package ldap

import (
	"testing"

	"github.com/vjeantet/goldap/message"
)

// resultCode round-trips a result response through its wire encoding
// and pulls the result code back out of it. The goldap result types
// expose setters but no getters, so the encoding is the only way to
// read it back.
func resultCode(t *testing.T, po message.ProtocolOp) int {
	t.Helper()

	m := message.NewLDAPMessageWithProtocolOp(po)
	m.SetMessageID(1)
	b, err := m.Write()
	if err != nil {
		t.Fatalf("encoding response: %s", err)
	}
	raw := b.Bytes()

	// Descend from the LDAPMessage SEQUENCE into the protocolOp,
	// whose first element is always the resultCode for the result
	// types this server sends.
	var e error
	off := 0
	if _, off, e = message.ParseTagAndLength(raw, off); e != nil {
		t.Fatalf("message tag: %s", e)
	}
	var id message.TagAndLength
	if id, off, e = message.ParseTagAndLength(raw, off); e != nil {
		t.Fatalf("messageID tag: %s", e)
	}
	off += id.Length
	if _, off, e = message.ParseTagAndLength(raw, off); e != nil {
		t.Fatalf("protocolOp tag: %s", e)
	}

	codeTL, off, e := message.ParseTagAndLength(raw, off)
	if e != nil {
		t.Fatalf("resultCode tag: %s", e)
	}
	if codeTL.Tag != 0x0a {
		t.Fatalf("first element of the protocolOp is tag %d, want 10 (ENUMERATED)", codeTL.Tag)
	}
	if off+codeTL.Length > len(raw) {
		t.Fatal("result code truncated")
	}
	code := 0
	for _, b := range raw[off : off+codeTL.Length] {
		code = code<<8 | int(b)
	}
	return code
}