//! Tiny system probes (kept dependency-free to stay lightweight).

/// Total physical memory in MiB (best effort; 8 GiB if unknown).
pub fn total_memory_mb() -> u64 {
    imp().unwrap_or(8192)
}

#[cfg(windows)]
fn imp() -> Option<u64> {
    use windows_sys::Win32::System::SystemInformation::{GlobalMemoryStatusEx, MEMORYSTATUSEX};
    let mut status: MEMORYSTATUSEX = unsafe { std::mem::zeroed() };
    status.dwLength = std::mem::size_of::<MEMORYSTATUSEX>() as u32;
    let ok = unsafe { GlobalMemoryStatusEx(&mut status) };
    (ok != 0).then_some(status.ullTotalPhys / 1024 / 1024)
}

#[cfg(target_os = "linux")]
fn imp() -> Option<u64> {
    let info = std::fs::read_to_string("/proc/meminfo").ok()?;
    let line = info.lines().find(|l| l.starts_with("MemTotal:"))?;
    let kb: u64 = line.split_whitespace().nth(1)?.parse().ok()?;
    Some(kb / 1024)
}

#[cfg(not(any(windows, target_os = "linux")))]
fn imp() -> Option<u64> {
    None
}

/// Recursively sum file sizes under `path`.
pub fn dir_size(path: &std::path::Path) -> u64 {
    let Ok(entries) = std::fs::read_dir(path) else { return 0 };
    entries
        .filter_map(|e| e.ok())
        .map(|e| match e.file_type() {
            Ok(t) if t.is_dir() => dir_size(&e.path()),
            Ok(t) if t.is_file() => e.metadata().map(|m| m.len()).unwrap_or(0),
            _ => 0,
        })
        .sum()
}