Reorganiza backend

backend/app/pipelines/graph_snapshot.py

@@ -0,0 +1,46 @@
+from __future__ import annotations
+
+from ..graph_export import edge_retrieval_query, graph_from_sparql_bindings
+from ..models import GraphResponse
+from ..sparql_engine import SparqlEngine
+from ..settings import Settings
+from .layout_spiral import spiral_positions
+
+
+async def fetch_graph_snapshot(
+    sparql: SparqlEngine,
+    *,
+    settings: Settings,
+    node_limit: int,
+    edge_limit: int,
+) -> GraphResponse:
+    """
+    Fetch a graph snapshot (nodes + edges) via SPARQL, independent of whether the
+    underlying engine is RDFLib or AnzoGraph.
+    """
+    edges_q = edge_retrieval_query(edge_limit=edge_limit, include_bnodes=settings.include_bnodes)
+    res = await sparql.query_json(edges_q)
+    bindings = (((res.get("results") or {}).get("bindings")) or [])
+    nodes, edges = graph_from_sparql_bindings(
+        bindings,
+        node_limit=node_limit,
+        include_bnodes=settings.include_bnodes,
+    )
+
+    # Add positions so the frontend doesn't need to run a layout.
+    xs, ys = spiral_positions(len(nodes))
+    for i, node in enumerate(nodes):
+        node["x"] = float(xs[i])
+        node["y"] = float(ys[i])
+
+    meta = GraphResponse.Meta(
+        backend=sparql.name,
+        ttl_path=settings.ttl_path if settings.graph_backend == "rdflib" else None,
+        sparql_endpoint=settings.effective_sparql_endpoint() if settings.graph_backend == "anzograph" else None,
+        include_bnodes=settings.include_bnodes,
+        node_limit=node_limit,
+        edge_limit=edge_limit,
+        nodes=len(nodes),
+        edges=len(edges),
+    )
+    return GraphResponse(nodes=nodes, edges=edges, meta=meta)