feat(notify): resolve theme icon names to files

qt6ct's icon_theme is authoritative on this desktop, with the GTK3
setting and hicolor as fallbacks. The lookup prefers scalable, then the
largest raster, and follows the theme's Inherits chain, so an app that
passes a name instead of a path gets an icon.

1 files changed, 70 insertions, 0 deletions

diff --git a/internal/notify/icons_test.go b/internal/notify/icons_test.go
new file mode 100644
index 0000000..527b330
--- /dev/null
+++ b/internal/notify/icons_test.go
@@ -0,0 +1,70 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+package notify
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestResolveIconPathAndURI(t *testing.T) {
+	if got := ResolveIcon("/usr/share/icons/x/apps/48/firefox.png"); got != "/usr/share/icons/x/apps/48/firefox.png" {
+		t.Fatalf("path passthrough: %q", got)
+	}
+	if got := ResolveIcon("file:///tmp/shot.png"); got != "/tmp/shot.png" {
+		t.Fatalf("uri: %q", got)
+	}
+	if got := ResolveIcon(""); got != "" {
+		t.Fatalf("empty: %q", got)
+	}
+}
+
+func TestResolveIconThemeName(t *testing.T) {
+	root := t.TempDir()
+	// Theme "Plum" inherits "Base"; the icon is only in Base.
+	theme := filepath.Join(root, "icons", "Plum")
+	base := filepath.Join(root, "icons", "Base")
+	plumIndex := filepath.Join(theme, "index.theme")
+	baseApp := filepath.Join(base, "apps", "48")
+	if err := os.MkdirAll(filepath.Join(theme, "apps", "scalable"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(baseApp, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(plumIndex, []byte("[Icon Theme]\nInherits=Base\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(baseApp, "firefox.svg"), []byte("<svg/>"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	t.Setenv("XDG_DATA_HOME", root)
+	t.Setenv("XDG_DATA_DIRS", "")
+	t.Setenv("HOME", filepath.Join(root, "home"))
+	if err := os.MkdirAll(filepath.Join(root, "home", ".config", "qt6ct"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "home", ".config", "qt6ct", "qt6ct.conf"), []byte("icon_theme=Plum\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	got := ResolveIcon("firefox")
+	want := filepath.Join(root, "icons", "Base", "apps", "48", "firefox.svg")
+	if got != want {
+		t.Fatalf("resolved %q, want %q", got, want)
+	}
+	if got := ResolveIcon("no-such-icon-xyz"); got != "" {
+		t.Fatalf("missing name must be empty, got %q", got)
+	}
+}