#include "eigen_reference_comparison.h"

#include <hdf5.h>

#include <array>
#include <charconv>
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <filesystem>
#include <fstream>
#include <limits>
#include <map>
#include <regex>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

#include "fesa/io/abaqus/domain_mapper.h"
#include "fesa/io/abaqus/input_reader.h"

#include "mitc4_drilling_reader.h"

namespace fesa::test {
namespace {

constexpr char kModesPath[] = "/steps/Step-1/eigen/modes";

class ComparisonFailure final : public std::runtime_error {
 public:
  ComparisonFailure(std::string code, std::string message)
      : std::runtime_error{std::move(message)}, code_{std::move(code)} {}

  const std::string& Code() const noexcept { return code_; }

 private:
  std::string code_;
};

[[noreturn]] void Fail(const std::string& code, const std::string& message) {
  throw ComparisonFailure{code, message};
}

Status FailureStatus(const EigenReferenceCase& reference_case,
                     const std::string& code, const std::string& message) {
  return Status::Failure(FailureCategory::kModel, {{Severity::kError,
                                                    code,
                                                    {},
                                                    "FREQUENCY",
                                                    reference_case.case_id,
                                                    message}});
}

class Hdf5Handle {
 public:
  using Closer = herr_t (*)(hid_t);

  Hdf5Handle() = default;
  Hdf5Handle(hid_t value, Closer closer) : value_{value}, closer_{closer} {}
  Hdf5Handle(const Hdf5Handle&) = delete;
  Hdf5Handle& operator=(const Hdf5Handle&) = delete;
  Hdf5Handle(Hdf5Handle&& other) noexcept
      : value_{other.value_}, closer_{other.closer_} {
    other.value_ = -1;
  }
  ~Hdf5Handle() {
    if (value_ >= 0 && closer_ != nullptr) {
      (void)closer_(value_);
    }
  }

  hid_t Get() const noexcept { return value_; }

 private:
  hid_t value_{-1};
  Closer closer_{nullptr};
};

hid_t RequireId(hid_t value, const char* message) {
  if (value < 0) {
    Fail("invalid-eigen-hdf5-schema", message);
  }
  return value;
}

void RequireHdf(herr_t value, const char* message) {
  if (value < 0) {
    Fail("invalid-eigen-hdf5-schema", message);
  }
}

std::string ReadUtf8Attribute(hid_t object, const char* name) {
  Hdf5Handle attribute{RequireId(H5Aopen(object, name, H5P_DEFAULT),
                                 "A required HDF5 attribute is missing."),
                       H5Aclose};
  Hdf5Handle type{RequireId(H5Aget_type(attribute.Get()),
                            "Unable to inspect an HDF5 attribute type."),
                  H5Tclose};
  if (H5Tget_class(type.Get()) != H5T_STRING ||
      H5Tget_cset(type.Get()) != H5T_CSET_UTF8 ||
      H5Tis_variable_str(type.Get()) <= 0) {
    Fail("invalid-eigen-hdf5-schema",
         "A required HDF5 string attribute has the wrong type.");
  }
  Hdf5Handle space{RequireId(H5Aget_space(attribute.Get()),
                             "Unable to inspect an HDF5 attribute shape."),
                   H5Sclose};
  if (H5Sget_simple_extent_ndims(space.Get()) != 0) {
    Fail("invalid-eigen-hdf5-schema",
         "A required HDF5 string attribute is not scalar.");
  }
  char* value = nullptr;
  RequireHdf(H5Aread(attribute.Get(), type.Get(), &value),
             "Unable to read an HDF5 string attribute.");
  if (value == nullptr) {
    Fail("invalid-eigen-hdf5-schema", "An HDF5 string attribute is null.");
  }
  const std::string result{value};
  RequireHdf(H5free_memory(value), "Unable to release HDF5 string memory.");
  return result;
}

std::uint64_t ReadUint64Attribute(hid_t object, const char* name) {
  Hdf5Handle attribute{RequireId(H5Aopen(object, name, H5P_DEFAULT),
                                 "A required HDF5 attribute is missing."),
                       H5Aclose};
  Hdf5Handle type{RequireId(H5Aget_type(attribute.Get()),
                            "Unable to inspect an HDF5 attribute type."),
                  H5Tclose};
  if (H5Tget_class(type.Get()) != H5T_INTEGER ||
      H5Tget_size(type.Get()) != sizeof(std::uint64_t) ||
      H5Tget_sign(type.Get()) != H5T_SGN_NONE) {
    Fail("invalid-eigen-hdf5-schema",
         "A required HDF5 integer attribute has the wrong type.");
  }
  Hdf5Handle space{RequireId(H5Aget_space(attribute.Get()),
                             "Unable to inspect an HDF5 attribute shape."),
                   H5Sclose};
  if (H5Sget_simple_extent_ndims(space.Get()) != 0) {
    Fail("invalid-eigen-hdf5-schema",
         "A required HDF5 integer attribute is not scalar.");
  }
  std::uint64_t value = 0U;
  RequireHdf(H5Aread(attribute.Get(), H5T_NATIVE_UINT64, &value),
             "Unable to read an HDF5 integer attribute.");
  return value;
}

struct Hdf5Mode {
  std::uint64_t mode_id;
  double eigenvalue;
  std::uint8_t classification;
  std::uint64_t cluster_id;
};

std::vector<Hdf5Mode> ReadModes(hid_t file, std::uint64_t expected_count,
                                const std::string& source_step_name) {
  Hdf5Handle dataset{RequireId(H5Dopen2(file, kModesPath, H5P_DEFAULT),
                               "The eigen modes dataset is missing."),
                     H5Dclose};
  Hdf5Handle space{RequireId(H5Dget_space(dataset.Get()),
                             "Unable to inspect the modes dataspace."),
                   H5Sclose};
  if (H5Sget_simple_extent_ndims(space.Get()) != 1) {
    Fail("invalid-eigen-hdf5-schema", "The modes dataset must be rank one.");
  }
  hsize_t count = 0U;
  RequireHdf(H5Sget_simple_extent_dims(space.Get(), &count, nullptr),
             "Unable to inspect the modes dataset extent.");
  if (count != expected_count) {
    Fail("eigen-mode-identity-mismatch",
         "The modes dataset count does not equal requested mode count.");
  }
  Hdf5Handle type{RequireId(H5Dget_type(dataset.Get()),
                            "Unable to inspect the modes dataset type."),
                  H5Tclose};
  if (H5Tget_class(type.Get()) != H5T_COMPOUND ||
      H5Tget_nmembers(type.Get()) != 4 ||
      H5Tget_member_index(type.Get(), "mode_id") < 0 ||
      H5Tget_member_index(type.Get(), "eigenvalue") < 0 ||
      H5Tget_member_index(type.Get(), "classification") < 0 ||
      H5Tget_member_index(type.Get(), "cluster_id") < 0) {
    Fail("invalid-eigen-hdf5-schema", "The modes compound schema is invalid.");
  }
  const std::array<hid_t, 4> expected_types{H5T_STD_U64LE, H5T_IEEE_F64LE,
                                            H5T_STD_U8LE, H5T_STD_U64LE};
  const std::array<const char*, 4> names{"mode_id", "eigenvalue",
                                         "classification", "cluster_id"};
  for (std::size_t index = 0U; index < names.size(); ++index) {
    Hdf5Handle member{
        RequireId(H5Tget_member_type(type.Get(), static_cast<unsigned>(index)),
                  "Unable to inspect a modes compound member."),
        H5Tclose};
    char* raw_name =
        H5Tget_member_name(type.Get(), static_cast<unsigned>(index));
    if (raw_name == nullptr) {
      Fail("invalid-eigen-hdf5-schema",
           "Unable to inspect a modes member name.");
    }
    const std::string member_name{raw_name};
    RequireHdf(H5free_memory(raw_name),
               "Unable to release a modes member name.");
    if (member_name != names[index] ||
        H5Tequal(member.Get(), expected_types[index]) <= 0) {
      Fail("invalid-eigen-hdf5-schema",
           "The modes compound member type or order is invalid.");
    }
  }
  Hdf5Handle memory_type{RequireId(H5Tcreate(H5T_COMPOUND, sizeof(Hdf5Mode)),
                                   "Unable to create a modes memory type."),
                         H5Tclose};
  RequireHdf(H5Tinsert(memory_type.Get(), "mode_id", HOFFSET(Hdf5Mode, mode_id),
                       H5T_NATIVE_UINT64),
             "Unable to define the mode identifier field.");
  RequireHdf(H5Tinsert(memory_type.Get(), "eigenvalue",
                       HOFFSET(Hdf5Mode, eigenvalue), H5T_NATIVE_DOUBLE),
             "Unable to define the eigenvalue field.");
  RequireHdf(H5Tinsert(memory_type.Get(), "classification",
                       HOFFSET(Hdf5Mode, classification), H5T_NATIVE_UINT8),
             "Unable to define the classification field.");
  RequireHdf(H5Tinsert(memory_type.Get(), "cluster_id",
                       HOFFSET(Hdf5Mode, cluster_id), H5T_NATIVE_UINT64),
             "Unable to define the cluster field.");
  std::vector<Hdf5Mode> modes(static_cast<std::size_t>(count));
  RequireHdf(H5Dread(dataset.Get(), memory_type.Get(), H5S_ALL, H5S_ALL,
                     H5P_DEFAULT, modes.data()),
             "Unable to read the modes dataset.");
  for (std::size_t index = 0U; index < modes.size(); ++index) {
    if (modes[index].mode_id != index + 1U ||
        modes[index].mode_id > static_cast<std::uint64_t>((
                                   std::numeric_limits<std::int64_t>::max)()) ||
        !std::isfinite(modes[index].eigenvalue)) {
      Fail("eigen-mode-identity-mismatch",
           "Mode IDs must be ordered one through requested mode count.");
    }
  }
  if (ReadUtf8Attribute(dataset.Get(), "quantity") != "eigenvalue" ||
      ReadUint64Attribute(dataset.Get(), "eigen_schema_version") != 1U ||
      ReadUtf8Attribute(dataset.Get(), "source_step_name") !=
          source_step_name ||
      ReadUtf8Attribute(dataset.Get(), "domain") != "mode" ||
      ReadUtf8Attribute(dataset.Get(), "component_names") != "Value" ||
      ReadUtf8Attribute(dataset.Get(), "component_unit_dimensions") !=
          "time^-2" ||
      ReadUtf8Attribute(dataset.Get(), "coordinate_system") != "scalar" ||
      ReadUtf8Attribute(dataset.Get(), "location") != "modal-frame") {
    Fail("invalid-eigen-hdf5-schema", "Modes dataset metadata is invalid.");
  }
  return modes;
}

double ParseFiniteNumber(const std::string& token) {
  static const std::regex number{
      R"([+-]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[Ee][+-]?[0-9]+)?)"};
  if (!std::regex_match(token, number)) {
    Fail("invalid-eigen-reference-text", "A TXT numeric token is malformed.");
  }
  double value = 0.0;
  const char* first = token.data() + (token.front() == '+' ? 1U : 0U);
  const auto conversion =
      std::from_chars(first, token.data() + token.size(), value);
  if (conversion.ec != std::errc{} ||
      conversion.ptr != token.data() + token.size() || !std::isfinite(value)) {
    Fail("invalid-eigen-reference-text", "A TXT Value is nonfinite.");
  }
  return value;
}

void RequireNumberSyntax(const std::string& token) {
  static const std::regex number{
      R"([+-]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[Ee][+-]?[0-9]+)?)"};
  if (!std::regex_match(token, number)) {
    Fail("invalid-eigen-reference-text", "A TXT numeric token is malformed.");
  }
}

std::map<std::uint64_t, double> ReadReferenceText(
    const std::filesystem::path& path) {
  std::ifstream stream{path, std::ios::binary};
  if (!stream) {
    Fail("needs-reference-artifacts",
         "The eigenvalue TXT artifact is missing.");
  }
  const std::regex row{
      R"(^[ \t]*Frame:[ \t]+Mode[ \t]+([0-9]+):[ \t]+Value[ \t]*=[ \t]*([+-]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[Ee][+-]?[0-9]+)?)[ \t]+Freq[ \t]*=[ \t]*([+-]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[Ee][+-]?[0-9]+)?)[ \t]+\(cycles/time\)[ \t]*$)"};
  std::map<std::uint64_t, double> rows;
  std::string line;
  while (std::getline(stream, line)) {
    if (!line.empty() && line.back() == '\r') {
      line.pop_back();
    }
    if (line.find_first_not_of(" \t") == std::string::npos) {
      continue;
    }
    std::smatch match;
    if (!std::regex_match(line, match, row)) {
      Fail("invalid-eigen-reference-text",
           "A TXT row is not exact Frame/Mode syntax.");
    }
    std::uint64_t mode_id = 0U;
    const std::string mode_text = match[1].str();
    const auto parsed = std::from_chars(
        mode_text.data(), mode_text.data() + mode_text.size(), mode_id);
    if (parsed.ec != std::errc{} ||
        parsed.ptr != mode_text.data() + mode_text.size() || mode_id == 0U ||
        mode_id > static_cast<std::uint64_t>(
                      (std::numeric_limits<std::int64_t>::max)()) ||
        !rows.emplace(mode_id, ParseFiniteNumber(match[2].str())).second) {
      Fail("eigen-mode-identity-mismatch",
           "TXT mode IDs must be unique positive integers.");
    }
    RequireNumberSyntax(match[3].str());
  }
  if (rows.empty()) {
    Fail("invalid-eigen-reference-text",
         "The eigenvalue TXT artifact is empty.");
  }
  return rows;
}

}  // namespace

Result<EigenReferenceComparisonReport> EigenReferenceComparison::Compare(
    const EigenReferenceCase& reference_case) {
  try {
    auto parsed = AbaqusInputReader{}.Read(reference_case.input_path);
    if (!parsed.HasValue()) {
      Fail("needs-reference-artifacts", "The eigen input cannot be parsed.");
    }
    auto domain = AbaqusDomainMapper{}.Map(parsed.Value());
    if (!domain.HasValue() || domain.Value().Frequency() == nullptr) {
      Fail("needs-reference-artifacts",
           "The input has no sole frequency step.");
    }
    const FrequencyStepDefinition& frequency = *domain.Value().Frequency();
    const std::uint64_t requested =
        static_cast<std::uint64_t>(frequency.requested_mode_count);
    const auto reference =
        ReadReferenceText(reference_case.eigenvalues_text_path);
    Hdf5Handle file{
        RequireId(H5Fopen(reference_case.results_hdf5_path.string().c_str(),
                          H5F_ACC_RDONLY, H5P_DEFAULT),
                  "The eigen HDF5 result is missing."),
        H5Fclose};
    Hdf5Handle metadata{
        RequireId(H5Gopen2(file.Get(), "/metadata", H5P_DEFAULT),
                  "The metadata group is missing."),
        H5Gclose};
    if (ReadUint64Attribute(metadata.Get(), "schema_version") != 0U ||
        ReadUint64Attribute(metadata.Get(), "eigen_schema_version") != 1U ||
        ReadUtf8Attribute(metadata.Get(), "feature_id") !=
            "mitc4-shell-feast-eigen2" ||
        ReadUtf8Attribute(metadata.Get(), "analysis_procedure") !=
            "linear-frequency" ||
        ReadUtf8Attribute(metadata.Get(), "mass_variant") != "derived-lumped" ||
        ReadUtf8Attribute(metadata.Get(), "normalization") != "mass" ||
        ReadUtf8Attribute(metadata.Get(), "eigensolver_backend") !=
            "MKL FEAST") {
      Fail("invalid-eigen-hdf5-schema",
           "The eigen result discriminator is invalid.");
    }
    const std::string expected_identity =
        "path=" + parsed.Value().source_path.generic_string() +
        ";content_identity=" + parsed.Value().source_content_identity;
    if (ReadUtf8Attribute(metadata.Get(), "source_input_identity") !=
        expected_identity) {
      Fail("eigen-source-identity-mismatch",
           "The HDF5 source input identity differs from the executed input.");
    }
    Hdf5Handle step{
        RequireId(H5Gopen2(file.Get(), "/steps/Step-1", H5P_DEFAULT),
                  "The eigen storage step is missing."),
        H5Gclose};
    if (ReadUtf8Attribute(step.Get(), "source_step_name") !=
            frequency.source_step_name_raw ||
        ReadUint64Attribute(step.Get(), "requested_mode_count") != requested ||
        ReadUint64Attribute(step.Get(), "returned_mode_count") != requested) {
      Fail("eigen-mode-identity-mismatch",
           "The HDF5 source step or requested mode count is inconsistent.");
    }
    const auto modes =
        ReadModes(file.Get(), requested, frequency.source_step_name_raw);
    if (reference.size() != modes.size()) {
      Fail("eigen-mode-identity-mismatch",
           "TXT and HDF5 mode inventories have different sizes.");
    }

    EigenReferenceComparisonReport report{};
    report.drilling_diagnostics = ReadMitc4DrillingReport(file.Get());
    if (report.drilling_diagnostics && !report.drilling_diagnostics->frames.empty())
      Fail("schema-mismatch", "Eigen drilling diagnostics must have no equilibrium frames.");
    report.case_id = reference_case.case_id;
    report.source_step_name = frequency.source_step_name_raw;
    report.requested_mode_count = requested;
    report.policy_id =
        ReferenceTolerancePolicy::kMitc4EigenFirstImplementationPolicyId;
    report.relative_rms_tolerance = ReferenceTolerancePolicy::kRelativeTolerance;
    std::vector<ReferenceToleranceFamily> families;
    families.reserve(modes.size());
    for (const auto& mode : modes) {
      const auto row = reference.find(mode.mode_id);
      if (row == reference.end()) {
        Fail("eigen-mode-identity-mismatch",
             "A HDF5 mode is missing from TXT.");
      }
      families.push_back({"case=" + reference_case.case_id +
                              ";source_step=" + frequency.source_step_name_raw +
                              ";mode_id=" + std::to_string(mode.mode_id) +
                              ";component=Value",
                          {"Value"},
                          true,
                          {{mode.eigenvalue, row->second}}});
    }
    const auto evaluation =
        ReferenceTolerancePolicy::EvaluateMitc4EigenFirstImplementation(families);
    if (!evaluation.valid || evaluation.families.size() != families.size()) {
      Fail("nonfinite-comparison-value",
           "Tolerance evaluation rejected modal values.");
    }
    report.families = evaluation.families;
    report.passed = evaluation.passed;
    for (std::size_t index = 0U; index < modes.size(); ++index) {
      const auto& policy = report.families[index];
      report.rows.push_back(
          {frequency.source_step_name_raw, modes[index].mode_id, "Value",
           modes[index].eigenvalue, reference.at(modes[index].mode_id),
           policy.rows[0U]});
    }
    return Result<EigenReferenceComparisonReport>::Success(std::move(report));
  } catch (const ComparisonFailure& exception) {
    return Result<EigenReferenceComparisonReport>::Failure(
        FailureStatus(reference_case, exception.Code(), exception.what()));
  } catch (const std::exception& exception) {
    return Result<EigenReferenceComparisonReport>::Failure(
        FailureStatus(reference_case, "eigen-reference-comparison-failure",
                      exception.what()));
  }
}

}  // namespace fesa::test