basic mastodon client implemented, will do more later

Signed-off-by: Xe <me@christine.website>

1 files changed, 104 insertions, 0 deletions

diff --git a/web/mastodon/websocket.go b/web/mastodon/websocket.go
new file mode 100644
index 0000000..bf6b846
--- /dev/null
+++ b/web/mastodon/websocket.go
@@ -0,0 +1,104 @@
+package mastodon
+
+import (
+	"context"
+	"encoding/json"
+	"net/url"
+	"time"
+
+	"nhooyr.io/websocket"
+	"within.website/ln"
+	"within.website/ln/opname"
+)
+
+// WSSubscribeRequest is a websocket instruction to subscribe to a streaming feed.
+type WSSubscribeRequest struct {
+	Type    string `json:"type"` // should be "subscribe" or "unsubscribe"
+	Stream  string `json:"stream"`
+	Hashtag string `json:"hashtag,omitempty"`
+}
+
+// WSMessage is a websocket message. Whenever you get something from the streaming service, it will fit into this box.
+type WSMessage struct {
+	Stream  []string `json:"stream"`
+	Event   string   `json:"event"`
+	Payload string   `json:"payload"` // json string
+}
+
+// StreamMessages is a low-level message streaming facility.
+func (c *Client) StreamMessages(ctx context.Context, subreq ...WSSubscribeRequest) (chan WSMessage, error) {
+	result := make(chan WSMessage, 10)
+	ctx = opname.With(ctx, "websocket-streaming")
+
+	u, err := c.server.Parse("/api/vi/streaming/")
+	if err != nil {
+		return nil, err
+	}
+
+	q := u.Query()
+	q.Set("access_token", c.token)
+	u.RawQuery = q.Encode()
+
+	go func(ctx context.Context) {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+			}
+
+			if err := doWebsocket(ctx, u, result, subreq); err != nil {
+				ln.Error(ctx, err, ln.Info("websocket error, retrying"))
+			}
+			time.Sleep(time.Minute)
+		}
+	}(ctx)
+
+	return result, nil
+}
+
+func doWebsocket(ctx context.Context, u *url.URL, result chan WSMessage, subreq []WSSubscribeRequest) error {
+	conn, _, err := websocket.Dial(ctx, u.String(), &websocket.DialOptions{})
+	if err != nil {
+		return err
+	}
+	defer conn.Close(websocket.StatusNormalClosure, "doWebsocket function returned")
+
+	for _, sub := range subreq {
+		data, err := json.Marshal(sub)
+		if err != nil {
+			return err
+		}
+		err = conn.Write(ctx, websocket.MessageText, data)
+		if err != nil {
+			return err
+		}
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+
+		default:
+		}
+
+		msgType, data, err := conn.Read(ctx)
+		if err != nil {
+			return err
+		}
+
+		if msgType != websocket.MessageText {
+			ln.Log(ctx, ln.Info("got non-text message from mastodon"))
+			continue
+		}
+
+		var msg WSMessage
+		err = json.Unmarshal(data, &msg)
+		if err != nil {
+			return err
+		}
+
+		result <- msg
+	}
+}