from fastapi import APIRouter, HTTPException
from fastapi.responses import RedirectResponse
from sqlalchemy.exc import IntegrityError

from app.db import database
from app.models import Url
from app.schemas import UrlPayload
from app.services import encoder

router = APIRouter()

@router.get("/{shortcode}")
async def redirect_to_original_url(shortcode: str):
    if not encoder.is_valid(shortcode):
        raise HTTPException(status_code=400, detail="Shortcode is not valid")

    query = Url.__table__.select().where(Url.shortcode == shortcode)
    url_result = await database.fetch_one(query)

    if url_result:
        return RedirectResponse(url=url_result.url, status_code=302)
    else:
        raise HTTPException(status_code=404, detail="Shortcode not found")


@router.post("/shorten")
async def create_url_shortcode(url_payload: UrlPayload):
    original_url = str(url_payload.url)

    query = "SELECT nextval('urls_id_seq')"
    next_id = await database.fetch_val(query)
    shortcode = encoder.encode(next_id)

    try:
        query = Url.__table__.insert().values({
            "id": next_id,
            "url": original_url,
            "shortcode": shortcode
        })
        await database.execute(query)

        return {"shortcode": shortcode, "original_url": original_url}
    except IntegrityError as e:
        if 'shortcode' in str(e):
            raise HTTPException(status_code=409, detail="Shortcode already in use")
        else:
            raise HTTPException(status_code=500, detail="Internal Server Error")