fbt-lib 0.1.18

// Source: https://github.com/assert-rs/dir-diff (Apache/MIT)
// Need to modify it so including it, will send PR and try to get it included
// upstream.

/// The various errors that can happen when diffing two directories
#[derive(Debug)]
pub enum DirDiffError {
    Io(std::io::Error),
    StripPrefix(std::path::StripPrefixError),
    WalkDir(walkdir::Error),
    UTF8Parsing(std::string::FromUtf8Error),
}

#[derive(Debug)]
pub enum DirDiff {
    ExpectedFileMissing {
        expected: std::path::PathBuf,
    },
    ExpectedFolderMissing {
        expected: std::path::PathBuf,
    },
    UnexpectedFileFound {
        found: std::path::PathBuf,
    },
    UnexpectedFolderFound {
        found: std::path::PathBuf,
    },
    FileTypeMismatch {
        file: std::path::PathBuf,
        expected: String,
        found: String,
    },
    ContentMismatch {
        file: std::path::PathBuf,
        expected: String,
        found: String,
    },
    NonContentFileMismatch {
        file: std::path::PathBuf,
    },
}

pub(crate) fn diff<A: AsRef<std::path::Path>, B: AsRef<std::path::Path>>(
    a_base: A,
    b_base: B,
) -> Result<Option<DirDiff>, DirDiffError> {
    use sha2::Digest;
    let mut a_walker = walk_dir(a_base)?;
    let mut b_walker = walk_dir(b_base)?;

    loop {
        match (a_walker.next(), b_walker.next()) {
            (Some(a), Some(b)) => {
                // first lets check the depth:
                // a > b: UnexpectedFileFound or UnexpectedFolderFound else
                // b > a: ExpectedFileMissing or ExpectedFolderMissing

                // if file names dont match how to find if we got a new entry
                // on left or extra entry on right? how do people actually
                // calculate diff?

                // then check file type

                // finally check file content if its a file

                // TODO: this is dummy code to test stuff
                let a = a?;
                let b = b?;
                if a.metadata()
                    .expect("Unable to retrieve metadata for found file/folder")
                    .is_dir()
                    && b.metadata()
                        .expect("Unable to retrieve metadata for found file/folder")
                        .is_dir()
                {
                    // Recursively check for the files in the directory
                    return diff(a.path(), b.path());
                }

                let found: std::path::PathBuf = b.path().into();

                if a.file_name() != b.file_name() {
                    return Ok(Some(if found.is_dir() {
                        DirDiff::UnexpectedFolderFound { found }
                    } else {
                        DirDiff::UnexpectedFileFound { found }
                    }));
                }
                if let (Ok(a_content), Ok(b_content)) = (
                    std::fs::read_to_string(a.path()),
                    std::fs::read_to_string(b.path()),
                ) {
                    if a_content != b_content {
                        return Ok(Some(DirDiff::ContentMismatch {
                            expected: b_content,
                            found: a_content,
                            file: found,
                        }));
                    }
                } else if let (Ok(a_content), Ok(b_content)) =
                    (std::fs::read(a.path()), std::fs::read(b.path()))
                {
                    if !sha2::Sha256::digest(a_content).eq(&sha2::Sha256::digest(b_content)) {
                        return Ok(Some(DirDiff::NonContentFileMismatch { file: found }));
                    }
                }
            }
            (None, Some(b)) => {
                // we have something in b, but a is done, lets iterate over all
                // entries in b, and put them in UnexpectedFileFound and
                // UnexpectedFolderFound
                let expected: std::path::PathBuf = b?.path().into();
                return Ok(Some(if expected.is_dir() {
                    DirDiff::ExpectedFolderMissing { expected }
                } else {
                    DirDiff::ExpectedFileMissing { expected }
                }));
            }
            (Some(a), None) => {
                // we have something in a, but b is done, lets iterate over all
                // entries in a, and put them in ExpectedFileMissing and
                // ExpectedFolderMissing
                let found: std::path::PathBuf = a?.path().into();
                return Ok(Some(if found.is_dir() {
                    DirDiff::UnexpectedFolderFound { found }
                } else {
                    DirDiff::UnexpectedFileFound { found }
                }));
            }
            (None, None) => break,
        }
    }

    Ok(None)
}

pub(crate) fn fix<A: AsRef<std::path::Path>, B: AsRef<std::path::Path>>(
    a_base: A,
    b_base: B,
) -> Result<(), DirDiffError> {
    fix_(a_base, b_base)?;
    Ok(())
}

fn fix_(src: impl AsRef<std::path::Path>, dst: impl AsRef<std::path::Path>) -> std::io::Result<()> {
    if dst.as_ref().exists() {
        std::fs::remove_dir_all(&dst)?;
    }
    std::fs::create_dir_all(&dst)?;
    let dir = std::fs::read_dir(src)?;
    for child in dir {
        let child = child?;
        if child.metadata()?.is_dir() {
            fix_(child.path(), dst.as_ref().join(child.file_name()))?;
        } else {
            std::fs::copy(child.path(), dst.as_ref().join(child.file_name()))?;
        }
    }
    Ok(())
}

fn walk_dir<P: AsRef<std::path::Path>>(path: P) -> Result<walkdir::IntoIter, std::io::Error> {
    let mut walkdir = walkdir::WalkDir::new(path)
        .sort_by(compare_by_file_name)
        .into_iter();
    if let Some(Err(e)) = walkdir.next() {
        Err(e.into())
    } else {
        Ok(walkdir)
    }
}

fn compare_by_file_name(a: &walkdir::DirEntry, b: &walkdir::DirEntry) -> std::cmp::Ordering {
    a.file_name().cmp(b.file_name())
}

impl From<std::io::Error> for DirDiffError {
    fn from(e: std::io::Error) -> DirDiffError {
        DirDiffError::Io(e)
    }
}

impl From<std::path::StripPrefixError> for DirDiffError {
    fn from(e: std::path::StripPrefixError) -> DirDiffError {
        DirDiffError::StripPrefix(e)
    }
}

impl From<walkdir::Error> for DirDiffError {
    fn from(e: walkdir::Error) -> DirDiffError {
        DirDiffError::WalkDir(e)
    }
}