# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
#
# 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.

import os
import sys
import logging
import functools
import paddle.distributed as dist

logger_initialized = {}


@functools.lru_cache()
def get_logger(name='root', log_file=None, log_level=logging.INFO):
    """Initialize and get a logger by name.
    If the logger has not been initialized, this method will initialize the
    logger by adding one or two handlers, otherwise the initialized logger will
    be directly returned. During initialization, a StreamHandler will always be
    added. If `log_file` is specified a FileHandler will also be added.
    Args:
        name (str): Logger name.
        log_file (str | None): The log filename. If specified, a FileHandler
            will be added to the logger.
        log_level (int): The logger level. Note that only the process of
            rank 0 is affected, and other processes will set the level to
            "Error" thus be silent most of the time.
    Returns:
        logging.Logger: The expected logger.
    """
    logger = logging.getLogger(name)
    if name in logger_initialized:
        return logger
    for logger_name in logger_initialized:
        if name.startswith(logger_name):
            return logger

    formatter = logging.Formatter(
        '[%(asctime)s] %(name)s %(levelname)s: %(message)s',
        datefmt="%Y/%m/%d %H:%M:%S")

    stream_handler = logging.StreamHandler(stream=sys.stdout)
    stream_handler.setFormatter(formatter)
    logger.addHandler(stream_handler)
    if log_file is not None and dist.get_rank() == 0:
        log_file_folder = os.path.split(log_file)[0]
        os.makedirs(log_file_folder, exist_ok=True)
        file_handler = logging.FileHandler(log_file, 'a')
        file_handler.setFormatter(formatter)
        logger.addHandler(file_handler)
    if dist.get_rank() == 0:
        logger.setLevel(log_level)
    else:
        logger.setLevel(logging.ERROR)
    logger_initialized[name] = True
    return logger