use eyre::{format_err, Result};
use log::{error, info, warn};
use std::os::unix::fs::symlink;
use tokio::{fs, process::Command};

use crate::{bootstrap::config::Config, cmd::version::version_string};

mod dmcrypt;
mod networks;
mod sshd;

pub async fn run() {
    if std::process::id() != 1 {
        error!("init must run as PID 1, not {}", std::process::id());
        std::process::exit(1);
    }

    unsafe {
        use std::env;
        env::set_var("PATH", "/bin:/sbin:/usr/bin:/usr/sbin");
        env::set_var("HOME", "/root");
    }

    info!("Welcome to {}", version_string());

    let uname = nix::sys::utsname::uname().expect("uname should work");
    let kernel_version = uname.release().to_string_lossy();
    info!("Linux version {kernel_version}");

    let cfg: Config = retry(async || {
        let cfg = (fs::read("config.yaml").await)
            .map_err(|e| format_err!("failed to read config: {e}"))?;
        serde_yaml::from_slice(cfg.as_slice())
            .map_err(|e| format_err!("failed to parse config: {e}"))
    })
    .await;

    info!("config loaded");
    info!("anti-phishing-code: {}", cfg.anti_phishing_code);

    // mount basic filesystems
    mount("none", "/proc", "proc", None).await;
    mount("none", "/sys", "sysfs", None).await;
    mount("none", "/dev", "devtmpfs", None).await;
    mount("none", "/dev/pts", "devpts", Some("gid=5,mode=620")).await;

    // mount modules
    if let Some(ref modules) = cfg.modules {
        retry_or_ignore(async || {
            info!("mounting modules");
            mount(modules, "/modules", "squashfs", None).await;

            fs::create_dir_all("/lib/modules").await?;
            let modules_path = &format!("/modules/lib/modules/{kernel_version}");

            if !std::fs::exists(modules_path)? {
                return Err(format_err!(
                    "invalid modules package: {modules_path} should exist"
                ));
            }

            symlink(modules_path, format!("/lib/modules/{kernel_version}"))?;
            Ok(())
        })
        .await;
    } else {
        warn!("modules NOT mounted (not configured)");
    }

    // open input channels
    tokio::spawn(crate::input::answer_requests_from_stdin());
    tokio::spawn(crate::input::answer_requests_from_socket());

    // init devices
    info!("initializing devices");
    start_daemon("udevd", &[]).await;

    exec("udevadm", &["trigger", "-c", "add", "-t", "devices"]).await;
    exec("udevadm", &["trigger", "-c", "add", "-t", "subsystems"]).await;
    exec("udevadm", &["settle"]).await;

    // networks
    networks::setup(&cfg).await;

    // Wireguard VPN
    // TODO startVPN()

    // SSH service
    sshd::start(&cfg).await;

    // dmcrypt blockdevs
    dmcrypt::setup(&cfg).await;
    // TODO setupCrypt(cfg.PreLVMCrypt, map[string]string{});

    // LVM
    // TODO setupLVM(cfg);

    // bootstrap the system
    // TODO bootstrap(cfg);

    // finalize
    // TODO finalizeBoot();

    exec_shell().await;
}

async fn mount(src: &str, dst: &str, fstype: &str, opts: Option<&str>) {
    if let Err(e) = fs::create_dir_all(dst).await {
        error!("failed to create dir {dst}: {e}");
    }

    let mut args = vec![src, dst, "-t", fstype];
    if let Some(opts) = opts {
        args.extend(["-o", opts]);
    }
    exec("mount", &args).await;
}

async fn start_daemon(prog: &str, args: &[&str]) {
    let (cmd_str, mut cmd) = cmd_str(prog, args);
    retry_or_ignore(async || {
        info!("starting as daemon: {cmd_str}");
        cmd.spawn()?;
        Ok(())
    })
    .await;
}

async fn exec(prog: &str, args: &[&str]) {
    let (cmd_str, mut cmd) = cmd_str(prog, args);
    retry_or_ignore(async || {
        info!("# {cmd_str}");
        let s = cmd.status().await?;
        if s.success() {
            Ok(())
        } else {
            Err(format_err!("command failed: {s}"))
        }
    })
    .await;
}

async fn input_line() -> String {
    use tokio::io::{stdin, AsyncBufReadExt, BufReader};
    let mut stdin = BufReader::new(stdin()).lines();
    let Ok(line) = stdin.next_line().await else {
        panic!("unable to read a line");
    };
    line.expect("stdin should not the closed")
}

async fn retry_or_ignore(mut action: impl AsyncFnMut() -> Result<()>) {
    loop {
        match action().await {
            Ok(_) => return,
            Err(e) => {
                error!("{e}");

                loop {
                    eprint!("[r]etry, [i]gnore, or [s]hell? ");

                    match input_line().await.trim() {
                        "r" => break,
                        "i" => return,
                        "s" => {
                            exec_shell().await;
                            break;
                        }
                        v => {
                            eprintln!("invalid choice: {v:?}");
                        }
                    };
                }
            }
        }
    }
}

async fn retry<T>(mut action: impl AsyncFnMut() -> Result<T>) -> T {
    loop {
        match action().await {
            Ok(v) => return v,
            Err(e) => {
                error!("{e}");

                loop {
                    eprint!("[r]etry, or [s]hell? ");

                    match input_line().await.trim() {
                        "r" => break,
                        "s" => {
                            exec_shell().await;
                            break;
                        }
                        v => {
                            eprintln!("invalid choice: {v:?}");
                        }
                    };
                }
            }
        }
    }
}

async fn exec_shell() {
    let mut child = match Command::new("ash").spawn() {
        Ok(c) => c,
        Err(e) => {
            error!("failed to exec shell: {e}");
            return;
        }
    };

    let _ = child.wait().await;
}

fn cmd_str(prog: &str, args: &[&str]) -> (String, Command) {
    use std::borrow::Cow;

    let mut buf = String::new();

    buf.push_str(&shell_escape::escape(Cow::Borrowed(prog)));

    for &arg in args {
        buf.push(' ');
        buf.push_str(&shell_escape::escape(Cow::Borrowed(arg)));
    }

    let mut cmd = Command::new(prog);
    cmd.args(args);

    (buf, cmd)
}