Get info about organisations from database table

This is the first step of replacing the `domains.yml` file.

In order to replicate the same functionality we get from the
`domains.yml` file and its associated code this commit adds a
`Organisation` model. This model copies a lot of methods from the
`AgreementInfo` class which wrapped the `domains.yml` file.

It factors out some stuff that would otherwise be duplicated between the
`Organisation` and `Service` model, in such a way that could be reused
for making other models in the future.

This commit doesn’t change other parts of the code to make use of this
new model yet – that will come in subsequent commits.

app/models/organisation.py

@@ -0,0 +1,140 @@
+from flask import Markup, abort
+
+from app.models import JSONModel
+
+
+class Organisation(JSONModel):
+
+    ALLOWED_PROPERTIES = {
+        'id',
+        'name',
+        'active',
+        'crown',
+        'organisation_type',
+        'letter_branding_id',
+        'email_branding_id',
+        'agreement_signed',
+        'agreement_signed_at',
+        'agreement_signed_by_id',
+        'agreement_signed_version',
+        'domains',
+    }
+
+    def __init__(self, _dict):
+
+        super().__init__(_dict)
+
+        if self._dict == {}:
+            self.name, self.crown, self.agreement_signed = None, None, None
+
+    @property
+    def crown_status(self):
+        return self.crown
+
+    @property
+    def as_human_readable(self):
+        if 'dwp.' in ''.join(self.domains):
+            return 'DWP - Requires OED approval'
+        if self.agreement_signed:
+            return 'Yes, on behalf of {}'.format(self.name)
+        elif self.owner:
+            return '{} (organisation is {}, {})'.format(
+                {
+                    False: 'No',
+                    None: 'Can’t tell',
+                }.get(self.agreement_signed),
+                self.name,
+                {
+                    True: 'a crown body',
+                    False: 'a non-crown body',
+                    None: 'crown status unknown',
+                }.get(self.crown_status),
+            )
+        else:
+            return 'Can’t tell (domain is {})'.format(self._domain)
+
+    @property
+    def as_info_for_branding_request(self):
+        return self.owner or 'Can’t tell (domain is {})'.format(self._domain)
+
+    @property
+    def as_jinja_template(self):
+        if self.crown_status is None:
+            return 'agreement-choose'
+        if self.agreement_signed:
+            return 'agreement-signed'
+        return 'agreement'
+
+    def as_terms_of_use_paragraph(self, **kwargs):
+        return Markup(self._as_terms_of_use_paragraph(**kwargs))
+
+    def _as_terms_of_use_paragraph(self, terms_link, download_link, support_link, signed_in):
+
+        if not signed_in:
+            return ((
+                '{} <a href="{}">Sign in</a> to download a copy '
+                'or find out if one is already in place.'
+            ).format(self._acceptance_required, terms_link))
+
+        if self.agreement_signed is None:
+            return ((
+                '{} <a href="{}">Download the agreement</a> or '
+                '<a href="{}">contact us</a> to find out if we already '
+                'have one in place with your organisation.'
+            ).format(self._acceptance_required, download_link, support_link))
+
+        if self.agreement_signed is False:
+            return ((
+                '{} <a href="{}">Download a copy</a>.'
+            ).format(self._acceptance_required, download_link))
+
+        return (
+            'Your organisation ({}) has already accepted the '
+            'GOV.UK&nbsp;Notify data sharing and financial '
+            'agreement.'.format(self.name)
+        )
+
+    def as_pricing_paragraph(self, **kwargs):
+        return Markup(self._as_pricing_paragraph(**kwargs))
+
+    def _as_pricing_paragraph(self, pricing_link, download_link, support_link, signed_in):
+
+        if not signed_in:
+            return ((
+                '<a href="{}">Sign in</a> to download a copy or find '
+                'out if one is already in place with your organisation.'
+            ).format(pricing_link))
+
+        if self.agreement_signed is None:
+            return ((
+                '<a href="{}">Download the agreement</a> or '
+                '<a href="{}">contact us</a> to find out if we already '
+                'have one in place with your organisation.'
+            ).format(download_link, support_link))
+
+        return (
+            '<a href="{}">Download the agreement</a> '
+            '({} {}).'.format(
+                download_link,
+                self.name,
+                {
+                    True: 'has already accepted it',
+                    False: 'hasn’t accepted it yet'
+                }.get(self.agreement_signed)
+            )
+        )
+
+    @property
+    def _acceptance_required(self):
+        return (
+            'Your organisation {} must also accept our data sharing '
+            'and financial agreement.'.format(
+                '({})'.format(self.name) if self.name else '',
+            )
+        )
+
+    @property
+    def crown_status_or_404(self):
+        if self.crown_status is None:
+            abort(404)
+        return self.crown_status