Calculate form ancillary data when fetching form data

Author: jb3

backend/routes/forms/form.py

@@ -1,9 +1,10 @@
 """Returns, updates or deletes a single form given an ID."""
 
+import enum
 import json.decoder
 
 import deepmerge
-from pydantic import ValidationError
+from pydantic import BaseModel, ValidationError
 from spectree.response import Response
 from starlette.authentication import requires
 from starlette.requests import Request
@@ -18,6 +19,33 @@
 PUBLIC_FORM_FEATURES = (constants.FormFeatures.OPEN, constants.FormFeatures.DISCOVERABLE)
 
 
+class SubmissionPrecheckSeverity(enum.StrEnum):
+    SECONDARY = "secondary"
+    WARNING = "warning"
+    DANGER = "danger"
+
+
+class SubmissionProblem(BaseModel):
+    severity: SubmissionPrecheckSeverity
+    message: str
+
+
+class SubmissionPrecheck(BaseModel):
+    problems: list[SubmissionProblem] = []
+    can_submit: bool = True
+
+
+class FormWithAncillaryData(Form):
+    """
+    Form model with ancillary data for the form.
+
+    This is used to return the form with additional information such as
+    whether the user has edit access or not.
+    """
+
+    submission_precheck: SubmissionPrecheck = SubmissionPrecheck()
+
+
 class SingleForm(Route):
     """
     Returns, updates or deletes a single form given an ID.
@@ -28,14 +56,17 @@ class SingleForm(Route):
     name = "form"
     path = "/{form_id:str}"
 
-    @api.validate(resp=Response(HTTP_200=Form, HTTP_404=ErrorMessage), tags=["forms"])
+    @api.validate(resp=Response(HTTP_200=FormWithAncillaryData, HTTP_404=ErrorMessage), tags=["forms"])
     async def get(self, request: Request) -> JSONResponse:
         """Returns single form information by ID."""
         form_id = request.path_params["form_id"].lower()
 
         if form_id == AUTH_FORM.id:
             # Empty form for login purposes
-            return JSONResponse(AUTH_FORM.dict(admin=False))
+            data = AUTH_FORM.dict(admin=False)
+            # Add in empty ancillary data
+            data["submission_precheck"] = SubmissionPrecheck().dict()
+            return JSONResponse(data)
 
         try:
             await discord.verify_edit_access(form_id, request)
@@ -53,10 +84,41 @@ async def get(self, request: Request) -> JSONResponse:
             filters["features"] = {"$in": ["OPEN", "DISCOVERABLE"]}
 
         form = await request.state.db.forms.find_one(filters)
+        form = FormWithAncillaryData(**form)
         if not form:
             return JSONResponse({"error": "not_found"}, status_code=404)
 
-        return JSONResponse(Form(**form).dict(admin=admin))
+        if constants.FormFeatures.OPEN.value not in form.features:
+            form.submission_precheck.problems.append(
+                SubmissionProblem(
+                    severity=SubmissionPrecheckSeverity.DANGER,
+                    message="This form is not open for submissions at the moment."
+                )
+            )
+            form.submission_precheck.can_submit = False
+        elif constants.FormFeatures.UNIQUE_RESPONDER.value in form.features:
+            user_id = request.user.payload["id"] if request.user.is_authenticated else None
+            if user_id:
+                existing_response = await request.state.db.responses.find_one(
+                    {"form_id": form_id, "user.id": user_id}
+                )
+                if existing_response:
+                    form.submission_precheck.problems.append(
+                        SubmissionProblem(
+                            severity=SubmissionPrecheckSeverity.DANGER,
+                            message="You have already submitted a response to this form."
+                        )
+                    )
+                    form.submission_precheck.can_submit = False
+            else:
+                form.submission_precheck.problems.append(
+                    SubmissionProblem(
+                        severity=SubmissionPrecheckSeverity.SECONDARY,
+                        message="You must login at the bottom of the page before submitting this form."
+                    )
+                )
+
+        return JSONResponse(form.dict(admin=admin))
 
     @requires(["authenticated"])
     @api.validate(