package server

import (
	"errors"
	"strings"

	"forge.redroom.link/yves/meowlib"
	"forge.redroom.link/yves/meowlib/client"
)

// Step2Fetch builds and returns the packed server message that retrieves the
// InvitationInitPayload from the server using the shortcode URL.
func Step2Fetch(invitationUrl string, serverPublicKey string, invitationPassword string) ([]byte, error) {
	meowurl := strings.Split(invitationUrl, "?")
	shortcode := meowurl[1]

	srv, err := client.CreateServerFromMeowUrl(meowurl[0])
	if err != nil {
		return nil, err
	}

	// Reuse the server entry if already known.
	dbsrv, err := client.GetConfig().GetIdentity().MessageServers.LoadServer(srv.Url)
	if err != nil {
		return nil, err
	}
	if dbsrv == nil {
		srv.PublicKey = serverPublicKey
		k, err := meowlib.NewKeyPair()
		if err != nil {
			return nil, err
		}
		srv.UserKp = k
		if err := client.GetConfig().GetIdentity().MessageServers.StoreServer(srv); err != nil {
			return nil, err
		}
	} else {
		if dbsrv.PublicKey != serverPublicKey {
			dbsrv.PublicKey = serverPublicKey
		}
		srv = dbsrv
	}

	toSrvMsg, err := srv.BuildToServerMessageInvitationRequest(shortcode, invitationPassword)
	if err != nil {
		return nil, err
	}
	return srv.ProcessOutboundMessage(toSrvMsg)
}

// Step2ReadResponse decodes the server response to a Step2Fetch and returns
// the InvitationInitPayload sent by the initiator.
func Step2ReadResponse(invitationData []byte, invitationServerUid string) (*meowlib.InvitationInitPayload, error) {
	srv, err := client.GetConfig().GetIdentity().MessageServers.LoadServer(invitationServerUid)
	if err != nil {
		return nil, err
	}
	serverMsg, err := srv.ProcessInboundServerResponse(invitationData)
	if err != nil {
		return nil, err
	}
	return meowlib.NewInvitationInitPayloadFromCompressed(serverMsg.Invitation.Payload)
}

// Step2PostAnswer wraps the invitee's already-built PackedUserMessage into a server
// message and posts it to the invitation server. The packed message is produced by
// messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard.
func Step2PostAnswer(invitationId string, packedMsg *meowlib.PackedUserMessage, invitationServerUid string, timeout int) ([]byte, error) {
	peer := client.GetConfig().GetIdentity().Peers.GetFromInvitationId(invitationId)
	if peer == nil {
		return nil, errors.New("no peer with that invitation id")
	}

	invitationServer, err := client.GetConfig().GetIdentity().MessageServers.LoadServer(invitationServerUid)
	if err != nil {
		return nil, err
	}

	toServerMessage, err := invitationServer.BuildToServerMessageInvitationAnswer(packedMsg, peer.MyIdentity.Public, invitationId, timeout)
	if err != nil {
		return nil, err
	}

	return invitationServer.ProcessOutboundMessage(toServerMessage)
}

// Step2PostAnswerReadResponse reads the server acknowledgement of a Step2PostAnswer.
func Step2PostAnswerReadResponse(invitationData []byte, invitationServerUid string) (*meowlib.Invitation, error) {
	srv, err := client.GetConfig().GetIdentity().MessageServers.LoadServer(invitationServerUid)
	if err != nil {
		return nil, err
	}
	serverMsg, err := srv.ProcessInboundServerResponse(invitationData)
	if err != nil {
		return nil, err
	}
	return serverMsg.Invitation, nil
}