.12345678901234567);
  EXPECT_NE(value.find('.'), std::string::npos);
  EXPECT_EQ(value.find(','), std::string::npos);
}

// NSNR-LOG-005 and NSNR-LOG-007
TEST(NewtonIterationLog, SerializesChannelDecisionsAndExplicitOutcomeFields) {
  TempDirectory directory{"channels"};
  const auto fields =
      WriteAndRead(directory.Path() / "model_log.txt", CompleteRecord());

  for (const std::string_view prefix :
       {"residual_force", "residual_moment", "correction_translation",
        "correction_rotation"}) {
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_channel"),
              std::string{prefix} + "_channel=" + std::string{prefix});
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_numerator_norm"),
              std::string{prefix} +
                  "_numerator_norm=0.0012345678901234567");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_denominator_scale"),
              std::string{prefix} +
                  "_denominator_scale=1.2345678901234567");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_branch"),
              std::string{prefix} + "_branch=relative");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_threshold"),
              std::string{prefix} + "_threshold=0.01");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_threshold_unit"),
              std::string{prefix} + "_threshold_unit=1");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_pass"),
              std::string{prefix} + "_pass=1");
  }
  EXPECT_EQ(FieldValue(fields, "last_completed_stage"),
            "last_completed_stage=convergence-gates");
  EXPECT_EQ(FieldValue(fields, "failing_stage"), "failing_stage=none");
  EXPECT_EQ(FieldValue(fields, "combined_pass"), "combined_pass=1");
  EXPECT_EQ(FieldValue(fields, "transition"), "transition=accept");
  EXPECT_EQ(FieldValue(fields, "outcome"), "outcome=accepted");
  EXPECT_EQ(FieldValue(fields, "diagnostic_code"), "diagnostic_code=none");
}

// NSNR-LOG-006
TEST(NewtonIterationLog, SerializesEmptyChannelsAsTypedZeroScaleDecisions) {
  TempDirectory directory{"zero-scale"};
  auto record = CompleteRecord();
  const std::vector<fesa::NewtonChannelUnit> units{
      fesa::NewtonChannelUnit::kForce, fesa::NewtonChannelUnit::kForceLength,
      fesa::NewtonChannelUnit::kLength, fesa::NewtonChannelUnit::kDimensionless};
  fesa::NewtonChannelDecision* decisions[]{
      &record.force_residual, &record.moment_residual,
      &record.translation_correction, &record.rotation_correction};
  for (std::size_t index = 0U; index < std::size(decisions); ++index) {
    decisions[index]->numerator_norm = 0.0;
    decisions[index]->denominator_scale = 0.0;
    decisions[index]->branch = fesa::NewtonConvergenceBranch::kZeroScale;
    decisions[index]->threshold = fesa::kNewtonZeroScaleThreshold;
    decisions[index]->threshold_unit = units[index];
    decisions[index]->passed = true;
  }

  const auto fields = WriteAndRead(directory.Path() / "model_log.txt", record);
  for (const std::string_view prefix :
       {"residual_force", "residual_moment", "correction_translation",
        "correction_rotation"}) {
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_numerator_norm"),
              std::string{prefix} + "_numerator_norm=0");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_denominator_scale"),
              std::string{prefix} + "_denominator_scale=0");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_branch"),
              std::string{prefix} + "_branch=zero-scale");
    EXPECT_EQ(FieldValue(fields, std::string{prefix} + "_threshold"),
              std::string{prefix} + "_threshold=0.001");
  }
  EXPECT_EQ(FieldValue(fields, "residual_force_threshold_unit"),
            "residual_force_threshold_unit=force");
  EXPECT_EQ(FieldValue(fields, "residual_moment_threshold_unit"),
            "residual_moment_threshold_unit=force*length");
  EXPECT_EQ(FieldValue(fields, "correction_translation_threshold_unit"),
            "correction_translation_threshold_unit=length");
  EXPECT_EQ(FieldValue(fields, "correction_rotation_threshold_unit"),
            "correction_rotation_threshold_unit=1");
}

// NSNR-LOG-008 and NSNR-LOG-009
TEST(NewtonIterationLog, EscapesStringsAndOmitsUnevaluatedFailureFields) {
  TempDirectory directory{"failure"};
  auto record = CompleteRecord();
  record.last_completed_stage = fesa::NewtonIterationStage::kInternalAssembled;
  record.failure = {true,
                    fesa::NewtonIterationStage::kExternalAssembled,
                    "load\\failure",
                    std::string{"external\tload\nmissing\r"} + '\0'};
  record.transition = "fail\ttransition";
  record.outcome = "failed\nrecord";
  record.diagnostic_code = std::string{"external\\load\r"} + '\0';
  const auto fields = WriteAndRead(directory.Path() / "model_log.txt", record);

  const std::string not_evaluated =
      "not-evaluated(external\\tload\\nmissing\\r\\0)";
  for (std::size_t index = 7U; index < 36U; ++index) {
    EXPECT_EQ(ValueAfterEquals(fields[index]), not_evaluated);
  }
  EXPECT_EQ(FieldValue(fields, "failing_stage"),
            "failing_stage=load-boundary");
  EXPECT_EQ(FieldValue(fields, "transition"),
            "transition=fail\\ttransition");
  EXPECT_EQ(FieldValue(fields, "outcome"), "outcome=failed\\nrecord");
  EXPECT_EQ(FieldValue(fields, "diagnostic_code"),
            "diagnostic_code=external\\\\load\\r\\0");
}

// NSNR-LOG-010
TEST(NewtonIterationLog, ReportsWriteFlushAndCloseStateFailures) {
  TempDirectory directory{"failures"};
  const auto path = directory.Path() / "model_log.txt";
  fesa::NewtonIterationLogWriter writer;
  ExpectLogOutputFailure(writer.Write(CompleteRecord()));
  ExpectLogOutputFailure(writer.Flush());
  ExpectLogOutputFailure(writer.Close());

  fesa::NewtonIterationLogWriter invalid_open_writer;
  ExpectLogOutputFailure(
      invalid_open_writer.Open(directory.Path() / "missing" / "log.txt"));

  fesa::NewtonIterationLogWriter closed_writer;
  ASSERT_TRUE(closed_writer.Open(path).IsOk());
  ASSERT_TRUE(closed_writer.Close().IsOk());
  ExpectLogOutputFailure(closed_writer.Write(CompleteRecord()));
  ExpectLogOutputFailure(closed_writer.Flush());
  ExpectLogOutputFailure(closed_writer.Close());
}

// NSNR-LOG-011
TEST(NewtonIterationLog, LeavesZeroByteLogForNonNewtonControlledFailurePath) {
  TempDirectory directory{"zero-byte"};
  const auto path = directory.Path() / "model_log.txt";
  fesa::NewtonIterationLogWriter writer;

  ASSERT_TRUE(writer.Open(path).IsOk());
  ASSERT_TRUE(writer.Close().IsOk());
  EXPECT_TRUE(std::filesystem::exists(path));
  EXPECT_EQ(std::filesystem::file_size(path), 0U);
}

// NSNR-LOG-012
TEST(NewtonIterationLog,
     SerializesEvaluatorProducedExternalScaleResidualDecisions) {
  TempDirectory directory{"external-scale"};
  const fesa::NewtonConvergenceInput zero_external{
      {"residual_force", VectorFrom({1.0e-3}), VectorFrom({2.0}),
       VectorFrom({0.0})},
      {"residual_moment", VectorFrom({1.0e-3}), VectorFrom({3.0}),
       VectorFrom({0.0})},
      {"correction_translation", VectorFrom({1.0e-2}), VectorFrom({1.0})},
      {"correction_rotation", VectorFrom({1.0e-2}), VectorFrom({1.0})},
  };
  const auto zero_decisions = fesa::EvaluateNewtonConvergence(zero_external);
  auto zero_record = CompleteRecord();
  zero_record.force_residual = zero_decisions.force_residual;
  zero_record.moment_residual = zero_decisions.moment_residual;
  zero_record.translation_correction = zero_decisions.translation_correction;
  zero_record.rotation_correction = zero_decisions.rotation_correction;
  zero_record.combined_passed = zero_decisions.combined_passed;
  const auto zero_fields =
      WriteAndRead(directory.Path() / "zero_log.txt", zero_record);

  ASSERT_EQ(zero_fields.size(), 39U);
  EXPECT_EQ(FieldValue(zero_fields, "schema"), "schema=nsnr-log-v1");
  EXPECT_EQ(FieldValue(zero_fields, "residual_force_denominator_scale"),
            "residual_force_denominator_scale=0");
  EXPECT_EQ(FieldValue(zero_fields, "residual_moment_denominator_scale"),
            "residual_moment_denominator_scale=0");
  EXPECT_EQ(FieldValue(zero_fields, "residual_force_branch"),
            "residual_force_branch=zero-scale");
  EXPECT_EQ(FieldValue(zero_fields, "residual_moment_branch"),
            "residual_moment_branch=zero-scale");
  EXPECT_EQ(FieldValue(zero_fields, "residual_force_threshold"),
            "residual_force_threshold=0.001");
  EXPECT_EQ(FieldValue(zero_fields, "residual_moment_threshold"),
            "residual_moment_threshold=0.001");
  EXPECT_EQ(FieldValue(zero_fields, "residual_force_threshold_unit"),
            "residual_force_threshold_unit=force");
  EXPECT_EQ(FieldValue(zero_fields, "residual_moment_threshold_unit"),
            "residual_moment_threshold_unit=force*length");

  const fesa::NewtonConvergenceInput nonzero_external{
      {"residual_force", VectorFrom({2.0e-2}), VectorFrom({2.0}),
       VectorFrom({1.0})},
      {"residual_moment", VectorFrom({2.0e-2}), VectorFrom({1.0}),
       VectorFrom({2.0})},
      {"correction_translation", VectorFrom({1.0e-2}), VectorFrom({1.0})},
      {"correction_rotation", VectorFrom({1.0e-2}), VectorFrom({1.0})},
  };
  const auto relative_decisions =
      fesa::EvaluateNewtonConvergence(nonzero_external);
  auto relative_record = CompleteRecord();
  relative_record.force_residual = relative_decisions.force_residual;
  relative_record.moment_residual = relative_decisions.moment_residual;
  relative_record.translation_correction =
      relative_decisions.translation_correction;
  relative_record.rotation_correction = relative_decisions.rotation_correction;
  relative_record.combined_passed = relative_decisions.combined_passed;
  const auto relative_fields =
      WriteAndRead(directory.Path() / "relative_log.txt", relative_record);

  ASSERT_EQ(relative_fields.size(), 39U);
  EXPECT_EQ(FieldValue(relative_fields, "residual_force_denominator_scale"),
            "residual_force_denominator_scale=2");
  EXPECT_EQ(FieldValue(relative_fields, "residual_moment_denominator_scale"),
            "residual_moment_denominator_scale=2");
  EXPECT_EQ(FieldValue(relative_fields, "residual_force_branch"),
            "residual_force_branch=relative");
  EXPECT_EQ(FieldValue(relative_fields, "residual_moment_branch"),
            "residual_moment_branch=relative");
  EXPECT_EQ(FieldValue(relative_fields, "residual_force_threshold"),
            "residual_force_threshold=0.01");
  EXPECT_EQ(FieldValue(relative_fields, "residual_moment_threshold"),
            "residual_moment_threshold=0.01");
  EXPECT_EQ(FieldValue(relative_fields, "residual_force_threshold_unit"),
            "residual_force_threshold_unit=1");
  EXPECT_EQ(FieldValue(relative_fields, "residual_moment_threshold_unit"),
            "residual_moment_threshold_unit=1");
}

fesa::DynamicNewtonIterationLogRecord CompleteDynamicRecord() {
  return {2U,
          3U,
          0.25,
          "convergence",
          "accepted",
          "",
          {2.0e-12, 0.0},
          {2.0, 0.0},
          {1.0e-11, 2.0e-11},
          {3.0e-11, 4.0e-11},
          {5.0e-11, 6.0e-11},
          {7.0e-11, 8.0e-11},
          true,
          true};
}

std::string ReadLogBytes(const std::filesystem::path& path) {
  std::ifstream input{path, std::ios::binary};
  return std::string{std::istreambuf_iterator<char>{input},
                     std::istreambuf_iterator<char>{}};
}

TEST(DynamicNewtonIterationLog, WritesTimeAndAllTwoChannelMetrics) {
  TempDirectory directory{"dynamic-complete"};
  const auto path = directory.Path() / "dynamic_log.txt";
  fesa::NewtonIterationLogWriter writer;
  const auto record = CompleteDynamicRecord();
  ASSERT_TRUE(writer.Open(path).IsOk());
  ASSERT_TRUE(writer.Write(record).IsOk());
  ASSERT_TRUE(writer.Flush().IsOk());
  ASSERT_TRUE(writer.Close().IsOk());
  const std::string bytes = ReadLogBytes(path);
  ASSERT_FALSE(bytes.empty());
  EXPECT_EQ(bytes.back(), '\n');
  EXPECT_EQ(std::count(bytes.begin(), bytes.end(), '\n'), 1);
  EXPECT_EQ(bytes.find('\r'), std::string::npos);
  EXPECT_EQ(bytes.find("target_factor"), std::string::npos);
  EXPECT_EQ(bytes.find("nsnr-log-v1"), std::string::npos);
  const auto fields = SplitTabs(bytes.substr(0U, bytes.size() - 1U));
  EXPECT_EQ(fields.size(), 24U);
  EXPECT_EQ(FieldValue(fields, "record"), "record=dynamic-newton-iteration");
  EXPECT_EQ(FieldValue(fields, "schema"), "schema=hht-log-v1");
  EXPECT_EQ(FieldValue(fields, "increment"), "increment=2");
  EXPECT_EQ(FieldValue(fields, "iteration"), "iteration=3");
  EXPECT_EQ(FieldValue(fields, "time"), "time=0.25");
  EXPECT_EQ(FieldValue(fields, "stage"), "stage=convergence");
  EXPECT_EQ(FieldValue(fields, "residual_u_branch"),
            "residual_u_branch=relative");
  EXPECT_EQ(FieldValue(fields, "residual_phi_branch"),
            "residual_phi_branch=zero-scale");
  EXPECT_EQ(FieldValue(fields, "residual_pass"), "residual_pass=1");
  EXPECT_EQ(FieldValue(fields, "correction_pass"), "correction_pass=1");
  const std::vector<std::pair<std::string, double>> expected{
      {"residual_u_numerator", 2.0e-12},
      {"residual_u_scale", 2.0},
      {"residual_phi_numerator", 0.0},
      {"residual_phi_scale", 0.0},
      {"coordinate_correction_u", 1.0e-11},
      {"coordinate_correction_phi", 2.0e-11},
      {"velocity_correction_u", 3.0e-11},
      {"velocity_correction_phi", 4.0e-11},
      {"acceleration_correction_u", 5.0e-11},
      {"acceleration_correction_phi", 6.0e-11},
      {"algorithmic_correction_u", 7.0e-11},
      {"algorithmic_correction_phi", 8.0e-11}};
  for (const auto& metric : expected) {
    const auto text = ValueAfterEquals(FieldValue(fields, metric.first));
    double value = 0.0;
    const auto parsed =
        std::from_chars(text.data(), text.data() + text.size(), value);
    EXPECT_EQ(parsed.ec, std::errc{});
    EXPECT_EQ(parsed.ptr, text.data() + text.size());
    EXPECT_DOUBLE_EQ(value, metric.second);
  }
}

TEST(DynamicNewtonIterationLog, EscapesFailureContextAndKeepsZeroScaleFailure) {
  TempDirectory directory{"dynamic-failure"};
  const auto path = directory.Path() / "dynamic_log.txt";
  auto record = CompleteDynamicRecord();
  record.stage = "mass\tcheck";
  record.outcome = "failed\ntrial";
  record.failure_code = "dynamic\\mass\rregularity";
  record.residual_numerator = {1.0, 0.0};
  record.residual_scale = {0.0, 0.0};
  record.residual_pass = false;
  record.correction_pass = false;
  fesa::NewtonIterationLogWriter writer;
  ASSERT_TRUE(writer.Open(path).IsOk());
  ASSERT_TRUE(writer.Write(record).IsOk());
  ASSERT_TRUE(writer.Close().IsOk());
  const auto bytes = ReadLogBytes(path);
  EXPECT_EQ(std::count(bytes.begin(), bytes.end(), '\n'), 1);
  const auto fields = SplitTabs(bytes.substr(0U, bytes.size() - 1U));
  EXPECT_EQ(FieldValue(fields, "stage"), "stage=mass\\tcheck");
  EXPECT_EQ(FieldValue(fields, "outcome"), "outcome=failed\\ntrial");
  EXPECT_EQ(FieldValue(fields, "failure_code"),
            "failure_code=dynamic\\\\mass\\rregularity");
  EXPECT_EQ(FieldValue(fields, "residual_u_numerator"),
            "residual_u_numerator=1");
  EXPECT_EQ(FieldValue(fields, "residual_u_scale"), "residual_u_scale=0");
  EXPECT_EQ(FieldValue(fields, "residual_u_branch"),
            "residual_u_branch=zero-scale");
  EXPECT_EQ(FieldValue(fields, "residual_pass"), "residual_pass=0");
}

TEST(DynamicNewtonIterationLog,
     InvalidEvidencePreservesFlushedPrefixAndFailsLifecycle) {
  using Record = fesa::DynamicNewtonIterationLogRecord;
  const double nan = std::numeric_limits<double>::quiet_NaN();
  const double infinity = std::numeric_limits<double>::infinity();
  const std::vector<std::function<void(Record&)>> mutations{
      [nan](Record& record) { record.time = nan; },
      [nan](Record& record) { record.residual_numerator[0U] = nan; },
      [infinity](Record& record) { record.residual_scale[1U] = infinity; },
      [nan](Record& record) { record.coordinate_correction[0U] = nan; },
      [infinity](Record& record) { record.velocity_correction[1U] = infinity; },
      [nan](Record& record) { record.acceleration_correction[0U] = nan; },
      [infinity](Record& record) {
        record.algorithmic_correction[1U] = infinity;
      },
      [](Record& record) { record.time = -0.1; },
      [](Record& record) { record.residual_scale[0U] = -1.0; },
      [](Record& record) { record.coordinate_correction[0U] = -1.0; },
      [](Record& record) { record.stage.clear(); },
      [](Record& record) { record.outcome.clear(); }};
  TempDirectory directory{"dynamic-invalid"};
  const auto path = directory.Path() / "dynamic_log.txt";
  for (std::size_t index = 0U; index < mutations.size(); ++index) {
    SCOPED_TRACE(index);
    fesa::NewtonIterationLogWriter writer;
    ASSERT_TRUE(writer.Open(path).IsOk());
    ASSERT_TRUE(writer.Write(CompleteDynamicRecord()).IsOk());
    ASSERT_TRUE(writer.Flush().IsOk());
    const std::string prefix = ReadLogBytes(path);
    auto invalid = CompleteDynamicRecord();
    mutations[index](invalid);
    ExpectLogOutputFailure(writer.Write(invalid));
    ExpectLogOutputFailure(writer.Write(CompleteDynamicRecord()));
    ExpectLogOutputFailure(writer.Flush());
    ExpectLogOutputFailure(writer.Close());
    EXPECT_EQ(ReadLogBytes(path), prefix);
  }
  fesa::NewtonIterationLogWriter unopened;
  ExpectLogOutputFailure(unopened.Write(CompleteDynamicRecord()));
}

}  // namespace