init commit

backend/app/routers/links.py

@@ -0,0 +1,55 @@
+from typing import Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy import or_
+from sqlalchemy.orm import Session
+
+from ..auth import verify_token
+from ..database import get_db
+from ..models import CrossPillarLink, RequirementNode
+from ..schemas import LinkCreate, LinkResponse
+
+router = APIRouter(prefix="/api/links", tags=["links"], dependencies=[Depends(verify_token)])
+
+
+@router.get("", response_model=list[LinkResponse])
+def list_links(
+    node_id: Optional[str] = Query(None, description="Filter links involving this node"),
+    db: Session = Depends(get_db),
+):
+    q = db.query(CrossPillarLink)
+    if node_id:
+        q = q.filter(
+            or_(
+                CrossPillarLink.source_id == node_id,
+                CrossPillarLink.target_id == node_id,
+            )
+        )
+    return q.all()
+
+
+@router.post("", response_model=LinkResponse, status_code=201)
+def create_link(data: LinkCreate, db: Session = Depends(get_db)):
+    if not db.get(RequirementNode, data.source_id):
+        raise HTTPException(404, f"Source {data.source_id} not found")
+    if not db.get(RequirementNode, data.target_id):
+        raise HTTPException(404, f"Target {data.target_id} not found")
+
+    existing = db.get(CrossPillarLink, (data.source_id, data.target_id))
+    if existing:
+        raise HTTPException(409, "Link already exists")
+
+    link = CrossPillarLink(**data.model_dump())
+    db.add(link)
+    db.commit()
+    db.refresh(link)
+    return link
+
+
+@router.delete("/{source_id}/{target_id}", status_code=204)
+def delete_link(source_id: str, target_id: str, db: Session = Depends(get_db)):
+    link = db.get(CrossPillarLink, (source_id, target_id))
+    if not link:
+        raise HTTPException(404, "Link not found")
+    db.delete(link)
+    db.commit()