package helpers

import (
	"errors"
	"os"
	"strings"

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

// InvitationStep2Answer creates the invitee's peer from an InvitationInitPayload and returns
// the new peer (STEP_2, invitee side — in-memory, no server involved).
func InvitationStep2Answer(payload *meowlib.InvitationInitPayload, nickname string, myNickname string, serverUids []string) (*client.Peer, string, error) {
	mynick := myNickname
	if myNickname == "" {
		mynick = client.GetConfig().GetIdentity().Nickname
	}
	peer, err := client.GetConfig().GetIdentity().InvitationStep2(mynick, nickname, serverUids, payload)
	if err != nil {
		return nil, "InvitationStep2Answer: InvitationStep2", err
	}
	client.GetConfig().GetIdentity().Save()
	return peer, "", nil
}

// InvitationStep2AnswerFile reads an InvitationInitPayload from a .mwiv file and creates the
// invitee's peer. It also writes the invitee's ContactCard response to a file (STEP_2_SEND, file variant).
func InvitationStep2AnswerFile(invitationFile string, nickname string, myNickname string, serverUids []string) (string, error) {
	if _, err := os.Stat(invitationFile); os.IsNotExist(err) {
		return "InvitationStep2AnswerFile: os.Stat", err
	}
	if !strings.HasSuffix(invitationFile, ".mwiv") {
		return "InvitationStep2AnswerFile: unsupported format", errors.New("only .mwiv files are supported")
	}
	data, err := os.ReadFile(invitationFile)
	if err != nil {
		return "InvitationStep2AnswerFile: os.ReadFile", err
	}
	payload, err := meowlib.NewInvitationInitPayloadFromCompressed(data)
	if err != nil {
		return "InvitationStep2AnswerFile: NewInvitationInitPayloadFromCompressed", err
	}

	mynick := myNickname
	if myNickname == "" {
		mynick = client.GetConfig().GetIdentity().Nickname
	}
	c := client.GetConfig()
	response, err := c.GetIdentity().InvitationStep2(mynick, nickname, serverUids, payload)
	if err != nil {
		return "InvitationStep2AnswerFile: InvitationStep2", err
	}

	filename := c.StoragePath + string(os.PathSeparator) + mynick + "-" + nickname + ".mwiv"
	if err := response.GetMyContact().WriteCompressed(filename); err != nil {
		return "InvitationStep2AnswerFile: WriteCompressed", err
	}
	c.GetIdentity().Save()
	return "", nil
}

// InvitationStep2AnswerMessage builds and returns the packed server message that posts the
// invitee's ContactCard (encrypted with the initiator's temp key) to the invitation server
// (STEP_2_SEND, through-server variant).
func InvitationStep2AnswerMessage(invitationId string, invitationServerUid string, timeout int) ([]byte, string, error) {
	peer := client.GetConfig().GetIdentity().Peers.GetFromInvitationId(invitationId)
	if peer == nil {
		return nil, "InvitationStep2AnswerMessage: peer not found", errors.New("no peer with that invitation id")
	}

	answermsg, err := peer.BuildInvitationStep2Message(peer.GetMyContact())
	if err != nil {
		return nil, "InvitationStep2AnswerMessage: BuildInvitationStep2Message", err
	}

	invitationServer, err := client.GetConfig().GetIdentity().MessageServers.LoadServer(invitationServerUid)
	if err != nil {
		return nil, "InvitationStep2AnswerMessage: LoadServer", err
	}

	packedMsg, err := peer.ProcessOutboundUserMessage(answermsg)
	if err != nil {
		return nil, "InvitationStep2AnswerMessage: ProcessOutboundUserMessage", err
	}

	toServerMessage, err := invitationServer.BuildToServerMessageInvitationAnswer(packedMsg, peer.MyIdentity.Public, invitationId, timeout)
	if err != nil {
		return nil, "InvitationStep2AnswerMessage: BuildToServerMessageInvitationAnswer", err
	}

	bytemsg, err := invitationServer.ProcessOutboundMessage(toServerMessage)
	if err != nil {
		return nil, "InvitationStep2AnswerMessage: ProcessOutboundMessage", err
	}
	return bytemsg, "", nil
}

// InvitationStep2AnswerMessageReadResponse reads the server acknowledgement of a Step2 answer.
func InvitationStep2AnswerMessageReadResponse(invitationData []byte, invitationServerUid string) (*meowlib.Invitation, string, error) {
	server, err := client.GetConfig().GetIdentity().MessageServers.LoadServer(invitationServerUid)
	if err != nil {
		return nil, "InvitationStep2AnswerMessageReadResponse: LoadServer", err
	}
	serverMsg, err := server.ProcessInboundServerResponse(invitationData)
	if err != nil {
		return nil, "InvitationStep2AnswerMessageReadResponse: ProcessInboundServerResponse", err
	}
	return serverMsg.Invitation, "", nil
}