affine_importer 0.1.2

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct VfsEntry {
  pub path: String,
  pub bytes: Vec<u8>,
}

pub fn normalize_import_path(path: &str) -> String {
  let mut parts = Vec::new();
  let path = path.replace('\\', "/");
  for part in path.split('/') {
    if part.is_empty() || part == "." {
      continue;
    }
    if part == ".." {
      if parts.last().is_some_and(|part| *part != "..") {
        parts.pop();
      } else {
        parts.push(part);
      }
      continue;
    }
    parts.push(part);
  }
  parts.join("/")
}

#[cfg(test)]
mod tests {
  use super::{VfsEntry, normalize_import_path};

  #[derive(Debug, Clone, Default, PartialEq, Eq)]
  struct Vfs {
    entries: Vec<VfsEntry>,
  }

  impl Vfs {
    fn insert(&mut self, path: impl Into<String>, bytes: Vec<u8>) -> crate::ImportResult<()> {
      let path = normalize_import_path(&path.into());
      if path.is_empty() {
        return Err(crate::ImportError::InvalidSource("empty path".to_string()));
      }
      if path.split('/').any(|part| part == "..") {
        return Err(crate::ImportError::InvalidSource(format!(
          "path escapes import root: {path}"
        )));
      }
      if is_system_path(&path) {
        return Ok(());
      }
      self.entries.push(VfsEntry { path, bytes });
      Ok(())
    }
  }

  fn is_system_path(path: &str) -> bool {
    path.split('/').any(|part| part == "__MACOSX" || part == ".DS_Store")
  }

  #[test]
  fn rejects_parent_segments() {
    let mut vfs = Vfs::default();
    let result = vfs.insert("../escape.md", b"bad".to_vec());

    assert!(matches!(result, Err(crate::ImportError::InvalidSource(_))));
  }
}