// Copyright 2024 Google LLC
// SPDX-License-Identifier: Apache-2.0
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "gemma/common.h"

#include <stddef.h>

#include <string>

#include "gemma/configs.h"

namespace gcpp {

void Wrap(const ModelConfig& config, size_t pos, std::string& prompt) {

  // Instruction-tuned models are trained to expect control tokens.
  if (config.wrapping == PromptWrapping::GEMMA_IT) {
    // Prepend "<end_of_turn>" if this is a multi-turn dialogue continuation.
    const std::string start = (pos == 0)
                                  ? "<start_of_turn>user\n"
                                  : "<end_of_turn>\n<start_of_turn>user\n";
    prompt = start + prompt + "<end_of_turn>\n<start_of_turn>model\n";
  }
}

}  // namespace gcpp