Add controlled service catalogue merge workflow

app/modules/services/ui.py

@@ -1,7 +1,5 @@
 from __future__ import annotations
 
-from datetime import datetime, timezone
-
 from fastapi import APIRouter, File, Form, Request, UploadFile
 from fastapi.responses import FileResponse, RedirectResponse, StreamingResponse
 from sqlalchemy import select
@@ -32,7 +30,7 @@ from app.modules.services.due_dates import (
     list_due_rules,
     parse_optional_date,
 )
-from app.modules.services.catalogue_export import build_service_catalogue_export
+from app.modules.services.catalogue_merge import build_merge_preview, merge_service_catalogues
 from app.modules.services.task_documents import (
     create_task_document_requirement,
     get_task_document_requirement,
@@ -335,8 +333,8 @@ def catalogue_list(request: Request, q: str = '', category_id: int | None = None
         db.close()
 
 
-@router.get('/catalogue/export')
-def catalogue_export(request: Request):
+@router.get('/catalogue/merge')
+def catalogue_merge_page(request: Request, source_id: int | None = None, target_id: int | None = None):
     db = CommonSessionLocal()
     try:
         user = get_current_user(request, db=db)
@@ -344,15 +342,88 @@ def catalogue_export(request: Request):
             return RedirectResponse(url='/login', status_code=303)
         if not _is_system_admin(db, user):
             return _redirect_denied()
-        require_permission(db, user, 'services.view')
+        require_permission(db, user, 'services.edit')
 
-        workbook_bytes = build_service_catalogue_export(db)
-        filename = f"service_catalogue_export_{datetime.now(timezone.utc).strftime('%Y%m%d_%H%M%S')}.xlsx"
-        return StreamingResponse(
-            iter([workbook_bytes]),
-            media_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
-            headers={'Content-Disposition': f'attachment; filename="{filename}"'},
+        services = db.execute(
+            select(ServiceCatalogue).order_by(ServiceCatalogue.is_active.desc(), ServiceCatalogue.service_code.asc())
+        ).scalars().all()
+        preview = None
+        error = None
+        if source_id and target_id:
+            try:
+                preview = build_merge_preview(db, source_id=source_id, target_id=target_id)
+            except ValueError as exc:
+                error = str(exc)
+
+        return _render(
+            request,
+            'modules/services/templates/services/catalogue_merge.html',
+            db,
+            user,
+            title='Merge Service Catalogue',
+            services=services,
+            source_id=source_id,
+            target_id=target_id,
+            preview=preview,
+            error=error,
         )
+    except Exception:
+        return _redirect_denied()
+    finally:
+        db.close()
+
+
+@router.post('/catalogue/merge')
+def catalogue_merge_submit(
+    request: Request,
+    source_id: int = Form(...),
+    target_id: int = Form(...),
+    confirmation: str = Form(...),
+    csrf_token: str = Form(...),
+):
+    validate_csrf(request, csrf_token)
+    db = CommonSessionLocal()
+    try:
+        user = get_current_user(request, db=db)
+        if not user:
+            return RedirectResponse(url='/login', status_code=303)
+        if not _is_system_admin(db, user):
+            return _redirect_denied()
+        require_permission(db, user, 'services.edit')
+
+        preview = build_merge_preview(db, source_id=source_id, target_id=target_id)
+        expected = f"MERGE {preview.source.service_code} INTO {preview.target.service_code}"
+        if confirmation.strip().upper() != expected.upper():
+            return RedirectResponse(
+                url=f'/services/catalogue/merge?source_id={source_id}&target_id={target_id}&error=confirmation',
+                status_code=303,
+            )
+
+        result = merge_service_catalogues(
+            db,
+            source_id=source_id,
+            target_id=target_id,
+            actor_user_id=user.id,
+        )
+        db.commit()
+
+        write_audit_log(
+            db,
+            action='services.catalogue.merged',
+            entity_type='service_catalogue',
+            entity_id=target_id,
+            entity_name=result['target_code'],
+            actor=user,
+            request=request,
+            details=result,
+        )
+        return RedirectResponse(url=f'/services/catalogue/{target_id}?merged=1', status_code=303)
+    except ValueError:
+        db.rollback()
+        return RedirectResponse(url='/services/catalogue/merge?error=invalid', status_code=303)
+    except Exception:
+        db.rollback()
+        raise
     finally:
         db.close()