from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session, joinedload
from uuid import UUID
from backend.database import get_db
from backend import models
from backend.schemas import ItemCreate, ItemOut, TagIdPayload, TagOut

router = APIRouter(prefix="/items", tags=["items"])


@router.get("/", response_model=list[ItemOut])
def list_items(db: Session = Depends(get_db)):
    items = db.query(models.Item).options(joinedload(models.Item.tags)).all()
    return items


@router.post("/", response_model=ItemOut)
def create_item(payload: ItemCreate, db: Session = Depends(get_db)):
    # Demo: use first user or create one if none exists
    user = db.query(models.User).first()
    if not user:
        from uuid import uuid4
        user = models.User(id=uuid4(), name="Demo")
        db.add(user)
        db.flush()

    # Create the item
    item = models.Item(user_id=user.id, name=payload.name)

    # Attach tags if provided
    if payload.tag_ids:
        tags = (
            db.query(models.Tag)
            .filter(models.Tag.id.in_(payload.tag_ids), models.Tag.user_id == user.id)
            .all()
        )
        item.tags.extend(tags)

    db.add(item)
    db.commit()
    db.refresh(item)

    return item

@router.post("/{item_id}/tags", response_model=ItemOut)
def add_tag_to_item(item_id: UUID, payload: TagIdPayload, db: Session = Depends(get_db)):
    tag_id = payload.tag_id
    item = db.get(models.Item, item_id)
    if not item:
        raise HTTPException(status_code=404, detail="Item not found")

    tag = db.get(models.Tag, tag_id)
    if not tag or tag.user_id != item.user_id:
        raise HTTPException(status_code=404, detail="Tag not found")
    
    if tag in item.tags:
        raise HTTPException(status_code=400, detail="Tag already associated with item")

    item.tags.append(tag)
    db.commit()
    db.refresh(item)
    return item

@router.delete("/{item_id}/tags/{tag_id}", response_model=ItemOut)
def remove_tag_from_item(item_id: UUID, tag_id: UUID, db: Session = Depends(get_db)):
    item = db.get(models.Item, item_id)
    if not item:
        raise HTTPException(status_code=404, detail="Item not found")

    tag = db.get(models.Tag, tag_id)
    if not tag or tag.user_id != item.user_id:
        raise HTTPException(status_code=404, detail="Tag not found")

    item.tags.remove(tag)
    db.commit()
    db.refresh(item)
    return item

@router.delete("/{item_id}", status_code=204)
def delete_item(item_id: UUID, db: Session = Depends(get_db)):
    item = db.get(models.Item, item_id)
    if not item:
        raise HTTPException(status_code=404, detail="Item not found")
    db.delete(item)
    db.commit()

@router.put("/{item_id}", response_model=ItemOut)
def update_item_name(item_id: UUID, payload: dict, db: Session = Depends(get_db)):
    item = db.get(models.Item, item_id)
    if not item:
        raise HTTPException(status_code=404, detail="Item not found")
    name = payload.get("name")
    if not name or not isinstance(name, str):
        raise HTTPException(status_code=400, detail="Missing or invalid name")
    item.name = name
    db.commit()
    db.refresh(item)
    return item