//! Internal utility functions.

/// Check if the Ruby VM is globally available.
///
/// Unfortunately there is no public API for this check, but there's a hidden
/// `ruby_current_vm_ptr` symbol in libruby 2.5 - 3.2 which we can use to
/// determine if the VM has been initialized, or shut down.
///
/// # Notes
///
/// Ruby 2.4 and below don't have a global VM pointer, so we can't check if it's
/// null. Ruby 2.4 is EOL, and support will be dropped soon anyway.
//
/// In Ruby 3.3, the global VM pointer is no longer exported, so there's no
/// simple way to check the global VM pointer, so instead we check if known
/// static value is non-zero.
///
/// On Ruby < 3.3, we also need to check if the global VM pointer is null to
/// ensure the VM hasn't stopped, which makes the function name a bit of a
/// misnomer... but in actuality this function can only guarantee that the
/// VM is started, not that it's still running.
#[allow(dead_code)]
pub(crate) unsafe fn is_ruby_vm_started() -> bool {
    #[cfg(ruby_engine = "mri")]
    let ret = {
        #[cfg(all(ruby_gt_2_4, ruby_lte_3_2))]
        let ret = !crate::hidden::ruby_current_vm_ptr.is_null();

        #[cfg(any(ruby_lte_2_4, ruby_gt_3_2))]
        let ret = crate::rb_cBasicObject != 0;

        ret
    };

    #[cfg(ruby_engine = "truffleruby")]
    let ret = crate::rb_cBasicObject != 0;

    ret
}

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

    rusty_fork_test! {
        #[test]
        fn test_is_ruby_vm_started() {
            assert!(!unsafe { is_ruby_vm_started() });

            #[cfg(windows)]
            {
                let mut argc = 0;
                let mut argv: [*mut std::os::raw::c_char; 0] = [];
                let mut argv = argv.as_mut_ptr();
                unsafe { rb_sys::rb_w32_sysinit(&mut argc, &mut argv) };
            }

            match unsafe { crate::ruby_setup() } {
                0 => {}
                code => panic!("Failed to setup Ruby (error code: {})", code),
            };

            assert!(unsafe { is_ruby_vm_started() });
        }
    }
}