from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from sqlalchemy import select
from sqlalchemy.orm import Session
from database import engine
from models import Todo
from sqlalchemy.exc import SQLAlchemyError

app = FastAPI()
app.add_middleware(
        CORSMiddleware,
        allow_origins=["*"],
        allow_credentials=True,
        allow_methods=["*"],
        allow_headers=["*"],
)

class todocreate(BaseModel):
    task: str

class todoupdate(BaseModel):
    completion: bool  | None = None
    task: str | None = None

class todoresponse(BaseModel):
    id: int
    task: str
    completion: bool
@app.get("/health")
def health():
    return {"status":"ok"}

@app.get("/todos", response_model=list[todoresponse])
def todos_get():
    with Session(engine) as session:
        statement = select(Todo)
        todos = session.scalars(statement).all()
        return todos

@app.post("/todos", response_model=todoresponse)
def todos_create(todo_data:todocreate):
    with Session(engine) as session:
        try:
            new_todo = Todo(task = todo_data.task)
            session.add(new_todo)
            session.commit()
            session.refresh(new_todo)
            return new_todo
        except SQLAlchemyError:
            session.rollback()
            raise


@app.patch("/todos/{todo_id}", response_model=todoresponse)
def todos_patch(todo_id:int, update_data:todoupdate):
    with Session(engine) as session:
        try:
            todo = session.get(Todo, todo_id)
            if todo is None:
                raise HTTPException(status_code = 404, detail = "Todo not found")
            if update_data.task is not None:
                todo.task = update_data.task
            if update_data.completion is not None:
                todo.completion = update_data.completion
            session.commit()
            session.refresh(todo)
            return todo
        except SQLAlchemyError:
            session.rollback()
            raise


@app.delete("/todos/{todo_id}", response_model=todoresponse)
def todos_delete(todo_id:int):
    with Session(engine) as session:
        try:
            todo = session.get(Todo, todo_id)
            if todo is None:
                raise HTTPException(status_code = 404, detail = "Todo not found")
            session.delete(todo)
            session.commit()
            return todo
        except SQLAlchemyError:
            session.rollback()
            raise