//go:build windows

package processor

import (
	"rpi5-health/internal/windows_system"
	"unsafe"

	"golang.org/x/sys/windows"
)

type DWORD uint32

type PFILETIME struct {
	dwLowDateTime  DWORD
	dwHighDateTime DWORD
}

func getWinCpuInfo(getSystemTimes *windows.LazyProc) ProcessorInformation {
	var lpIdleTime PFILETIME
	var lpKernelTime PFILETIME
	var lpUserTime PFILETIME

	getSystemTimes.Call(
		uintptr(unsafe.Pointer(&lpIdleTime)),
		uintptr(unsafe.Pointer(&lpKernelTime)),
		uintptr(unsafe.Pointer(&lpUserTime)),
	)

	timeSpentIdlingTicks := fileTimeToTicks(lpIdleTime)
	timeSpentByKernelTicks := fileTimeToTicks(lpKernelTime) - timeSpentIdlingTicks // kernel time includes idling by default
	timeSpentByUserTicks := fileTimeToTicks(lpUserTime)

	return ProcessorInformation{
		IdleTimeSinceBoot:   timeSpentIdlingTicks,
		KernelTimeSinceBoot: timeSpentByKernelTicks,
		UserTimeSinceBoot:   timeSpentByUserTicks,
	}
}

func fileTimeToTicks(filetime PFILETIME) uint64 {
	// 100 nanosecond intervals since 1601, january 1
	return (uint64(filetime.dwHighDateTime) << 32) | uint64(filetime.dwLowDateTime)
}

func GetCPUInformation() ProcessorInformation {
	return getWinCpuInfo(windows_system.GetWindowsTools().SystemTimes)
}