package xinput_devnodes

// #cgo CFLAGS: -g --std=gnu99 -pedantic -Wall
// #cgo LDFLAGS: -lX11 -lXi 
// #include "devnodes.h"
// #include <stdlib.h>
// #include <string.h>
import "C"
import (
	"fmt"
	"unsafe"
	"regexp"
	"errors"
	"os"
)


func FindKeyboardDevNode() string {
	xslaveinfos, freeMethod := GetXSlaveInfo()
	defer freeMethod()

	re := regexp.MustCompile(`(?i).*keyboard.*`)
	for _, xslaveinfo := range xslaveinfos {
		name, devNode := C.GoString(xslaveinfo.name), C.GoString(xslaveinfo.dev_node)
		if re.MatchString(name) {
			return devNode
		}
	}
	return ""
}


func Print() {
	xslaveinfos, freeMethod := GetXSlaveInfo()
	defer freeMethod()

	for _, xslaveinfo := range xslaveinfos {
		fmt.Printf("%s = %s\n", C.GoString(xslaveinfo.name), C.GoString(xslaveinfo.dev_node))
	}
}


func GetXSlaveInfo() ([]C.XSlaveInfo, func()) {
	xDisplayName := C.CString(tryGetXDisplay())
	defer C.free(unsafe.Pointer(xDisplayName))

	var error C.int
	xslaves := C.get_slave_info(xDisplayName, &error)
	if (error != C.int(0)) {
		panic(convertErrorIntToGoError(error))
	}

	arr := (*[1 << 30]C.XSlaveInfo)(unsafe.Pointer(xslaves.slaves))
	slice := arr[:xslaves.length:xslaves.length]
	freeMethod := func() {
		C.free_xslaves(xslaves)
	}

	return slice, freeMethod
}

func tryGetXDisplay() string {
	display := os.Getenv("DISPLAY")
	if display == "" {
		panic(errors.New("DISPLAY envvar not set"))
	}
	return display
}

func convertErrorIntToGoError(err C.int) error {
	errorMsg := ""
	switch err {
	case C.MALLOCFAIL:
		errorMsg = "Memory allocation failed"
	case C.XSLAVESFULL:
		errorMsg = "XSlaves full"
	case C.BADDISPLAY:
		errorMsg = "Failed to open X display"
	case C.XINPUTEXTUNAVAIL:
		errorMsg = "XInput extension unavailable"
	case C.XINPUT20UNAVAIL:
		errorMsg = "XInput extension is not 2.0"
	case C.XINPUTQUERYVERSIONFAILED:
		errorMsg = "Failed to query XInput extension version"
	case C.XSLAVEINFOQUERYFAILED:
		errorMsg = "Failed to query XInput slaves"
	default:
		errorMsg = fmt.Sprintf("Unknown error from devnodes.h: %v", err)
	}
	return errors.New(errorMsg)
}