Shields (#17)

* First attempt

* Working

* Tweak the mode handling a bit

frog_api/views/data.py

@@ -93,6 +93,53 @@ class ProjectDataView(APIView):
         return Response({project_slug: versions})
 
 
+def get_progress_shield(
+    request: Request, project_slug: str, version_slug: str, category_slug: str
+) -> dict[str, Any]:
+    latest = get_latest_entry(project_slug, version_slug, "default")
+
+    project = get_project(project_slug)
+    version = get_version(version_slug, project)
+    category = get_category(category_slug, version)
+
+    params = request.query_params
+    if not params:
+        raise InvalidDataException("No measure or total specified")
+
+    try:
+        measure = params["measure"]
+        numerator = latest[0]["measures"][measure]
+    except:
+        raise InvalidDataException("No measure specified")
+
+    label = params.get(
+        "label",
+        " ".join(
+            [
+                version.name,
+                category.name,
+                str(measure),
+            ]
+        ),
+    )
+
+    try:
+        total = params["total"]
+        denominator = latest[0]["measures"][total]
+    except:
+        raise InvalidDataException("No total specified")
+
+    fraction = float(numerator) / float(denominator)
+    message = f"{fraction:.2%}"
+
+    color = params.get("color", "yellow" if fraction < 1.0 else "green")
+
+    return {"schemaVersion": 1, "label": label, "message": message, "color": color}
+
+
+VALID_MODES: set[str] = {"latest", "all", "shield"}
+
+
 class VersionDataView(APIView):
     """
     API endpoint that returns data for overall progress for a version of a project.
@@ -145,10 +192,19 @@ class VersionDataView(APIView):
         category_slug = DEFAULT_CATEGORY_SLUG
 
         mode = self.request.query_params.get("mode", "latest")
+        if mode not in VALID_MODES:
+            raise InvalidDataException(f"Invalid mode specified: {mode}")
+
         if mode == "latest":
             entries = get_latest_entry(project_slug, version_slug, category_slug)
         elif mode == "all":
             entries = get_all_entries(project_slug, version_slug, category_slug)
+        elif mode == "shield":
+            return Response(
+                get_progress_shield(
+                    self.request, project_slug, version_slug, category_slug
+                )
+            )
 
         response_json = {project_slug: {version_slug: {category_slug: entries}}}
 
@@ -181,10 +237,19 @@ class CategoryDataView(APIView):
         """
 
         mode = self.request.query_params.get("mode", "latest")
+        if mode not in VALID_MODES:
+            raise InvalidDataException(f"Invalid mode specified: {mode}")
+
         if mode == "latest":
             entries = get_latest_entry(project_slug, version_slug, category_slug)
         elif mode == "all":
             entries = get_all_entries(project_slug, version_slug, category_slug)
+        elif mode == "shield":
+            return Response(
+                get_progress_shield(
+                    self.request, project_slug, version_slug, category_slug
+                )
+            )
 
         response_json = {project_slug: {version_slug: {category_slug: entries}}}