package main

import (
	"embed"
	"log"
	"unsafe"

	"github.com/jchv/go-webview2"
	"golang.org/x/sys/windows"
)

//go:embed web/wallpaper.html
var fs embed.FS

var (
	user32                  = windows.NewLazySystemDLL("user32.dll")
	procFindWindowW         = user32.NewProc("FindWindowW")
	procFindWindowExW       = user32.NewProc("FindWindowExW")
	procSendMessageTimeoutW = user32.NewProc("SendMessageTimeoutW")
	procSetParent           = user32.NewProc("SetParent")
	procGetForegroundWindow = user32.NewProc("GetForegroundWindow")
	procGetWindowRect       = user32.NewProc("GetWindowRect")
	procGetSystemMetrics    = user32.NewProc("GetSystemMetrics")
	procMoveWindow          = user32.NewProc("MoveWindow")
	procShowWindow          = user32.NewProc("ShowWindow")
	procSetProcessDPIAware  = user32.NewProc("SetProcessDPIAware")
	procSetWindowLongPtrW   = user32.NewProc("SetWindowLongPtrW")
	procGetMessageW         = user32.NewProc("GetMessageW")
	procPostMessageW        = user32.NewProc("PostMessageW")
	procTranslateMessage    = user32.NewProc("TranslateMessage")
	procDispatchMessageW    = user32.NewProc("DispatchMessageW")
)

var wv webview2.WebView
var wvHwnd uintptr
var jsQueue = make(chan string, 64)
var paused int32

const wmEvalJS = 0x0401

func evalJS(js string) {
	select {
	case jsQueue <- js:
		log.Println("evalJS queued:", js[:min(len(js), 60)])
	default:
		log.Println("jsQueue full, dropping eval")
	}
	if wvHwnd != 0 {
		procPostMessageW.Call(wvHwnd, wmEvalJS, 0, 0)
	}
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func findWorkerW() uintptr {
	progman, _, _ := procFindWindowW.Call(
		uintptr(unsafe.Pointer(windows.StringToUTF16Ptr("Progman"))), 0)
	if progman == 0 {
		return 0
	}
	var result uintptr
	procSendMessageTimeoutW.Call(progman, 0x052C, 0, 0, 0x0000, 1000, uintptr(unsafe.Pointer(&result)))
	shellDefView, _, _ := procFindWindowExW.Call(progman, 0,
		uintptr(unsafe.Pointer(windows.StringToUTF16Ptr("SHELLDLL_DefView"))), 0)
	workerwAfterShell, _, _ := procFindWindowExW.Call(progman, shellDefView,
		uintptr(unsafe.Pointer(windows.StringToUTF16Ptr("WorkerW"))), 0)
	if workerwAfterShell != 0 {
		return workerwAfterShell
	}
	ww, _, _ := procFindWindowExW.Call(progman, 0,
		uintptr(unsafe.Pointer(windows.StringToUTF16Ptr("WorkerW"))), 0)
	return ww
}

func getScreenSize() (int32, int32) {
	w, _, _ := procGetSystemMetrics.Call(0)
	h, _, _ := procGetSystemMetrics.Call(1)
	return int32(w), int32(h)
}