package pipeline

import (

	"os"

	"syscall"

	"unsafe"

)

// forceLog should rarely be used. It forceable logs an entry to the

// Windows Event Log (on Windows) or to the SysLog (on Linux)

func forceLog(level LogLevel, msg string) {

	var el eventType

	switch level {

	case LogError, LogFatal, LogPanic:

		el = elError

	case LogWarning:

		el = elWarning

	case LogInfo:

		el = elInfo

	}

	// We are logging it, ensure trailing newline

	if len(msg) == 0 || msg[len(msg)-1] != '\n' {

		msg += "\n" // Ensure trailing newline

	}

	reportEvent(el, 0, msg)

}

type eventType int16

const (

	elSuccess eventType = 0

	elError   eventType = 1

	elWarning eventType = 2

	elInfo    eventType = 4

)

var reportEvent = func() func(eventType eventType, eventID int32, msg string) {

	advAPI32 := syscall.MustLoadDLL("advapi32.dll") // lower case to tie in with Go's sysdll registration

	registerEventSource := advAPI32.MustFindProc("RegisterEventSourceW")

	sourceName, _ := os.Executable()

	sourceNameUTF16, _ := syscall.UTF16PtrFromString(sourceName)

	handle, _, lastErr := registerEventSource.Call(uintptr(0), uintptr(unsafe.Pointer(sourceNameUTF16)))

	if lastErr == nil { // On error, logging is a no-op

		return func(eventType eventType, eventID int32, msg string) {}

	}

	reportEvent := advAPI32.MustFindProc("ReportEventW")

	return func(eventType eventType, eventID int32, msg string) {

		s, _ := syscall.UTF16PtrFromString(msg)

		_, _, _ = reportEvent.Call(

			uintptr(handle),             // HANDLE  hEventLog

			uintptr(eventType),          // WORD    wType

			uintptr(0),                  // WORD    wCategory

			uintptr(eventID),            // DWORD   dwEventID

			uintptr(0),                  // PSID    lpUserSid

			uintptr(1),                  // WORD    wNumStrings

			uintptr(0),                  // DWORD   dwDataSize

			uintptr(unsafe.Pointer(&s)), // LPCTSTR *lpStrings

			uintptr(0))                  // LPVOID  lpRawData

	}

}()