bloat/mastodon/streaming_ws.go

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2019-12-13 20:08:26 +02:00
package mastodon
import (
"context"
"encoding/json"
"fmt"
"net/url"
"path"
"strings"
"github.com/gorilla/websocket"
)
// WSClient is a WebSocket client.
type WSClient struct {
websocket.Dialer
client *Client
}
// NewWSClient return WebSocket client.
func (c *Client) NewWSClient() *WSClient { return &WSClient{client: c} }
// Stream is a struct of data that flows in streaming.
type Stream struct {
Event string `json:"event"`
Payload interface{} `json:"payload"`
}
// StreamingWSUser return channel to read events on home using WebSocket.
func (c *WSClient) StreamingWSUser(ctx context.Context) (chan Event, error) {
return c.streamingWS(ctx, "user", "")
}
// StreamingWSPublic return channel to read events on public using WebSocket.
func (c *WSClient) StreamingWSPublic(ctx context.Context, isLocal bool) (chan Event, error) {
s := "public"
if isLocal {
s += ":local"
}
return c.streamingWS(ctx, s, "")
}
// StreamingWSHashtag return channel to read events on tagged timeline using WebSocket.
func (c *WSClient) StreamingWSHashtag(ctx context.Context, tag string, isLocal bool) (chan Event, error) {
s := "hashtag"
if isLocal {
s += ":local"
}
return c.streamingWS(ctx, s, tag)
}
// StreamingWSList return channel to read events on a list using WebSocket.
func (c *WSClient) StreamingWSList(ctx context.Context, id string) (chan Event, error) {
return c.streamingWS(ctx, "list", string(id))
}
func (c *WSClient) streamingWS(ctx context.Context, stream, tag string) (chan Event, error) {
params := url.Values{}
params.Set("access_token", c.client.config.AccessToken)
params.Set("stream", stream)
if tag != "" {
params.Set("tag", tag)
}
u, err := changeWebSocketScheme(c.client.config.Server)
if err != nil {
return nil, err
}
u.Path = path.Join(u.Path, "/api/v1/streaming")
u.RawQuery = params.Encode()
q := make(chan Event)
go func() {
defer close(q)
for {
err := c.handleWS(ctx, u.String(), q)
if err != nil {
return
}
}
}()
return q, nil
}
func (c *WSClient) handleWS(ctx context.Context, rawurl string, q chan Event) error {
conn, err := c.dialRedirect(rawurl)
if err != nil {
q <- &ErrorEvent{err: err}
// End.
return err
}
// Close the WebSocket when the context is canceled.
go func() {
<-ctx.Done()
conn.Close()
}()
for {
select {
case <-ctx.Done():
q <- &ErrorEvent{err: ctx.Err()}
// End.
return ctx.Err()
default:
}
var s Stream
err := conn.ReadJSON(&s)
if err != nil {
q <- &ErrorEvent{err: err}
// Reconnect.
break
}
err = nil
switch s.Event {
case "update":
var status Status
err = json.Unmarshal([]byte(s.Payload.(string)), &status)
if err == nil {
q <- &UpdateEvent{Status: &status}
}
case "notification":
var notification Notification
err = json.Unmarshal([]byte(s.Payload.(string)), &notification)
if err == nil {
q <- &NotificationEvent{Notification: &notification}
}
case "delete":
if f, ok := s.Payload.(float64); ok {
q <- &DeleteEvent{ID: fmt.Sprint(int64(f))}
} else {
q <- &DeleteEvent{ID: strings.TrimSpace(s.Payload.(string))}
}
}
if err != nil {
q <- &ErrorEvent{err}
}
}
return nil
}
func (c *WSClient) dialRedirect(rawurl string) (conn *websocket.Conn, err error) {
for {
conn, rawurl, err = c.dial(rawurl)
if err != nil {
return nil, err
} else if conn != nil {
return conn, nil
}
}
}
func (c *WSClient) dial(rawurl string) (*websocket.Conn, string, error) {
conn, resp, err := c.Dial(rawurl, nil)
if err != nil && err != websocket.ErrBadHandshake {
return nil, "", err
}
defer resp.Body.Close()
if loc := resp.Header.Get("Location"); loc != "" {
u, err := changeWebSocketScheme(loc)
if err != nil {
return nil, "", err
}
return nil, u.String(), nil
}
return conn, "", err
}
func changeWebSocketScheme(rawurl string) (*url.URL, error) {
u, err := url.Parse(rawurl)
if err != nil {
return nil, err
}
switch u.Scheme {
case "http":
u.Scheme = "ws"
case "https":
u.Scheme = "wss"
}
return u, nil
}