use clap::{Arg, ArgAction, Command};
use mount::MntEntries;
use shitbox::{args, Cmd};
use std::{
    fs::File,
    io::{self, BufRead, BufReader},
};

#[derive(Debug, Default)]
pub struct Swapoff;

impl Cmd for Swapoff {
    fn cli(&self) -> clap::Command {
        Command::new("swapoff")
            .about("disable devices and files for paging and swapping")
            .author("Nathan Fisher")
            .version(env!("CARGO_PKG_VERSION"))
            .args([
                Arg::new("all")
                    .help("Disable swapping on all known swap devices and files as found in /etc/fstab.")
                    .short('a')
                    .long("all")
                    .action(ArgAction::SetTrue),
                args::verbose(),
                Arg::new("device")
                    .num_args(1..)
                    .conflicts_with("all")
                    .required_unless_present("all"),
            ])
    }

    fn run(&self, matches: &clap::ArgMatches) -> Result<(), Box<dyn std::error::Error>> {
        if matches.get_flag("all") {
            if let Ok(entries) = MntEntries::new("/etc/fstab") {
                for e in entries.filter(|x| &x.fstype == "swap") {
                    if e.is_swapped() {
                        let dev = e
                            .device()?
                            .to_str()
                            .ok_or(io::Error::new(io::ErrorKind::Other, "utf8 error"))?
                            .to_string();
                        mount::swapoff(&dev)?;
                        if matches.get_flag("verbose") {
                            println!("swapoff {dev}");
                        }
                    }
                }
            }
        } else if let Some(devices) = matches.get_many::<String>("device") {
            'devloop: for d in devices {
                let fd = File::open("/proc/swaps")?;
                let reader = BufReader::new(fd);
                for line in reader.lines() {
                    let line = line?;
                    let swap = line.split_whitespace().next().ok_or(io::Error::new(
                        io::ErrorKind::Other,
                        "Error reading /proc/swaps",
                    ))?;
                    if swap == d {
                        mount::swapoff(d)?;
                        if matches.get_flag("verbose") {
                            println!("swapoff {d}");
                        }
                        continue 'devloop;
                    }
                }
                let msg = format!("{d} is not swapped");
                return Err(Box::new(io::Error::new(io::ErrorKind::Other, msg)));
            }
        }
        Ok(())
    }

    fn path(&self) -> Option<shitbox::Path> {
        Some(shitbox::Path::Sbin)
    }
}