package libsignal

/*
#include <signal_protocol.h>
*/
import "C"

import (
	"runtime"
	"unsafe"
)

// Address identifies a Signal Protocol session peer: a logical recipient
// name (for OMEMO, a bare JID) plus a numeric device ID.
type Address struct {
	Name     string
	DeviceID uint32
}

// withCAddress converts addr to a C signal_protocol_address and invokes fn
// with a pointer to it. The pointer - and the memory its name field borrows
// from addr.Name - is only valid for the duration of fn; it must not be
// retained past fn's return.
func withCAddress(addr Address, fn func(*C.signal_protocol_address)) {
	nameBytes := []byte(addr.Name)
	var namePtr *C.char
	if len(nameBytes) > 0 {
		namePtr = (*C.char)(unsafe.Pointer(&nameBytes[0]))
	}
	cAddr := C.signal_protocol_address{
		name:      namePtr,
		name_len:  C.size_t(len(nameBytes)),
		device_id: C.int32_t(addr.DeviceID),
	}
	fn(&cAddr)
	runtime.KeepAlive(nameBytes)
}

// addressFromC copies a C signal_protocol_address into a Go Address.
func addressFromC(addr *C.signal_protocol_address) Address {
	return Address{
		Name:     C.GoStringN(addr.name, C.int(addr.name_len)),
		DeviceID: uint32(addr.device_id),
	}
}