Add Mastodon widget (#3)

![Screenshot 2025-05-19 at 13 13 10](https://github.com/user-attachments/assets/ac2adf28-1bc0-46ac-a2d1-8f439912bc7e)
glanceapp · bartolomej · May 18, 2025 · May 19, 2025 · May 19, 2025 · May 19, 2025
commit 5161ee932a82ef96be63c28e02c66866f299b149
diff --git a/config/llms.yml b/config/llms.yml
@@ -21,6 +21,18 @@
           widgets:
             - type: hacker-news
             - type: lobsters
+            - type: mastodon
+              instance-url: https://mastodon.social
+              accounts:
+                - huggingface
+                - openai
+                - anthropic
+              hashtags:
+                - ai
+                - llm
+                - machinelearning
+              limit: 15
+              collapse-after: 5
 
         - type: group
           widgets:

diff --git a/internal/glance/widget-hacker-news.go b/internal/glance/widget-hacker-news.go
@@ -64,7 +64,7 @@ func (widget *hackerNewsWidget) update(ctx context.Context) {
 	widget.Posts = posts
 
 	if widget.filterQuery != "" {
-		widget.filter(widget.filterQuery)
+		widget.rankByRelevancy(widget.filterQuery)
 	}
 }
 
@@ -168,7 +168,7 @@ func fetchHackerNewsPosts(sort string, limit int, commentsUrlTemplate string) (f
 	return fetchHackerNewsPostsFromIds(postIds, commentsUrlTemplate)
 }
 
-func (widget *hackerNewsWidget) filter(query string) {
+func (widget *hackerNewsWidget) rankByRelevancy(query string) {
 	llm, err := NewLLM()
 	if err != nil {
 		slog.Error("Failed to initialize LLM", "error", err)

diff --git a/internal/glance/widget-lobsters.go b/internal/glance/widget-lobsters.go
@@ -61,11 +61,11 @@ func (widget *lobstersWidget) update(ctx context.Context) {
 	widget.Posts = posts
 
 	if widget.filterQuery != "" {
-		widget.filter(widget.filterQuery)
+		widget.rankByRelevancy(widget.filterQuery)
 	}
 }
 
-func (widget *lobstersWidget) filter(query string) {
+func (widget *lobstersWidget) rankByRelevancy(query string) {
 	llm, err := NewLLM()
 	if err != nil {
 		slog.Error("Failed to initialize LLM", "error", err)

diff --git a/internal/glance/widget-mastodon.go b/internal/glance/widget-mastodon.go
@@ -0,0 +1,241 @@
+package glance
+
+import (
+	"context"
+	"fmt"
+	"html/template"
+	"log/slog"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"golang.org/x/net/html"
+)
+
+type mastodonWidget struct {
+	widgetBase     `yaml:",inline"`
+	Posts          forumPostList `yaml:"-"`
+	InstanceURL    string        `yaml:"instance-url"`
+	Accounts       []string      `yaml:"accounts"`
+	Hashtags       []string      `yaml:"hashtags"`
+	Limit          int           `yaml:"limit"`
+	CollapseAfter  int           `yaml:"collapse-after"`
+	ShowThumbnails bool          `yaml:"-"`
+}
+
+func (widget *mastodonWidget) initialize() error {
+	if widget.InstanceURL == "" {
+		return fmt.Errorf("instance-url is required")
+	}
+
+	widget.
+		withTitle("Mastodon").
+		withTitleURL(widget.InstanceURL).
+		withCacheDuration(30 * time.Minute)
+
+	if widget.Limit <= 0 {
+		widget.Limit = 15
+	}
+
+	if widget.CollapseAfter == 0 || widget.CollapseAfter < -1 {
+		widget.CollapseAfter = 5
+	}
+
+	return nil
+}
+
+func (widget *mastodonWidget) update(ctx context.Context) {
+	posts, err := fetchMastodonPosts(widget.InstanceURL, widget.Accounts, widget.Hashtags)
+
+	if !widget.canContinueUpdateAfterHandlingErr(err) {
+		return
+	}
+
+	if widget.Limit < len(posts) {
+		posts = posts[:widget.Limit]
+	}
+
+	widget.Posts = posts
+
+	if widget.filterQuery != "" {
+		widget.rankByRelevancy(widget.filterQuery)
+	}
+}
+
+func (widget *mastodonWidget) Render() template.HTML {
+	return widget.renderTemplate(widget, forumPostsTemplate)
+}
+
+type mastodonPostResponseJson struct {
+	ID        string    `json:"id"`
+	Content   string    `json:"content"`
+	URL       string    `json:"url"`
+	CreatedAt time.Time `json:"created_at"`
+	Reblogs   int       `json:"reblogs_count"`
+	Favorites int       `json:"favourites_count"`
+	Replies   int       `json:"replies_count"`
+	Account   struct {
+		Username string `json:"username"`
+		URL      string `json:"url"`
+	} `json:"account"`
+	MediaAttachments []struct {
+		URL string `json:"url"`
+	} `json:"media_attachments"`
+	Tags []struct {
+		Name string `json:"name"`
+	} `json:"tags"`
+}
+
+func fetchMastodonPosts(instanceURL string, accounts []string, hashtags []string) (forumPostList, error) {
+	instanceURL = strings.TrimRight(instanceURL, "/")
+	var posts forumPostList
+
+	// Fetch posts from specified accounts
+	for _, account := range accounts {
+		url := fmt.Sprintf("%s/api/v1/accounts/%s/statuses", instanceURL, account)
+		request, err := http.NewRequest("GET", url, nil)
+		if err != nil {
+			return nil, err
+		}
+
+		accountPosts, err := decodeJsonFromRequest[[]mastodonPostResponseJson](defaultHTTPClient, request)
+		if err != nil {
+			slog.Error("Failed to fetch Mastodon account posts", "error", err, "account", account)
+			continue
+		}
+
+		for _, post := range accountPosts {
+			forumPost := convertMastodonPostToForumPost(post)
+			posts = append(posts, forumPost)
+		}
+	}
+
+	// Fetch posts from specified hashtags
+	for _, hashtag := range hashtags {
+		url := fmt.Sprintf("%s/api/v1/timelines/tag/%s", instanceURL, hashtag)
+		request, err := http.NewRequest("GET", url, nil)
+		if err != nil {
+			return nil, err
+		}
+
+		hashtagPosts, err := decodeJsonFromRequest[[]mastodonPostResponseJson](defaultHTTPClient, request)
+		if err != nil {
+			slog.Error("Failed to fetch Mastodon hashtag posts", "error", err, "hashtag", hashtag)
+			continue
+		}
+
+		for _, post := range hashtagPosts {
+			forumPost := convertMastodonPostToForumPost(post)
+			posts = append(posts, forumPost)
+		}
+	}
+
+	if len(posts) == 0 {
+		return nil, errNoContent
+	}
+
+	return posts, nil
+}
+
+func convertMastodonPostToForumPost(post mastodonPostResponseJson) forumPost {
+	tags := make([]string, len(post.Tags))
+	for i, tag := range post.Tags {
+		tags[i] = "#" + tag.Name
+	}
+
+	plainText := extractTextFromHTML(post.Content)
+	title := oneLineTitle(plainText, 50)
+
+	forumPost := forumPost{
+		ID:            post.ID,
+		Title:         title,
+		Description:   plainText,
+		DiscussionUrl: post.URL,
+		CommentCount:  post.Replies,
+		Score:         post.Reblogs + post.Favorites,
+		TimePosted:    post.CreatedAt,
+		// TODO(pulse): Hide tags for now, as they introduce too much noise
+		// Tags:          tags,
+	}
+
+	if len(post.MediaAttachments) > 0 {
+		forumPost.ThumbnailUrl = post.MediaAttachments[0].URL
+	}
+
+	return forumPost
+}
+
+func extractTextFromHTML(htmlStr string) string {
+	doc, err := html.Parse(strings.NewReader(htmlStr))
+	if err != nil {
+		return htmlStr
+	}
+	var b strings.Builder
+	var f func(*html.Node)
+	f = func(n *html.Node) {
+		if n.Type == html.TextNode {
+			b.WriteString(n.Data)
+		}
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			f(c)
+		}
+	}
+	f(doc)
+	return strings.TrimSpace(b.String())
+}
+
+func oneLineTitle(text string, maxLen int) string {
+	// Replace newlines and tabs with spaces, collapse multiple spaces
+	re := regexp.MustCompile(`\s+`)
+	t := re.ReplaceAllString(text, " ")
+	t = strings.TrimSpace(t)
+	if utf8.RuneCountInString(t) > maxLen {
+		runes := []rune(t)
+		return string(runes[:maxLen-1]) + "…"
+	}
+	return t
+}
+
+func (widget *mastodonWidget) rankByRelevancy(query string) {
+	llm, err := NewLLM()
+	if err != nil {
+		slog.Error("Failed to initialize LLM", "error", err)
+		return
+	}
+
+	feed := make([]feedEntry, 0, len(widget.Posts))
+	for _, e := range widget.Posts {
+		feed = append(feed, feedEntry{
+			ID:          e.ID,
+			Title:       e.Title,
+			Description: e.Description,
+			URL:         e.TargetUrl,
+			ImageURL:    e.ThumbnailUrl,
+			PublishedAt: e.TimePosted,
+		})
+	}
+
+	matches, err := llm.filterFeed(context.Background(), feed, query)
+	if err != nil {
+		slog.Error("Failed to filter Mastodon posts", "error", err)
+		return
+	}
+
+	matchesMap := make(map[string]feedMatch)
+	for _, match := range matches {
+		matchesMap[match.ID] = match
+	}
+
+	filtered := make(forumPostList, 0, len(matches))
+	for _, e := range widget.Posts {
+		if match, ok := matchesMap[e.ID]; ok {
+			e.MatchSummary = match.Highlight
+			e.MatchScore = match.Score
+			filtered = append(filtered, e)
+		}
+	}
+
+	widget.Posts = filtered
+}
diff --git a/internal/glance/widget-rss.go b/internal/glance/widget-rss.go
@@ -95,11 +95,11 @@ func (widget *rssWidget) update(ctx context.Context) {
 	widget.Items = items
 
 	if widget.filterQuery != "" {
-		widget.filter(widget.filterQuery)
+		widget.rankByRelevancy(widget.filterQuery)
 	}
 }
 
-func (widget *rssWidget) filter(query string) {
+func (widget *rssWidget) rankByRelevancy(query string) {
 	llm, err := NewLLM()
 	if err != nil {
 		slog.Error("Failed to initialize LLM", "error", err)

diff --git a/internal/glance/widget.go b/internal/glance/widget.go
@@ -39,6 +39,8 @@ func newWidget(widgetType string) (widget, error) {
 		w = &iframeWidget{}
 	case "html":
 		w = &htmlWidget{}
+	case "mastodon":
+		w = &mastodonWidget{}
 	case "hacker-news":
 		w = &hackerNewsWidget{}
 	case "releases":