use reqwest::{blocking::Client, cookie::Jar};
use std::{collections::HashMap, env, fs, path::PathBuf, sync::Arc};

const BASE_URL: &str = "https://adventofcode.com";
const YEAR: &str = "2022";

fn main() {
    // get env and dotenv into hashmap
    let file = fs::read_to_string(".env").unwrap_or(String::new());
    let env = file
        .lines()
        .filter_map(|line| line.split_once('='))
        .map(|(key, value)| (key.to_string(), value.to_string()))
        .chain(env::vars())
        .collect::<HashMap<_, _>>();

    // create session cookie
    let session = env
        .get("SESSION")
        .expect("SESSION environment variable not set, retrieve it from https://adventofcode.com");
    let cookie = format!("session={session}");

    // setup client
    let jar = Arc::new(Jar::default());
    jar.add_cookie_str(&cookie, &BASE_URL.parse().unwrap());
    let client = Client::builder().cookie_provider(jar).build().unwrap();

    // download until day fails
    for day in 1..=25 {
        let path = PathBuf::from(format!("input/day{day}.txt"));
        if path.try_exists().is_err() {
            let url = format!("{BASE_URL}/{YEAR}/day/{day}/input");
            let Ok(res) = client.get(url).send() else {
                break
            };
            fs::write(path, res.text().unwrap()).unwrap();
        }
    }
}