OPDS2 + ODL Handle case where no licenses are available (PP-1716) (#2057

)

* Fix handling of case where no copies are available.

* Fix case where there are no licenses when we think there are some.

* Updated

* Add another test case.

src/palace/manager/api/odl/api.py

@@ -266,9 +266,7 @@ def get_license_status_document(self, loan: Loan) -> dict[str, Any]:
                 f"status code {response.status_code}. Expected 2XX. Response headers: {header_string}. "
                 f"Response content: {response_string}."
             )
-            raise RemoteIntegrationException(
-                url, "License Status Document request failed."
-            ) from e
+            raise
         try:
             status_doc = json.loads(response.content)
         except ValueError as e:
@@ -424,7 +422,29 @@ def _checkout(
             raise NoAvailableCopies()
         loan, ignore = license.loan_to(patron)
 
-        doc = self.get_license_status_document(loan)
+        try:
+            doc = self.get_license_status_document(loan)
+        except BadResponseException as e:
+            _db.delete(loan)
+            response = e.response
+            # DeMarque sends "application/api-problem+json", but the ODL spec says we should
+            # expect "application/problem+json", so we need to check for both.
+            if response.headers.get("Content-Type") in [
+                "application/api-problem+json",
+                "application/problem+json",
+            ]:
+                try:
+                    json_response = response.json()
+                except ValueError:
+                    json_response = {}
+
+                if (
+                    json_response.get("type")
+                    == "http://opds-spec.org/odl/error/checkout/unavailable"
+                ):
+                    raise NoAvailableCopies()
+            raise
+
         status = doc.get("status")
 
         if status not in [self.READY_STATUS, self.ACTIVE_STATUS]:

tests/files/odl/unavailable.json

@@ -0,0 +1 @@
+{"type":"http://opds-spec.org/odl/error/checkout/unavailable","title":"the license has reached its concurrent checkouts limit","detail":"all 1 of 1 concurrent loans exceeded","status":400}

tests/manager/api/odl/test_api.py

@@ -4,6 +4,7 @@
 import json
 import urllib
 import uuid
+from functools import partial
 from typing import Any
 from unittest.mock import MagicMock
 from urllib.parse import parse_qs, urlparse
@@ -50,7 +51,7 @@
 from palace.manager.sqlalchemy.model.work import Work
 from palace.manager.sqlalchemy.util import create
 from palace.manager.util.datetime_helpers import datetime_utc, utc_now
-from palace.manager.util.http import RemoteIntegrationException
+from palace.manager.util.http import BadResponseException, RemoteIntegrationException
 from tests.fixtures.database import DatabaseTransactionFixture
 from tests.fixtures.odl import OPDS2WithODLApiFixture
 
@@ -714,6 +715,60 @@ def test_checkout_no_available_copies(
 
         assert 0 == db.session.query(Loan).count()
 
+    @pytest.mark.parametrize(
+        "response_type",
+        ["application/api-problem+json", "application/problem+json"],
+    )
+    def test_checkout_no_available_copies_unknown_to_us(
+        self,
+        db: DatabaseTransactionFixture,
+        opds2_with_odl_api_fixture: OPDS2WithODLApiFixture,
+        response_type: str,
+    ) -> None:
+        """
+        The title has no available copies, but we are out of sync with the distributor, so we think there
+        are copies available.
+        """
+        checkout = partial(
+            opds2_with_odl_api_fixture.api.checkout,
+            opds2_with_odl_api_fixture.patron,
+            "pin",
+            opds2_with_odl_api_fixture.pool,
+            MagicMock(),
+        )
+
+        # We think there are copies available.
+        opds2_with_odl_api_fixture.setup_license(concurrency=1, available=1)
+
+        # But the distributor says there are no available copies.
+        opds2_with_odl_api_fixture.mock_http.queue_response(
+            400,
+            response_type,
+            content=opds2_with_odl_api_fixture.files.sample_text("unavailable.json"),
+        )
+
+        with pytest.raises(NoAvailableCopies):
+            checkout()
+
+        assert db.session.query(Loan).count() == 0
+
+        # Test the case where we get bad JSON back from the distributor.
+        opds2_with_odl_api_fixture.mock_http.queue_response(
+            400,
+            response_type,
+            content="hot garbage",
+        )
+
+        with pytest.raises(BadResponseException):
+            checkout()
+
+        # Test the case where we just get an unknown bad response.
+        opds2_with_odl_api_fixture.mock_http.queue_response(
+            500, "text/plain", content="halt and catch fire 🔥"
+        )
+        with pytest.raises(BadResponseException):
+            checkout()
+
     def test_checkout_no_licenses(
         self,
         db: DatabaseTransactionFixture,