pkg/atlas: Implement mainmenupromos override for outdated clients

2 files changed, 41 insertions, 0 deletions

diff --git a/pkg/atlas/config.go b/pkg/atlas/config.go
index 4300d04..a416ff7 100644
--- a/pkg/atlas/config.go
+++ b/pkg/atlas/config.go
@@ -145,6 +145,11 @@ type Config struct {
 	//  - file:/path/to/mainmenupromos.json
 	API0_MainMenuPromos string `env:"ATLAS_API0_MAINMENUPROMOS=none"`
 
+	// If provided, the mainmenupromos will be merged with the provided source
+	// (same syntax as API0_MAINEMENUPROMOS) if the client is older than the
+	// API0_MinimumLauncherVersion.
+	API0_MainMenuPromos_UpdateNeeded string `env:"ATLAS_API0_MAINMENUPROMOS_UPDATENEEDED"`
+
 	// The email address to use for Origin login. If not provided, usernames are
 	// not resolved during authentication. If it begins with @, it is treated
 	// as the name of a systemd credential to load.
diff --git a/pkg/atlas/server.go b/pkg/atlas/server.go
index e780b87..d1f7c7d 100644
--- a/pkg/atlas/server.go
+++ b/pkg/atlas/server.go
@@ -299,6 +299,9 @@ func NewServer(c *Config) (*Server, error) {
 	} else {
 		return nil, fmt.Errorf("initialize main menu promos: %w", err)
 	}
+	if err := configureMainMenuPromosUpdateNeeded(c, s.API0); err != nil {
+		return nil, fmt.Errorf("configure main menu promos when update needed: %w", err)
+	}
 	if ip2l, err := configureIP2Location(c); err == nil {
 		if ip2l != nil {
 			s.reload = append(s.reload, func() {
@@ -685,6 +688,39 @@ func configureMainMenuPromos(c *Config) (func(*http.Request) api0.MainMenuPromos
 	}
 }
 
+func configureMainMenuPromosUpdateNeeded(c *Config, h *api0.Handler) error {
+	switch typ, arg, _ := strings.Cut(c.API0_MainMenuPromos_UpdateNeeded, ":"); typ {
+	case "none":
+		return nil
+	case "file":
+		p, err := filepath.Abs(arg)
+		if err != nil {
+			return fmt.Errorf("file: resolve %q: %w", arg, err)
+		}
+		fn1 := h.MainMenuPromos
+		h.MainMenuPromos = func(r *http.Request) api0.MainMenuPromos {
+			var mmp api0.MainMenuPromos
+			if fn1 != nil {
+				mmp = fn1(r)
+			}
+			if r == nil || !h.CheckLauncherVersion(r) {
+				if buf, err1 := os.ReadFile(p); err1 != nil {
+					err = err1
+				} else if err = json.Unmarshal(buf, &mmp); err != nil {
+					err = err1
+				}
+			}
+			return mmp
+		}
+		if h.MainMenuPromos(nil); err != nil {
+			return fmt.Errorf("file: %w", err)
+		}
+		return nil
+	default:
+		return fmt.Errorf("unknown source %q", typ)
+	}
+}
+
 func configureIP2Location(c *Config) (*ip2xMgr, error) {
 	if c.IP2Location == "" {
 		return nil, nil