use crate::error::{WError, WResult};
use std::{
    io::Read,
    net::{TcpListener, TcpStream},
    process::{Command, Stdio},
    time::Duration,
};

pub fn daemon() -> WResult<()> {
    let address = "0.0.0.0:21367";
    let listener = TcpListener::bind(address).map_err(WError::DaemonSocketBindError)?;
    println!("Listening for TCP packets at {}", address);
    for mut stream in listener.incoming() {
        match &mut stream {
            Ok(stream) => {
                if let Err(e) = handle_connection(stream) {
                    eprintln!("Failed to handle request {}", e);
                }
            }
            Err(e) => eprintln!("{}", e),
        }
    }

    Ok(())
}

fn handle_connection(stream: &mut TcpStream) -> WResult<()> {
    // TODO: Slowloris
    stream
        .set_read_timeout(Some(Duration::from_secs(5)))
        .map_err(WError::DaemonConnectionReadError)?;
    let command = read_command(stream)?;
    match command.as_str() {
        "shutdown" => execute_shutdown_command(),
        _ => Err(WError::DaemonInvalidRequest(command)),
    }
}

fn execute_shutdown_command() -> WResult<()> {
    let mut shutdown_cmd = build_shutdown_cmd();
    shutdown_cmd.stdout(Stdio::piped());
    shutdown_cmd.stderr(Stdio::piped());

    let output = shutdown_cmd
        .output()
        .map_err(|e| WError::DaemonCommandError(e.to_string()))?;
    let status_code = output
        .status
        .code()
        .ok_or(WError::DaemonCommandError("No exit code returned!".to_string()))?;

    if status_code != 0 {
        return Err(WError::DaemonCommandExecutionError(output));
    };

    Ok(())
}

fn read_command(stream: &mut TcpStream) -> WResult<String> {
    let mut buf = Vec::new();
    let read = stream
        .read_to_end(&mut buf)
        .map_err(WError::DaemonConnectionReadError)?;
    let command = String::from_utf8_lossy(&buf[..read]).to_string();
    Ok(command)
}

// TODO: Use DBus to send a message to systemd instead of spawning a new process
fn build_shutdown_cmd() -> Command {
    let mut cmd = Command::new("systemctl");
    cmd.arg("poweroff");

    cmd
}