#  Copyright (c) 2005 Gavin E. Crooks <gec@threeplusone.com>
#
#  This software is distributed under the MIT Open Source License.
#  <http://www.opensource.org/licenses/mit-license.html>
#
#  Permission is hereby granted, free of charge, to any person obtaining a
#  copy of this software and associated documentation files (the "Software"),
#  to deal in the Software without restriction, including without limitation
#  the rights to use, copy, modify, merge, publish, distribute, sublicense,
#  and/or sell copies of the Software, and to permit persons to whom the
#  Software is furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included
#  in all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#  THE SOFTWARE.
#


"""Extra utilities and core classes not in standard python.
"""

import pkg_resources

__all__ = ('isblank', 'isfloat', 'isint', 'ischar',
           'remove_whitespace', 'invert_dict', 'stdrepr',
           'Token', 'Reiterate', 'deoptparse', 'crc32',
           'crc64', 'FileIndex',
           'ArgumentError', 'group_count',
           'resource_string', 'resource_stream', 'resource_filename')


def isblank(s):
    """Is this whitespace or an empty string?"""
    if isinstance(s, str):
        if not s:
            return True
        else:
            return s.isspace()
    else:
        return False


def isfloat(s):
    """Does this object represent a floating point number? """
    try:
        float(s)
        return True
    except (ValueError, TypeError):
        return False


def isint(s):
    """Does this object represent an integer?"""
    try:
        int(s)
        return True
    except (ValueError, TypeError):
        return False


def ischar(s):
    """Does this object represent a character?"""
    # Adapted from: https://stackoverflow.com/a/14321721 and
    # https://mail.python.org/pipermail/python-list/2007-March/425058.html
    return isinstance(s, str) and bool(s) and s == len(s) * s[0]


def remove_whitespace(astring):
    """Remove all whitespace from a string."""
    # TODO: Is this horrible slow?
    return "".join(astring.split())


def invert_dict(dictionary):
    """Constructs a new dictionary with inverted mappings so that keys
    become values and vice versa. If the values of the original dictionary
    are not unique then only one of the original keys will be included
    in the new dictionary.
    """
    return dict((value, key) for key, value in dictionary.items())


def stdrepr(obj, attributes=None, name=None):
    """Create a standard representation of an object."""
    if name is None:
        name = obj.__class__.__name__
    if attributes is None:
        attributes = obj.__class__.__slots__
    args = []
    for a in attributes:
        if a[0] == '_':
            continue        # pragma: no cover
        args.append('%s=%s' % (a, repr(getattr(obj, a))))
    args = ',\n'.join(args).replace('\n', '\n    ')
    return '%s(\n    %s\n)' % (name, args)


def group_count(i):
    """An iteration that returns tuples of items and the number of consecutive
    occurrences. Thus group_count('aabbbc') yields ('a',2), ('b',3), ('c',1)
    """
    from itertools import groupby
    return [(item, sum(1 for n in group)) for item, group in groupby(i)]


class Token(object):
    """Represents the items returned by a file scanner, normally processed
    by a parser.

    Attributes :
    o typeof    -- a string describing the kind of token
    o data      -- the value of the token
    o lineno    -- the line of the file on which the data was found (if known)
    o offset    -- the offset of the data within the line (if known)
    """
    __slots__ = ['typeof', 'data', 'lineno', 'offset']

    def __init__(self, typeof, data=None, lineno=-1, offset=-1):
        self.typeof = typeof
        self.data = data
        self.lineno = lineno
        self.offset = offset

    def __repr__(self):
        return stdrepr(self)

    def __str__(self):
        coord = str(self.lineno)
        if self.offset != -1:
            coord += ':' + str(self.offset)
        coord = coord.ljust(7)
        return ((coord + '  ' + self.typeof + ' : ').ljust(32) +
                str(self.data or ''))


class Reiterate(object):
    """ A flexible wrapper around a simple iterator.
    """

    def __new__(cls, iterator):
        if isinstance(iterator, cls):
            return iterator
        new = object.__new__(cls)
        new._iterator = iter(iterator)
        new._stack = []
        new._index = 0
        return new

    def __init__(self, *args, **kw):
        pass

    def __iter__(self):
        return self

    def __next__(self):
        """Return the next item in the iteration."""
        self._index += 1
        if self._stack:
            return self._stack.pop()
        else:
            return next(self._iterator)

    next = __next__

    def index(self):
        """The number of items returned. Incremented by next(), decremented
        by push(), unchanged by peek()  """
        return self._index

    def push(self, item):
        """Push an item back onto the top of the iterator,"""
        self._index -= 1
        self._stack.append(item)

    def peek(self):
        """Returns the next item, but does not advance the iteration.
        Returns None if no more items. (Bit may also return None as the
        next item.)"""
        try:
            item = next(self)
            self.push(item)
            return item
        except StopIteration:
            return None

    def has_item(self):
        """More items to return?"""
        try:
            item = next(self)
            self.push(item)
            return True
        except StopIteration:
            return False


# End class Reiterate


def crc32(string: str) -> str:
    """Return the standard CRC32 checksum as a hexidecimal string."""
    import binascii
    return "%08X" % binascii.crc32(string.encode())


_crc64_table = None


def crc64(string: str) -> str:
    """ Calculate ISO 3309 standard cyclic redundancy checksum.
    Used, for example, by SWISS-PROT.

    Returns : The CRC as a hexadecimal string.

    Reference:
    o W. H. Press, S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery,
     "Numerical recipes in C", 2nd ed., Cambridge University Press.
     Pages 896ff.
    """
    # Adapted from biopython, which was adapted from bioperl
    global _crc64_table
    if _crc64_table is None:
        # Initialisation of CRC64 table
        table = []
        for i in range(256):
            k = i
            part_h = 0
            for j in range(8):
                rflag = k & 1
                k >>= 1
                if part_h & 1:
                    k |= (1 << 31)      # pragma: no cover
                part_h >>= 1
                if rflag:
                    part_h ^= 0xd8000000
            table.append(part_h)
        _crc64_table = tuple(table)

    crcl = 0
    crch = 0
    for c in string:
        shr = (crch & 0xFF) << 24
        temp1h = crch >> 8
        temp1l = (crcl >> 8) | shr
        idx = (crcl ^ ord(c)) & 0xFF
        crch = temp1h ^ _crc64_table[idx]
        crcl = temp1l

    return "%08X%08X" % (crch, crcl)

# End crc64


class FileIndex(object):
    """Line based random access to a file. Quickly turn a file into a read-only
    database.

    Attr:
    - indexfile -- The file to be indexed. Can be set to None and latter
                replaced with a new file handle, for exampel, if you need to
                close and latter reopen the file.

    Bugs:
        User must set the indexedfile to None before pickling this class.

    """
    __slots__ = ['indexedfile', '_parser', '_positions', '_keys', '_key_dict']

    def __init__(self, indexedfile, linekey=None, parser=None):
        """

        Args:
        - indexedfile -- The file to index
        - linekey -- An optional function. keyofline() will be passed each line
            of the file in turn and should return a string to index the line,
            or None. If keyofline() is supplied, then only lines that generate
            keys are indexed.
        - parser -- An optional parser. A function that reads from a file
            handle positioned at the start of a record and returns an object.
        """

        def default_parser(seekedfile):
            return seekedfile.readline()

        if parser is None:
            parser = default_parser
        self._parser = parser

        indexedfile.seek(0)
        positions = []
        keys = []

        while True:
            position = indexedfile.tell()
            line = indexedfile.readline()
            if line == '':
                break

            if linekey:
                k = linekey(line)
                if k is None:
                    continue
                keys.append(k)

            positions.append(position)

        self.indexedfile = indexedfile
        self._positions = tuple(positions)

        if linekey:
            self._keys = tuple(keys)
            self._key_dict = dict(zip(keys, positions))

    def tell(self, item):
        if isinstance(item, str):
            p = self._key_dict[item]
        else:
            p = self._positions[item]
        return p

    # def seek(self, item):
    #     """Seek the indexfile to the position of item."""
    #     self.indexedfile.seek(self.tell(item))

    def __iter__(self):
        for i in range(0, len(self)):
            yield self[i]

    def __len__(self):
        return len(self._positions)

    def __getitem__(self, item):
        self.indexedfile.seek(self.tell(item))
        return self._parser(self.indexedfile)

    def __contains__(self, item):
        try:
            self.tell(item)
            return True
        except KeyError:
            return False
        except IndexError:
            return False

# End class FileIndex


class ArgumentError(ValueError):
    """ A subclass of ValueError raised when a function receives an argument
    that has the right type but an inappropriate value, and the situation is
    not described by a more precise exception such as IndexError. The name of
    the argument or component at fault and (optionally) the value
    are also stored.
    """

    def __init__(self, message, key, value=None):
        """ Args:
        - msg -- An error message.
        - key -- The name of the argument or component at fault.
        - value -- Optional value of the argument.
        """
        ValueError.__init__(self, key, message)
        # Changed .message to .msg because of deprecation warning in python 2.6
        self.msg = message
        self.key = key
        self.value = value

# end class ArgumentError


# TODO: Replace with direct calls to pkg_resources
def resource_string(modulename, resource, basefilename=None):
    """Locate and return a resource as a string.
    >>> f = resource_string( __name__, 'somedatafile', __file__)
    """
    return pkg_resources.resource_string(modulename, resource)


def resource_stream(modulename, resource, basefilename=None):
    """Locate and return a resource as a stream.
    >>> f = resource_stream( __name__, 'somedatafile', __file__)
    """
    return open(resource_filename(modulename, resource, basefilename))


def resource_filename(modulename, resource, basefilename=None):
    """Locate and return a resource filename.
    >>> f = resource_filename( __name__, 'somedatafile', __file__)
    """
    return pkg_resources.resource_filename(modulename, resource)