fix: register missing Situation endpoint route (#798)

[tejasva-vardhan]

Overview

This PR resolves #798 by properly registering the GET /api/where/situation/{id} route in the REST API. While the handler logic was present, it was not wired to the router, causing a 404/HTML fallback when requesting real-time service alerts.

Changes

• Route Registration: Registered the missing endpoint in internal/restapi/routes.go.
• Logic Implementation: Re-implemented the situationHandler to correctly fetch and format service alerts using api.extractAndValidateID.
• Data Access: Added GetAllAlerts() in internal/gtfs/realtime.go to provide access to the in-memory GTFS-RT alert store.
• Testing: Added unit tests in internal/restapi/situation_handler_test.go (verified with go test).

Verification (Before vs After)

To ensure full parity with the legacy OBA Java API, I verified the fix using both the maglev-validator and manual browser testing.

1. Maglev Validator Comparison

Local Maglev (localhost:4000) vs Production Java API (api.pugetsound.onebusaway.org).

Stage	Comparison Result
Before (Gap)
After (Fixed)

2. Browser Manual Testing

Endpoint: /api/where/situation/1_84714.json?key=test

Stage	Response Screenshot
Before (404)
After (200 OK)

---

Note for Reviewers: - Only core logic files for the fix are included in this PR.

• Windows-specific driver changes (modernc.org/sqlite) and local performance bypasses were intentionally excluded to maintain upstream standards.

[tejasva-vardhan]

@aaronbrethorst @Ahmedhossamdev would love any review on this!

[tejasva-vardhan]

@aaronbrethorst @fletcherw @Ahmedhossamdev @burma-shave would love any review on this!!

[aaronbrethorst]

Code review

Found 2 issues:

1. The branch is stale and no longer compiles against main — the green checks are from March and were run against an older base. Two symbols this PR depends on have changed since: sort was dropped from internal/gtfs/realtime.go's import block in favor of slices (PR refactor: replace sort package with slices for improved sorting performance #809, "refactor: replace sort package with slices"), so sort.Strings(feedIDs) is now undefined: sort; and Manager.AddTestAlert was renamed to AddAlertForTest (internal/gtfs/gtfs_manager.go:819), so situation_handler_test.go:45 no longer resolves. GitHub still reports the PR as MERGEABLE/CLEAN, so merging as-is would break the build on main. Needs a rebase plus slices.Sort(feedIDs) and AddAlertForTest.

maglev/internal/gtfs/realtime.go

Lines 213 to 215 in c9cfa01

	}
	sort.Strings(feedIDs)

maglev/internal/restapi/situation_handler_test.go

Lines 44 to 46 in c9cfa01

	}
	api.GtfsManager.AddTestAlert(alert)

2. The len(situations) == 0 guard is unreachable. BuildSituationReferences (internal/restapi/reference_utils.go:136) appends unconditionally once per input alert, so a one-element input always yields a one-element result. The 500 path can never be taken and has no test. (CONTRIBUTING.md says "Every new branch or condition introduced by a PR needs test coverage — untested code paths and leftover dead code are common review findings.")

maglev/internal/restapi/situation_handler.go

Lines 32 to 38 in c9cfa01

	situations := api.BuildSituationReferences([]gtfs.Alert{alert})
	if len(situations) == 0 {
	api.serverErrorResponse(w, r, fmt.Errorf("unexpected empty situation build for id %q", situationID))
	return
	}

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[aaronbrethorst]

Thanks for this, and sorry it sat for so long — that's on us, not you. The endpoint design is right: the handler shape matches our other simple-ID real-time endpoints, extractAndValidateID handles the .json suffix the way the rest of the API does, and putting GetAllAlerts on the manager with dedup-by-ID across feeds under the read lock is the correct place for that logic.

The blocker is that the branch has gone stale, and in a way that GitHub is actively hiding from us. The PR shows as mergeable with green checks, but those checks ran on 2026-03-28 against a main that no longer exists. There's no textual conflict, so nothing flags it — but merging as-is breaks the build in two places:

1. sort is no longer imported in internal/gtfs/realtime.go.

GetAllAlerts calls sort.Strings(feedIDs). Since this branch was opened, #809 ("refactor: replace sort package with slices") removed the sort import from that file — main now uses slices.Sort throughout (three call sites). Because your diff only adds a function body and doesn't touch the import block, the merge result is a file that calls sort.Strings with no sort import: undefined: sort.

Swap it for slices.Sort(feedIDs) to match the surrounding code.

2. AddTestAlert no longer exists.

situation_handler_test.go calls api.GtfsManager.AddTestAlert(alert). On main that helper is named AddAlertForTest (internal/gtfs/gtfs_manager.go:819); AddTestAlert isn't defined anywhere in the repo now. Renaming the call is the whole fix.

A rebase onto main plus those two changes should get CI running against reality again.

Two smaller things while you're in there:

• The len(situations) == 0 guard in situationHandler is unreachable. BuildSituationReferences appends exactly one Situation per input alert unconditionally, so a one-element input always yields one element. It's dead code and it's the one branch with no test — I'd just drop it.
• TestSituationHandlerWithSituation builds the alert with Header and Description but only asserts on id, reason, and severity. The translated-string fields are the ones most likely to regress silently; asserting summary and description would make the test earn its keep.

One note that isn't about your code: issue #798 claims the handler and tests already existed and just needed wiring up. That isn't true of main — neither situation_handler.go nor its test exists there, and this PR creates both. So this is a new endpoint implementation, not a one-line route registration. Worth knowing since it means there's no prior art to match, and also worth flagging that we have no spec for this endpoint: it isn't in the maglev wiki, it isn't in testdata/openapi.yml, and the docs repo only describes situation as a referenced element, not a standalone method. I'm comfortable with the envelope you chose, but if you have a reference response from a production OBA server, that'd be good to capture.

Related: references is always empty here, even though a situation's allAffects can carry agency/route/stop/trip IDs that a client would want resolved. Not a blocker given there's no spec to point at, but worth a thought.

Rebase and fix the two build breaks and I'll take another look promptly.

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Review details

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Review profile: ASSERTIVE

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Run ID: f2ca956e-a8c1-4413-9eec-8ffd11c8c15a

📥 Commits

Reviewing files that changed from the base of the PR and between 8554824 and 185369a.

📒 Files selected for processing (4)

• internal/gtfs/realtime.go
• internal/restapi/routes.go
• internal/restapi/situation_handler.go
• internal/restapi/situation_handler_test.go

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[tejasva-vardhan]

@aaronbrethorst
Rebased onto current main and addressed the review:

• slices.Sort(feedIDs) in GetAllAlerts
• AddAlertForTest in the handler test
• Dropped the unreachable len(situations) == 0 guard
• Asserted summary and description on the 200 path

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud