#include "ui_scroll.h"
#include <iostream>

namespace {
int forwarded{};
long long totalDelta{};
LRESULT CALLBACK observe(HWND w,UINT msg,WPARAM wp,LPARAM lp,UINT_PTR,DWORD_PTR)
{
    if(msg==WM_MOUSEWHEEL) { ++forwarded; totalDelta+=GET_WHEEL_DELTA_WPARAM(wp); }
    return DefSubclassProc(w,msg,wp,lp);
}
void require(bool ok,const char *message) { if(!ok) throw std::runtime_error(message); }
void wheel(HWND w,int delta) { SendMessageW(w,WM_MOUSEWHEEL,MAKEWPARAM(0,(WORD)(short)delta),0); }
void flush(HWND w) { SendMessageW(w,WM_TIMER,ks::ScrollFrameTimer,0); }
}
int main()
{
    INITCOMMONCONTROLSEX init{sizeof(init),ICC_STANDARD_CLASSES|ICC_LISTVIEW_CLASSES};
    InitCommonControlsEx(&init);
    auto instance=GetModuleHandleW(nullptr);
    auto parent=CreateWindowW(L"STATIC",L"Scroll regression",WS_OVERLAPPEDWINDOW,0,0,500,400,nullptr,nullptr,instance,nullptr);
    try {
        auto list=CreateWindowW(L"LISTBOX",L"",WS_CHILD|WS_VSCROLL,0,0,300,200,parent,nullptr,instance,nullptr);
        for(int i=0;i<2000;++i) SendMessageW(list,LB_ADDSTRING,0,(LPARAM)L"row");
        SendMessageW(list,LB_SETCURSEL,5,0);
        SendMessageW(list,LB_SETTOPINDEX,0,0);
        ks::enableWheelBatching(list,true);
        for(int i=0;i<1000;++i) wheel(list,-120);
        require(SendMessageW(list,LB_GETTOPINDEX,0,0)==0,"burst is deferred to one frame");
        flush(list);
        UINT lines{}; SystemParametersInfoW(SPI_GETWHEELSCROLLLINES,0,&lines,0);
        require(!lines || SendMessageW(list,LB_GETTOPINDEX,0,0)>0,"burst moves list");
        require(SendMessageW(list,LB_GETCURSEL,0,0)==5,"scroll does not change selection");
        for(int i=0;i<1000;++i) wheel(list,120);
        flush(list);
        require(SendMessageW(list,LB_GETTOPINDEX,0,0)==0,"reverse burst clamps at top");
        wheel(list,-60); flush(list);
        require(SendMessageW(list,LB_GETTOPINDEX,0,0)==0,"partial wheel step is retained");
        wheel(list,-60); flush(list);
        require(!lines || SendMessageW(list,LB_GETTOPINDEX,0,0)>0,"partial steps combine across frames");
        DestroyWindow(list);
        for(auto cls:{L"EDIT",WC_LISTVIEWW,L"COMBOBOX",L"STATIC"}) {
            auto w=CreateWindowW(cls,L"",WS_CHILD|WS_VSCROLL,0,0,300,200,parent,nullptr,instance,nullptr);
            require(w!=nullptr,"native scroll control created");
            SetWindowSubclass(w,observe,1,0); ks::enableWheelBatching(w);
            forwarded=0; totalDelta=0;
            for(int i=0;i<100;++i) wheel(w,-120);
            require(forwarded==0,"native wheel burst is batched");
            flush(w);
            require(forwarded==1 && totalDelta==-12000,"one native dispatch preserves burst distance");
            wheel(w,60); flush(w);
            require(forwarded==2 && totalDelta==-11940,"native partial steps are preserved");
            forwarded=0; totalDelta=0;
            for(int i=0;i<400;++i) wheel(w,-120);
            flush(w); flush(w);
            require(forwarded==2 && totalDelta==-48000,"large native burst is not truncated to 16 bits");
            SendMessageW(w,WM_TIMER,ks::ScrollIdleTimer,0);
            DestroyWindow(w);
        }
        DestroyWindow(parent);
        std::cout<<"Passed shared wheel batching regressions (list, edit, table, combo, window)\n";
        return 0;
    } catch(const std::exception &e) {
        DestroyWindow(parent); std::cerr<<e.what()<<'\n'; return 1;
    }
}