use std::env;

use std::path::PathBuf;
use std::str::FromStr;
use time::ext::NumericalDuration;
use time::Duration;
use tokio::fs;

#[derive(Clone)]
pub struct Config {
    pub static_dir: PathBuf,
    pub files_dir: PathBuf,
    pub max_file_size: Option<u64>,
    pub no_auth_limits: Option<NoAuthLimits>,
    pub enable_rate_limit: bool,
    pub proxied: bool,
    pub rate_limit_replenish_seconds: u64,
    pub rate_limit_burst: u32,
}

#[derive(Clone)]
pub struct NoAuthLimits {
    pub auth_password: String,
    pub max_time: Duration,
    pub large_file_max_time: Duration,
    pub large_file_size: u64,
}

pub async fn from_env() -> Config {
    let max_file_size = env::var("UPLOAD_MAX_BYTES")
        .ok()
        .and_then(|variable| variable.parse().ok())
        .or(Some(8 * 1024 * 1024))
        .filter(|&max_file_size| max_file_size != 0);

    let static_dir =
        PathBuf::from(env::var("STATIC_DIR").unwrap_or_else(|_| "./static".to_owned()));
    let files_dir = PathBuf::from(env::var("FILES_DIR").unwrap_or_else(|_| "./files".to_owned()));
    fs::create_dir_all(&files_dir)
        .await
        .expect("could not create directory for storing files");

    let no_auth_limits = get_no_auth_limits();

    // default to 480requests/8h
    let enable_rate_limit = matches!(env::var("RATE_LIMIT").as_deref(), Ok("true") | Err(_));
    let proxied = env::var("RATE_LIMIT_PROXIED").as_deref() == Ok("true");
    let rate_limit_replenish_seconds = env::var("RATE_LIMIT_REPLENISH_SECONDS")
        .ok()
        .and_then(|rate_limit| rate_limit.parse().ok())
        .unwrap_or(60);
    let rate_limit_burst = env::var("RATE_LIMIT_BURST")
        .ok()
        .and_then(|burst| burst.parse().ok())
        .unwrap_or(480);

    Config {
        static_dir,
        files_dir,
        max_file_size,
        no_auth_limits,
        enable_rate_limit,
        proxied,
        rate_limit_replenish_seconds,
        rate_limit_burst,
    }
}

fn get_no_auth_limits() -> Option<NoAuthLimits> {
    match (
        env::var("AUTH_PASSWORD").ok(),
        env_number::<i64>("NO_AUTH_MAX_TIME"),
        env_number::<i64>("NO_AUTH_LARGE_FILE_MAX_TIME"),
        env_number("NO_AUTH_LARGE_FILE_SIZE"),
    ) {
        (Some(auth_password), Some(max_time), Some(large_file_max_time), Some(large_file_size)) => {
            Some(NoAuthLimits {
                auth_password,
                max_time: max_time.seconds(),
                large_file_max_time: large_file_max_time.seconds(),
                large_file_size,
            })
        }
        (None, None, None, None) => None,
        _ => {
            panic!("Incomplete NO_AUTH configuration: All environment variables must be specified")
        }
    }
}

fn env_number<T: FromStr>(variable: &str) -> Option<T> {
    env::var(variable).ok().and_then(|n| n.parse::<T>().ok())
}