feat(api): add online badge

_oas/openapi.yaml

@@ -25,6 +25,22 @@ paths:
                 $ref: "#/components/schemas/Status"
         default:
           $ref: "#/components/responses/Error"
+  /badge/telegram/online:
+    parameters:
+      - required: true
+        in: query
+        name: groups
+        schema:
+          type: array
+          items:
+            type: string
+    get:
+      operationId: "getTelegramOnlineBadge"
+      responses:
+        200:
+          $ref: "#/components/responses/SVG"
+        default:
+          $ref: "#/components/responses/Error"
   /badge/telegram/{group_name}:
     parameters:
       - required: true
@@ -43,23 +59,7 @@ paths:
             type: string
       responses:
         200:
-          description: Badge
-          headers:
-            Cache-Control:
-              description: "The Cache-Control header provides important info on how long a response may be considered fresh"
-              schema:
-                type: string
-              example: "max-age=3600, public, must-revalidate"
-            ETag:
-              description: "The ETag header provides a unique identifier for the response"
-              schema:
-                type: string
-              example: "W/\"123456789\""
-          content:
-            "image/svg+xml":
-              schema:
-                type: string
-                format: binary
+          $ref: "#/components/responses/SVG"
         default:
           $ref: "#/components/responses/Error"
 components:
@@ -70,6 +70,24 @@ components:
         "application/json":
           schema:
             $ref: "#/components/schemas/Error"
+    SVG:
+      description: Badge
+      headers:
+        Cache-Control:
+          description: "The Cache-Control header provides important info on how long a response may be considered fresh"
+          schema:
+            type: string
+          example: "max-age=3600, public, must-revalidate"
+        ETag:
+          description: "The ETag header provides a unique identifier for the response"
+          schema:
+            type: string
+          example: "W/\"123456789\""
+      content:
+        "image/svg+xml":
+          schema:
+            type: string
+            format: binary
   schemas:
     Error:
       type: object

internal/api/badge.go

@@ -36,38 +36,7 @@ func etag(name string, data []byte) string {
 	return fmt.Sprintf(`W/"%s-%d-%08X"`, name, len(data), crc)
 }
 
-func (s Server) GetTelegramBadge(ctx context.Context, params oas.GetTelegramBadgeParams) (*oas.GetTelegramBadgeOKHeaders, error) {
-	var members int
-	{
-		peer, err := s.resolver.ResolveDomain(ctx, params.GroupName)
-		if err != nil {
-			return nil, errors.Wrap(err, "resolve domain")
-		}
-		var inputChannel tg.InputChannel
-		inputChannel.FillFrom(peer.(*tg.InputPeerChannel))
-		full, err := s.tg.API().ChannelsGetFullChannel(ctx, &inputChannel)
-		if err != nil {
-			return nil, errors.Wrap(err, "get chat")
-		}
-		members = full.FullChat.(*tg.ChannelFull).ParticipantsCount
-		s.lg.Info("Got chat",
-			zap.Int("participants", members),
-		)
-	}
-	var (
-		title = params.Title.Or(params.GroupName)
-		text  = strconv.Itoa(members)
-		u     = &url.URL{
-			Scheme: "https",
-			Host:   "img.shields.io",
-			Path:   generateBadgePath(title, text, "179cde"),
-		}
-	)
-	{
-		q := u.Query()
-		q.Set("logo", "telegram")
-		u.RawQuery = q.Encode()
-	}
+func (s Server) download(ctx context.Context, u *url.URL) (*oas.SVGHeaders, error) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), http.NoBody)
 	if err != nil {
 		return nil, errors.Wrap(err, "create request")
@@ -82,11 +51,79 @@ func (s Server) GetTelegramBadge(ctx context.Context, params oas.GetTelegramBadg
 		return nil, errors.Wrap(err, "read body")
 	}
 
-	return &oas.GetTelegramBadgeOKHeaders{
+	return &oas.SVGHeaders{
 		CacheControl: oas.NewOptString("no-cache"),
-		ETag:         oas.NewOptString(etag(params.GroupName, data)),
-		Response: oas.GetTelegramBadgeOK{
+		ETag:         oas.NewOptString(etag("svg", data)),
+		Response: oas.SVG{
 			Data: bytes.NewReader(data),
 		},
 	}, nil
 }
+
+func (s Server) fetchChannel(ctx context.Context, name string) (*tg.ChannelFull, error) {
+	peer, err := s.resolver.ResolveDomain(ctx, name)
+	if err != nil {
+		return nil, errors.Wrap(err, "resolve domain")
+	}
+	var inputChannel tg.InputChannel
+	inputChannel.FillFrom(peer.(*tg.InputPeerChannel))
+	full, err := s.tg.API().ChannelsGetFullChannel(ctx, &inputChannel)
+	if err != nil {
+		return nil, errors.Wrap(err, "get chat")
+	}
+	v := full.FullChat.(*tg.ChannelFull)
+	s.lg.Info("Got chat",
+		zap.String("name", name),
+		zap.Int64("id", v.ID),
+		zap.Int("participants", v.ParticipantsCount),
+		zap.Int("online", v.OnlineCount),
+	)
+	return v, nil
+}
+
+func (s Server) GetTelegramOnlineBadge(ctx context.Context, params oas.GetTelegramOnlineBadgeParams) (*oas.SVGHeaders, error) {
+	var count int
+	for _, name := range params.Groups {
+		full, err := s.fetchChannel(ctx, name)
+		if err != nil {
+			return nil, errors.Wrap(err, "get chat")
+		}
+		count += full.OnlineCount
+	}
+	var (
+		text = strconv.Itoa(count)
+		u    = &url.URL{
+			Scheme: "https",
+			Host:   "img.shields.io",
+			Path:   generateBadgePath("online", text, "green"),
+		}
+	)
+	{
+		q := u.Query()
+		q.Set("logo", "telegram")
+		u.RawQuery = q.Encode()
+	}
+	return s.download(ctx, u)
+}
+
+func (s Server) GetTelegramBadge(ctx context.Context, params oas.GetTelegramBadgeParams) (*oas.SVGHeaders, error) {
+	channel, err := s.fetchChannel(ctx, params.GroupName)
+	if err != nil {
+		return nil, errors.Wrap(err, "get chat")
+	}
+	var (
+		title = params.Title.Or(params.GroupName)
+		text  = strconv.Itoa(channel.ParticipantsCount)
+		u     = &url.URL{
+			Scheme: "https",
+			Host:   "img.shields.io",
+			Path:   generateBadgePath(title, text, "179cde"),
+		}
+	)
+	{
+		q := u.Query()
+		q.Set("logo", "telegram")
+		u.RawQuery = q.Encode()
+	}
+	return s.download(ctx, u)
+}