[OSDEV-2068] Enable users to download their own data without impacts to free & purchased data download allowances

doc/release/RELEASE-NOTES.md

@@ -11,6 +11,8 @@ This project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html
 
 ### Code/API changes
 * [OSDEV-2137](https://opensupplyhub.atlassian.net/browse/OSDEV-2137) - Switched to a custom, page-compatible keyset for the `/facilities-downloads` endpoint, enabling more efficient, cursor-based pagination and improved download performance and compatibility.
+* [OSDEV-2068](https://opensupplyhub.atlassian.net/browse/OSDEV-2068) - Enabled users to download their own data without impacting free & purchased data-download allowances. Introduced `is_same_contributor` field in the GET `/api/facilities-downloads` response.
+
 
 ### Release instructions
 * Ensure that the following commands are included in the `post_deployment` command:

src/django/api/facilities_download_view_set.py

@@ -9,6 +9,7 @@
     FacilityDownloadSerializerEmbedMode
 from api.serializers.utils import get_embed_contributor_id_from_query_params
 from api.services.facilities_download_service import FacilitiesDownloadService
+from api.serializers.facility.utils import is_same_contributor_for_queryset
 from api.constants import PaginationConfig
 
 
@@ -44,10 +45,17 @@ def list(self, request):
 
         base_qs = FacilitiesDownloadService.get_filtered_queryset(request)
 
+        is_same_contributor = is_same_contributor_for_queryset(
+            base_qs,
+            request
+        )
+
         limit = None
+
         if (
             not switch_is_active('private_instance')
             and not self.__is_embed_mode()
+            and not is_same_contributor
         ):
             limit = FacilitiesDownloadService.get_download_limit(request)
 
@@ -78,9 +86,14 @@ def list(self, request):
             )
 
         list_serializer = self.get_serializer(items)
-        rows = [f['row'] for f in list_serializer.data]
+        rows = [facility_data['row'] for facility_data in list_serializer.data]
         headers = list_serializer.child.get_headers()
-        data = {'rows': rows, 'headers': headers}
+
+        data = {
+            'rows': rows,
+            'headers': headers,
+            'is_same_contributor': is_same_contributor
+        }
 
         payload = {
             'next': next_link,
@@ -94,18 +107,23 @@ def list(self, request):
             payload['count'] = base_qs.count()
 
         if is_last_page and limit:
-            total_records = (page - 1) * page_size + len(items)
-            prev_free = getattr(limit, 'free_download_records', 0)
-            prev_paid = getattr(limit, 'paid_download_records', 0)
+            # Charge for the full result set, not just the last page size
+            returned_count = base_qs.count()
+
+            prev_free_amount = getattr(limit, 'free_download_records', 0)
+            prev_paid_amount = getattr(limit, 'paid_download_records', 0)
+
             FacilitiesDownloadService.register_download_if_needed(
                 limit,
-                total_records
-            )
-            FacilitiesDownloadService.send_email_if_needed(
-                request,
-                limit,
-                prev_free,
-                prev_paid
+                returned_count,
+                is_same_contributor
             )
+            if returned_count:
+                FacilitiesDownloadService.send_email_if_needed(
+                    request,
+                    limit,
+                    prev_free_amount,
+                    prev_paid_amount
+                )
 
         return Response(payload)

src/django/api/models/facility_download_limit.py

@@ -53,17 +53,34 @@ class FacilityDownloadLimit(models.Model):
     objects = FacilityDownloadLimitManager()
 
     @transaction.atomic
-    def register_download(self, records_to_subtract):
+    def register_download(
+        self,
+        records_to_subtract: int,
+    ):
         self.refresh_from_db()
 
-        if self.free_download_records >= records_to_subtract:
-            self.free_download_records -= records_to_subtract
+        # Prevent overdrafts by capping to remaining quota
+        remaining_quota = (self.free_download_records or 0) + \
+            (self.paid_download_records or 0)
+        to_subtract = min(
+            max(records_to_subtract, 0),
+            remaining_quota
+        )
+
+        if to_subtract == 0:
+            return
+
+        if self.free_download_records >= to_subtract:
+            self.free_download_records -= to_subtract
         else:
             remaining_records = (
-                records_to_subtract - self.free_download_records
+                to_subtract - self.free_download_records
             )
             self.free_download_records = 0
-            self.paid_download_records -= remaining_records
+            self.paid_download_records = max(
+                self.paid_download_records - remaining_records,
+                0
+            )
 
         self.save()
 

src/django/api/serializers/facility/utils.py

@@ -1,4 +1,4 @@
-from typing import Union
+from typing import (Iterable, Union)
 from itertools import groupby
 
 from api.constants import FacilityClaimStatuses
@@ -346,3 +346,22 @@ def add_http_prefix_to_url(value: str) -> str:
     ):
         value = f"https://{value}"
     return value
+
+
+def is_same_contributor_for_queryset(queryset: Iterable, request) -> bool:
+    contributor = getattr(request.user, 'contributor', None)
+    if not contributor:
+        return False
+    current_user_contributor_id = contributor.id
+
+    found_any_facility = False
+    for facility in queryset:
+        found_any_facility = True
+        facility_contributor_ids = [
+            contributor.get('id') for contributor in facility.contributors
+            if contributor.get('id') is not None
+        ]
+        if current_user_contributor_id not in facility_contributor_ids:
+            return False
+
+    return found_any_facility

src/django/api/services/facilities_download_service.py

@@ -95,9 +95,28 @@ def enforce_limits(qs, limit, is_first_page):
             )
 
     @staticmethod
-    def register_download_if_needed(limit, record_count):
-        if limit:
-            limit.register_download(record_count)
+    def check_pagination(page_queryset):
+        if page_queryset is None:
+            raise ValidationError("Invalid pageSize parameter")
+        return page_queryset
+
+    @staticmethod
+    def register_download_if_needed(
+        limit: FacilityDownloadLimit,
+        records_returned: int,
+        is_same_contributor: bool = False
+    ):
+        if is_same_contributor or not limit:
+            return
+        try:
+            count = int(records_returned)
+        except (TypeError, ValueError):
+            count = 0
+
+        if count <= 0:
+            return
+
+        limit.register_download(count)
 
     @staticmethod
     def send_email_if_needed(