"""
The Clients endpoint
"""
from fastapi import APIRouter, HTTPException 
from sqlmodel import select
from app.api.deps import SessionDep, exists
from app.schemas.models import Client
from app.schemas.schemas import ClientCreate, ClientUpdate
from pydantic import ValidationError
from typing import Sequence, List, Optional

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


@router.get("/", response_model=List[Client])
def fetch_clients(session: SessionDep) -> Sequence[Client]:
    """Fetch client list
    """
    clients = session.exec(select(Client)).all()
    return clients


@router.post("/", response_model=ClientCreate)
def create_client(client_data: ClientCreate, session: SessionDep) -> Client:
    """Create a client
    """
    existing = exists(session, Client, tin_number=client_data.tin_number)
    if existing:
        raise HTTPException(status_code=400, detail="Client with this tin number already exists")

    try:
        client = Client.model_validate(client_data)
    except ValidationError as e:
        raise HTTPException(status_code=400, detail=e.errors())

    session.add(client)
    session.commit()
    session.refresh(client)
    return client


@router.get("/{client_id}", response_model=Client)
def get_client(client_id: int, session: SessionDep) -> Optional[Client]:
    """Returns a client by its ID
    """
    stmt = select(Client).where(Client.id == client_id)
    result: Optional[Client] = session.exec(stmt).first()

    if not result:
        raise HTTPException(status_code=404, detail="Client not found")
    
    return result


@router.patch("/{client_id}", response_model=ClientCreate)
def update_client(
    client_id: int,
    client_data: ClientUpdate,
    session: SessionDep) -> Optional[Client]:
    """Updates a client using its ID
    """
    client = session.get(Client, client_id)
    if not client:
        raise HTTPException(status_code=404, detail="Client not found")
    
    update_fields = client_data.model_dump(exclude_unset=True)

    for key, value in update_fields.items():
        setattr(client, key, value)
    
    session.add(client)
    session.commit()
    session.refresh(client)
    return client


@router.delete("/{client_id}", status_code=204)
def delete_client(client_id: int, session: SessionDep):
    """Deletes a client
    """
    client = session.get(Client, client_id)

    if not client:
        raise HTTPException(status_code=404, detail="Client not found")
    
    session.delete(client)
    session.commit()