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()