feat: apply configured default user avatars

server/default_avatar.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"encoding/json"
+	"hash/fnv"
+	"strings"
+
+	"github.com/tinode/chat/server/store"
+	"github.com/tinode/chat/server/store/types"
+)
+
+const (
+	imAssetsConfigGroup             = "im_assets"
+	imDefaultMaleAvatarURLsConfig   = "default_user_avatar_male_urls"
+	imDefaultFemaleAvatarURLsConfig = "default_user_avatar_female_urls"
+)
+
+func applyDefaultUserAvatar(data map[string]any, userID, gender string) {
+	if data == nil || strings.TrimSpace(stringFromAny(data["avatar_file_id"])) != "" {
+		return
+	}
+	if avatarURL := defaultUserAvatarURL(userID, gender); avatarURL != "" {
+		data["avatar_file_id"] = avatarURL
+	}
+}
+
+func defaultUserAvatarURL(userID, gender string) string {
+	if store.ThirdPartyConfig == nil {
+		return ""
+	}
+	values, err := store.ThirdPartyConfig.Get(imAssetsConfigGroup, imDefaultMaleAvatarURLsConfig, imDefaultFemaleAvatarURLsConfig)
+	if err != nil {
+		return ""
+	}
+	key := imDefaultMaleAvatarURLsConfig
+	if strings.EqualFold(strings.TrimSpace(gender), "female") {
+		key = imDefaultFemaleAvatarURLsConfig
+	}
+	urls := parseDefaultAvatarURLs(values[key])
+	if len(urls) == 0 && key == imDefaultFemaleAvatarURLsConfig {
+		urls = parseDefaultAvatarURLs(values[imDefaultMaleAvatarURLsConfig])
+	}
+	if len(urls) == 0 {
+		return ""
+	}
+	return urls[defaultAvatarIndex(userID, len(urls))]
+}
+
+func parseDefaultAvatarURLs(raw string) []string {
+	var urls []string
+	if err := json.Unmarshal([]byte(strings.TrimSpace(raw)), &urls); err != nil {
+		return nil
+	}
+	out := urls[:0]
+	for _, url := range urls {
+		if url = strings.TrimSpace(url); url != "" {
+			out = append(out, url)
+		}
+	}
+	return out
+}
+
+func defaultAvatarIndex(userID string, count int) int {
+	if count <= 1 {
+		return 0
+	}
+	uid := types.ParseUserId(strings.TrimSpace(userID))
+	if uid.IsZero() {
+		uid = types.ParseUid(strings.TrimSpace(userID))
+	}
+	if !uid.IsZero() {
+		return int(uint64(uid) % uint64(count))
+	}
+	h := fnv.New32a()
+	_, _ = h.Write([]byte(userID))
+	return int(h.Sum32() % uint32(count))
+}