//! Headless dedicated server.
//!
//! ```text
//! game-server [--port 5000] [--save saves/server.rsn | --no-save] [--map maps/station.tmx]
//! ```

use std::{path::PathBuf, time::Duration};

use bevy::{app::ScheduleRunnerPlugin, log::LogPlugin, prelude::*, state::app::StatesPlugin};
use bevy_replicon::prelude::*;
use bevy_replicon_renet::RepliconRenetPlugins;
use game_core::CorePlugin;
use game_server::{GameServerPlugin, NetworkServerPlugin, ServerSettings};

fn main() -> AppExit {
    let mut port = game_core::DEFAULT_PORT;
    let mut settings = ServerSettings {
        save_path: Some(PathBuf::from("saves/server.rsn")),
        ..Default::default()
    };
    let mut args = std::env::args().skip(1);
    while let Some(arg) = args.next() {
        let mut value = |name: &str| {
            args.next()
                .unwrap_or_else(|| usage(&format!("{name} needs a value")))
        };
        match arg.as_str() {
            "--port" => {
                port = value("--port")
                    .parse()
                    .unwrap_or_else(|_| usage("invalid port"))
            }
            "--save" => settings.save_path = Some(value("--save").into()),
            "--no-save" => settings.save_path = None,
            "--map" => settings.map = value("--map"),
            "-h" | "--help" => usage(""),
            other => usage(&format!("unknown argument `{other}`")),
        }
    }

    App::new()
        .add_plugins((
            MinimalPlugins.set(ScheduleRunnerPlugin::run_loop(Duration::from_secs_f64(
                1.0 / 60.0,
            ))),
            StatesPlugin,
            LogPlugin::default(),
            bevy::app::TerminalCtrlCHandlerPlugin,
            RepliconPlugins,
            RepliconRenetPlugins,
            CorePlugin,
            GameServerPlugin { settings },
            NetworkServerPlugin { port },
        ))
        .run()
}

fn usage(error: &str) -> ! {
    if !error.is_empty() {
        eprintln!("error: {error}\n");
    }
    eprintln!(
        "usage: game-server [--port PORT] [--save FILE | --no-save] [--map MAP]\n\n\
         --port   UDP port to listen on (default {})\n\
         --save   persistent world file (default saves/server.rsn)\n\
         --map    Tiled map relative to the assets directory (default {})",
        game_core::DEFAULT_PORT,
        game_core::DEFAULT_MAP
    );
    std::process::exit(if error.is_empty() { 0 } else { 2 })
}