checksum.rs

//! File checksum computing and checksum file writing.
use std::{
    borrow::Cow,
    fs::File,
    io::{self, Write},
    path::{Path, PathBuf},
};

use log::{debug, error, info, warn};
use rayon::{iter::ParallelIterator, prelude::ParallelBridge};
use sha2::{Digest, Sha384};

use crate::error::Error;

pub trait Checksum {
    /// compute the hash of the file pointed by the filepath by using [io::copy] between a file handler and the hasher.
    /// As such, it shouldn't make the program go OOM with big files, but it has not been tested.
    /// Can return an error if there has been problems regarding IO.
    #[inline]
    fn get_hash<R>(reader: &mut R, hasher: &mut Sha384) -> Result<String, Error>
    where
        R: std::io::Read,
    {
        io::copy(reader, hasher)?;
        let result = format!("{:x}", hasher.finalize_reset());
        Ok(result)
    }

    /// corpus/lang/lang_part_x.jsonl
    #[inline]
    fn get_hash_path(src: &Path, hasher: &mut Sha384) -> Result<String, Error> {
        let mut f = File::open(src)?;
        Self::get_hash(&mut f, hasher)
    }

    /// this should operate on the wide-level.
    fn checksum_folder(src: &Path, num_threads: usize) -> Result<(), Error> {
        if num_threads != 1 {
            rayon::ThreadPoolBuilder::new()
                .num_threads(num_threads)
                .build_global()?;
        }

        if src.is_file() {
            // TODO #86442 merged
            // return Err(io::Error::new(
            //     io::ErrorKind::IsADirectory,
            //     format!("{}", src),
            // ));
            error!("Checksum only works on folders!");
            return Err(io::Error::new(io::ErrorKind::InvalidInput, format!("{:?}", src)).into());
        }

        let language_dirs = std::fs::read_dir(src)?.filter_map(|entry| {
            // check entry validity
            let entry = match entry {
                Ok(e) => e.path(),
                Err(e) => {
                    error!("error with directory entry {:?}", e);
                    return None;
                }
            };

            // filter out files
            if !entry.is_dir() {
                warn!("{:?} is not a directory: ignoring checksum op", entry);
                None
            } else {
                Some(entry)
            }
        });

        let language_dirs_par = language_dirs.par_bridge();
        language_dirs_par.for_each(|language_dir| match Self::get_write_hashes(&language_dir) {
            Ok(_) => (),
            Err(e) => error!("Error with directory {:?}: {:?}", language_dir, e),
        });
        Ok(())
    }

    #[inline]
    /// convinience function for checksum_folder
    /// TODO: move out of trait
    fn get_write_hashes(src: &Path) -> Result<(), Error> {
        debug!("Getting hashes for {:?}", src);
        let hashes = Self::checksum_lang(src)?;
        let checksum_filepath = src.to_path_buf().join("checksum.sha384");
        debug!("writing checksums in {:?}", checksum_filepath);
        let mut checksum_file = File::create(&checksum_filepath)?;
        Self::write_checksum(&mut checksum_file, hashes)?;
        Ok(())
    }
    fn write_checksum<W: Write>(
        writer: &mut W,
        hashes: Vec<(PathBuf, String)>,
    ) -> Result<(), Error> {
        for (path, hash) in hashes {
            if let Some(filename) = path.file_name() {
                let filename = if let Some(filename_string) = filename.to_str() {
                    Cow::from(filename_string)
                } else {
                    let filename_string = filename.to_string_lossy();
                    warn!(
                        "could not convert path to string: {:?}, using {} in replacement.",
                        filename, filename_string
                    );
                    filename_string
                };
                writeln!(writer, "{} {}", hash, filename)?;
            } else {
                warn!("Could not get filename for {:?}: ignoring in checksum. Add manually if necessary.", path);
            }
        }
        Ok(())
    }
    /// this should operate on lang-level
    fn checksum_lang(src: &Path) -> Result<Vec<(PathBuf, String)>, Error> {
        let mut hasher = Sha384::new();
        let mut hashes = Vec::new();
        for filepath in std::fs::read_dir(src)? {
            let filepath = filepath?.path();
            debug!("hashing {:?}", filepath);
            let hash = Self::get_hash_path(&filepath, &mut hasher)?;
            hashes.push((filepath, hash));
        }
        Ok(hashes)
    }
}

#[cfg(test)]
mod tests {
    use sha2::Digest;

    use std::fs::File;
    use std::io::Write;
    use std::path::PathBuf;
    use tempfile::TempDir;

    use sha2::Sha384;

    use crate::error::Error;
    use crate::ops::Checksum;

    fn gen_dummy_corpus() -> Result<TempDir, Error> {
        let corpus_dir = tempfile::tempdir().unwrap();

        let (langs, contents): (Vec<&str>, Vec<&str>) = [
            ("fr", r#"{{"content":"foo_french"}}"#),
            ("en", r#"{{"content":"foo_english"}}"#),
            ("de", r#"{{"content":"foo_german"}}"#),
            ("es", r#"{{"content":"foo_spanish"}}"#),
        ]
        .iter()
        .cloned()
        .unzip();
        for (lang, content) in langs.iter().zip(contents.iter()) {
            let path = corpus_dir.path();
            let lang_dir = path.join(lang);
            std::fs::create_dir(&lang_dir)?;
            let lang_text_file = lang_dir.clone().join(format!("{lang}.jsonl"));
            let mut f = File::create(&lang_text_file)?;
            write!(&mut f, "{content}")?;
        }

        Ok(corpus_dir)
    }
    #[test]
    fn test_write_checksum() {
        struct DummyChecksum;
        impl Checksum for DummyChecksum {}

        let hashes = vec![
            (PathBuf::from("fr.txt"), "hash_for_fr.txt".to_string()),
            (PathBuf::from("en.txt"), "hash_for_en.txt".to_string()),
            (PathBuf::from("es.txt"), "hash_for_es.txt".to_string()),
            (PathBuf::from("de.txt"), "hash_for_de.txt".to_string()),
        ];
        let expected = "hash_for_fr.txt fr.txt
hash_for_en.txt en.txt
hash_for_es.txt es.txt
hash_for_de.txt de.txt
";
        let mut checksum_writer = Vec::new();
        DummyChecksum::write_checksum(&mut checksum_writer, hashes).unwrap();
        let checksum_string = String::from_utf8(checksum_writer).unwrap();
        assert_eq!(expected, &checksum_string);
    }

    #[test]
    fn test_get_write_hashes() -> Result<(), Error> {
        struct DummyChecksum;
        impl Checksum for DummyChecksum {}

        let lang = tempfile::tempdir()?;
        let lang_corpus = lang.path().join("fr.txt");
        let text = "foo bar baz quux";
        let mut f = File::create(&lang_corpus)?;
        f.write(text.as_bytes())?;

        DummyChecksum::get_write_hashes(lang.path())?;

        let checksum_file = lang.path().join("checksum.sha384");
        let checksums = std::fs::read_to_string(&checksum_file)?;

        let mut x = checksums.split(' ').take(2);
        let (checksum, filename) = (x.next(), x.next());

        let mut hasher = Sha384::new();
        hasher.update(text.as_bytes());
        let expected_checksum = format!("{:x}", hasher.finalize_reset());
        let expected_filename = "fr.txt\n";

        assert_eq!(checksum.unwrap(), &expected_checksum);
        assert_eq!(filename.unwrap(), expected_filename);

        Ok(())
    }
    #[test]
    fn test_checksum_lang() -> Result<(), Error> {
        struct DummyChecksum;
        impl Checksum for DummyChecksum {}

        let corpus_dir = tempfile::tempdir().unwrap();

        let (langs, contents): (Vec<&str>, Vec<&str>) = [
            ("fr", r#"{{"content":"foo_french"}}"#),
            ("en", r#"{{"content":"foo_english"}}"#),
            ("de", r#"{{"content":"foo_german"}}"#),
            ("es", r#"{{"content":"foo_spanish"}}"#),
        ]
        .iter()
        .cloned()
        .unzip();
        for (lang, content) in langs.iter().zip(contents.iter()) {
            let path = corpus_dir.path();
            let lang_dir = path.join(lang);
            std::fs::create_dir(&lang_dir)?;
            let lang_text_file = lang_dir.clone().join(format!("{lang}.jsonl"));
            let mut f = File::create(&lang_text_file)?;
            write!(&mut f, "{content}")?;
        }

        for (lang, content) in langs.iter().zip(contents) {
            // corpora are not split, so there's only one file (hence [0]). We then take the hash (hence .1)
            let hash = &DummyChecksum::checksum_lang(&corpus_dir.path().join(lang))?[0].1;
            let expected = {
                let mut hasher = Sha384::new();
                let mut reader = content.as_bytes();
                DummyChecksum::get_hash(&mut reader, &mut hasher)?
            };

            assert_eq!(hash, &expected);
        }

        Ok(())
    }

    #[test]
    fn test_checksum_folder() -> Result<(), Error> {
        struct DummyChecksum;
        impl Checksum for DummyChecksum {}

        let corpus_dir = tempfile::tempdir().unwrap();

        let (langs, contents): (Vec<&str>, Vec<&str>) = [
            ("fr", r#"{{"content":"foo_french"}}"#),
            ("en", r#"{{"content":"foo_english"}}"#),
            ("de", r#"{{"content":"foo_german"}}"#),
            ("es", r#"{{"content":"foo_spanish"}}"#),
        ]
        .iter()
        .cloned()
        .unzip();

        for (lang, content) in langs.iter().zip(contents.iter()) {
            let path = corpus_dir.path();
            let lang_dir = path.join(lang);
            std::fs::create_dir(&lang_dir)?;
            let lang_text_file = lang_dir.clone().join(format!("{lang}.jsonl"));
            let mut f = File::create(&lang_text_file)?;
            write!(&mut f, "{content}")?;
        }

        let corpus_path = corpus_dir.path();
        DummyChecksum::checksum_folder(corpus_path, 1)?;

        for dir in std::fs::read_dir(&corpus_path)? {
            let dir = dir?;
            let mut hashes: Vec<(_, _)> = Vec::new();
            let mut hashes_from_files: Vec<(_, _)> = Vec::new();
            let mut hasher = Sha384::new();
            for language_dir in std::fs::read_dir(dir.path())? {
                let language_dir = language_dir?;

                let current_path = language_dir.path();
                let extension = current_path.extension().and_then(|x| x.to_str());
                match extension {
                    None => (),
                    Some("jsonl") => {
                        let hash = DummyChecksum::get_hash_path(&current_path, &mut hasher)?;
                        let filename = current_path.clone();
                        let filename = filename.file_name().map(|f| f.to_owned());

                        let filename = filename.unwrap().into_string();
                        hashes.push((filename.unwrap(), hash));
                    }
                    Some("sha384") => {
                        let checksums = std::fs::read_to_string(current_path)?;
                        let parts: Vec<String> = checksums
                            .split(' ')
                            .take(2)
                            .map(|x| x.to_string())
                            .collect();
                        let hash = parts[0].clone();
                        let filename = parts[1].clone().replace('\n', "");
                        hashes_from_files.push((filename, hash));
                    }
                    _ => (),
                }
            }

            assert_eq!(hashes, hashes_from_files);
        }

        Ok(())
    }
}