remove pdf/png code from admin app entirely

while PDFs work on paas, they only do that because it turns out the
python buildpack happens to have imagemagick preinstalled - if that
ever changes then it'd break. so move those to the template preview
service. This also means we can get rid of weazyprint and wand
dependencies

app/main/views/send.py

@@ -19,7 +19,6 @@ from flask import (
 )
 
 from flask_login import login_required, current_user
-from flask_weasyprint import HTML, render_pdf
 
 from notifications_utils.columns import Columns
 from notifications_utils.recipients import RecipientCSV, first_column_headings, validate_and_format_phone_number
@@ -36,9 +35,9 @@ from app.utils import (
     get_errors_for_csv,
     Spreadsheet,
     get_help_argument,
-    get_template,
+    get_template
-    png_from_pdf,
 )
+from app.template_previews import TemplatePreview
 
 
 def get_page_headings(template_type):
@@ -291,24 +290,14 @@ def check_messages(service_id, template_type, upload_id):
     )
 
 
-@main.route("/services/<service_id>/<template_type>/check/<upload_id>.pdf", methods=['GET'])
+@main.route("/services/<service_id>/<template_type>/check/<upload_id>.<filetype>", methods=['GET'])
 @login_required
 @user_has_permissions('send_texts', 'send_emails', 'send_letters')
-def check_messages_as_pdf(service_id, template_type, upload_id):
+def check_messages_preview(service_id, template_type, upload_id, filetype):
     template = _check_messages(
         service_id, template_type, upload_id, letters_as_pdf=True
     )['template']
-    return render_pdf(HTML(string=str(template)))
+    return TemplatePreview.from_utils_template(template, filetype)
-
-
-@main.route("/services/<service_id>/<template_type>/check/<upload_id>.png", methods=['GET'])
-@login_required
-@user_has_permissions('send_texts', 'send_emails', 'send_letters')
-def check_messages_as_png(service_id, template_type, upload_id):
-    return send_file(**png_from_pdf(
-        check_messages_as_pdf(service_id, template_type, upload_id)
-    ))
-
 
 @main.route("/services/<service_id>/<template_type>/check/<upload_id>", methods=['POST'])
 @login_required

app/main/views/templates.py

@@ -1,6 +1,5 @@
 from datetime import datetime, timedelta
 from string import ascii_uppercase
-from io import StringIO
 
 from flask import (
     request,
@@ -9,21 +8,17 @@ from flask import (
     url_for,
     flash,
     abort,
-    send_file,
-    current_app
 )
 from flask_login import login_required, current_user
-from flask_weasyprint import HTML, render_pdf
 from dateutil.parser import parse
-import requests
 
 from notifications_utils.formatters import escape_html
-from notifications_utils.template import LetterPreviewTemplate
 from notifications_utils.recipients import first_column_headings
 from notifications_python_client.errors import HTTPError
 
 from app.main import main
-from app.utils import user_has_permissions, get_template, png_from_pdf
+from app.utils import user_has_permissions, get_template
+from app.template_previews import TemplatePreview
 from app.main.forms import (
     ChooseTemplateType,
     SMSTemplateForm,
@@ -89,37 +84,12 @@ def view_template(service_id, template_id):
     )
 
 
-def get_template_preview(service_id, template_id, filetype):
+@main.route("/services/<service_id>/templates/<template_id>.<filetype>")
+@login_required
+@user_has_permissions('view_activity', admin_override=True)
+def view_letter_template_as_filetype(service_id, template_id, filetype):
     db_template = service_api_client.get_service_template(service_id, template_id)['data']
-    data = {
+    return TemplatePreview.from_database_object(db_template, filetype)
-        "letter_contact_block": current_service['letter_contact_block'],
-        "admin_base_url": current_app.config['ADMIN_BASE_URL'],
-        "template": db_template,
-        "values": None
-    }
-    resp = requests.post(
-        '{}/preview.{}'.format(current_app.config['TEMPLATE_PREVIEW_SERVICE_URL'], filetype),
-        json=data,
-        headers={'Authorization': 'Token my-secret-key'}
-    )
-    return resp
-
-
-@main.route("/services/<service_id>/templates/<template_id>.pdf")
-@login_required
-@user_has_permissions('view_activity', admin_override=True)
-def view_letter_template_as_pdf(service_id, template_id):
-    resp = get_template_preview(service_id, template_id, 'pdf')
-    return (resp.content, resp.status_code, resp.headers.items())
-
-
-@main.route("/services/<service_id>/templates/<template_id>.png")
-@login_required
-@user_has_permissions('view_activity', admin_override=True)
-def view_letter_template_as_png(service_id, template_id):
-    resp = get_template_preview(service_id, template_id, 'png')
-    return (resp.content, resp.status_code, resp.headers.items())
-
 
 def _view_template_version(service_id, template_id, version, letters_as_pdf=False):
     return dict(template=get_template(
@@ -153,7 +123,7 @@ def view_template_version(service_id, template_id, version):
     )
 
 
-@main.route("/services/<service_id>/templates/<template_id>/version/<int:version>.pdf")
+@main.route("/services/<service_id>/templates/<template_id>/version/<int:version>.<filetype>")
 @login_required
 @user_has_permissions(
     'view_activity',
@@ -164,31 +134,9 @@ def view_template_version(service_id, template_id, version):
     admin_override=True,
     any_=True
 )
-def view_template_version_as_pdf(service_id, template_id, version):
+def view_template_version_preview(service_id, template_id, version, filetype):
-    return render_pdf(HTML(string=str(
+    db_template = service_api_client.get_service_template(service_id, template_id, version=version)['data']
-        LetterPreviewTemplate(
+    return TemplatePreview.from_database_object(db_template, filetype)
-            service_api_client.get_service_template(service_id, template_id, version=version)['data'],
-            contact_block=current_service['letter_contact_block'],
-            admin_base_url=current_app.config['ADMIN_BASE_URL']
-        )
-    )))
-
-
-@main.route("/services/<service_id>/templates/<template_id>/version/<int:version>.png")
-@login_required
-@user_has_permissions(
-    'view_activity',
-    'send_texts',
-    'send_emails',
-    'manage_templates',
-    'manage_api_keys',
-    admin_override=True,
-    any_=True
-)
-def view_template_version_as_png(service_id, template_id, version):
-    return send_file(**png_from_pdf(
-        view_template_version_as_pdf(service_id, template_id, version)
-    ))
 
 
 @main.route("/services/<service_id>/templates/add", methods=['GET', 'POST'])

app/template_previews.py

@@ -1,17 +1,29 @@
-from flask import current_app, current_service
+from flask import current_app
 import requests
 
+from app import current_service
 
-def get_template_preview(template, filetype):
+
-    data = {
+class TemplatePreview:
-        "letter_contact_block": current_service['letter_contact_block'],
+    @classmethod
-        "admin_base_url": current_app.config['ADMIN_BASE_URL'],
+    def from_database_object(cls, template, filetype, values=None):
-        "template": template,
+        data = {
-        "values": None
+            "letter_contact_block": current_service['letter_contact_block'],
-    }
+            "admin_base_url": current_app.config['ADMIN_BASE_URL'],
-    resp = requests.post(
+            "template": template,
-        '{}/preview.{}'.format(current_app.config['TEMPLATE_PREVIEW_SERVICE_URL'], filetype),
+            "values": values
-        json=data,
+        }
-        headers={'Authorization': 'Token my-secret-key'}
+        resp = requests.post(
-    )
+            '{}/preview.{}'.format(current_app.config['TEMPLATE_PREVIEW_SERVICE_URL'], filetype),
-    return (resp.content, resp.status_code, resp.headers.items())
+            json=data,
+            headers={'Authorization': 'Token my-secret-key'}
+        )
+        return (resp.content, resp.status_code, resp.headers.items())
+
+    @classmethod
+    def from_utils_template(cls, template, filetype):
+        return cls.from_database_object(
+            template._template,
+            filetype,
+            template.values
+        )

app/utils.py

@@ -16,8 +16,6 @@ from flask import (
 )
 from flask_login import current_user
 
-from wand.image import Image
-
 from notifications_utils.template import (
     SMSPreviewTemplate,
     EmailPreviewTemplate,
@@ -327,21 +325,6 @@ def get_template(
             )
 
 
-def png_from_pdf(pdf_endpoint):
-    output = BytesIO()
-    with Image(
-        blob=pdf_endpoint.get_data(),
-        resolution=150,
-    ) as image:
-        with image.convert('png') as converted:
-            converted.save(file=output)
-    output.seek(0)
-    return dict(
-        filename_or_fp=output,
-        mimetype='image/png',
-    )
-
-
 def get_current_financial_year():
     now = datetime.utcnow()
     current_month = int(now.strftime('%-m'))

requirements.txt

@@ -4,9 +4,7 @@ Flask==0.10.1
 Flask-Script==2.0.5
 Flask-WTF==0.11
 Flask-Login==0.3.2
-Flask-WeasyPrint==0.5
 
-html5lib==1.0b10
 credstash==1.8.0
 boto3==1.4.4
 Pygments==2.0.2
@@ -20,7 +18,6 @@ pyexcel-xlsx==0.1.0
 pyexcel-ods3==0.1.1
 pytz==2016.4
 six==1.10.0
-wand==0.4.4
 gunicorn==19.6.0
 whitenoise==1.0.6  #manages static assets