Outbound live stream notifications (#1663)

* First pass at browser, discord, twilio notifications

* Commit updated Javascript packages

* Remove twilio notification support

* Email notifications/smtp support

* Fix Firefox notification support, remove chrome checks

* WIP more email work

* Add support for twitter notifications

* Add stream title to discord and twitter notifications

* Update notification registration modal

* Fix hide/show email section

* Commit updated API documentation

* Commit updated Javascript packages

* Fix post-rebase missing var

* Remove unused var

* Handle unsubscribe errors for browser push

* Standardize email config prop names

* Allow overriding go live email template

* Some notifications cleanup

* Commit updated Javascript packages

* Remove email/smtp/mailjet support

* Remove more references to email notifications

Co-authored-by: Owncast <owncast@owncast.online>

notifications/twitter/twitter.go

@@ -0,0 +1,78 @@
+package twitter
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/dghubble/oauth1"
+	"github.com/g8rswimmer/go-twitter/v2"
+)
+
+/*
+1. developer.twitter.com. Apply to be a developer if needed.
+2. Projects and apps -> Your project name
+3. Settings.
+4. Scroll down to"User authentication settings" Edit
+5. Enable OAuth 1.0a with Read/Write permissions.
+6. Fill out the form with your information. Callback can be anything.
+7. Go to your project "Keys and tokens"
+8. Generate API key and secret.
+9. Generate access token and secret. Verify it says "Read and write permissions."
+10. Generate bearer token.
+*/
+
+type authorize struct {
+	Token string
+}
+
+func (a authorize) Add(req *http.Request) {
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", a.Token))
+}
+
+// Twitter is an instance of the Twitter notifier.
+type Twitter struct {
+	apiKey            string
+	apiSecret         string
+	accessToken       string
+	accessTokenSecret string
+	bearerToken       string
+}
+
+// New returns a new instance of the Twitter notifier.
+func New(apiKey, apiSecret, accessToken, accessTokenSecret, bearerToken string) (*Twitter, error) {
+	if apiKey == "" || apiSecret == "" || accessToken == "" || accessTokenSecret == "" || bearerToken == "" {
+		return nil, errors.New("missing some or all of the required twitter configuration values")
+	}
+
+	return &Twitter{
+		apiKey:            apiKey,
+		apiSecret:         apiSecret,
+		accessToken:       accessToken,
+		accessTokenSecret: accessTokenSecret,
+		bearerToken:       bearerToken,
+	}, nil
+}
+
+// Notify will send a notification to Twitter with the supplied text.
+func (t *Twitter) Notify(text string) error {
+	config := oauth1.NewConfig(t.apiKey, t.apiSecret)
+	token := oauth1.NewToken(t.accessToken, t.accessTokenSecret)
+	httpClient := config.Client(oauth1.NoContext, token)
+
+	client := &twitter.Client{
+		Authorizer: authorize{
+			Token: t.bearerToken,
+		},
+		Client: httpClient,
+		Host:   "https://api.twitter.com",
+	}
+
+	req := twitter.CreateTweetRequest{
+		Text: text,
+	}
+
+	_, err := client.CreateTweet(context.Background(), req)
+	return err
+}