use super::Cmd;
use clap::{Arg, ArgAction, Command};
use md5::{Digest, Md5};
use std::{
    fmt::Write,
    fs::File,
    io::{self, BufRead, BufReader, Read},
    process, error::Error,
};

#[derive(Debug, Default)]
pub struct Md5sum;

impl Cmd for Md5sum {
    fn cli(&self) -> clap::Command {
        Command::new("md5sum")
            .about("compute and check MD5 message digest")
            .author("Nathan Fisher")
            .version(env!("CARGO_PKG_VERSION"))
            .args([
                Arg::new("check")
                    .help("read checksums from the FILEs and check them")
                    .short('c')
                    .long("check")
                    .action(ArgAction::SetTrue),
                Arg::new("file")
                    .value_name("FILE")
                    .num_args(1..)
                    .default_value("-"),
            ])
    }

    fn run(&self, matches: Option<&clap::ArgMatches>) -> Result<(), Box<dyn std::error::Error>> {
        let Some(matches) = matches else {
            return Err(io::Error::new(io::ErrorKind::Other, "no input").into());
        };
        if let Some(files) = matches.get_many::<String>("file") {
            let mut erred = 0;
            for f in files {
                if matches.get_flag("check") {
                    if f == "-" {
                        return Err(
                            io::Error::new(io::ErrorKind::Other, "no file specified").into()
                        );
                    }
                    let fd = File::open(f)?;
                    let reader = BufReader::new(fd);
                    for line in reader.lines() {
                        let line = line?;
                        let mut split = line.split_whitespace();
                        let sum = split.next().ok_or::<Box<dyn Error>>(
                            io::Error::new(io::ErrorKind::Other, "invalid checksum file").into(),
                        )?;
                        let file = split.next().ok_or::<Box<dyn Error>>(
                            io::Error::new(io::ErrorKind::Other, "invalid checksum file").into(),
                        )?;
                        let mut hasher = Md5::new();
                        let mut buf = vec![];
                        let mut fd = File::open(file)?;
                        let _s = fd.read_to_end(&mut buf)?;
                        hasher.update(&buf);
                        let res = hasher.finalize();
                        let mut s = String::new();
                        for c in res {
                            write!(s, "{c:x}")?;
                        }
                        if s.as_str() == sum {
                            println!("{file}: OK");
                        } else {
                            println!("{file}: FAILED");
                            erred += 1;
                        }
                    }
                } else {
                    let mut hasher = Md5::new();
                    let mut buf = vec![];
                    if f == "-" {
                        let _s = io::stdin().read_to_end(&mut buf)?;
                    } else {
                        let mut fd = File::open(f)?;
                        let _s = fd.read_to_end(&mut buf)?;
                    }
                    hasher.update(&buf);
                    let res = hasher.finalize();
                    for c in res {
                        print!("{c:x}");
                    }
                    println!("  {f}");
                }
            }
            if erred > 0 {
                println!("md5sum: WARNING: {erred} computed checksum did NOT match");
                process::exit(1);
            }
        }
        Ok(())
    }

    fn path(&self) -> Option<crate::Path> {
        Some(crate::Path::UsrBin)
    }
}