package messages

import (
	"errors"

	"forge.redroom.link/yves/meowlib"
	"forge.redroom.link/yves/meowlib/client"
	"google.golang.org/protobuf/proto"
)

// Step3InitiatorFinalizesInviteeAndCreatesContactCard is called by the initiator when the
// step-2 answer (serialized Invitation bytes) arrives. It decrypts the invitee's ContactCard,
// upgrades the pending peer with the invitee's real keys, and returns a serialized Invitation
// (step=3) whose Payload is the initiator's ContactCard, ready to be consumed directly by
// Step4InviteeFinalizesInitiator on the invitee side.
func Step3InitiatorFinalizesInviteeAndCreatesContactCard(invitationBytes []byte) ([]byte, error) {
	var invitation meowlib.Invitation
	if err := proto.Unmarshal(invitationBytes, &invitation); err != nil {
		return nil, err
	}

	var invitationAnswer meowlib.PackedUserMessage
	if err := proto.Unmarshal(invitation.Payload, &invitationAnswer); err != nil {
		return nil, err
	}

	peer := client.GetConfig().GetIdentity().Peers.GetFromInvitationId(invitation.Uuid)
	if peer == nil {
		return nil, errors.New("no peer for invitation uuid " + invitation.Uuid)
	}
	// Guard against duplicate delivery (e.g., same answer from multiple servers).
	if peer.InvitationKp == nil {
		return nil, nil
	}

	usermsg, err := peer.ProcessInboundStep2UserMessage(&invitationAnswer, invitation.From)
	if err != nil {
		return nil, err
	}

	var inviteeCC meowlib.ContactCard
	if err := proto.Unmarshal(usermsg.Invitation.Payload, &inviteeCC); err != nil {
		return nil, err
	}

	myCC, _, err := client.GetConfig().GetIdentity().InvitationStep3(&inviteeCC)
	if err != nil {
		return nil, err
	}
	client.GetConfig().GetIdentity().Save()

	ccBytes, err := proto.Marshal(myCC)
	if err != nil {
		return nil, err
	}
	inv := &meowlib.Invitation{
		Uuid:    myCC.InvitationId,
		Step:    3,
		Payload: ccBytes,
	}
	return proto.Marshal(inv)
}