// Copyright 2024 DeepMind Technologies Limited
//
// AlphaFold 3 source code is licensed under CC BY-NC-SA 4.0. To view a copy of
// this license, visit https://creativecommons.org/licenses/by-nc-sa/4.0/
//
// To request access to the AlphaFold 3 model parameters, follow the process set
// out at https://github.com/google-deepmind/alphafold3. You may only use these
// if received directly from Google. Use is subject to terms of use available at
// https://github.com/google-deepmind/alphafold3/blob/main/WEIGHTS_TERMS_OF_USE.md

#include <cstddef>

#include "absl/container/flat_hash_map.h"
#include "absl/log/check.h"
#include "absl/strings/string_view.h"
#include "absl/types/span.h"
#include "alphafold3/parsers/cpp/cif_dict_lib.h"
#include "pybind11/gil.h"
#include "pybind11/pybind11.h"
#include "pybind11/pytypes.h"
#include "pybind11/stl.h"
#include "pybind11_abseil/absl_casters.h"

namespace alphafold3 {
namespace {
namespace py = pybind11;

// If present, returns the _atom_site.type_symbol. If not, infers it using
// _atom_site.label_comp_id (residue name), _atom_site.label_atom_id (atom name)
// and the CCD.
py::list GetOrInferTypeSymbol(const CifDict& mmcif,
                              const py::object& atom_id_to_type_symbol) {
  const auto& type_symbol = mmcif["_atom_site.type_symbol"];
  const int num_atom = mmcif["_atom_site.id"].size();
  py::list patched_type_symbol(num_atom);
  if (type_symbol.empty()) {
    const auto& label_comp_id = mmcif["_atom_site.label_comp_id"];
    const auto& label_atom_id = mmcif["_atom_site.label_atom_id"];
    CHECK_EQ(label_comp_id.size(), num_atom);
    CHECK_EQ(label_atom_id.size(), num_atom);
    for (int i = 0; i < num_atom; i++) {
      patched_type_symbol[i] =
          atom_id_to_type_symbol(label_comp_id[i], label_atom_id[i]);
    }
  } else {
    for (int i = 0; i < num_atom; i++) {
      patched_type_symbol[i] = type_symbol[i];
    }
  }
  return patched_type_symbol;
}

absl::flat_hash_map<absl::string_view, absl::string_view>
GetInternalToAuthorChainIdMap(const CifDict& mmcif) {
  const auto& label_asym_ids = mmcif["_atom_site.label_asym_id"];
  const auto& auth_asym_ids = mmcif["_atom_site.auth_asym_id"];
  CHECK_EQ(label_asym_ids.size(), auth_asym_ids.size());

  absl::flat_hash_map<absl::string_view, absl::string_view> mapping;
  for (size_t i = 0, num_rows = label_asym_ids.size(); i < num_rows; ++i) {
    // Use only the first internal_chain_id occurrence to generate the mapping.
    // It should not matter as there should not be a case where a single
    // internal chain ID would map to more than one author chain IDs (i.e. the
    // mapping should be injective). Since we need this method to be fast, we
    // choose not to check it.
    mapping.emplace(label_asym_ids[i], auth_asym_ids[i]);
  }
  return mapping;
}

}  // namespace

namespace py = pybind11;

void RegisterModuleMmcifAtomSite(pybind11::module m) {
  m.def("get_or_infer_type_symbol", &GetOrInferTypeSymbol, py::arg("mmcif"),
        py::arg("atom_id_to_type_symbol"));

  m.def("get_internal_to_author_chain_id_map", &GetInternalToAuthorChainIdMap,
        py::arg("mmcif"), py::call_guard<py::gil_scoped_release>());
}

}  // namespace alphafold3