#include "fesa/fesa.hpp"

#include <cmath>
#include <functional>
#include <iostream>
#include <type_traits>
#include <stdexcept>
#include <string>
#include <vector>

static_assert(std::is_same_v<fesa::Real, double>, "Real must remain double");
static_assert(std::is_same_v<fesa::GlobalId, std::int64_t>, "GlobalId must remain int64");
static_assert(std::is_same_v<fesa::LocalIndex, std::int64_t>, "LocalIndex must remain int64");
static_assert(std::is_same_v<fesa::EquationId, std::int64_t>, "EquationId must remain int64");
static_assert(std::is_same_v<fesa::SparseIndex, std::int64_t>, "SparseIndex must remain int64");

namespace {

using TestFn = std::function<void()>;

struct TestCase {
  std::string name;
  TestFn fn;
};

std::vector<TestCase>& registry() {
  static std::vector<TestCase> tests;
  return tests;
}

struct RegisterTest {
  RegisterTest(std::string name, TestFn fn) {
    registry().push_back({std::move(name), std::move(fn)});
  }
};

#define FESA_TEST(name)                                      \
  void name();                                               \
  RegisterTest register_##name(#name, name);                 \
  void name()

#define FESA_CHECK(expr)                                                                 \
  do {                                                                                   \
    if (!(expr)) {                                                                       \
      throw std::runtime_error(std::string("check failed: ") + #expr);                  \
    }                                                                                    \
  } while (false)

#define FESA_CHECK_NEAR(actual, expected, tol)                                            \
  do {                                                                                   \
    const auto actual_value = (actual);                                                   \
    const auto expected_value = (expected);                                               \
    if (std::fabs(actual_value - expected_value) > (tol)) {                              \
      throw std::runtime_error(std::string("near check failed: ") + #actual);           \
    }                                                                                    \
  } while (false)

std::string sourceRoot() {
#ifdef FESA_SOURCE_DIR
  return FESA_SOURCE_DIR;
#else
  return ".";
#endif
}

std::string phase1Input() {
  return R"inp(
*Node
1, 0, 0, 0
2, 1, 0, 0
3, 1, 1, 0
4, 0, 1, 0
*Element, type=S4, elset=EALL
1, 1, 2, 3, 4
*Nset, nset=LEFT
1, 4
*Nset, nset=RIGHT
2, 3
*Elset, elset=EALL
1
*Material, name=STEEL
*Elastic
1000.0, 0.3
*Shell Section, elset=EALL, material=STEEL
0.1
*Boundary
LEFT, 1, 6, 0
RIGHT, 1, 2, 0
RIGHT, 4, 6, 0
*Cload
2, 3, -1
3, 3, -1
*Step, name=Step-1
*Static
*End Step
)inp";
}

fesa::Domain parsedPhase1Domain() {
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(phase1Input());
  FESA_CHECK(parsed.ok());
  auto diagnostics = fesa::validateDomain(parsed.domain);
  FESA_CHECK(!fesa::hasError(diagnostics));
  return parsed.domain;
}

const fesa::Diagnostic* findDiagnostic(const std::vector<fesa::Diagnostic>& diagnostics, const std::string& code) {
  for (const auto& diagnostic : diagnostics) {
    if (diagnostic.code == code) {
      return &diagnostic;
    }
  }
  return nullptr;
}

std::size_t diagnosticCount(const std::vector<fesa::Diagnostic>& diagnostics, const std::string& code) {
  std::size_t count = 0;
  for (const auto& diagnostic : diagnostics) {
    if (diagnostic.code == code) {
      ++count;
    }
  }
  return count;
}

fesa::Domain singleElementValidationDomain() {
  fesa::Domain domain;
  domain.nodes[1] = {1, {0, 0, 0}};
  domain.nodes[2] = {2, {1, 0, 0}};
  domain.nodes[3] = {3, {1, 1, 0}};
  domain.nodes[4] = {4, {0, 1, 0}};
  domain.elements[1] = {1, fesa::ElementType::MITC4, {1, 2, 3, 4}, "EALL"};
  domain.element_sets["eall"] = {"EALL", {1}};
  domain.node_sets["all_nodes"] = {"ALL_NODES", {1, 2, 3, 4}};
  domain.materials["mat"] = {"MAT", 1000.0, 0.3};
  domain.shell_sections.push_back({"EALL", "MAT", 0.1});
  domain.loads.push_back({"2", 3, -1.0});
  return domain;
}

fesa::Domain noncontiguousDofDomain() {
  fesa::Domain domain;
  domain.nodes[30] = {30, {1, 1, 0}};
  domain.nodes[10] = {10, {0, 0, 0}};
  domain.nodes[40] = {40, {0, 1, 0}};
  domain.nodes[20] = {20, {1, 0, 0}};
  domain.elements[5] = {5, fesa::ElementType::MITC4, {10, 20, 30, 40}, "EALL"};
  domain.element_sets["eall"] = {"EALL", {5}};
  domain.node_sets["clamped"] = {"CLAMPED", {20}};
  domain.materials["mat"] = {"MAT", 1000.0, 0.3};
  domain.shell_sections.push_back({"EALL", "MAT", 0.1});
  domain.boundary_conditions.push_back({"CLAMPED", 1, 6, 0.0});
  domain.boundary_conditions.push_back({"30", 1, 2, 0.0});
  return domain;
}

}  // namespace

FESA_TEST(core_types_and_dof_mapping_are_stable) {
  FESA_CHECK(sizeof(fesa::Real) == 8);
  FESA_CHECK(sizeof(fesa::GlobalId) == 8);
  FESA_CHECK(sizeof(fesa::LocalIndex) == 8);
  FESA_CHECK(sizeof(fesa::EquationId) == 8);
  FESA_CHECK(sizeof(fesa::SparseIndex) == 8);
  FESA_CHECK(std::numeric_limits<fesa::GlobalId>::is_signed);
  FESA_CHECK(std::numeric_limits<fesa::LocalIndex>::is_signed);
  FESA_CHECK(std::numeric_limits<fesa::EquationId>::is_signed);
  FESA_CHECK(std::numeric_limits<fesa::SparseIndex>::is_signed);

  const auto dofs = fesa::allDofs();
  FESA_CHECK(dofs.size() == 6);
  for (std::size_t i = 0; i < dofs.size(); ++i) {
    const int abaqus_number = static_cast<int>(i + 1);
    FESA_CHECK(fesa::abaqusDofNumber(dofs[i]) == abaqus_number);
    FESA_CHECK(fesa::dofFromAbaqus(abaqus_number).value() == dofs[i]);
    FESA_CHECK(std::string(fesa::dofLabel(dofs[i])) == fesa::displacementComponentLabels()[i]);
  }
  FESA_CHECK(!fesa::dofFromAbaqus(0).has_value());
  FESA_CHECK(!fesa::dofFromAbaqus(7).has_value());
}

FESA_TEST(parser_accepts_phase1_subset) {
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(phase1Input());
  FESA_CHECK(parsed.ok());
  FESA_CHECK(parsed.domain.nodes.size() == 4);
  FESA_CHECK(parsed.domain.elements.size() == 1);
  FESA_CHECK(parsed.domain.node_sets.at("left").node_ids.size() == 2);
  FESA_CHECK(parsed.domain.element_sets.at("eall").element_ids.size() == 1);
  FESA_CHECK(parsed.domain.materials.at("steel").elastic_modulus == 1000.0);
  FESA_CHECK(parsed.domain.shell_sections.front().thickness == 0.1);
  FESA_CHECK(parsed.domain.boundary_conditions.size() == 3);
  FESA_CHECK(parsed.domain.loads.size() == 2);
}

FESA_TEST(parser_accepts_repeated_and_generated_sets) {
  const std::string text = R"inp(
*Node
1, 0, 0, 0
2, 1, 0, 0
3, 1, 1, 0
4, 0, 1, 0
*Element, type=S4, elset=EALL
1, 1, 2, 3, 4
*Nset, nset=FIXED
1, 2, 2
3
*Nset, nset=FIXED, generate
3, 4, 1
*Nset, nset=LOADS, generate
2, 4, 2
*Elset, elset=EALL
1, 1
*Elset, elset=CHECK, generate
1, 5, 2
*Material, name=MAT
*Elastic
2.0D5, 0.25
*Shell Section, elset=EALL, material=MAT
0.2
*Boundary
FIXED, 1, 6
*Cload
LOADS, 3, -2.5
*Step, name=Step-A, nlgeom=NO
*Static
*End Step
)inp";
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(text);
  FESA_CHECK(parsed.ok());
  FESA_CHECK(parsed.domain.node_sets.at("fixed").node_ids == std::vector<fesa::GlobalId>({1, 2, 3, 4}));
  FESA_CHECK(parsed.domain.node_sets.at("loads").node_ids == std::vector<fesa::GlobalId>({2, 4}));
  FESA_CHECK(parsed.domain.element_sets.at("eall").element_ids == std::vector<fesa::GlobalId>({1}));
  FESA_CHECK(parsed.domain.element_sets.at("check").element_ids == std::vector<fesa::GlobalId>({1, 3, 5}));
  FESA_CHECK(parsed.domain.materials.at("mat").elastic_modulus == 2.0e5);
  FESA_CHECK(parsed.domain.steps.front().name == "Step-A");
}

FESA_TEST(parser_accepts_keyword_line_continuation) {
  const std::string text = R"inp(
*Node
1, 0, 0, 0
2, 1, 0, 0
3, 1, 1, 0
4, 0, 1, 0
*Element,
 type=S4, elset=EALL
1, 1, 2, 3, 4
*Nset,
 nset=FIXED, generate
1, 4, 3
*Elset,
 elset=EALL
1
*Material,
 name=MAT
*Elastic
2.0e5, 0.25
*Shell Section,
 elset=EALL, material=MAT
0.2
*Boundary
FIXED, 1, 6
*Cload
2, 3, -1.0
*Step,
 name=Step-1
*Static
*End Step
)inp";
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(text);
  FESA_CHECK(parsed.ok());
  FESA_CHECK(parsed.domain.elements.at(1).source_elset == "EALL");
  FESA_CHECK(parsed.domain.node_sets.at("fixed").node_ids == std::vector<fesa::GlobalId>({1, 4}));
  FESA_CHECK(parsed.domain.materials.count("mat") == 1);
  FESA_CHECK(parsed.domain.shell_sections.front().material == "MAT");
}

FESA_TEST(parser_rejects_unsupported_features) {
  const std::string text = R"inp(
*Part, name=P1
*Assembly, name=A1
*Instance, name=I1, part=P1
*Include, input=other.inp
*Node
1, 0, 0, 0
*Element, type=S4R
1, 1, 2, 3, 4
*Density
7850
*Step, nlgeom=YES
*End Step
)inp";
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(text);
  FESA_CHECK(!parsed.ok());
  FESA_CHECK(diagnosticCount(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-KEYWORD") >= 4);
  FESA_CHECK(fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-KEYWORD"));
  FESA_CHECK(fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-ELEMENT"));
  FESA_CHECK(fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-NLGEOM"));
}

FESA_TEST(parser_rejects_unsupported_keyword_parameters_and_modes) {
  const std::string text = R"inp(
*Node, input=nodes.csv
1, 0, 0, 0
2, 1, 0, 0
3, 1, 1, 0
4, 0, 1, 0
*Element, type=S4, elset=EALL, orientation=OR1
1, 1, 2, 3, 4
*Nset, nset=FIXED, unsorted
1, 4
*Material, name=MAT, description=bad
*Elastic, type=ENGINEERING CONSTANTS
2.0e5, 0.25
*Shell Section, elset=EALL, material=MAT, offset=SPOS
0.2, 5
*Boundary, op=NEW
FIXED, 1, 6
*Cload, amplitude=A1
2, 3, -1.0
*Step, name=Step-1, inc=100
*Static, stabilize
*End Step
)inp";
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(text, "unsupported_modes.inp");
  FESA_CHECK(!parsed.ok());
  FESA_CHECK(diagnosticCount(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-PARAMETER") >= 8);
  FESA_CHECK(fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-SHELL-SECTION-UNSUPPORTED"));
}

FESA_TEST(parser_diagnostics_include_file_line_and_keyword) {
  const std::string text = R"inp(
*Node
1, bad, 0, 0
*Boundary
FIXED, 7, 7
)inp";
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseString(text, "malformed.inp");
  FESA_CHECK(!parsed.ok());

  const fesa::Diagnostic* node = findDiagnostic(parsed.diagnostics, "FESA-PARSE-NODE-NUMERIC");
  FESA_CHECK(node != nullptr);
  FESA_CHECK(node->source.file == "malformed.inp");
  FESA_CHECK(node->source.line == 3);
  FESA_CHECK(node->source.keyword == "node");

  const fesa::Diagnostic* boundary = findDiagnostic(parsed.diagnostics, "FESA-PARSE-BOUNDARY-DOF");
  FESA_CHECK(boundary != nullptr);
  FESA_CHECK(boundary->source.file == "malformed.inp");
  FESA_CHECK(boundary->source.line == 5);
  FESA_CHECK(boundary->source.keyword == "boundary");
}

FESA_TEST(quad01_reference_input_remains_unsupported) {
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseFile(sourceRoot() + "/references/quad_01.inp");
  FESA_CHECK(!parsed.ok());
  FESA_CHECK(fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-KEYWORD") ||
             fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-ELEMENT"));
}

FESA_TEST(quad02_original_reference_input_remains_unsupported) {
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseFile(sourceRoot() + "/references/quad_02.inp");
  FESA_CHECK(!parsed.ok());
  FESA_CHECK(fesa::containsDiagnostic(parsed.diagnostics, "FESA-PARSE-UNSUPPORTED-KEYWORD"));
}

FESA_TEST(quad02_phase1_normalized_input_uses_supported_subset) {
  fesa::AbaqusInputParser parser;
  auto parsed = parser.parseFile(sourceRoot() + "/references/quad_02_phase1.inp");
  FESA_CHECK(parsed.ok());
  FESA_CHECK(parsed.domain.nodes.size() == 121);
  FESA_CHECK(parsed.domain.elements.size() == 100);
  FESA_CHECK(parsed.domain.node_sets.at("fixed_boundary").node_ids.size() == 40);
  FESA_CHECK(parsed.domain.node_sets.at("load_node").node_ids.size() == 1);
  FESA_CHECK(parsed.domain.element_sets.at("all_elements").element_ids.size() == 100);
  FESA_CHECK(parsed.domain.materials.at("material_1").elastic_modulus == 7.0e10);
  FESA_CHECK(parsed.domain.shell_sections.front().thickness == 1.0);
}

FESA_TEST(domain_validation_reports_missing_property_and_targets) {
  fesa::Domain domain;
  domain.nodes[1] = {1, {0, 0, 0}};
  domain.nodes[2] = {2, {1, 0, 0}};
  domain.nodes[3] = {3, {1, 1, 0}};
  domain.nodes[4] = {4, {0, 1, 0}};
  domain.elements[1] = {1, fesa::ElementType::MITC4, {1, 2, 3, 99}, ""};
  domain.shell_sections.push_back({"MISSING_ELSET", "MISSING_MAT", 0.1});
  domain.loads.push_back({"MISSING", 3, 1.0});
  auto diagnostics = fesa::validateDomain(domain);
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-ELEMENT-MISSING-NODE"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-PROPERTY"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-ELSET"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-MATERIAL"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-NSET"));
  for (const auto& diagnostic : diagnostics) {
    FESA_CHECK(!diagnostic.code.empty());
    FESA_CHECK(!diagnostic.message.empty());
    FESA_CHECK(!diagnostic.source.keyword.empty());
  }
}

FESA_TEST(domain_validation_reports_missing_sets_and_set_members) {
  auto domain = singleElementValidationDomain();
  domain.shell_sections.clear();
  domain.shell_sections.push_back({"MISSING_ELSET", "MISSING_MAT", 0.1});
  domain.node_sets["bad_nodes"] = {"BAD_NODES", {1, 99}};
  domain.element_sets["bad_elements"] = {"BAD_ELEMENTS", {1, 77}};
  domain.boundary_conditions.push_back({"MISSING_BOUNDARY_SET", 1, 6, 0.0});
  domain.boundary_conditions.push_back({"BAD_NODES", 1, 1, 0.0});
  domain.loads.push_back({"MISSING_LOAD_SET", 3, 1.0});
  domain.loads.push_back({"BAD_NODES", 3, 1.0});

  auto diagnostics = fesa::validateDomain(domain);
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-ELSET"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-MATERIAL"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-NSET"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-NSET-MISSING-NODE"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-ELSET-MISSING-ELEMENT"));

  const auto* missing_set = findDiagnostic(diagnostics, "FESA-VALIDATION-MISSING-NSET");
  FESA_CHECK(missing_set != nullptr);
  FESA_CHECK(missing_set->message.find("MISSING_BOUNDARY_SET") != std::string::npos ||
             missing_set->message.find("MISSING_LOAD_SET") != std::string::npos);

  const auto* missing_node = findDiagnostic(diagnostics, "FESA-VALIDATION-NSET-MISSING-NODE");
  FESA_CHECK(missing_node != nullptr);
  FESA_CHECK(missing_node->message.find("BAD_NODES") != std::string::npos);
  FESA_CHECK(missing_node->message.find("99") != std::string::npos);
}

FESA_TEST(domain_validation_reports_nonpositive_thickness_and_invalid_dofs) {
  auto domain = singleElementValidationDomain();
  domain.shell_sections.front().thickness = 0.0;
  domain.boundary_conditions.push_back({"ALL_NODES", 0, 1, 0.0});
  domain.loads.push_back({"2", 7, 1.0});

  auto diagnostics = fesa::validateDomain(domain);
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-NONPOSITIVE-THICKNESS"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-BOUNDARY-DOF"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-VALIDATION-CLOAD-DOF"));

  const auto* thickness = findDiagnostic(diagnostics, "FESA-VALIDATION-NONPOSITIVE-THICKNESS");
  FESA_CHECK(thickness != nullptr);
  FESA_CHECK(thickness->message.find("EALL") != std::string::npos);

  const auto* load_dof = findDiagnostic(diagnostics, "FESA-VALIDATION-CLOAD-DOF");
  FESA_CHECK(load_dof != nullptr);
  FESA_CHECK(load_dof->message.find("DOF 7") != std::string::npos);
}

FESA_TEST(domain_validation_reports_no_active_elements_and_missing_load) {
  fesa::Domain domain;
  domain.nodes[1] = {1, {0, 0, 0}};
  auto diagnostics = fesa::validateDomain(domain);
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-SINGULAR-NO-ACTIVE-ELEMENTS"));
  FESA_CHECK(fesa::containsDiagnostic(diagnostics, "FESA-SINGULAR-NO-NONZERO-LOAD"));
  for (const auto& diagnostic : diagnostics) {
    FESA_CHECK(diagnostic.code.find("MESH") == std::string::npos);
  }
}

FESA_TEST(domain_validation_reports_no_free_dofs) {
  auto domain = singleElementValidationDomain();
  domain.boundary_conditions.push_back({"ALL_NODES", 1, 6, 0.0});

  auto diagnostics = fesa::validateDomain(domain);
  const auto* no_free = findDiagnostic(diagnostics, "FESA-SINGULAR-NO-FREE-DOFS");
  FESA_CHECK(no_free != nullptr);
  FESA_CHECK(no_free->source.keyword == "dof");
  FESA_CHECK(no_free->message.find("No free DOFs") != std::string::npos);
}

FESA_TEST(domain_validation_reports_free_untouched_dofs_for_isolated_nodes) {
  auto domain = singleElementValidationDomain();
  domain.nodes[99] = {99, {10, 0, 0}};
  domain.boundary_conditions.push_back({"ALL_NODES", 1, 6, 0.0});

  auto diagnostics = fesa::validateDomain(domain);
  const auto* untouched = findDiagnostic(diagnostics, "FESA-SINGULAR-DOF-UNTOUCHED");
  FESA_CHECK(untouched != nullptr);
  FESA_CHECK(untouched->source.keyword == "dof");
  FESA_CHECK(untouched->message.find("Node 99") != std::string::npos);
  FESA_CHECK(untouched->message.find("UX") != std::string::npos);
}

FESA_TEST(domain_validation_reports_weak_drilling_dof_smoke) {
  auto domain = singleElementValidationDomain();
  domain.boundary_conditions.push_back({"ALL_NODES", 1, 5, 0.0});

  auto diagnostics = fesa::validateDomain(domain);
  const auto* weak_drilling = findDiagnostic(diagnostics, "FESA-SINGULAR-WEAK-DRILLING-DOF");
  FESA_CHECK(weak_drilling != nullptr);
  FESA_CHECK(weak_drilling->severity == fesa::Severity::Warning);
  FESA_CHECK(weak_drilling->source.keyword == "dof");
  FESA_CHECK(weak_drilling->message.find("RZ") != std::string::npos);
}

FESA_TEST(dof_manager_owns_equation_numbering_and_reconstruction) {
  auto domain = parsedPhase1Domain();
  fesa::DofManager dofs(domain);
  FESA_CHECK(dofs.fullDofCount() == 24);
  FESA_CHECK(dofs.freeDofCount() == 2);
  FESA_CHECK(dofs.isConstrained(1, fesa::Dof::UX));
  FESA_CHECK(dofs.equation(2, fesa::Dof::UZ) == 0);
  FESA_CHECK(dofs.equation(3, fesa::Dof::UZ) == 1);
  auto full = dofs.reconstructFullVector({-0.1, -0.2});
  FESA_CHECK_NEAR(full[static_cast<std::size_t>(dofs.fullIndex(2, fesa::Dof::UZ))], -0.1, 1.0e-15);
  FESA_CHECK_NEAR(full[static_cast<std::size_t>(dofs.fullIndex(1, fesa::Dof::UX))], 0.0, 1.0e-15);
}

FESA_TEST(dof_manager_preserves_global_order_for_noncontiguous_nodes) {
  auto domain = noncontiguousDofDomain();
  fesa::DofManager dofs(domain);

  FESA_CHECK(dofs.nodeIds() == std::vector<fesa::GlobalId>({10, 20, 30, 40}));
  FESA_CHECK(dofs.fullDofCount() == 24);
  for (std::size_t node_offset = 0; node_offset < dofs.nodeIds().size(); ++node_offset) {
    const fesa::GlobalId node_id = dofs.nodeIds()[node_offset];
    for (fesa::Dof dof : fesa::allDofs()) {
      const fesa::LocalIndex expected = static_cast<fesa::LocalIndex>(6 * node_offset + fesa::dofIndex(dof));
      FESA_CHECK(dofs.fullIndex(node_id, dof) == expected);
      const auto address = dofs.fullDof(expected);
      FESA_CHECK(address.node_id == node_id);
      FESA_CHECK(address.dof == dof);
    }
  }
}

FESA_TEST(dof_manager_partitions_constraints_and_equations_deterministically) {
  auto domain = noncontiguousDofDomain();
  fesa::DofManager dofs(domain);

  FESA_CHECK(dofs.constrainedDofCount() == 8);
  FESA_CHECK(dofs.freeDofCount() == 16);
  FESA_CHECK(dofs.constrainedFullIndices() == std::vector<fesa::LocalIndex>({6, 7, 8, 9, 10, 11, 12, 13}));
  FESA_CHECK(dofs.freeFullIndices() ==
             std::vector<fesa::LocalIndex>({0, 1, 2, 3, 4, 5, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23}));
  FESA_CHECK(dofs.equation(10, fesa::Dof::UX) == 0);
  FESA_CHECK(dofs.equation(20, fesa::Dof::RZ) == -1);
  FESA_CHECK(dofs.equation(30, fesa::Dof::UX) == -1);
  FESA_CHECK(dofs.equation(30, fesa::Dof::UZ) == 6);
  FESA_CHECK(dofs.equation(40, fesa::Dof::RZ) == 15);
}

FESA_TEST(dof_manager_reduces_and_reconstructs_full_vectors) {
  auto domain = noncontiguousDofDomain();
  fesa::DofManager dofs(domain);

  std::vector<fesa::Real> full(static_cast<std::size_t>(dofs.fullDofCount()), 0.0);
  for (std::size_t i = 0; i < full.size(); ++i) {
    full[i] = static_cast<fesa::Real>(100 + i);
  }

  auto reduced = dofs.reduceFullVector(full);
  FESA_CHECK(reduced.size() == static_cast<std::size_t>(dofs.freeDofCount()));
  FESA_CHECK_NEAR(reduced[0], full[0], 1.0e-15);
  FESA_CHECK_NEAR(reduced[6], full[14], 1.0e-15);
  FESA_CHECK_NEAR(reduced.back(), full[23], 1.0e-15);

  auto reconstructed = dofs.reconstructFullVector(reduced);
  for (fesa::LocalIndex full_index = 0; full_index < dofs.fullDofCount(); ++full_index) {
    const auto address = dofs.fullDof(full_index);
    if (dofs.isConstrained(address.node_id, address.dof)) {
      FESA_CHECK_NEAR(reconstructed[static_cast<std::size_t>(full_index)], 0.0, 1.0e-15);
    } else {
      FESA_CHECK_NEAR(reconstructed[static_cast<std::size_t>(full_index)], full[static_cast<std::size_t>(full_index)], 1.0e-15);
    }
  }
}

FESA_TEST(dof_manager_provides_element_sparse_connectivity_inputs) {
  auto domain = parsedPhase1Domain();
  fesa::DofManager dofs(domain);
  const auto& element = domain.elements.at(1);

  auto full_indices = dofs.elementFullDofIndices(element);
  auto equation_ids = dofs.elementEquationIds(element);

  for (fesa::LocalIndex i = 0; i < 24; ++i) {
    FESA_CHECK(full_indices[static_cast<std::size_t>(i)] == i);
  }
  for (fesa::LocalIndex i = 0; i < 6; ++i) {
    FESA_CHECK(equation_ids[static_cast<std::size_t>(i)] == -1);
    FESA_CHECK(equation_ids[static_cast<std::size_t>(18 + i)] == -1);
  }
  FESA_CHECK(equation_ids[static_cast<std::size_t>(6 + fesa::dofIndex(fesa::Dof::UZ))] == 0);
  FESA_CHECK(equation_ids[static_cast<std::size_t>(12 + fesa::dofIndex(fesa::Dof::UZ))] == 1);
  FESA_CHECK(equation_ids[static_cast<std::size_t>(6 + fesa::dofIndex(fesa::Dof::UX))] == -1);
}

FESA_TEST(full_vector_reaction_recovery_uses_full_system_quantities) {
  auto domain = noncontiguousDofDomain();
  fesa::DofManager dofs(domain);
  fesa::DenseMatrix k_full(dofs.fullDofCount(), dofs.fullDofCount());
  std::vector<fesa::Real> u_full(static_cast<std::size_t>(dofs.fullDofCount()), 0.0);
  std::vector<fesa::Real> f_full(static_cast<std::size_t>(dofs.fullDofCount()), 0.0);

  const fesa::LocalIndex support_ux = dofs.fullIndex(20, fesa::Dof::UX);
  const fesa::LocalIndex free_uz = dofs.fullIndex(30, fesa::Dof::UZ);
  k_full(support_ux, support_ux) = 10.0;
  k_full(support_ux, free_uz) = 2.0;
  k_full(free_uz, support_ux) = 2.0;
  k_full(free_uz, free_uz) = 5.0;
  u_full[static_cast<std::size_t>(free_uz)] = 3.0;
  f_full[static_cast<std::size_t>(support_ux)] = 1.0;
  f_full[static_cast<std::size_t>(free_uz)] = 7.0;

  auto reaction = fesa::recoverFullReaction(k_full, u_full, f_full);
  FESA_CHECK_NEAR(reaction[static_cast<std::size_t>(support_ux)], 5.0, 1.0e-15);
  FESA_CHECK_NEAR(reaction[static_cast<std::size_t>(free_uz)], 8.0, 1.0e-15);
}

FESA_TEST(gaussian_solver_solves_and_diagnoses_singular_systems) {
  fesa::DenseMatrix a(2, 2);
  a(0, 0) = 2.0;
  a(0, 1) = 1.0;
  a(1, 0) = 1.0;
  a(1, 1) = 3.0;
  fesa::GaussianEliminationSolver solver;
  auto solved = solver.solve(a, {1.0, 2.0});
  FESA_CHECK(solved.ok());
  FESA_CHECK_NEAR(solved.x[0], 0.2, 1.0e-12);
  FESA_CHECK_NEAR(solved.x[1], 0.6, 1.0e-12);

  fesa::DenseMatrix singular(2, 2);
  singular(0, 0) = 1.0;
  singular(0, 1) = 2.0;
  singular(1, 0) = 2.0;
  singular(1, 1) = 4.0;
  auto failed = solver.solve(singular, {1.0, 2.0});
  FESA_CHECK(!failed.ok());
  FESA_CHECK(fesa::containsDiagnostic(failed.diagnostics, "FESA-SINGULAR-SOLVER"));
}

FESA_TEST(results_writer_uses_step_frame_fields_for_u_and_rf) {
  auto domain = parsedPhase1Domain();
  fesa::DofManager dofs(domain);
  std::vector<fesa::Real> u(static_cast<std::size_t>(dofs.fullDofCount()), 0.0);
  std::vector<fesa::Real> rf(static_cast<std::size_t>(dofs.fullDofCount()), 0.0);
  u[static_cast<std::size_t>(dofs.fullIndex(2, fesa::Dof::UZ))] = -0.1;
  rf[static_cast<std::size_t>(dofs.fullIndex(1, fesa::Dof::UZ))] = 1.0;
  fesa::InMemoryResultsWriter writer;
  writer.writeLinearStatic(domain, dofs, u, rf);
  const auto& result = writer.result();
  FESA_CHECK(result.schema_name == "FESA_RESULTS");
  FESA_CHECK(result.schema_version == 1);
  FESA_CHECK(result.solver_name == "FESA");
  FESA_CHECK(result.dof_convention == "UX,UY,UZ,RX,RY,RZ");
  FESA_CHECK(result.sign_convention == "Abaqus-compatible");
  FESA_CHECK(result.precision == "double");
  FESA_CHECK(result.index_type == "int64");
  FESA_CHECK(result.steps.size() == 1);
  FESA_CHECK(result.steps[0].name == "Step-1");
  FESA_CHECK(result.steps[0].frames.size() == 1);
  const auto& frame = result.steps[0].frames[0];
  FESA_CHECK(frame.frame_id == 0);
  FESA_CHECK(frame.increment == 1);
  FESA_CHECK(frame.iteration == 0);
  FESA_CHECK(frame.converged);
  FESA_CHECK_NEAR(frame.step_time, 1.0, 1.0e-15);
  FESA_CHECK_NEAR(frame.total_time, 1.0, 1.0e-15);
  FESA_CHECK(frame.field_outputs.count("U") == 1);
  FESA_CHECK(frame.field_outputs.count("RF") == 1);
  const auto& u_field = frame.field_outputs.at("U");
  const auto& rf_field = frame.field_outputs.at("RF");
  FESA_CHECK(u_field.name == "U");
  FESA_CHECK(u_field.position == "NODAL");
  FESA_CHECK(u_field.entity_type == "node");
  FESA_CHECK(u_field.basis == "GLOBAL");
  FESA_CHECK(u_field.component_labels == fesa::displacementComponentLabels());
  FESA_CHECK(rf_field.name == "RF");
  FESA_CHECK(rf_field.position == "NODAL");
  FESA_CHECK(rf_field.entity_type == "node");
  FESA_CHECK(rf_field.basis == "GLOBAL");
  FESA_CHECK(rf_field.component_labels == fesa::reactionComponentLabels());
  FESA_CHECK(u_field.component_labels[2] == "UZ");
  FESA_CHECK(rf_field.component_labels[2] == "RFZ");
  FESA_CHECK(u_field.entity_ids.size() == domain.nodes.size());
  FESA_CHECK(rf_field.entity_ids.size() == domain.nodes.size());
}

FESA_TEST(displacement_csv_loader_accepts_quad01_format) {
  auto table = fesa::loadDisplacementCsv(sourceRoot() + "/references/quad_01_displacements.csv");
  FESA_CHECK(!fesa::hasError(table.diagnostics));
  FESA_CHECK(table.rows.size() == 121);
  FESA_CHECK(table.rows.count(1) == 1);
}

FESA_TEST(displacement_csv_loader_accepts_quad02_format) {
  auto table = fesa::loadDisplacementCsv(sourceRoot() + "/references/quad_02_displacements.csv");
  FESA_CHECK(!fesa::hasError(table.diagnostics));
  FESA_CHECK(table.rows.size() == 121);
  FESA_CHECK(table.rows.count(2) == 1);
  FESA_CHECK(table.rows.at(2).values[2] < 0.0);
}

FESA_TEST(displacement_csv_loader_reports_required_header_errors) {
  auto table = fesa::loadDisplacementCsvFromString("Node Label,U-U1,U-U2,U-U3,UR-UR1,UR-UR2\n"
                                                   "1,0,0,0,0,0\n",
                                                   "missing-header.csv");
  FESA_CHECK(fesa::containsDiagnostic(table.diagnostics, "FESA-CSV-MISSING-COLUMN"));
}

FESA_TEST(displacement_csv_loader_reports_duplicate_node_rows) {
  auto table = fesa::loadDisplacementCsvFromString("Node Label,U-U1,U-U2,U-U3,UR-UR1,UR-UR2,UR-UR3\n"
                                                   "1,0,0,0,0,0,0\n"
                                                   "1,0,0,0,0,0,0\n",
                                                   "duplicate-node.csv");
  FESA_CHECK(fesa::containsDiagnostic(table.diagnostics, "FESA-CSV-DUPLICATE-NODE"));
}

FESA_TEST(displacement_csv_loader_reports_missing_and_non_numeric_node_rows) {
  auto table = fesa::loadDisplacementCsvFromString("Node Label,U-U1,U-U2,U-U3,UR-UR1,UR-UR2,UR-UR3\n"
                                                   ",0,0,0,0,0,0\n"
                                                   "two,0,0,0,0,0,0\n"
                                                   "3,0,not-a-number,0,0,0,0\n",
                                                   "invalid-node-row.csv");
  FESA_CHECK(diagnosticCount(table.diagnostics, "FESA-CSV-NODE") == 2);
  FESA_CHECK(fesa::containsDiagnostic(table.diagnostics, "FESA-CSV-NUMERIC"));
}

FESA_TEST(displacement_comparator_matches_by_node_id_not_row_order) {
  fesa::FieldOutput actual;
  actual.name = "U";
  actual.position = "NODAL";
  actual.entity_type = "node";
  actual.basis = "GLOBAL";
  actual.entity_ids = {2, 1};
  actual.component_labels = fesa::displacementComponentLabels();
  actual.values = {{{2, 0, 0, 0, 0, 0}}, {{1, 0, 0, 0, 0, 0}}};
  fesa::CsvDisplacementTable expected;
  expected.rows[1] = {1, {1, 0, 0, 0, 0, 0}};
  expected.rows[2] = {2, {2, 0, 0, 0, 0, 0}};
  auto compared = fesa::compareDisplacements(actual, expected, {1.0e-12, 1.0e-12, 1.0});
  FESA_CHECK(compared.pass);
}

FESA_TEST(displacement_comparator_uses_absolute_and_relative_tolerances) {
  fesa::FieldOutput actual;
  actual.name = "U";
  actual.position = "NODAL";
  actual.entity_type = "node";
  actual.basis = "GLOBAL";
  actual.entity_ids = {10};
  actual.component_labels = fesa::displacementComponentLabels();
  actual.values = {{{5.0e-7, 100.0005, 0, 0, 0, 0}}};
  fesa::CsvDisplacementTable expected;
  expected.rows[10] = {10, {0.0, 100.0, 0, 0, 0, 0}};

  auto loose = fesa::compareDisplacements(actual, expected, {1.0e-6, 1.0e-5, 1.0});
  FESA_CHECK(loose.pass);
  FESA_CHECK_NEAR(loose.max_abs_error, 5.0e-4, 1.0e-12);

  auto strict = fesa::compareDisplacements(actual, expected, {1.0e-8, 1.0e-8, 1.0});
  FESA_CHECK(!strict.pass);
  FESA_CHECK(fesa::containsDiagnostic(strict.diagnostics, "FESA-COMPARE-TOLERANCE"));
}

FESA_TEST(displacement_comparator_rejects_wrong_component_labels_and_missing_nodes) {
  fesa::FieldOutput actual;
  actual.name = "U";
  actual.position = "NODAL";
  actual.entity_type = "node";
  actual.basis = "GLOBAL";
  actual.entity_ids = {1};
  actual.component_labels = fesa::reactionComponentLabels();
  actual.values = {{{0, 0, 0, 0, 0, 0}}};
  fesa::CsvDisplacementTable expected;
  expected.rows[2] = {2, {0, 0, 0, 0, 0, 0}};

  auto compared = fesa::compareDisplacements(actual, expected, {1.0e-12, 1.0e-12, 1.0});
  FESA_CHECK(!compared.pass);
  FESA_CHECK(fesa::containsDiagnostic(compared.diagnostics, "FESA-COMPARE-COMPONENT-LABELS"));
  FESA_CHECK(fesa::containsDiagnostic(compared.diagnostics, "FESA-COMPARE-MISSING-ACTUAL"));
}

FESA_TEST(displacement_comparator_reports_duplicate_actual_nodes) {
  fesa::FieldOutput actual;
  actual.name = "U";
  actual.position = "NODAL";
  actual.entity_type = "node";
  actual.basis = "GLOBAL";
  actual.entity_ids = {1, 1};
  actual.component_labels = fesa::displacementComponentLabels();
  actual.values = {{{0, 0, 0, 0, 0, 0}}, {{0, 0, 0, 0, 0, 0}}};
  fesa::CsvDisplacementTable expected;
  expected.rows[1] = {1, {0, 0, 0, 0, 0, 0}};

  auto compared = fesa::compareDisplacements(actual, expected, {1.0e-12, 1.0e-12, 1.0});
  FESA_CHECK(!compared.pass);
  FESA_CHECK(fesa::containsDiagnostic(compared.diagnostics, "FESA-COMPARE-DUPLICATE-ACTUAL"));
}

FESA_TEST(mitc4_shape_functions_and_stiffness_baseline) {
  auto shape = fesa::shapeFunctions(0.25, -0.5);
  const fesa::Real sum = shape.n[0] + shape.n[1] + shape.n[2] + shape.n[3];
  FESA_CHECK_NEAR(sum, 1.0, 1.0e-15);

  const std::array<fesa::Vec3, 4> coords = {{{0, 0, 0}, {1, 0, 0}, {1, 1, 0}, {0, 1, 0}}};
  fesa::MITC4ElementKernel kernel;
  auto k = kernel.stiffness(coords, 1000.0, 0.3, 0.1);
  FESA_CHECK(k.rows() == 24);
  FESA_CHECK(k.cols() == 24);
  for (fesa::LocalIndex i = 0; i < 24; ++i) {
    for (fesa::LocalIndex j = 0; j < 24; ++j) {
      FESA_CHECK_NEAR(k(i, j), k(j, i), 1.0e-8);
    }
  }

  std::vector<fesa::Real> uniform_translation(24, 0.0);
  for (int node = 0; node < 4; ++node) {
    uniform_translation[static_cast<std::size_t>(6 * node + 0)] = 1.0;
  }
  auto internal = k.multiply(uniform_translation);
  fesa::Real norm = 0.0;
  for (auto value : internal) {
    norm += std::fabs(value);
  }
  FESA_CHECK(norm < 1.0e-8);
}

FESA_TEST(linear_static_analysis_solves_u_and_recovers_full_vector_rf) {
  auto domain = parsedPhase1Domain();
  fesa::LinearStaticAnalysis analysis;
  auto result = analysis.run(domain);
  FESA_CHECK(result.ok());
  FESA_CHECK(result.state.converged);
  FESA_CHECK(result.result_file.steps.size() == 1);
  const auto& frame = result.result_file.steps[0].frames[0];
  FESA_CHECK(frame.field_outputs.count("U") == 1);
  FESA_CHECK(frame.field_outputs.count("RF") == 1);
  fesa::Real total_rf_z = 0.0;
  fesa::DofManager dofs(domain);
  for (auto node_id : dofs.nodeIds()) {
    total_rf_z += result.state.reaction_full[static_cast<std::size_t>(dofs.fullIndex(node_id, fesa::Dof::UZ))];
  }
  FESA_CHECK_NEAR(total_rf_z, 2.0, 1.0e-8);
}

int main() {
  int failed = 0;
  for (const auto& test : registry()) {
    try {
      test.fn();
      std::cout << "[PASS] " << test.name << '\n';
    } catch (const std::exception& error) {
      ++failed;
      std::cerr << "[FAIL] " << test.name << ": " << error.what() << '\n';
    }
  }
  if (failed != 0) {
    std::cerr << failed << " test(s) failed\n";
    return 1;
  }
  std::cout << registry().size() << " test(s) passed\n";
  return 0;
}