Add importer for Printful Orders.csv file

import2ledger/importers/printful.py

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+import re
+
+from . import _csv
+from .. import strparse
+
+
+class SalesImporter(_csv.CSVImporterBase):
+    DECIMAL_FIELDS = {
+        'Products': 'products',
+        'Shipping': 'shipping_fees',
+        'Tax': 'tax',
+        'VAT': 'vat',
+        'Total': 'amount',
+        'Discount': 'discount',
+    }
+    NEEDED_FIELDS = {'Printful ID', *DECIMAL_FIELDS}
+    COPIED_FIELDS = {}
+    CURRENCY_MAP = {
+        '$': 'USD',
+        '€': 'EUR',
+        '£': 'GBP',
+        'AU$': 'AUD',
+        'C$': 'CAD',
+    }
+    currency_regexp = re.compile(r'-?(?P<currency>\D*)\d.*')
+
+    def __init__(self, input_file):
+        # Orders.csv file is in UTF-8-SIG encoding and begins with a byte order
+        # mark character \ufeff. This happens *after* NEEDED_FIELDS is
+        # checked. This encoding check is done conditionally to handle the
+        # situation where someone has modified the CSV and saved as UTF-8.
+        first_char = input_file.read(1)
+        input_file.seek(0)
+        if first_char == '\ufeff':
+            input_file.reconfigure(encoding='UTF-8-SIG')
+        super().__init__(input_file)
+
+    def _read_row(self, row):
+        if row['Date'].startswith('Total paid'):
+            return None
+
+        # Parse the currency values. A hyphen represents zero.
+        record = {
+            self.DECIMAL_FIELDS[key]: strparse.currency_decimal(row[key] if row[key] != '-' else '0')
+            for key in self.DECIMAL_FIELDS
+        }
+
+        # Most importers don't deal with multiple currencies. There are
+        # libraries that partly help with currency codes and symbols, but the
+        # codes/symbols Printful use have some quirks, so it's easier to do this
+        # ourselves.
+        currency_code = re.match(self.currency_regexp, row['Total']).group('currency')
+        record['currency'] = self.CURRENCY_MAP.get(currency_code, currency_code).replace('$', '')
+
+        record['date'] = strparse.date(row['Date'], '%B %d, %Y')
+        record['order_id'] = row['Order'].lstrip('Order ')
+        record['payee'] = 'Printful'  # Not used but required to be set
+        return record