blasphem/pkg/wsapi/api.go

package wsapi

import (
	"context"
	"encoding/json"
	"errors"
	"strings"

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

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

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

type Type string
type MsgBase struct {
	ID   *int `json:"id,omitempty"`
	Type Type `json:"type"`
}

type (
	wsSession struct {
		conn  *websocket.Conn
		b     core.Blas
		ec    echo.Context
		write chan<- interface{}

		user         *auth.User
		refreshToken *auth.RefreshToken
	}

	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, cmdSplit []string) (core.NewData, core.Handler, error) {
	if wse, ok := wsm.r[cmd]; ok {
		return wse.dataNew, wse.hnd, nil
	}

	if wse, ok := wsm.r[cmdSplit[0]]; ok {
		return wse.dataNew, wse.hnd, nil
	}

	return nil, nil, NoSuchHandlerErr
}

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,
	}

	return ws
}

func (ws *wsSession) Conn() *websocket.Conn {
	return ws.conn
}

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

func (ws *wsSession) Go(ctx context.Context) error {
	authP := &authPhase{ws}
	err := ws.sendAuthRequired()
	if err != nil {
		return err
	}

	_, rdr, err := ws.conn.NextReader()
	if err != nil {
		return err
	}

	err = authP.handleMsg(ctx, rdr)
	if err != nil || ws.refreshToken == nil {
		return err
	}

	// command phase

	msgChan := make(chan map[string]interface{})
	write := make(chan interface{})
	ws.write = write
	defer close(write)

	cCtx, cancel := context.WithCancel(ctx)
	defer cancel()

	go func(ctx context.Context, ch chan<- map[string]interface{}) {
		defer close(ch)
		for {
			if err := ctx.Err(); err != nil {
				return
			}

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

			var msgMap map[string]interface{}
			err = json.NewDecoder(rdr).Decode(&msgMap)
			if err != nil {
				ws.writeError(-1, Error{Code: "invalid_format", Message: err.Error()})
			}

			ch <- msgMap

		}
	}(cCtx, msgChan)

	for {
		select {
		case msg, ok := <-msgChan:
			if !ok {
				return nil
			}

			err = ws.handleMsg(ctx, msg)
			if err != nil {
				log.Error().Err(err).Msg("handleMsg")
			}
		case <-ctx.Done():
			close(msgChan) // maybe remove this?
			return nil
		case m := <-write:
			err := ws.conn.WriteJSON(m)
			if err != nil {
				log.Error().Err(err).Msg("writeMsg")
			}
		}
	}
}

func (ws *wsSession) Write(msg interface{}) {
	ws.write <- msg
}

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

func (ws *wsSession) handleMsg(ctx context.Context, msgMap map[string]interface{}) error {
	if err := ctx.Err(); err != nil {
		return nil
	}

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

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

	id := int(idFl)

	cmd := strings.Split(msgType, "/")

	newData, hand, err := ws.b.WSCommandHandler(cmd[0], cmd)
	switch err {
	case nil:
	case NoSuchHandlerErr:
		ws.writeError(id, Error{
			Code:    "invalid_type",
			Message: "no such command",
		})

		return nil
	default:
		log.Error().Err(err).Msg("dispatch")
		return nil
	}

	nd := newData(cmd)
	if _, ok := nd.(map[string]interface{}); !ok {
		err := mapstructure.Decode(&msgMap, &nd)
		if err != nil {
			ws.writeError(id, Error{
				Code:    "invalid_format",
				Message: err.Error(),
			})

			return nil
		}
	}

	err = hand(ctx, ws, id, cmd, nd)
	if err != nil {
		log.Error().Err(err).Msg("dispatch")
	}

	return nil
}