import pickle
import os.path
import logging
from os import getenv
from datetime import date
from dataclasses import dataclass
from googleapiclient.discovery import build
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request


@dataclass
class SheetsRow:
    interval: str
    name: str
    last_done: str

    def __str__(self):
        return f"{self.interval}, {self.name}, {self.last_done}"


# If modifying these scopes, delete the file token.pickle.
SCOPES = ["https://www.googleapis.com/auth/spreadsheets.readonly"]


def _get_or_default(list, index, default=""):
    try:
        return list[index]
    except IndexError:
        return default


def _row_to_dataclass(values):
    interval = _get_or_default(values, 0, "")
    name = _get_or_default(values, 1, "")

    today = date.today()
    last_done = _get_or_default(values, 2, today.strftime("%Y-%m-%d"))
    return SheetsRow(interval, name, last_done)


def authenticate_and_fetch_sheets_data():
    logging.info("Reading Google credentials and authenticating...")
    creds = None
    # The file token.pickle stores the user's access and refresh tokens, and is
    # created automatically when the authorization flow completes for the first
    # time.
    if os.path.exists("token.pickle"):
        with open("token.pickle", "rb") as token:
            creds = pickle.load(token)
    # If there are no (valid) credentials available, let the user log in.
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file("credentials.json", SCOPES)
            creds = flow.run_local_server(port=0)
        # Save the credentials for the next run
        with open("token.pickle", "wb") as token:
            pickle.dump(creds, token)

    service = build("sheets", "v4", credentials=creds, cache_discovery=False)

    # Call the Sheets API
    logging.info("Calling Sheets API to fetch data...")
    sheet = service.spreadsheets()
    result = (
        sheet.values()
        .get(
            spreadsheetId=getenv("SHEETS_SPREADSHEET_ID"),
            range=getenv("SHEETS_RANGE"),
        )
        .execute()
    )

    rows = result.get("values", [])
    logging.info(f"Fetched {len(rows)} rows of data")
    return map(_row_to_dataclass, rows)