doing-config 0.1.5

use std::path::{Path, PathBuf};

use doing_error::{Error, Result};

/// Expands a leading `~` in a path to the user's home directory.
///
/// Returns the path unchanged if it does not start with `~`.
/// Returns an error if `$HOME` cannot be resolved.
pub fn expand_tilde(path: &Path) -> Result<PathBuf> {
  let s = path.to_string_lossy();
  if let Some(rest) = s.strip_prefix("~/") {
    let home = dir_spec::home().ok_or_else(|| Error::Config("$HOME is not set".into()))?;
    Ok(home.join(rest))
  } else if s == "~" {
    dir_spec::home().ok_or_else(|| Error::Config("$HOME is not set".into()))
  } else {
    Ok(path.to_path_buf())
  }
}

#[cfg(test)]
mod test {
  use super::*;

  mod expand_tilde {
    use super::*;

    #[test]
    fn it_expands_bare_tilde() {
      let result = expand_tilde(Path::new("~")).unwrap();

      assert!(result.is_absolute());
      assert!(!result.to_string_lossy().contains('~'));
    }

    #[test]
    fn it_expands_tilde_prefix() {
      let result = expand_tilde(Path::new("~/Documents/file.txt")).unwrap();

      assert!(result.is_absolute());
      assert!(result.ends_with("Documents/file.txt"));
    }

    #[test]
    fn it_leaves_absolute_paths_unchanged() {
      let path = Path::new("/usr/local/bin");
      let result = expand_tilde(path).unwrap();

      assert_eq!(result, path);
    }

    #[test]
    fn it_leaves_relative_paths_unchanged() {
      let path = Path::new("relative/path");
      let result = expand_tilde(path).unwrap();

      assert_eq!(result, path);
    }
  }
}