# Copyright (c) 2016 PaddlePaddle Authors. 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.
"""
Creator package contains some simple reader creator, which could
be used in user program.
"""

__all__ = ['np_array', 'text_file', 'recordio']


def np_array(x):
    """
    Creates a reader that yields elements of x, if it is a
    numpy vector. Or rows of x, if it is a numpy matrix.
    Or any sub-hyperplane indexed by the highest dimension.

    :param x: the numpy array to create reader from.
    :returns: data reader created from x.
    """

    def reader():
        if x.ndim < 1:
            yield x

        for e in x:
            yield e

    return reader


def text_file(path):
    """
    Creates a data reader that outputs text line by line from given text file.
    Trailing new line ('\\\\n') of each line will be removed.

    Args:
        path (str): path of the text file.
    
    Returns: 
        callable: data reader of text file.
    """

    def reader():
        f = open(path, "r")
        for l in f:
            yield l.rstrip('\n')
        f.close()

    return reader


def recordio(paths, buf_size=100):
    """
    Creates a data reader from given RecordIO file paths separated 
    by ",", glob pattern is supported.

    Args:
        paths (str|list(str)): path of recordio files.
        buf_size (int): prefetched buffer size. 

    Returns:
        callable: data reader of recordio files.
    """

    import recordio as rec
    import paddle.reader.decorator as dec
    import six
    import six.moves.cPickle as pickle

    def reader():
        if isinstance(paths, six.string_types):
            path = paths
        elif isinstance(paths, six.binary_type):
            path = paths.decode()
        else:
            path = ",".join(paths)
        f = rec.reader(path)
        while True:
            r = f.read()
            if r is None:
                break
            yield pickle.loads(r)
        f.close()

    return dec.buffered(reader, buf_size)
