# Copyright (C) 2003-2005 Peter J. Verveer
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above
#    copyright notice, this list of conditions and the following
#    disclaimer in the documentation and/or other materials provided
#    with the distribution.
#
# 3. The name of the author may not be used to endorse or promote
#    products derived from this software without specific prior
#    written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
# GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

from collections.abc import Iterable
import warnings
import numpy


def _extend_mode_to_code(mode):
    """Convert an extension mode to the corresponding integer code.
    """
    if mode == 'nearest':
        return 0
    elif mode == 'wrap':
        return 1
    elif mode in ['reflect', 'grid-mirror']:
        return 2
    elif mode == 'mirror':
        return 3
    elif mode == 'constant':
        return 4
    elif mode == 'grid-wrap':
        return 5
    elif mode == 'grid-constant':
        return 6
    else:
        raise RuntimeError('boundary mode not supported')


def _normalize_sequence(input, rank):
    """If input is a scalar, create a sequence of length equal to the
    rank by duplicating the input. If input is a sequence,
    check if its length is equal to the length of array.
    """
    is_str = isinstance(input, str)
    if not is_str and isinstance(input, Iterable):
        normalized = list(input)
        if len(normalized) != rank:
            err = "sequence argument must have length equal to input rank"
            raise RuntimeError(err)
    else:
        normalized = [input] * rank
    return normalized


def _get_output(output, input, shape=None, complex_output=False):
    if shape is None:
        shape = input.shape
    if output is None:
        if not complex_output:
            output = numpy.zeros(shape, dtype=input.dtype.name)
        else:
            complex_type = numpy.promote_types(input.dtype, numpy.complex64)
            output = numpy.zeros(shape, dtype=complex_type)
    elif isinstance(output, (type, numpy.dtype)):
        # Classes (like `np.float32`) and dtypes are interpreted as dtype
        if complex_output and numpy.dtype(output).kind != 'c':
            warnings.warn("promoting specified output dtype to complex")
            output = numpy.promote_types(output, numpy.complex64)
        output = numpy.zeros(shape, dtype=output)
    elif isinstance(output, str):
        output = numpy.typeDict[output]
        if complex_output and numpy.dtype(output).kind != 'c':
            raise RuntimeError("output must have complex dtype")
        output = numpy.zeros(shape, dtype=output)
    elif output.shape != shape:
        raise RuntimeError("output shape not correct")
    elif complex_output and output.dtype.kind != 'c':
        raise RuntimeError("output must have complex dtype")
    return output