#include "fesa/app/fesa_application.h"

#include <gtest/gtest.h>
#include <hdf5.h>

#include <array>
#include <atomic>
#include <chrono>
#include <cstddef>
#include <filesystem>
#include <fstream>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

namespace {

constexpr const char* kStepRoot = "/steps/Step-1/frames/0";

class TempDirectory {
 public:
  explicit TempDirectory(const std::string& label) {
    static std::atomic<unsigned long long> sequence{0U};
    const auto tick =
        std::chrono::steady_clock::now().time_since_epoch().count();
    path_ = std::filesystem::temp_directory_path() /
            ("fesa-step24-app-" + label + "-" + std::to_string(tick) + "-" +
             std::to_string(sequence.fetch_add(1U)));
    std::error_code error;
    if (!std::filesystem::create_directory(path_, error) || error) {
      throw std::runtime_error{"Unable to create the Step 24 app 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_;
};

class CurrentDirectoryGuard {
 public:
  explicit CurrentDirectoryGuard(const std::filesystem::path& replacement)
      : original_{std::filesystem::current_path()} {
    std::filesystem::current_path(replacement);
  }

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

  ~CurrentDirectoryGuard() {
    std::error_code ignored;
    std::filesystem::current_path(original_, ignored);
  }

 private:
  std::filesystem::path original_;
};

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

  Hdf5Handle(const 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;
    other.closer_ = nullptr;
  }
  ~Hdf5Handle() {
    if (value_ >= 0 && closer_ != nullptr) {
      (void)closer_(value_);
    }
  }

  hid_t Get() const noexcept { return value_; }

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

void WriteText(const std::filesystem::path& path, const std::string& text) {
  std::ofstream stream{path, std::ios::binary | std::ios::trunc};
  stream.write(text.data(), static_cast<std::streamsize>(text.size()));
  if (!stream) {
    throw std::runtime_error{"Unable to write the Step 24 app input."};
  }
}

std::string AxialDeck(const bool constrained, const bool zero_length,
                      const bool output_requests) {
  const std::string second_node =
      zero_length ? "2, 0., 0., 0.\n" : "2, 2., 0., 0.\n";
  const std::string boundaries =
      constrained ? "*Boundary\nRoot, 1, 6\nTip, 2, 6\n" : "";
  const std::string outputs = output_requests ? R"inp(*Output, field
*Node Output
U, RF
*Element Output, directions=YES
S, SF
*Output, history
*Contact Output
)inp"
                                              : "";

  return std::string{R"inp(*Part, name=BeamPart
*Node
1, 0., 0., 0.
)inp"} + second_node +
         R"inp(*Element, type=B33
1, 1, 2
*Elset, elset=BeamSet
1
*Beam General Section, elset=BeamSet, material=Steel, section=GENERAL
2., 0.5, 0., 0.75, 0.25
0., 1., 0.
*End Part
*Assembly, name=Assembly
*Instance, name=Beam-1, part=BeamPart
*End Instance
*Nset, nset=Root, instance=Beam-1
1
*Nset, nset=Tip, instance=Beam-1
2
*End Assembly
*Material, name=Steel
*Elastic
100., 0.25
)inp" + boundaries +
         R"inp(*Step, name=Load, nlgeom=NO
*Static
0.1, 1., 0.01, 1.
*Cload
Tip, 1, 10.
)inp" + outputs +
         R"inp(*End Step
)inp";
}

std::string AllConstrainedShellDeck() {
  return R"inp(*Part, name=ShellPart
*Node
1, 0., 0., 0.
2, 1., 0., 0.
3, 1., 1., 0.
4, 0., 1., 0.
*Element, type=S4
1, 1, 2, 3, 4
*Elset, elset=ShellSet
1
*Shell Section, elset=ShellSet, material=Steel
0.1
*End Part
*Assembly, name=Assembly
*Instance, name=Shell-1, part=ShellPart
*End Instance
*Nset, nset=All, instance=Shell-1
1, 2, 3, 4
*End Assembly
*Material, name=Steel
*Elastic
1000., 0.25
*Boundary
All, 1, 6
*Step, name=Load, nlgeom=NO
*Static
0.1, 1., 0.01, 1.
*End Step
)inp";
}

Hdf5Handle OpenFile(const std::filesystem::path& path) {
  const hid_t file =
      H5Fopen(path.string().c_str(), H5F_ACC_RDONLY, H5P_DEFAULT);
  if (file < 0) {
    throw std::runtime_error{"Unable to open the CLI HDF5 artifact."};
  }
  return Hdf5Handle{file, H5Fclose};
}

Hdf5Handle OpenDataset(const hid_t file, const std::string& path) {
  const hid_t dataset = H5Dopen2(file, path.c_str(), H5P_DEFAULT);
  if (dataset < 0) {
    throw std::runtime_error{"Unable to open mandatory dataset: " + path};
  }
  return Hdf5Handle{dataset, H5Dclose};
}

std::vector<hsize_t> DatasetDimensions(const hid_t file,
                                       const std::string& path) {
  const auto dataset = OpenDataset(file, path);
  Hdf5Handle space{H5Dget_space(dataset.Get()), H5Sclose};
  const int rank = H5Sget_simple_extent_ndims(space.Get());
  if (space.Get() < 0 || rank < 0) {
    throw std::runtime_error{"Unable to inspect mandatory dataset dimensions."};
  }
  std::vector<hsize_t> dimensions(static_cast<std::size_t>(rank));
  if (rank > 0 &&
      H5Sget_simple_extent_dims(space.Get(), dimensions.data(), nullptr) < 0) {
    throw std::runtime_error{"Unable to read mandatory dataset dimensions."};
  }
  return dimensions;
}

std::vector<double> ReadDoubleDataset(const hid_t file,
                                      const std::string& path) {
  const auto dimensions = DatasetDimensions(file, path);
  std::size_t count = 1U;
  for (const hsize_t dimension : dimensions) {
    count *= static_cast<std::size_t>(dimension);
  }
  const auto dataset = OpenDataset(file, path);
  std::vector<double> values(count);
  if (!values.empty() && H5Dread(dataset.Get(), H5T_NATIVE_DOUBLE, H5S_ALL,
                                 H5S_ALL, H5P_DEFAULT, values.data()) < 0) {
    throw std::runtime_error{"Unable to read mandatory numeric results."};
  }
  return values;
}

std::string ReadStringAttribute(const hid_t object, const char* name) {
  Hdf5Handle attribute{H5Aopen(object, name, H5P_DEFAULT), H5Aclose};
  Hdf5Handle type{H5Aget_type(attribute.Get()), H5Tclose};
  if (attribute.Get() < 0 || type.Get() < 0 ||
      H5Tget_class(type.Get()) != H5T_STRING ||
      H5Tis_variable_str(type.Get()) <= 0) {
    throw std::runtime_error{"Expected a variable-length string attribute."};
  }
  char* raw = nullptr;
  if (H5Aread(attribute.Get(), type.Get(), &raw) < 0 || raw == nullptr) {
    throw std::runtime_error{"Unable to read the HDF5 identity attribute."};
  }
  const std::string value{raw};
  (void)H5free_memory(raw);
  return value;
}

void ExpectMandatoryInventory(const hid_t file) {
  for (const char* path :
       {"/metadata", "/model/nodes", "/model/elements",
        "/steps/Step-1/frames/0/nodal/displacement",
        "/steps/Step-1/frames/0/nodal/reaction",
        "/steps/Step-1/frames/0/element/end_force_local",
        "/steps/Step-1/frames/0/element/section_resultant",
        "/steps/Step-1/frames/0/element/generalized_strain",
        "/steps/Step-1/frames/0/element/generalized_resultant",
        "/steps/Step-1/frames/0/element/stress_s11", "/diagnostics"}) {
    EXPECT_GT(H5Lexists(file, path, H5P_DEFAULT), 0) << path;
  }
}

void ExpectFesaHdf5Identity(const std::filesystem::path& output,
                            const std::filesystem::path& input) {
  ASSERT_TRUE(std::filesystem::exists(output));
  ASSERT_GT(H5Fis_hdf5(output.string().c_str()), 0);
  const auto file = OpenFile(output);
  ExpectMandatoryInventory(file.Get());
  Hdf5Handle metadata{H5Gopen2(file.Get(), "/metadata", H5P_DEFAULT), H5Gclose};
  ASSERT_GE(metadata.Get(), 0);
  EXPECT_EQ(ReadStringAttribute(metadata.Get(), "feature_id"),
            "linear-static-3d-euler-beam");
  const std::string normalized_input =
      std::filesystem::absolute(input).lexically_normal().generic_u8string();
  EXPECT_EQ(ReadStringAttribute(metadata.Get(), "source_input_identity")
                .find("path=" + normalized_input + ";content_identity="),
            0U);
}

void ExpectShellHdf5Identity(const std::filesystem::path& output,
                             const std::filesystem::path& input) {
  ASSERT_TRUE(std::filesystem::exists(output));
  ASSERT_GT(H5Fis_hdf5(output.string().c_str()), 0);
  const auto file = OpenFile(output);
  Hdf5Handle metadata{H5Gopen2(file.Get(), "/metadata", H5P_DEFAULT), H5Gclose};
  ASSERT_GE(metadata.Get(), 0);
  EXPECT_EQ(ReadStringAttribute(metadata.Get(), "feature_id"),
            "linear-static-mitc4-shell");
  EXPECT_GT(H5Lexists(file.Get(),
                      "/steps/Step-1/frames/0/element/shell/generalized_strain",
                      H5P_DEFAULT),
            0);
  EXPECT_EQ(DatasetDimensions(file.Get(),
                              "/steps/Step-1/frames/0/nodal/displacement"),
            (std::vector<hsize_t>{4U, 6U}));
  const std::string normalized_input =
      std::filesystem::absolute(input).lexically_normal().generic_u8string();
  EXPECT_EQ(ReadStringAttribute(metadata.Get(), "source_input_identity")
                .find("path=" + normalized_input + ";content_identity="),
            0U);
}

struct AppRun {
  int exit_code;
  std::string standard_error;
};

AppRun RunApplication(const std::vector<std::string>& arguments) {
  testing::internal::CaptureStderr();
  try {
    const int exit_code = fesa::FesaApplication{}.Run(arguments);
    return {exit_code, testing::internal::GetCapturedStderr()};
  } catch (...) {
    (void)testing::internal::GetCapturedStderr();
    throw;
  }
}

void ExpectDiagnosticFieldOrder(const std::string& text) {
  ASSERT_FALSE(text.empty());
  std::size_t cursor = 0U;
  for (const char* field : {"severity", "code", "file", "line", "keyword",
                            "entity_identity", "message"}) {
    const auto position = text.find(field, cursor);
    ASSERT_NE(position, std::string::npos)
        << "Missing or out-of-order diagnostic field: " << field
        << "\nstderr:\n"
        << text;
    cursor = position + std::string{field}.size();
  }
}

std::vector<std::string> ExplicitOutputArguments(
    const std::filesystem::path& input, const std::filesystem::path& output) {
  // FesaApplication receives argv[0]-excluded operands and options.
  return {input.string(), "--output", output.string()};
}

}  // namespace

TEST(LinearStaticCli, DefaultAndExplicitOutputProduceFesaHdf5) {
  TempDirectory directory{"paths"};
  const auto input = directory.Path() / "model.inp";
  WriteText(input, AxialDeck(true, false, false));

  const auto default_output = directory.Path() / "results.h5";
  {
    CurrentDirectoryGuard current_directory{directory.Path()};
    const auto result = RunApplication({input.string()});
    ASSERT_EQ(result.exit_code, 0) << result.standard_error;
  }
  ExpectFesaHdf5Identity(default_output, input);

  const auto explicit_output = directory.Path() / "named-output.h5";
  const auto result =
      RunApplication(ExplicitOutputArguments(input, explicit_output));
  ASSERT_EQ(result.exit_code, 0) << result.standard_error;
  ExpectFesaHdf5Identity(explicit_output, input);
}

TEST(LinearStaticCli, ReturnsEveryExactExitCodeAndOrderedDiagnostic) {
  TempDirectory directory{"exit-codes"};
  const auto valid_input = directory.Path() / "valid.inp";
  const auto model_input = directory.Path() / "invalid-model.inp";
  const auto solver_input = directory.Path() / "singular.inp";
  WriteText(valid_input, AxialDeck(true, false, false));
  WriteText(model_input, AxialDeck(true, true, false));
  WriteText(solver_input, AxialDeck(false, false, false));

  const auto success = RunApplication(
      ExplicitOutputArguments(valid_input, directory.Path() / "success.h5"));
  const auto usage = RunApplication({});
  const auto missing_input = directory.Path() / "missing.inp";
  const auto input = RunApplication({missing_input.string()});
  const auto repeated_output =
      RunApplication({missing_input.string(), "--output", "--output"});
  const auto unknown_output_option =
      RunApplication({missing_input.string(), "--output", "--bogus"});
  const auto model = RunApplication(ExplicitOutputArguments(
      model_input, directory.Path() / "model-failure.h5"));
  const auto solver = RunApplication(ExplicitOutputArguments(
      solver_input, directory.Path() / "solver-failure.h5"));
  const auto output = RunApplication(ExplicitOutputArguments(
      valid_input, directory.Path() / "nonexistent-parent" / "results.h5"));

  EXPECT_EQ(success.exit_code, 0) << success.standard_error;
  EXPECT_EQ(usage.exit_code, 2);
  EXPECT_EQ(input.exit_code, 3);
  EXPECT_EQ(model.exit_code, 4);
  EXPECT_EQ(solver.exit_code, 5);
  EXPECT_EQ(output.exit_code, 6);

  ExpectDiagnosticFieldOrder(usage.standard_error);
  ExpectDiagnosticFieldOrder(input.standard_error);
  ExpectDiagnosticFieldOrder(model.standard_error);
  ExpectDiagnosticFieldOrder(solver.standard_error);
  ExpectDiagnosticFieldOrder(output.standard_error);
  EXPECT_EQ(repeated_output.exit_code, 2);
  ExpectDiagnosticFieldOrder(repeated_output.standard_error);
  EXPECT_NE(repeated_output.standard_error.find("code=cli-usage"),
            std::string::npos);
  EXPECT_EQ(unknown_output_option.exit_code, 2);
  ExpectDiagnosticFieldOrder(unknown_output_option.standard_error);
  EXPECT_NE(unknown_output_option.standard_error.find("code=cli-usage"),
            std::string::npos);
}

TEST(LinearStaticCli, OutputRequestsDoNotFilterMandatoryResults) {
  TempDirectory directory{"output-requests"};
  const auto plain_input = directory.Path() / "plain.inp";
  const auto requested_input = directory.Path() / "requested.inp";
  const auto plain_output = directory.Path() / "plain.h5";
  const auto requested_output = directory.Path() / "requested.h5";
  WriteText(plain_input, AxialDeck(true, false, false));
  WriteText(requested_input, AxialDeck(true, false, true));

  const auto plain =
      RunApplication(ExplicitOutputArguments(plain_input, plain_output));
  const auto requested = RunApplication(
      ExplicitOutputArguments(requested_input, requested_output));
  ASSERT_EQ(plain.exit_code, 0) << plain.standard_error;
  ASSERT_EQ(requested.exit_code, 0) << requested.standard_error;

  const auto plain_file = OpenFile(plain_output);
  const auto requested_file = OpenFile(requested_output);
  ExpectMandatoryInventory(plain_file.Get());
  ExpectMandatoryInventory(requested_file.Get());

  for (const char* suffix :
       {"/nodal/displacement", "/nodal/reaction", "/element/end_force_local",
        "/element/section_resultant", "/element/generalized_strain",
        "/element/generalized_resultant"}) {
    const std::string path = std::string{kStepRoot} + suffix;
    EXPECT_EQ(ReadDoubleDataset(requested_file.Get(), path),
              ReadDoubleDataset(plain_file.Get(), path))
        << path;
  }
  EXPECT_EQ(DatasetDimensions(plain_file.Get(), "/diagnostics"),
            std::vector<hsize_t>({0U}));
  const auto requested_diagnostics =
      DatasetDimensions(requested_file.Get(), "/diagnostics");
  ASSERT_EQ(requested_diagnostics.size(), 1U);
  EXPECT_GT(requested_diagnostics[0U], 0U);
}

// MITC4-FLOW-001: shell input uses the unchanged application route and syntax.
TEST(Mitc4ShellCli, WritesShellHdf5ThroughTheExistingApplicationRoute) {
  TempDirectory directory{"shell-route"};
  const auto input = directory.Path() / "shell.inp";
  const auto output = directory.Path() / "shell-results.h5";
  WriteText(input, AllConstrainedShellDeck());

  const auto result = RunApplication(ExplicitOutputArguments(input, output));
  ASSERT_EQ(result.exit_code, 0) << result.standard_error;
  ExpectShellHdf5Identity(output, input);
}