package files

import (
	"errors"
	"os"
	"strings"

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

// Step2ReadAndAnswer reads an InvitationInitPayload from a .mwiv file, creates the
// invitee's peer entry, and writes the encrypted ContactCard (PackedUserMessage) to a
// .mwiv file for the initiator to pick up and process in step 3.
func Step2ReadAndAnswer(invitationFile string, nickname string, myNickname string, serverUids []string) error {
	if _, err := os.Stat(invitationFile); os.IsNotExist(err) {
		return err
	}
	if !strings.HasSuffix(invitationFile, ".mwiv") {
		return errors.New("only .mwiv files are supported")
	}
	data, err := os.ReadFile(invitationFile)
	if err != nil {
		return err
	}
	payload, err := meowlib.NewInvitationInitPayloadFromCompressed(data)
	if err != nil {
		return err
	}

	mynick := myNickname
	if mynick == "" {
		mynick = client.GetConfig().GetIdentity().Nickname
	}

	packed, peer, err := messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard(payload, nickname, mynick, serverUids)
	if err != nil {
		return err
	}

	// Wrap the PackedUserMessage in an Invitation so the initiator (step3) has the
	// invitee's public key available for signature verification without an extra file.
	packedBytes, err := proto.Marshal(packed)
	if err != nil {
		return err
	}
	invitation := &meowlib.Invitation{
		Uuid:    peer.InvitationId,
		Step:    2,
		From:    peer.MyIdentity.Public,
		Payload: packedBytes,
	}
	out, err := proto.Marshal(invitation)
	if err != nil {
		return err
	}

	c := client.GetConfig()
	filename := c.StoragePath + string(os.PathSeparator) + mynick + "-" + nickname + ".mwiv"
	return os.WriteFile(filename, out, 0600)
}