blasphem/pkg/wsapi/api.go

package wsapi

import (
	"encoding/json"
	"errors"
	"io"

	"dynatron.me/x/blasphem/pkg/auth"
	"dynatron.me/x/blasphem/pkg/blas/core"

	"github.com/gorilla/websocket"
	"github.com/labstack/echo/v4"
	"github.com/rs/zerolog/log"
)

var (
	NoSuchHandlerErr = errors.New("bad websocket command")
	NoMessageIDErr = errors.New("no message ID")
)

type Type string
type MsgBase struct {
	Type Type `json:"type"`
}

type (
	wsSession struct {
		*websocket.Conn
		b  core.Blas
		ec echo.Context
		h  phaseHandler

		user         *auth.User
		refreshToken *auth.RefreshToken
	}

	phaseHandler interface {
		handleMsg(io.Reader) error
	}

	cmdHandler struct {
		*wsSession
	}

	wsEntry struct {
		dataNew core.NewData
		hnd     core.Handler
	}

	wsRegistry map[string]wsEntry

	wsManager struct {
		r wsRegistry
	}
)

func (wsm *wsManager) RegisterWSCommand(cmd string, hnd core.Handler, dataNew core.NewData) {
	wsm.r[cmd] = wsEntry{
		dataNew: dataNew,
		hnd:     hnd,
	}
}

func (wsm *wsManager) WSCommandHandler(cmd string) (core.NewData, core.Handler, error) {
	wse, ok := wsm.r[cmd]
	if !ok {
		return nil, nil, NoSuchHandlerErr
	}

	return wse.dataNew, wse.hnd, nil
}

func NewManager() core.WebSocketManager {
	return &wsManager{
		r: make(wsRegistry),
	}
}

func NewSession(s core.Blas, c echo.Context, conn *websocket.Conn) core.WebSocketSession {
	ws := &wsSession{
		Conn: conn,
		b:    s,
		ec:   c,
	}

	ws.h = &authPhase{ws}

	return ws
}

func (ws *wsSession) Blas() core.Blas { return ws.b }

func (ws *wsSession) Go() error {
	err := ws.sendAuthRequired()
	if err != nil {
		return err
	}

	for {
		_, rdr, err := ws.NextReader()
		if err != nil {
			log.Error().Err(err).Str("remote", ws.ec.Request().RemoteAddr).Msg("websocket read fail")
			return err
		}

		err = ws.h.handleMsg(rdr)
		if err != nil {
			return err
		}
	}
}

type cmdMsg struct {
}

type MsgType string
const (
	ResultMsgType MsgType = "result"
)

type Error struct {
	Code string `json:"code"`
	Message string `json:"message"`
}

type WSError struct {
	ID *int `json:"id,omitempty"`
	Type MsgType `json:"type"`
	Success bool `json:"success"`
	Error Error `json:"error"`
}

func (ws *cmdHandler) writeError(id int, err Error) error {
	return ws.WriteJSON(WSError{
		ID: &id,
		Type: ResultMsgType,
		Success: false,
		Error: err,
	})
}

func (ws *cmdHandler) handleMsg(r io.Reader) error {
	var msgMap map[string]interface{}
	err := json.NewDecoder(r).Decode(&msgMap)
	if err != nil {
		return err
	}

	msgType, ok := msgMap["type"].(string)
	if !ok {
		return NoSuchHandlerErr
	}

	idFl, ok := msgMap["id"].(float64)
	if !ok {
		return ws.WriteJSON(
			WSError{
				Type: ResultMsgType,
				Success: false,
				Error: Error{
					Code: "invalid_id",
					Message: "command has no ID",
				},
			})
	}

	id := int(idFl)

	newData, hand, err := ws.b.WSCommandHandler(msgType)
	switch err {
	case nil:
	case NoSuchHandlerErr:
		return ws.writeError(id, Error{
			Code: "invalid_type",
			Message: "no such command",
		})
	default:
		return err
	}

	nd := newData()
	return hand(ws, id, nd)
}