import csv

from . import _csv

from .. import strparse

class PaymentImporter(_csv.CSVImporterBase):

    DATE_FIELD = 'Date of Donation'

    NAME_FIELDS = ['Donor First Name', 'Donor Last Name']

    DECIMAL_FIELDS = {

        'Donation Amount': 'donation_amount',

        'Matched Amount': 'match_amount',

        'Total': 'amount',

    }

    NEEDED_FIELDS = frozenset([

        DATE_FIELD,

        *NAME_FIELDS,

        *DECIMAL_FIELDS,

    ])

    COPIED_FIELDS = {

        'Participating Corporation': 'corporation',

        'Project': 'project',

        'Comment': 'comment',

        'Transaction ID': 'transaction_id',

        'Donation Frequency': 'frequency',

    }

    TEMPLATE_KEY = 'template benevity payments'

    DATE_FMT = '%Y-%m-%d'

    NOT_SHARED = 'Not shared by donor'

    @classmethod

    def _read_header(cls, source):

        needed_keys = cls.NEEDED_FIELDS.union(cls.COPIED_FIELDS)

        header = {}

        for row in csv.reader(source):

            row_len = len(row)

            if row_len < 2:

                pass

            elif row_len == 2:

                header[row[0]] = row[1]

            elif needed_keys.issubset(row):

                return header, csv.DictReader(source, row)

            else:

                break

        raise ValueError("source is not a Benevity CSV")

    @classmethod

    def can_import(cls, input_file):

        try:

            header, _ = cls._read_header(input_file)

        except ValueError:

            return False

        else:

            return bool(header)

    def __init__(self, input_file):

        header, self.in_csv = self._read_header(input_file)

        self.entry_seed = {

            'currency': header['Currency'],

            'disbursement_id': header['Disbursement ID'],

            'reference': header['Payment Reference'],

        }

    def _read_row(self, row):

        try:

            date = strparse.date(row[self.DATE_FIELD], self.DATE_FMT)

        except ValueError:

            return None

        if all(row[key] == self.NOT_SHARED for key in self.NAME_FIELDS):

            payee = 'Anonymous'

        else:

            payee = ' '.join(row[key] for key in self.NAME_FIELDS)

        retval = {

            'date': date,

            'payee': payee,

        }

        retval.update((retkey, strparse.currency_decimal(row[rowkey]))

                      for rowkey, retkey in self.DECIMAL_FIELDS.items())

        return retval