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mod error;
mod flags;
mod main_result;
use std::{
borrow::Cow,
collections::HashMap,
env,
fs,
hash::Hash,
io::{self, BufRead, BufReader, Write},
iter,
path::Path,
process::{Command, Stdio}
};
use {
error::Error,
main_result::MainResult
};
use {
flags::Flags,
getopt::{Opt, Parser},
tempfile::{Builder, NamedTempFile, TempDir}
};
fn main() -> MainResult {
work().into()
}
fn work() -> Result<(), Error> {
// TODO: Don't allocate the arguments in a Vec!
let argv = env::args().collect::<Vec<String>>();
let mut flags = Flags::default();
let mut opts = Parser::new(&argv, ":0ei");
// TODO: Perhaps implement FromIterator for Flags?
opts.by_ref().map(Result::ok).try_for_each(|o| Some(match o? {
Opt('0', None) => flags.nul = true,
Opt('e', None) => flags.encode = true,
Opt('i', None) => flags.individual = true,
_ => return None,
})).ok_or(Error::BadArgs)?;
let (cmd, args) = argv[opts.index()..].split_first()
.ok_or(Error::BadArgs)?;
let old_files = io::stdin().lines()
.map(|l| l.map_err(Error::from)
.and_then(|l| if l.is_empty() { Err(Error::BadArgs) } else { Ok(l) })
.map(|l| encode_string(&l)))
.collect::<Result<Vec<String>, Error>>()?;
duplicate_elements(old_files.iter()).map_or(Ok(()), |dups| {
Err(Error::DupInputElems(dups.cloned().collect()))
})?;
let mut child = Command::new(cmd)
.args(args)
.stdin(Stdio::piped())
.stdout(Stdio::piped())
.spawn()
.map_err(|e| Error::SpawnFailed(cmd.to_owned(), e))?;
// TODO: Don’t use expect, create a custom error for this
child.stdin.take().map(|mut stdin| {
old_files.iter().try_for_each(|f| writeln!(stdin, "{f}"))
}).expect("Failed to open child stdin")?;
// On failure we exit with NOP error, because the expectation is that the process we spawned
// that failed will have printed an error message to stderr.
let output = child.wait_with_output().map_err(Error::from)
.and_then(|o| if o.status.success() { Ok(o) } else { Err(Error::Nop) })?;
let new_files = std::str::from_utf8(&output.stdout)?.lines()
.map(|s| Ok(if flags.encode {
Cow::Owned(decode_string(Cow::Borrowed(s))?)
} else {
Cow::Borrowed(s)
})).collect::<Result<Vec<Cow<'_, str>>, Error>>()?;
if old_files.len() != new_files.len() {
return Err(Error::BadLengths);
}
duplicate_elements(new_files.iter()).map_or(Ok(()), |dups| {
Err(Error::DupOutputElems(dups.map(|d| d.to_string()).collect()))
})?;
let tmpdir = Builder::new().prefix("mmv").tempdir()?;
let mut conflicts = Vec::<&str>::new();
iter::zip(old_files.iter(), new_files.iter())
.filter(|(x, y)| x != y)
.try_for_each(|(x, y)| try_move(&mut conflicts, &tmpdir, x, y))?;
conflicts.iter().try_for_each(|c| do_move(&tmpdir, c))?;
Ok(())
}
fn duplicate_elements<T>(iter: T) -> Option<impl Iterator<Item = T::Item>>
where
T: IntoIterator,
T::Item: Eq + Hash
{
let mut elems: HashMap<T::Item, bool> = HashMap::new();
let mut fail = false;
for elem in iter.into_iter() {
elems.entry(elem)
.and_modify(|b| { *b = true; fail = true; })
.or_insert(false);
}
fail.then(|| elems.into_iter().filter_map(|(e, b)| b.then_some(e)))
}
fn encode_string(s: &str) -> String {
s.chars().flat_map(|c| {
let cs = match c {
'\\' => ['\\', '\\'],
'\n' => ['\\', 'n' ],
_ => [c, '\0'],
};
cs.into_iter().enumerate()
.filter(|(i, c)| *i != 1 || *c != '\0')
.map(|(_, c)| c)
}).collect::<String>()
}
fn decode_string(s: Cow<'_, str>) -> Result<String, Error> {
let mut pv = false;
let mut fail = false;
match s {
Cow::Owned(s) => {
let bs = s.as_bytes();
bs.iter().for_each(|b| match (pv, *b) {
(true, b'\\') => pv = false,
(true, b'n') => pv = false,
(true, _) => { pv = false; fail = true },
(false, b'\\') => pv = true,
(false, _) => {},
});
if fail || pv {
return Err(Error::BadDecoding(s.to_string()));
}
let mut bs = s.into_bytes();
bs.retain_mut(|b| match (pv, *b) {
(true, b'\\') => { pv = false; true },
(true, b'n') => { pv = false; *b = b'\n'; true },
(true, _) => unreachable!(),
(false, b'\\') => { pv = true; false },
(false, _) => true,
});
Ok(String::from_utf8(bs).unwrap())
},
Cow::Borrowed(s) => {
s.chars()
.map(|c| Ok(match (pv, c) {
(true, '\\') => { pv = false; Some('\\') },
(true, 'n') => { pv = false; Some('\n') },
(true, _) => { pv = false; return Err(()); },
(false, '\\') => { pv = true; None },
(false, _) => { Some(c) } }))
.filter_map(Result::transpose)
.collect::<Result<String, ()>>()
.map_err(|()| Error::BadDecoding(s.to_string()))
},
}
}
fn decode_from_file(tmpfile: &NamedTempFile) -> Result<Vec<String>, Error> {
BufReader::new(tmpfile).lines()
.map(|l| l.map_err(Error::from).and_then(|l| decode_string(Cow::Owned(l))))
.filter(|s| s.as_ref().map_or(true, |s| !s.is_empty()))
.collect()
}
fn try_move<'a>(
conflicts: &mut Vec<&'a str>,
tmpdir: &TempDir,
old: &str,
new: &'a str
) -> Result<(), io::Error> {
if Path::new(new).exists() {
let new_loc = tmpdir.path().to_str().unwrap().to_owned() + "/" + new;
fs::rename(old, new_loc)?;
conflicts.push(new);
} else {
fs::rename(old, new)?;
}
Ok(())
}
fn do_move(tmpdir: &TempDir, new: &str) -> Result<(), io::Error> {
let old = tmpdir.path().to_str().unwrap().to_owned() + "/" + new;
fs::rename(old, new)?;
Ok(())
}
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