# Copyright 2024 Bytedance Ltd. and/or its affiliates
#
# 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
#
#     http://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.
"""
Offline evaluate the performance of a generated file using reward model and ground truth verifier.
The input is a parquet file that contains N generated sequences and (optional) the ground truth.

"""

from collections import defaultdict

import hydra
import numpy as np
import pandas as pd
import ray
from tqdm import tqdm

from verl.utils.fs import copy_to_local


def get_custom_reward_fn(config):
    import importlib.util
    import os

    reward_fn_config = config.get("custom_reward_function") or {}
    file_path = reward_fn_config.get("path")
    if not file_path:
        return None

    if not os.path.exists(file_path):
        raise FileNotFoundError(f"Reward function file '{file_path}' not found.")

    spec = importlib.util.spec_from_file_location("custom_module", file_path)
    module = importlib.util.module_from_spec(spec)
    try:
        spec.loader.exec_module(module)
    except Exception as e:
        raise RuntimeError(f"Error loading module from '{file_path}'") from e

    function_name = reward_fn_config.get("name")

    if not hasattr(module, function_name):
        raise AttributeError(f"Reward function '{function_name}' not found in '{file_path}'.")

    print(f"using customized reward function '{function_name}' from '{file_path}'")

    return getattr(module, function_name)


@ray.remote
def process_item(reward_fn, data_source, response_lst, reward_data):
    ground_truth = reward_data["ground_truth"]
    score_lst = [reward_fn(data_source, r, ground_truth) for r in response_lst]
    return data_source, np.mean(score_lst)


@hydra.main(config_path="config", config_name="evaluation", version_base=None)
def main(config):
    local_path = copy_to_local(config.data.path)
    dataset = pd.read_parquet(local_path)
    responses = dataset[config.data.response_key]
    data_sources = dataset[config.data.data_source_key]
    reward_model_data = dataset[config.data.reward_model_key]

    total = len(dataset)

    # Initialize Ray
    if not ray.is_initialized():
        ray.init(num_cpus=config.ray_init.num_cpus)

    # evaluate test_score based on data source
    data_source_reward = defaultdict(list)
    compute_score = get_custom_reward_fn(config)

    # Create remote tasks
    remote_tasks = [process_item.remote(compute_score, data_sources[i], responses[i], reward_model_data[i]) for i in range(total)]

    # Process results as they come in
    with tqdm(total=total) as pbar:
        while len(remote_tasks) > 0:
            # Use ray.wait to get completed tasks
            done_ids, remote_tasks = ray.wait(remote_tasks)
            for result_id in done_ids:
                data_source, score = ray.get(result_id)
                data_source_reward[data_source].append(score)
                pbar.update(1)

    metric_dict = {}
    for data_source, rewards in data_source_reward.items():
        metric_dict[f"test_score/{data_source}"] = np.mean(rewards)

    print(metric_dict)


if __name__ == "__main__":
    main()
