use super::Cmd;
use crate::args;
use blake2b_simd::Params;
use clap::{value_parser, Arg, Command};
use std::{
    fs::File,
    io::{self, BufRead, BufReader, Read},
    process,
};

#[derive(Debug, Default)]
pub struct B2sum;

impl Cmd for B2sum {
    fn cli(&self) -> clap::Command {
        Command::new("b2sum")
            .about("compute and check MD5 message digest")
            .author("Nathan Fisher")
            .version(env!("CARGO_PKG_VERSION"))
            .args([
                args::check(),
                args::file(),
                Arg::new("length")
                    .help(
                        "digest length in bits; must not exceed the max for the \
                        blake2 algorithm and must be a multiple of 8",
                    )
                    .short('l')
                    .long("length")
                    .default_value("512")
                    .value_parser(value_parser!(usize)),
            ])
    }

    fn run(&self, matches: &clap::ArgMatches) -> Result<(), Box<dyn std::error::Error>> {
        if let Some(files) = matches.get_many::<String>("file") {
            let mut erred = 0;
            let len = matches.get_one("length").unwrap_or(&512);
            if *len % 8 != 0 {
                let msg = format!("bad hash length: {len}");
                return Err(io::Error::new(io::ErrorKind::Other, msg).into());
            }
            let len = len / 8;
            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::<io::Error>(
                            io::Error::new(io::ErrorKind::Other, "invalid checksum file").into(),
                        )?;
                        let file = split.next().ok_or::<io::Error>(
                            io::Error::new(io::ErrorKind::Other, "invalid checksum file").into(),
                        )?;
                        let mut buf = vec![];
                        let mut fd = File::open(file)?;
                        fd.read_to_end(&mut buf)?;
                        let hash = Params::new()
                            .hash_length(len)
                            .to_state()
                            .update(&buf)
                            .finalize();
                        if hash.to_hex().as_str() == sum {
                            println!("{file}: OK");
                        } else {
                            println!("{file}: FAILED");
                            erred += 1;
                        }
                    }
                } else {
                    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)?;
                    }
                    let hash = Params::new()
                        .hash_length(len)
                        .to_state()
                        .update(&buf)
                        .finalize();
                    println!("{}  {f}", &hash.to_hex());
                }
            }
            if erred > 0 {
                println!("b2sum: WARNING: {erred} computed checksum did NOT match");
                process::exit(1);
            }
        }
        Ok(())
    }

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