refactor(gameplay): extract start/show transitions from lobby views

lobby/views.py

@@ -1,7 +1,7 @@
-import json
-import random
 from datetime import timedelta
 
+import json
+import random
 from django.contrib.auth.decorators import login_required
 from django.db import IntegrityError, transaction
 from django.http import HttpRequest, JsonResponse
@@ -11,14 +11,10 @@ from django.views.decorators.http import require_GET, require_POST
 from fupogfakta.models import Category, GameSession, Guess, LieAnswer, Player, Question, RoundConfig, RoundQuestion, ScoreEvent
 from fupogfakta.payloads import (
     build_leaderboard as _build_leaderboard,
-    build_lie_started_payload as _build_lie_started_payload,
     build_phase_view_model as _build_phase_view_model,
-    build_question_shown_payload as _build_question_shown_payload,
-    build_question_shown_response as _build_question_shown_response,
     build_reveal_payload as _build_reveal_payload,
     build_round_question_payload as _build_round_question_payload,
     build_scoreboard_phase_event as _build_scoreboard_phase_event,
-    build_start_round_response as _build_start_round_response,
 )
 from fupogfakta.services import (
     finish_game as _finish_game,
@@ -27,7 +23,9 @@ from fupogfakta.services import (
     promote_reveal_to_scoreboard as _promote_reveal_to_scoreboard,
     resolve_scores as _resolve_scores,
     select_round_question as _select_round_question,
+    show_question as _show_question,
     start_next_round as _start_next_round,
+    start_round as _start_round,
 )
 from realtime.broadcast import sync_broadcast_phase_event
 
@@ -255,72 +253,23 @@ def start_round(request: HttpRequest, code: str) -> JsonResponse:
             status=403,
         )
 
-    if session.status != GameSession.Status.LOBBY:
-        return api_error(
-            request,
-            code="round_start_invalid_phase",
-            status=400,
-        )
-
     try:
-        category = Category.objects.get(slug=category_slug, is_active=True)
-    except Category.DoesNotExist:
-        return api_error(
-            request,
-            code="category_not_found",
-            status=404,
-        )
-
-    if not Question.objects.filter(category=category, is_active=True).exists():
-        return api_error(
-            request,
-            code="category_has_no_questions",
-            status=400,
-        )
-
-    with transaction.atomic():
-        session = GameSession.objects.select_for_update().get(pk=session.pk)
-        if session.status != GameSession.Status.LOBBY:
-            return api_error(
-                request,
-                code="round_start_invalid_phase",
-                status=400,
-            )
-
-        if RoundConfig.objects.filter(session=session, number=session.current_round).exists():
-            return api_error(
-                request,
-                code="round_already_configured",
-                status=409,
-            )
-
-        round_config = RoundConfig(
-            session=session,
-            number=session.current_round,
-            category=category,
-        )
-
-        try:
-            round_question = _select_round_question(session, round_config)
-        except ValueError as exc:
-            return api_error(request, code=str(exc), status=400)
-
-        round_config.save()
-        session.status = GameSession.Status.LIE
-        session.save(update_fields=["status"])
-
-    lie_started_payload = _build_lie_started_payload(session, round_config, round_question)
+        transition = _start_round(session, category_slug)
+    except ValueError as exc:
+        error_code = str(exc)
+        error_status = {
+            "category_not_found": 404,
+            "round_already_configured": 409,
+        }.get(error_code, 400)
+        return api_error(request, code=error_code, status=error_status)
 
     sync_broadcast_phase_event(
-        session.code,
-        "phase.lie_started",
-        lie_started_payload,
+        transition.session.code,
+        transition.phase_event_name,
+        transition.phase_event_payload,
     )
 
-    return JsonResponse(
-        _build_start_round_response(session, round_config, round_question),
-        status=201,
-    )
+    return JsonResponse(transition.response_payload, status=201)
 
 
 @require_POST
@@ -344,45 +293,18 @@ def show_question(request: HttpRequest, code: str) -> JsonResponse:
             status=403,
         )
 
-    if session.status != GameSession.Status.LIE:
-        return api_error(
-            request,
-            code="show_question_invalid_phase",
-            status=400,
-        )
-
     try:
-        round_config = RoundConfig.objects.get(session=session, number=session.current_round)
-    except RoundConfig.DoesNotExist:
-        return api_error(
-            request,
-            code="round_config_missing",
-            status=400,
-        )
-
-    existing_round_question = _get_current_round_question(session)
-    if existing_round_question is not None:
-        round_question = existing_round_question
-    else:
-        try:
-            round_question = _select_round_question(session, round_config)
-        except ValueError as exc:
-            return api_error(request, code=str(exc), status=400)
-
-    lie_deadline_at = round_question.shown_at + timedelta(seconds=round_config.lie_seconds)
-
-    lie_deadline_iso = lie_deadline_at.isoformat()
+        transition = _show_question(session)
+    except ValueError as exc:
+        return api_error(request, code=str(exc), status=400)
 
     sync_broadcast_phase_event(
-        session.code,
-        "phase.question_shown",
-        _build_question_shown_payload(round_question, lie_deadline_iso, round_config.lie_seconds),
+        transition.session.code,
+        transition.phase_event_name,
+        transition.phase_event_payload,
     )
 
-    return JsonResponse(
-        _build_question_shown_response(round_question, lie_deadline_iso, round_config.lie_seconds),
-        status=201,
-    )
+    return JsonResponse(transition.response_payload, status=201)
 
 
 @require_POST