# Copyright 2022 Zilliz. All rights reserved.
#
# 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.

from itertools import groupby
from typing import List

from towhee import register
from towhee.operator import PyOperator


@register(output_schema=['vec'])
class SelectVideo(PyOperator):
    def __init__(self, top_k: int, reduce_function: str = 'sum', reverse: bool = True):
        self.top_k = top_k
        self.reduce_function = reduce_function
        self.reverse = reverse

    def _select(self, video_urls, scores):
        assert len(video_urls) == len(scores), 'len(video_urls) must equal len(scores)'

        video2score_list = [{'video_url': video_url, 'score': score} for video_url, score in zip(video_urls, scores)]
        video2score_list.sort(key=lambda d: d['video_url'])
        reduced_dict = {}

        for video_url, items in groupby(video2score_list, key=lambda d: d['video_url']):
            video_score_list = [item['score'] for item in items]
            if self.reduce_function == 'sum':
                reduced_value = sum(video_score_list)
            elif self.reduce_function == 'mean':
                reduced_value = sum(video_score_list) / len(video_score_list)
            elif self.reduce_function == 'max':
                reduced_value = max(video_score_list)
            elif self.reduce_function == 'min':
                reduced_value = min(video_score_list)
            else:
                raise Exception('unknown reduce_function')
            reduced_dict[video_url] = reduced_value

        sorted_video_urls = [k for k, v in sorted(reduced_dict.items(), key=lambda item: item[1], reverse=self.reverse)]
        top_k = min(self.top_k, len(sorted_video_urls))

        return sorted_video_urls[:top_k]

    def __call__(self, video_urls: List[str], scores: List[float]) -> List[str]:
        """
        args:
            video_urls
            scores
        return:
            video_list
        """
        if isinstance(video_urls[0], list):
            video_urls = sum(video_urls, [])
            scores = sum(scores, [])
        if isinstance(video_urls[0], str):
            return self._select(video_urls, scores)


# if __name__ == '__main__':
#     op = SelectVideo(top_k=2, reverse=True, reduce_function='min')
#     res = op(['a', 'a', 'c', 'a', 'b', 'b', 'c', 'c'],
#              [2, 1, 9, 5, 2, 1, 2, 2]
#              )
#     print(res)