#
#  Copyright (c) 2009 Helmut Merz helmutm@cy55.de
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
"""
Base implementation for import adapters.

$Id$
"""

import csv

from zope import component
from zope.interface import implements
from zope.cachedescriptors.property import Lazy

from cybertools.external.base import BaseReader
from cybertools.external.element import Element


class CsvReader(BaseReader):

    elementFactories = {None: Element}
    fieldNames = ()
    start = stop = None

    def read(self, input):
        result = []
        reader = csv.DictReader(input, self.fieldNames)
        lastIdentifiers = {}
        for idx, row in enumerate(list(reader)[self.start:self.stop]):
            currentElements = {}
            for k, v in row.items():
                if k is None:
                    continue
                type = None
                if '.' in k:
                    type, k = k.split('.', 1)
                element = currentElements.get(type)
                if element is None:
                    ef = self.elementFactories.get(type)
                    if ef is None:
                        raise ValueError('Missing element factory for %r.' % type)
                    element = currentElements[type] = ef()
                    element.type = type
                element[k] = v      # ?TODO: unmarshall
            for element in sorted(currentElements.values(), key=lambda x: x.order):
                id = element.identifier
                if not id or id != lastIdentifiers.get(element.type):
                    element.setParent(currentElements)
                    result.append(element)
                    lastIdentifiers[element.type] = id
        return result