Source code for matrixb.source

# file matrixb/source/__init__.py

# Copyright (c) 2019-2020 Kevin Crouse
#
# 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.
#
# @license: http://www.apache.org/licenses/LICENSE-2.0
# @author: Kevin Crouse (krcrouse@gmail.com)


from .base import SourceBase
#from .matrix import Matrix
from .resident import Resident
from .csv import CSV
from .googlesheet import GoogleSheet
from .xls import XLS
from .xlsx import XLSX


import re
import os

def find_source_class(extension=None, filename=None):
    """ Returns a valid source class given the paramers passed in.

    Args:
        extension (str, optional): The file extension the source class is based on. Should be just the extension. Case insensitive; the 'period' is allowed, but not expected). Examples: 'CSV', 'xlsx', '.ods')
        filename (str, optional): A full filename, form which the extension will be extracted.

    Returns:
        A matrixb.source.SourceBase class for the given extension, if one exists.
        None if the extension is identified but no source class exists.

    Raises:
        Exception if no extension could be determined."""

    if extension:
        if extension[0] == '.':
            extension = extension[1:]
        extension = extension.upper().strip()
    elif not filename:
        raise Exception("No parameters were passed into find_source_class. extension or filename is required.")
    else:
        extre = re.search(r'\.(\w+)$', filename)
        if not extre:
            raise Exception("failed to identify correct source module for file named '"+filename+"'. matrixb can only load files of known types with appropriate extensions - build the source by hand for custom filenames.")
        extension = extre.group(1).upper()

    # see if it is a class loaded into the matrixb.source namespace
    if extension in globals():
        srccls = globals()[extension]
        if not issubclass(srccls, SourceBase):
            raise Exception("Extension " + extension + " appears to have a module/class that matches it, but is not a subclass of SourceBase.")
        return(srccls)
    return

def factory(source, *args, **kwargs):
    """A function to allow for the generic import of any file-based source.

    Args:
        source: A key that determines the source. The following are recognized. For any other source type, instantiate the source object directly:
            1. filename with a known extension (csv, ods, xls, xlsx)
            2. matrix (list of lists)
            3. A Google Spreadsheet ID. It is assumed that an alphanumeric character string of >10 characters that matches \w{10,} is such a sheet.
        All other parameters are delegated to the matrix source class without validation. It is assumed that the source class or subclass will handle them.

    Returns:
        An object that is the appropriate descendant of SourceBase.
    """

    if type(source) is list:
        if type(source[0]) is list:
            return Resident(source, **kwargs)
        else:
            raise Exception("Cannot auto-identify the source for a single-dimenson list")

    if type(source) is not str:
        raise Exception("Expecting the type provided to the matrix source to be a matrix or a string")

    extmatch = re.search(r'\.(\w+)$', source)
    if not extmatch:
        # check for google sheet
        if re.match(r'\w{10,}', source):
            return(GoogleSheet(source, *args, **kwargs))
        else:
            raise Exception("Cannot identify an extension or valid source for " + str(source))

    extension = extmatch.group(1).upper()
    if extension not in globals():
        raise Exception("Cannot find a built-in matrix source class to handle extension " + extension.lower())
    source_class = globals()[extension]
    return(source_class(source, *args, **kwargs))

class Importer():
    """ Kept to maintain legacy code """
    def __new__(cls, *args, **kwargs):
        source = factory(*args, **kwargs)
        return(source)