// thunks.cpp — runtime replacements called by AC into our DLL
#include "thunks.h"
#include "ac_addrs.h"

// ===== v5 — replacement PurgeResource for RenderSurface / RenderTexture =====
//
// Vtable slots use thiscall (ECX = this). MSVC __fastcall(arg1, arg2)
// receives arg1 in ECX and arg2 in EDX. EDX is scratch from the caller
// and isn't used, so we make it an unused parameter.
//
// Effect: instead of the no-op stub `mov al,1; ret`, we now actually
// call Destroy() on the resource (frees its D3D handle + heap state)
// then return 1 so PurgeOldResources marks it cleanly purged.

typedef void (__fastcall *destroy_fn_t)(void* self, void* edx_unused);

extern "C" int __fastcall purge_rendersurface_thunk(void* self, void* /*edx*/) {
    ((destroy_fn_t)ac::V5_RS_DESTROY_VA)(self, 0);
    return 1;
}

extern "C" int __fastcall purge_rendertexture_thunk(void* self, void* /*edx*/) {
    ((destroy_fn_t)ac::V5_RT_DESTROY_VA)(self, 0);
    return 1;
}

// ===== v14 — CEnvCell::Destroy ClipPlaneList cleanup =====
//
// EoR's CEnvCell::Destroy contains an 18-byte cleanup block at
// 0x0052E661 that only zeros cplane_num without freeing the underlying
// ClipPlaneList object. We replace those 18 bytes with a 5-byte
// JMP rel32 into the naked thunk below + 13 NOPs.
//
// Register context at entry (preserved from caller):
//   esi = `this` (CEnvCell)
//   ebx = 0     (cleared earlier in Destroy — relied on by the original
//                buggy `mov [eax], ebx`)
//   edi/ebp = live in surrounding loop
//
// On exit, we JMP to V14_RESUME_VA (the instruction immediately after
// the 18-byte block).

extern "C" __declspec(naked) void v14_clipplane_cleanup_thunk() {
    __asm {
        pushad                                ; preserve everything
        mov     edi, [esi + 0xDC]             ; outer ClipPlaneList wrapper ptr
        test    edi, edi
        jz      done
        mov     ecx, [edi]                    ; inner ClipPlaneList ptr
        test    ecx, ecx
        jz      free_outer
        // Free the inner ClipPlaneList properly
        push    ecx
        mov     eax, ac::V14_CLIPPLANELIST_DTOR
        call    eax                           ; ClipPlaneList::~ClipPlaneList (thiscall)
        pop     ecx
        push    ecx
        mov     eax, ac::V14_OPERATOR_DELETE
        call    eax                           ; operator delete(inner)
        add     esp, 4
    free_outer:
        push    edi
        mov     eax, ac::V14_OPERATOR_DELETE_ARR
        call    eax                           ; operator delete[](outer)
        add     esp, 4
        mov     dword ptr [esi + 0xDC], 0     ; clear back-pointer
    done:
        popad
        push    ac::V14_RESUME_VA             ; jmp to resume point
        ret
    }
}