// sacredK.dll entry point. Loaded into sacred.exe by the launcher before the
// game's own entry point runs, so every hook is in place from the first
// instruction of game code.

#include <string>

#include <windows.h>
#include <detours.h>

#include "re/config.h"
#include "re/crash.h"
#include "re/hook.h"
#include "re/log.h"
#include "re/patch.h"

namespace {

// The only build we support: Sacred Gold 2.28, sacred.exe
// sha256 fe774c6f985b02c9ce03103c2e55e5d853258c0cc3c737ccd211219c74460cb9.
// Every hook address in this project is specific to it.
constexpr DWORD kExpectedTimestamp = 0x451BBE74;
constexpr DWORD kExpectedSizeOfImage = 0x01999000;

std::wstring ModuleDir(HMODULE module) {
    wchar_t path[MAX_PATH];
    DWORD length = GetModuleFileNameW(module, path, MAX_PATH);
    std::wstring dir(path, length);
    return dir.substr(0, dir.find_last_of(L"\\/") + 1);
}

bool IsSupportedGameBuild() {
    auto base = reinterpret_cast<const BYTE*>(GetModuleHandleW(nullptr));
    auto dos = reinterpret_cast<const IMAGE_DOS_HEADER*>(base);
    auto nt = reinterpret_cast<const IMAGE_NT_HEADERS32*>(base + dos->e_lfanew);
    re::Log("game image: timestamp 0x%08lx, size 0x%08lx", nt->FileHeader.TimeDateStamp,
            nt->OptionalHeader.SizeOfImage);
    return nt->FileHeader.TimeDateStamp == kExpectedTimestamp &&
           nt->OptionalHeader.SizeOfImage == kExpectedSizeOfImage;
}

void Startup(HMODULE module) {
    std::wstring dir = ModuleDir(module);
    re::OpenLog((dir + L"sacredK.log").c_str());
    re::SetConfigPath(dir + L"sacredK.ini");
    re::Log("sacredK loaded");
    re::InstallCrashHandler(dir);

    if (!IsSupportedGameBuild()) {
        re::Log("unsupported sacred.exe build, no hooks installed");
        MessageBoxW(nullptr,
                    L"This sacred.exe is not the supported Sacred Gold 2.28 build.\n"
                    L"sacredK will not patch it; the game runs unmodified.",
                    L"sacredK", MB_OK | MB_ICONWARNING);
        return;
    }
    if (re::ConfigInt("debug", "WaitForDebugger", 0)) {
        re::Log("waiting up to 60 s for a debugger to attach");
        for (int i = 0; i < 600 && !IsDebuggerPresent(); ++i) {
            Sleep(100);
        }
        re::Log(IsDebuggerPresent() ? "debugger attached" : "no debugger, continuing");
    }
    re::InstallHooks();
    re::RunStartupFunctions();
}

} // namespace

BOOL APIENTRY DllMain(HMODULE module, DWORD reason, LPVOID) {
    if (DetourIsHelperProcess()) {
        return TRUE;
    }
    if (reason == DLL_PROCESS_ATTACH) {
        DisableThreadLibraryCalls(module);
        DetourRestoreAfterWith();
        Startup(module);
    }
    return TRUE;
}