package main

import (
	"fmt"
	"os"
	"syscall"
)

func loadDLL(dllPath string) (syscall.Handle, error) {
	if _, err := os.Stat(dllPath); os.IsNotExist(err) {
		return 0, fmt.Errorf("DLL file does not exist: %s", dllPath)
	}

	dll, err := syscall.LoadLibrary(dllPath)
	if err != nil {
		return 0, fmt.Errorf("load DLL failed: %v", err)
	}

	globalLogger.Info("[辅助程序] 成功加载DLL: %s", dllPath)
	return dll, nil
}

func getLoaderProcAddress(dll syscall.Handle, name string, legacyOffset uintptr) (uintptr, error) {
	addr, err := syscall.GetProcAddress(dll, name)
	if err == nil && addr != 0 {
		return addr, nil
	}
	bundle := resolveDLLBundle()
	if supportsLegacyLoaderOffsets(bundle.LoaderVersion) {
		globalLogger.Warn("[辅助程序] Loader %s 未导出 %s，回退使用旧版偏移 0x%x", bundle.LoaderVersion, name, legacyOffset)
		return uintptr(dll) + legacyOffset, nil
	}
	return 0, fmt.Errorf("Loader %s does not export %s; legacy offsets are only allowed for %s", bundle.LoaderVersion, name, fallbackDLLVersion)
}

func supportsLegacyLoaderOffsets(version string) bool {
	switch version {
	case fallbackDLLVersion, "5.0.8.6009":
		return true
	default:
		return false
	}
}

func getLoaderFunctions(dll syscall.Handle) (*LoaderFunctions, error) {
	const (
		GetUserWxWorkVersion  = 0x4B70
		UseUtf8               = 0x4A60
		UseRecvJsUnicode      = 0x4AC0
		InitWxWorkSocket      = 0x4B10
		SetDataLocationPath   = 0x5460
		InjectWxWork          = 0x4BF0
		InjectWxWorkMultiOpen = 0x4E80
		InjectWxWorkPid       = 0x50D0
		DestroyWxWork         = 0x5310
		SendWxWorkData        = 0x5800
	)

	var err error
	funcs := &LoaderFunctions{}

	funcs.GetUserWxWorkVersion, err = getLoaderProcAddress(dll, "GetUserWxWorkVersion", GetUserWxWorkVersion)
	if err != nil {
		return nil, err
	}
	funcs.UseUtf8, err = getLoaderProcAddress(dll, "UseUtf8", UseUtf8)
	if err != nil {
		return nil, err
	}
	funcs.UseRecvJsUnicode, err = getLoaderProcAddress(dll, "UseRecvJsUnicode", UseRecvJsUnicode)
	if err != nil {
		return nil, err
	}
	funcs.InitWxWorkSocket, err = getLoaderProcAddress(dll, "InitWxWorkSocket", InitWxWorkSocket)
	if err != nil {
		return nil, err
	}
	funcs.SetDataLocationPath, err = getLoaderProcAddress(dll, "SetDataLocationPath", SetDataLocationPath)
	if err != nil {
		return nil, err
	}
	funcs.InjectWxWorkPid, err = getLoaderProcAddress(dll, "InjectWxWorkPid", InjectWxWorkPid)
	if err != nil {
		return nil, err
	}
	funcs.DestroyWxWork, err = getLoaderProcAddress(dll, "DestroyWxWork", DestroyWxWork)
	if err != nil {
		return nil, err
	}
	funcs.InjectWxWork, err = getLoaderProcAddress(dll, "InjectWxWork", InjectWxWork)
	if err != nil {
		return nil, err
	}
	funcs.InjectWxWorkMultiOpen, err = getLoaderProcAddress(dll, "InjectWxWorkMultiOpen", InjectWxWorkMultiOpen)
	if err != nil {
		return nil, err
	}
	funcs.SendWxWorkData, err = getLoaderProcAddress(dll, "SendWxWorkData", SendWxWorkData)
	if err != nil {
		return nil, err
	}

	globalLogger.Info("[辅助程序] 成功获取Loader DLL函数指针")
	return funcs, nil
}