// Part of the Crubit project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#include "rs_bindings_from_cc/ir_from_cc.h"

#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "absl/container/flat_hash_map.h"
#include "absl/log/check.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
#include "absl/strings/substitute.h"
#include "absl/types/span.h"
#include "rs_bindings_from_cc/bazel_types.h"
#include "rs_bindings_from_cc/frontend_action.h"
#include "rs_bindings_from_cc/ir.h"
#include "clang/Frontend/FrontendAction.h"
#include "clang/Tooling/Tooling.h"

namespace crubit {

static constexpr absl::string_view kVirtualHeaderPath =
    "ir_from_cc_virtual_header.h";
static constexpr absl::string_view kVirtualInputPath =
    "ir_from_cc_virtual_input.cc";

absl::StatusOr<IR> IrFromCc(
    const absl::string_view extra_source_code_for_testing,
    const BazelLabel current_target,
    absl::Span<const HeaderName> public_headers,
    absl::flat_hash_map<const HeaderName, const std::string>
        virtual_headers_contents_for_testing,
    absl::flat_hash_map<const HeaderName, const BazelLabel> headers_to_targets,
    absl::Span<const std::string> extra_rs_srcs,
    absl::Span<const absl::string_view> clang_args,
    absl::Span<const std::string> extra_instantiations) {
  // Caller should verify that the inputs are not empty.
  CHECK(!extra_source_code_for_testing.empty() || !public_headers.empty() ||
        !extra_instantiations.empty());
  CHECK(!extra_source_code_for_testing.empty() || !headers_to_targets.empty() ||
        !extra_instantiations.empty());

  clang::tooling::FileContentMappings file_contents;

  for (auto const& name_and_content : virtual_headers_contents_for_testing) {
    file_contents.push_back({std::string(name_and_content.first.IncludePath()),
                             name_and_content.second});
  }

  // Tests may inject `extra_source_code_for_testing` - it needs to be appended
  // to `public_headers` and exposed via `file_contents` virtual file system.
  std::vector<HeaderName> augmented_public_headers(public_headers.begin(),
                                                   public_headers.end());
  if (!extra_source_code_for_testing.empty()) {
    file_contents.push_back({std::string(kVirtualHeaderPath),
                             std::string(extra_source_code_for_testing)});
    HeaderName header_name = HeaderName(std::string(kVirtualHeaderPath));
    augmented_public_headers.push_back(header_name);
    headers_to_targets.insert({header_name, current_target});
  }

  std::string virtual_input_file_content;
  for (const HeaderName& header_name : augmented_public_headers) {
    absl::SubstituteAndAppend(&virtual_input_file_content, "#include \"$0\"\n",
                              header_name.IncludePath());
  }
  if (!extra_instantiations.empty()) {
    absl::SubstituteAndAppend(&virtual_input_file_content, "namespace $0 {\n",
                              kInstantiationsNamespaceName);
    int counter = 0;
    for (const std::string& extra_instantiation : extra_instantiations) {
      absl::SubstituteAndAppend(&virtual_input_file_content,
                                "using __cc_template_instantiation_$0 = $1;\n",
                                counter++, extra_instantiation);
    }
    absl::SubstituteAndAppend(&virtual_input_file_content,
                              "}  // namespace $0\n",
                              kInstantiationsNamespaceName);
  }
  std::vector<std::string> args_as_strings{
      "-std=gnu++17",
      // Parse non-doc comments that are used as documention
      "-fparse-all-comments"};
  args_as_strings.insert(args_as_strings.end(), clang_args.begin(),
                         clang_args.end());

  Invocation invocation(current_target, augmented_public_headers,
                        headers_to_targets);
  if (!clang::tooling::runToolOnCodeWithArgs(
          std::make_unique<FrontendAction>(invocation),
          virtual_input_file_content, args_as_strings, kVirtualInputPath,
          "rs_bindings_from_cc",
          std::make_shared<clang::PCHContainerOperations>(), file_contents)) {
    return absl::Status(absl::StatusCode::kInvalidArgument,
                        "Could not compile header contents");
  }

  invocation.ir_.items.reserve(invocation.ir_.items.size() +
                               extra_rs_srcs.size());
  int i = 0;
  for (const std::string& extra_source : extra_rs_srcs) {
    // TODO(jeanpierreda): It'd be nice to give these human-readable names, e.g. the
    // name of the file without the `.rs`, but it's also annoying to handle name
    // collisions.
    ItemId id(reinterpret_cast<uintptr_t>(&extra_source));
    invocation.ir_.items.push_back(UseMod{
        .path = extra_source,
        .mod_name = Identifier(absl::StrCat("__crubit_mod_", i)),
        .id = id,
    });
    invocation.ir_.top_level_item_ids.push_back(id);
    ++i;
  }
  return invocation.ir_;
}

}  // namespace crubit