use anyhow::{Context, Result};
use clap::Parser;
use dosh::auth::{build_bootstrap, encode_bootstrap, load_or_create_server_secret};
use dosh::config::load_server_config;
use dosh::native::{host_public_key, host_public_key_line, load_or_create_host_key};

#[derive(Debug, Parser)]
#[command(
    name = "dosh-auth",
    version = dosh::build_info::VERSION,
    long_version = dosh::build_info::LONG_VERSION
)]
struct Args {
    #[arg(long, default_value_t = 1)]
    protocol: u8,
    #[arg(long)]
    nonce: Option<String>,
    #[arg(long)]
    host_key: bool,
    #[arg(long, default_value = "default")]
    session: String,
    #[arg(long, default_value = "read-write")]
    mode: String,
    #[arg(long, default_value = "80x24")]
    size: String,
    #[arg(long, default_value = "dev")]
    client_version: String,
    #[arg(long)]
    udp_host: Option<String>,
}

fn main() -> Result<()> {
    let args = Args::parse();
    anyhow::ensure!(args.protocol == 1, "unsupported protocol {}", args.protocol);
    let config = load_server_config(None)?;
    if args.host_key {
        let signing_key = load_or_create_host_key(&config)?;
        println!("{}", host_public_key_line(&host_public_key(&signing_key)));
        return Ok(());
    }
    let secret = load_or_create_server_secret(&config)?;
    let nonce = parse_nonce(args.nonce.as_deref().context("--nonce is required")?)?;
    let size = parse_size(&args.size)?;
    let user = std::env::var("USER").unwrap_or_else(|_| "unknown".to_string());
    let udp_host = args.udp_host.unwrap_or_else(|| "127.0.0.1".to_string());
    let resp = build_bootstrap(
        &config,
        &secret,
        user,
        args.session,
        args.mode,
        size,
        nonce,
        udp_host,
    )?;
    println!("{}", encode_bootstrap(&resp)?);
    Ok(())
}

fn parse_nonce(raw: &str) -> Result<[u8; 12]> {
    let bytes = base64::Engine::decode(&base64::engine::general_purpose::URL_SAFE_NO_PAD, raw)
        .context("decode nonce")?;
    anyhow::ensure!(bytes.len() == 12, "nonce must decode to 12 bytes");
    let mut out = [0u8; 12];
    out.copy_from_slice(&bytes);
    Ok(out)
}

fn parse_size(raw: &str) -> Result<(u16, u16)> {
    let (cols, rows) = raw.split_once('x').context("size must be COLSxROWS")?;
    Ok((cols.parse()?, rows.parse()?))
}