Add page to create new letter branding

This has a form with 3 fields - the file upload field, logo name, and an
optional logo domain. Logos need to be uploaded in `.svg` format and we
then convert this to `.png` format and upload both file types to S3 as
well as saving the letter branding details in the database.

tests/app/main/views/test_letter_branding.py

@@ -0,0 +1,228 @@
+from io import BytesIO
+
+import pytest
+from bs4 import BeautifulSoup
+from flask import current_app, url_for
+
+from app.main.views.letter_branding import get_png_file_from_svg
+from app.s3_client.s3_logo_client import LETTER_TEMP_LOGO_LOCATION
+
+
+def test_create_letter_branding_does_not_show_branding_info(logged_in_platform_admin_client):
+    response = logged_in_platform_admin_client.get(
+        url_for('.create_letter_branding')
+    )
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+
+    assert page.select_one('#logo-img > img') is None
+    assert page.select_one('#name').attrs.get('value') == ''
+    assert page.select_one('#domain').attrs.get('value') == ''
+
+
+def test_create_letter_branding_when_uploading_valid_file(
+    mocker,
+    logged_in_platform_admin_client,
+    fake_uuid
+):
+    with logged_in_platform_admin_client.session_transaction() as session:
+        user_id = session["user_id"]
+
+    filename = 'test.svg'
+    expected_temp_filename = LETTER_TEMP_LOGO_LOCATION.format(user_id=user_id, unique_id=fake_uuid, filename=filename)
+
+    mock_s3_upload = mocker.patch('app.s3_client.s3_logo_client.utils_s3upload')
+    mocker.patch('app.s3_client.s3_logo_client.uuid.uuid4', return_value=fake_uuid)
+    mock_delete_temp_files = mocker.patch('app.main.views.letter_branding.delete_letter_temp_file')
+
+    response = logged_in_platform_admin_client.post(
+        url_for('.create_letter_branding'),
+        data={'file': (BytesIO(''.encode('utf-8')), filename)},
+        follow_redirects=True
+    )
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+
+    assert page.select_one('#logo-img > img').attrs['src'].endswith(expected_temp_filename)
+    assert mock_s3_upload.called
+    mock_delete_temp_files.assert_not_called()
+
+
+def test_create_letter_branding_when_uploading_invalid_file(logged_in_platform_admin_client):
+    response = logged_in_platform_admin_client.post(
+        url_for('.create_letter_branding'),
+        data={'file': (BytesIO(''.encode('utf-8')), 'test.png')},
+        follow_redirects=True
+    )
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+
+    assert page.find('h1').text == 'Add letter branding'
+    assert page.select_one('.error-message').text.strip() == 'SVG Images only!'
+
+
+def test_create_letter_branding_deletes_temp_files_when_uploading_a_new_file(
+    mocker,
+    logged_in_platform_admin_client,
+    fake_uuid,
+):
+    with logged_in_platform_admin_client.session_transaction() as session:
+        user_id = session["user_id"]
+
+    temp_logo = LETTER_TEMP_LOGO_LOCATION.format(user_id=user_id, unique_id=fake_uuid, filename='temp.svg')
+
+    mock_s3_upload = mocker.patch('app.s3_client.s3_logo_client.utils_s3upload')
+    mock_delete_temp_files = mocker.patch('app.main.views.letter_branding.delete_letter_temp_file')
+
+    response = logged_in_platform_admin_client.post(
+        url_for('.create_letter_branding', logo=temp_logo),
+        data={'file': (BytesIO(''.encode('utf-8')), 'new.svg')},
+        follow_redirects=True
+    )
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+
+    assert mock_s3_upload.called
+    assert mock_delete_temp_files.called
+    assert page.find('h1').text == 'Add letter branding'
+
+
+def test_create_new_letter_branding_shows_preview_of_logo(
+    mocker,
+    logged_in_platform_admin_client,
+    fake_uuid
+):
+    with logged_in_platform_admin_client.session_transaction() as session:
+        user_id = session["user_id"]
+
+    temp_logo = LETTER_TEMP_LOGO_LOCATION.format(user_id=user_id, unique_id=fake_uuid, filename='temp.svg')
+
+    response = logged_in_platform_admin_client.get(
+        url_for('.create_letter_branding', logo=temp_logo)
+    )
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+
+    assert page.find('h1').text == 'Add letter branding'
+    assert page.select_one('#logo-img > img').attrs['src'].endswith(temp_logo)
+
+
+def test_create_letter_branding_shows_an_error_when_submitting_details_with_no_logo(
+    logged_in_platform_admin_client,
+    fake_uuid
+):
+    response = logged_in_platform_admin_client.post(
+        url_for('.create_letter_branding'),
+        data={
+            'name': 'Test brand',
+            'domain': 'bl.uk',
+            'operation': 'branding-details'
+        }
+    )
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+
+    assert page.find('h1').text == 'Add letter branding'
+    assert page.select_one('.error-message').text.strip() == 'You need to upload a file to submit'
+
+
+@pytest.mark.parametrize('domain', ['bl.uk', ''])
+def test_create_letter_branding_persists_logo_when_all_data_is_valid(
+    mocker,
+    logged_in_platform_admin_client,
+    fake_uuid,
+    domain
+):
+    with logged_in_platform_admin_client.session_transaction() as session:
+        user_id = session["user_id"]
+
+    temp_logo = LETTER_TEMP_LOGO_LOCATION.format(user_id=user_id, unique_id=fake_uuid, filename='test.svg')
+
+    mock_letter_client = mocker.patch('app.main.views.letter_branding.letter_branding_client')
+    mock_template_preview = mocker.patch(
+        'app.main.views.letter_branding.get_png_file_from_svg',
+        return_value='fake_png')
+    mock_persist_logo = mocker.patch('app.main.views.letter_branding.persist_logo')
+    mock_upload_png = mocker.patch('app.main.views.letter_branding.upload_letter_png_logo')
+    mock_delete_temp_files = mocker.patch('app.main.views.letter_branding.delete_letter_temp_files_created_by')
+
+    # TODO: remove platform admin page mocks once we no longer redirect there
+    mocker.patch('app.main.views.platform_admin.make_columns')
+    mocker.patch('app.main.views.platform_admin.platform_stats_api_client.get_aggregate_platform_stats')
+    mocker.patch('app.main.views.platform_admin.complaint_api_client.get_complaint_count')
+
+    response = logged_in_platform_admin_client.post(
+        url_for('.create_letter_branding', logo=temp_logo),
+        data={
+            'name': 'Test brand',
+            'domain': 'bl.uk',
+            'operation': 'branding-details'
+        },
+        follow_redirects=True
+    )
+
+    assert response.status_code == 200
+
+    mock_letter_client.create_letter_branding.assert_called_once_with(
+        domain='bl.uk', filename='{}-test'.format(fake_uuid), name='Test brand'
+    )
+    assert mock_template_preview.called
+    mock_persist_logo.assert_called_once_with(
+        temp_logo,
+        'letters/static/images/letter-template/{}-test.svg'.format(fake_uuid)
+    )
+    mock_upload_png.assert_called_once_with(
+        'letters/static/images/letter-template/{}-test.png'.format(fake_uuid),
+        'fake_png',
+        current_app.config['AWS_REGION']
+    )
+    mock_delete_temp_files.assert_called_once_with(user_id)
+
+
+def test_create_letter_branding_shows_errors_on_name_and_domain_fields(
+    logged_in_platform_admin_client,
+    fake_uuid
+):
+    with logged_in_platform_admin_client.session_transaction() as session:
+        user_id = session["user_id"]
+
+    temp_logo = LETTER_TEMP_LOGO_LOCATION.format(user_id=user_id, unique_id=fake_uuid, filename='test.svg')
+
+    response = logged_in_platform_admin_client.post(
+        url_for('.create_letter_branding', logo=temp_logo),
+        data={
+            'name': '',
+            'domain': 'example.com',
+            'operation': 'branding-details'
+        }
+    )
+
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+    error_messages = page.find_all('span', class_='error-message')
+
+    assert page.find('h1').text == 'Add letter branding'
+    assert len(error_messages) == 2
+    assert error_messages[0].text.strip() == 'This field is required.'
+    assert error_messages[1].text.strip() == 'Not a known government domain (you might need to update domains.yml)'
+
+
+def test_get_png_file_from_svg(client, mocker, fake_uuid):
+    mocker.patch.dict(
+        'flask.current_app.config',
+        {'TEMPLATE_PREVIEW_API_HOST': 'localhost', 'TEMPLATE_PREVIEW_API_KEY': 'abc'}
+    )
+    tp_mock = mocker.patch('app.main.views.letter_branding.requests_get')
+    filename = LETTER_TEMP_LOGO_LOCATION.format(user_id=fake_uuid, unique_id=fake_uuid, filename='test.svg')
+
+    get_png_file_from_svg(filename)
+
+    tp_mock.assert_called_once_with(
+        'localhost/temp-{}_{}-test.svg.png'.format(fake_uuid, fake_uuid),
+        headers={'Authorization': 'Token abc'}
+    )