//! Vtable patching utilities for WA.exe's .rdata vtables.

use core::mem::size_of;

/// Temporarily make a vtable region writable, run a patcher closure, then
/// restore the original memory protection.
///
/// # Safety
/// `vtable_addr` must point to a valid vtable with at least `slots` entries.
pub unsafe fn patch_vtable(
    vtable_addr: *mut u32,
    slots: usize,
    patcher: impl FnOnce(*mut u32),
) -> Result<(), &'static str> {
    let mut old_protect: u32 = 0;
    let ok = windows_sys::Win32::System::Memory::VirtualProtect(
        vtable_addr as *mut core::ffi::c_void,
        slots * size_of::<u32>(),
        0x04, // PAGE_READWRITE
        &mut old_protect,
    );
    if ok == 0 {
        return Err("VirtualProtect failed on vtable");
    }

    patcher(vtable_addr);

    windows_sys::Win32::System::Memory::VirtualProtect(
        vtable_addr as *mut core::ffi::c_void,
        slots * size_of::<u32>(),
        old_protect,
        &mut old_protect,
    );
    Ok(())
}