lz4r 1.10.0

//! File size queries backed by `std::fs` metadata.
//!
//! Provides three functions:
//! - [`get_open_file_size`]  — byte length of an already-open [`std::fs::File`]
//! - [`get_file_size`]       — byte length of a file at a given path
//! - [`get_total_file_size`] — summed byte length over a slice of paths
//!
//! Non-regular files (directories, pipes, sockets) and unreachable paths
//! contribute `0`, avoiding error propagation through bulk size operations.

use std::fs::{self, File};
use std::path::Path;

/// Returns the size in bytes of the open file `file`.
///
/// Returns `0` if `file` does not refer to a regular file (e.g. stdin, a pipe,
/// or a directory). Use [`get_file_size`] when only a path is available.
pub fn get_open_file_size(file: &File) -> u64 {
    file.metadata()
        .ok()
        .filter(|m| m.file_type().is_file())
        .map(|m| m.len())
        .unwrap_or(0)
}

/// Returns the size in bytes of the regular file at `path`.
///
/// Returns `0` if the path does not exist, is not a regular file, or cannot
/// be stat-ted. This makes the function safe to use in accumulation loops
/// without requiring callers to handle per-file errors.
pub fn get_file_size(path: &Path) -> u64 {
    fs::metadata(path)
        .ok()
        .filter(|m| m.file_type().is_file())
        .map(|m| m.len())
        .unwrap_or(0)
}

/// Returns the total size in bytes of all regular files in `paths`.
///
/// Each element is queried with [`get_file_size`]; non-regular files and
/// unreachable paths contribute `0`. Returns `0` for an empty slice.
pub fn get_total_file_size(paths: &[&Path]) -> u64 {
    paths.iter().map(|p| get_file_size(p)).sum()
}

// ─── Tests ────────────────────────────────────────────────────────────────────

#[cfg(test)]
mod tests {
    use super::*;
    use std::io::Write;
    use tempfile::TempDir;

    // ── get_file_size ─────────────────────────────────────────────────────────

    #[test]
    fn get_file_size_matches_metadata_len() {
        let dir = TempDir::new().unwrap();
        let path = dir.path().join("test.bin");
        let data = b"hello lz4";
        fs::write(&path, data).unwrap();
        let expected = fs::metadata(&path).unwrap().len();
        assert_eq!(get_file_size(&path), expected);
        assert_eq!(get_file_size(&path), data.len() as u64);
    }

    #[test]
    fn get_file_size_returns_zero_for_nonexistent_path() {
        let path = Path::new("/nonexistent/__lz4_file_size_test__.bin");
        assert_eq!(get_file_size(path), 0);
    }

    #[test]
    fn get_file_size_returns_zero_for_directory() {
        let dir = TempDir::new().unwrap();
        assert_eq!(get_file_size(dir.path()), 0);
    }

    // ── get_open_file_size ────────────────────────────────────────────────────

    #[test]
    fn get_open_file_size_matches_file_contents() {
        let dir = TempDir::new().unwrap();
        let path = dir.path().join("open_test.bin");
        let data = b"open file size test";
        fs::write(&path, data).unwrap();
        let file = File::open(&path).unwrap();
        assert_eq!(get_open_file_size(&file), data.len() as u64);
    }

    #[test]
    fn get_open_file_size_of_written_file_reflects_content() {
        let dir = TempDir::new().unwrap();
        let path = dir.path().join("written.bin");
        let mut file = File::create(&path).unwrap();
        let data = b"some content";
        file.write_all(data).unwrap();
        file.flush().unwrap();
        assert_eq!(get_open_file_size(&file), data.len() as u64);
    }

    // ── get_total_file_size ───────────────────────────────────────────────────

    #[test]
    fn get_total_file_size_empty_slice_returns_zero() {
        assert_eq!(get_total_file_size(&[]), 0);
    }

    #[test]
    fn get_total_file_size_sums_all_files() {
        let dir = TempDir::new().unwrap();
        let p1 = dir.path().join("a.bin");
        let p2 = dir.path().join("b.bin");
        fs::write(&p1, b"aaa").unwrap();
        fs::write(&p2, b"bbbbb").unwrap();
        let total = get_total_file_size(&[p1.as_path(), p2.as_path()]);
        assert_eq!(total, 3 + 5);
    }

    #[test]
    fn get_total_file_size_skips_nonexistent() {
        let dir = TempDir::new().unwrap();
        let p1 = dir.path().join("real.bin");
        fs::write(&p1, b"12345").unwrap();
        let missing = Path::new("/nonexistent/__lz4_missing__.bin");
        let total = get_total_file_size(&[p1.as_path(), missing]);
        assert_eq!(total, 5);
    }
}