/*
   factoriauth - An unofficial authentication server for Factorio
   Copyright (C) 2024 lambda@xiretza.xyz

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

#![warn(
    clippy::pedantic,
    clippy::as_conversions,
    clippy::unwrap_used, // allow case by case, add comment explaining why panic can't happen
    clippy::expect_used // allow case by case, expect message should be self-explanatory
)]
#![forbid(unsafe_code)]

mod auth;
mod config;
mod db;
mod secrets;
mod server;

use std::{env, path::PathBuf, sync::Arc};

use auth::{
    AuthenticationBackend, ServerPadlockGenerator, UserAuthenticator, UserServerKeyGenerator,
};
use clap::{Parser, Subcommand};
use color_eyre::{eyre::Context, Result};
use config::Config;
use db::{Database, SqliteDatabase};
use tokio::sync::Mutex;
use tracing::{event, instrument, level_filters::LevelFilter, Level};
use tracing_error::ErrorLayer;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter};

#[instrument]
fn init() -> Result<()> {
    const FILTER_ENV_VAR: &str = EnvFilter::DEFAULT_ENV;

    color_eyre::install()?;

    let mut filter_error = None;
    let filter_layer = EnvFilter::builder()
        .with_env_var(FILTER_ENV_VAR)
        .try_from_env()
        .unwrap_or_else(|e| {
            // sure would be nice if the error type was useful
            if env::var_os(FILTER_ENV_VAR).is_some() {
                filter_error = Some(e);
            }

            EnvFilter::builder()
                .with_default_directive(LevelFilter::INFO.into())
                .parse_lossy("")
        });
    let fmt_layer = tracing_subscriber::fmt::layer().with_target(true);

    tracing_subscriber::registry()
        .with(filter_layer)
        .with(fmt_layer)
        .with(ErrorLayer::default())
        .init();

    if let Some(e) = filter_error {
        event!(
            Level::WARN,
            error = %e,
            r#"Tracing filter env variable `{FILTER_ENV_VAR}` contained invalid data, falling back to "info""#
        );
    }

    Ok(())
}

#[instrument]
async fn load_config(path: &str) -> Result<Config> {
    event!(Level::DEBUG, "Loading config");

    let content = tokio::fs::read_to_string(path).await?;

    Ok(toml::from_str(&content)?)
}

#[derive(Debug, Clone, Subcommand)]
enum Command {
    /// Run factoriauth
    Run,
}

#[derive(Debug, Clone, Parser)]
struct Args {
    /// Path to the configuration file.
    #[arg(short, long, default_value = "config.toml")]
    config: String,

    #[command(subcommand)]
    command: Command,
}

#[tokio::main]
#[instrument]
async fn main() -> Result<()> {
    let args = Args::parse();

    match args.command {
        Command::Run => {}
    }

    init().context("Failed to initialize tracing")?;

    let config = load_config(&args.config).await.with_context(|| {
        if let Ok(path) = PathBuf::from(&args.config).canonicalize() {
            format!("Failed to load config from {path:?}")
        } else {
            format!("Failed to load config from invalid path {}", &args.config)
        }
    })?;

    let database: Arc<Mutex<Box<dyn Database + Send>>> = Arc::new(Mutex::new(Box::new(
        SqliteDatabase::open(&config.database.connection_string)
            .await
            .context("Failed to open database")?,
    )));

    let mut auth_backends = vec![];
    for (i, c) in config.auth_backends.into_iter().enumerate() {
        auth_backends.push(
            AuthenticationBackend::new(c)
                .await
                .with_context(|| format!("Failed to initialize backend {i}"))?,
        );
    }

    let user_authenticator = Arc::new(UserAuthenticator::new(Arc::clone(&database), auth_backends));
    let padlock_generator = Arc::new(ServerPadlockGenerator::new(config.padlock, database)?);
    let user_server_key_generator = Arc::new(UserServerKeyGenerator::new(
        Arc::clone(&user_authenticator),
        Arc::clone(&padlock_generator),
    ));

    tokio::spawn(server::run(
        config.listen,
        user_authenticator,
        padlock_generator,
        user_server_key_generator,
    ))
    .await??;

    Ok(())
}