import uuid
from typing import List, Optional

from fastapi import APIRouter, Depends, HTTPException, Request
from pydantic import BaseModel, Field
from sqlalchemy.orm import Session, selectinload

from game.card import compute_deck_type
from core.database import get_db
from core.dependencies import get_current_user, limiter, parse_uuid
from core.models import Card as CardModel
from core.models import Deck as DeckModel
from core.models import DeckCard as DeckCardModel
from core.models import User as UserModel

router = APIRouter()


class DeckUpdate(BaseModel):
  name: Optional[str] = Field(None, max_length=64)
  # The real constraint is the 50-cost rule enforced at game start, but cost is
  # per-card so an unbounded list is still a cheap way to make us do arbitrary
  # work. Cheapest cards are 1 cost, so 60 can't hide a legal deck.
  card_ids: Optional[List[str]] = Field(None, max_length=60)


@router.get("/decks")
def get_decks(user: UserModel = Depends(get_current_user), db: Session = Depends(get_db)):
  decks = db.query(DeckModel).options(
    selectinload(DeckModel.deck_cards).selectinload(DeckCardModel.card)
  ).filter(
    DeckModel.user_id == user.id,
    DeckModel.deleted == False
  ).order_by(DeckModel.created_at).all()
  result = []
  for deck in decks:
    cards = [dc.card for dc in deck.deck_cards]
    result.append({
      "id": str(deck.id),
      "name": deck.name,
      "card_count": len(cards),
      "total_cost": sum(card.cost for card in cards),
      "times_played": deck.times_played,
      "wins": deck.wins,
      "losses": deck.losses,
      "deck_type": compute_deck_type(cards),
    })
  return result


@router.post("/decks")
@limiter.limit("30/minute")
def create_deck(request: Request, user: UserModel = Depends(get_current_user), db: Session = Depends(get_db)):
  count = db.query(DeckModel).filter(DeckModel.user_id == user.id).count()
  deck = DeckModel(id=uuid.uuid4(), user_id=user.id, name=f"Deck #{count + 1}")
  db.add(deck)
  db.commit()
  return {"id": str(deck.id), "name": deck.name, "card_count": 0}


@router.patch("/decks/{deck_id}")
# Generous: the deck editor saves on every change.
@limiter.limit("120/minute")
def update_deck(request: Request, deck_id: str, body: DeckUpdate, user: UserModel = Depends(get_current_user), db: Session = Depends(get_db)):
  deck = db.query(DeckModel).filter(DeckModel.id == parse_uuid(deck_id, "deck_id"), DeckModel.user_id == user.id).first()
  if not deck:
    raise HTTPException(status_code=404, detail="Deck not found")
  if body.name is not None:
    deck.name = body.name
  if body.card_ids is not None:
    try:
      parsed_ids = [uuid.UUID(cid) for cid in body.card_ids]
    except ValueError:
      raise HTTPException(status_code=400, detail="Invalid card IDs")

    # deck_cards is keyed on (deck_id, card_id), so a repeated id would blow up
    # on flush. dict.fromkeys dedupes while keeping the submitted order.
    unique_ids = list(dict.fromkeys(parsed_ids))

    # Without this the only constraint is the FK, so any card UUID that exists
    # is accepted — including another user's. Public profiles hand those out.
    owned = db.query(CardModel.id).filter(
      CardModel.id.in_(unique_ids),
      CardModel.user_id == user.id,
    ).all()
    if len(owned) != len(unique_ids):
      raise HTTPException(status_code=400, detail="Some cards are not in your collection")

    db.query(DeckCardModel).filter(DeckCardModel.deck_id == deck.id).delete()
    for card_id in unique_ids:
      db.add(DeckCardModel(deck_id=deck.id, card_id=card_id))
    if deck.times_played > 0:
      deck.wins = 0
      deck.losses = 0
      deck.times_played = 0
  db.commit()
  return {"id": str(deck.id), "name": deck.name}


@router.delete("/decks/{deck_id}")
def delete_deck(deck_id: str, user: UserModel = Depends(get_current_user), db: Session = Depends(get_db)):
  deck = db.query(DeckModel).filter(DeckModel.id == parse_uuid(deck_id, "deck_id"), DeckModel.user_id == user.id).first()
  if not deck:
    raise HTTPException(status_code=404, detail="Deck not found")
  if deck.times_played > 0:
    deck.deleted = True
  else:
    db.delete(deck)
  db.commit()
  return {"message": "Deleted"}


@router.get("/decks/{deck_id}/cards")
def get_deck_cards(deck_id: str, user: UserModel = Depends(get_current_user), db: Session = Depends(get_db)):
  deck = db.query(DeckModel).filter(DeckModel.id == parse_uuid(deck_id, "deck_id"), DeckModel.user_id == user.id).first()
  if not deck:
    raise HTTPException(status_code=404, detail="Deck not found")
  deck_cards = db.query(DeckCardModel).options(
    selectinload(DeckCardModel.card)
  ).filter(DeckCardModel.deck_id == deck.id).all()
  return [{"id": str(dc.card_id), "cost": dc.card.cost} for dc in deck_cards]