// 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/src_code_gen.h"

#include <string>

#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "common/ffi_types.h"
#include "common/status_macros.h"
#include "rs_bindings_from_cc/ir.h"
#include "llvm/Support/FormatVariadic.h"

namespace crubit {

// FFI equivalent of `Bindings`.
struct FfiBindings {
  FfiU8SliceBox rs_api;
  FfiU8SliceBox rs_api_impl;
  FfiU8SliceBox error_report;
  FfiU8SliceBox fatal_errors;
};

// This function is implemented in Rust.
extern "C" FfiBindings GenerateBindingsImpl(
    FfiU8Slice json, FfiU8Slice crubit_support_path_format,
    FfiU8Slice clang_format_exe_path, FfiU8Slice rustfmt_exe_path,
    FfiU8Slice rustfmt_config_path, bool generate_error_report,
    Environment environment);

// Creates `Bindings` instance from copied data from `ffi_bindings`.
static absl::StatusOr<Bindings> MakeBindingsFromFfiBindings(
    const FfiBindings& ffi_bindings) {
  Bindings bindings;

  const FfiU8SliceBox& fatal_errors = ffi_bindings.fatal_errors;
  std::string fatal_errors_string(fatal_errors.ptr, fatal_errors.size);
  if (!fatal_errors_string.empty()) {
    return absl::InvalidArgumentError(fatal_errors_string);
  }

  const FfiU8SliceBox& rs_api = ffi_bindings.rs_api;
  const FfiU8SliceBox& rs_api_impl = ffi_bindings.rs_api_impl;
  const FfiU8SliceBox& error_report = ffi_bindings.error_report;

  bindings.rs_api = std::string(rs_api.ptr, rs_api.size);
  bindings.rs_api_impl = std::string(rs_api_impl.ptr, rs_api_impl.size);
  bindings.error_report = std::string(error_report.ptr, error_report.size);
  return bindings;
}

// Deallocates given `ffi_bindings` instance that was created in Rust.
static void FreeFfiBindings(FfiBindings ffi_bindings) {
  FreeFfiU8SliceBox(ffi_bindings.rs_api);
  FreeFfiU8SliceBox(ffi_bindings.rs_api_impl);
  FreeFfiU8SliceBox(ffi_bindings.error_report);
}

absl::StatusOr<Bindings> GenerateBindings(
    const IR& ir, absl::string_view crubit_support_path_format,
    absl::string_view clang_format_exe_path, absl::string_view rustfmt_exe_path,
    absl::string_view rustfmt_config_path, bool generate_error_report,
    Environment environment) {
  std::string json = llvm::formatv("{0}", ir.ToJson());
  FfiBindings ffi_bindings = GenerateBindingsImpl(
      MakeFfiU8Slice(json), MakeFfiU8Slice(crubit_support_path_format),
      MakeFfiU8Slice(clang_format_exe_path), MakeFfiU8Slice(rustfmt_exe_path),
      MakeFfiU8Slice(rustfmt_config_path), generate_error_report, environment);
  CRUBIT_ASSIGN_OR_RETURN(Bindings bindings,
                          MakeBindingsFromFfiBindings(ffi_bindings));
  FreeFfiBindings(ffi_bindings);
  return bindings;
}

}  // namespace crubit