Extract Spreadsheet model from app/utils.py

`app/utils.py` is a bit of a dumping ground for things we don’t have a
better place for.

We now have a place and structure for storing ‘model’ code (‘model’ in
the model, view, controller (MVC) sense of the word).

This commit moves the spreadsheet model to that place.

app/utils.py

@@ -1,20 +1,15 @@
-import csv
 import os
 import re
 import unicodedata
 from datetime import datetime, timedelta, timezone
 from functools import wraps
-from io import BytesIO, StringIO
 from itertools import chain
 from math import floor, log10
 from numbers import Number
-from os import path
 from urllib.parse import urlparse
 
 import ago
 import dateutil
-import pyexcel
-import pyexcel_xlsx
 import pytz
 from dateutil import parser
 from flask import (
@@ -53,6 +48,7 @@ from orderedset._orderedset import OrderedSet
 from werkzeug.datastructures import MultiDict
 from werkzeug.routing import RequestRedirect
 
+from app.models.spreadsheet import Spreadsheet
 from app.notify_client.organisations_api_client import organisations_client
 
 SENDING_STATUSES = ['created', 'pending', 'sending', 'pending-virus-check']
@@ -289,105 +285,6 @@ def id_safe(string):
     return email_safe(string, whitespace='-')
 
 
-class Spreadsheet():
-
-    ALLOWED_FILE_EXTENSIONS = ('csv', 'xlsx', 'xls', 'ods', 'xlsm', 'tsv')
-
-    def __init__(self, csv_data=None, rows=None, filename=''):
-
-        self.filename = filename
-
-        if csv_data and rows:
-            raise TypeError('Spreadsheet must be created from either rows or CSV data')
-
-        self._csv_data = csv_data or ''
-        self._rows = rows or []
-
-    @property
-    def as_dict(self):
-        return {
-            'file_name': self.filename,
-            'data': self.as_csv_data
-        }
-
-    @property
-    def as_csv_data(self):
-        if not self._csv_data:
-            with StringIO() as converted:
-                output = csv.writer(converted)
-                for row in self._rows:
-                    output.writerow(row)
-                self._csv_data = converted.getvalue()
-        return self._csv_data
-
-    @classmethod
-    def can_handle(cls, filename):
-        return cls.get_extension(filename) in cls.ALLOWED_FILE_EXTENSIONS
-
-    @staticmethod
-    def get_extension(filename):
-        return path.splitext(filename)[1].lower().lstrip('.')
-
-    @staticmethod
-    def normalise_newlines(file_content):
-        return '\r\n'.join(file_content.read().decode('utf-8').splitlines())
-
-    @classmethod
-    def from_rows(cls, rows, filename=''):
-        return cls(rows=rows, filename=filename)
-
-    @classmethod
-    def from_dict(cls, dictionary, filename=''):
-        return cls.from_rows(
-            zip(
-                *sorted(dictionary.items(), key=lambda pair: pair[0])
-            ),
-            filename=filename,
-        )
-
-    @classmethod
-    def from_file(cls, file_content, filename=''):
-        extension = cls.get_extension(filename)
-
-        if extension == 'csv':
-            return cls(csv_data=Spreadsheet.normalise_newlines(file_content), filename=filename)
-
-        if extension == 'tsv':
-            file_content = StringIO(
-                Spreadsheet.normalise_newlines(file_content))
-
-        instance = cls.from_rows(
-            pyexcel.iget_array(
-                file_type=extension,
-                file_stream=file_content),
-            filename)
-        pyexcel.free_resources()
-        return instance
-
-    @classmethod
-    def from_file_form(cls, form):
-        return cls.from_file(
-            form.file.data,
-            filename=form.file.data.filename,
-        )
-
-    @property
-    def as_rows(self):
-        if not self._rows:
-            self._rows = list(csv.reader(
-                StringIO(self._csv_data),
-                quoting=csv.QUOTE_MINIMAL,
-                skipinitialspace=True,
-            ))
-        return self._rows
-
-    @property
-    def as_excel_file(self):
-        io = BytesIO()
-        pyexcel_xlsx.save_data(io, {'Sheet 1': self.as_rows})
-        return io.getvalue()
-
-
 def get_help_argument():
     return request.args.get('help') if request.args.get('help') in ('1', '2', '3') else None