island: scene icon map logic and its tests

1 files changed, 77 insertions, 0 deletions

diff --git a/desktop/island/SceneIcons.js b/desktop/island/SceneIcons.js
new file mode 100644
index 0000000..28118b7
--- /dev/null
+++ b/desktop/island/SceneIcons.js
@@ -0,0 +1,77 @@
+// 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.
+
+.pragma library
+
+// The starter map, used when the config file is missing or unreadable, and the
+// seed for the settings page. The md-* glyphs are supplementary-plane, so they
+// are surrogate pairs; a five-digit \u escape would be a different character.
+var defaults = {
+    generic: "\udb80\uded7",        // md-help_circle
+    scenes: {
+        "Desktop": "\udb80\udf79",      // md-monitor
+        "Webcam Only": "\udb81\udd67",  // md-video
+        "Window Only": "\uf2d0",        // fa-window_maximize
+        "Intervallo": "\udb80\udd76",   // md-coffee
+    },
+};
+
+// Exactly one code point; a surrogate pair counts as one.
+function validGlyph(s) {
+    if (typeof s !== "string" || s === "") return false;
+    let n = 0;
+    for (let i = 0; i < s.length; i++) {
+        const c = s.charCodeAt(i);
+        if (c >= 0xD800 && c <= 0xDBFF && i + 1 < s.length) {
+            const d = s.charCodeAt(i + 1);
+            if (d >= 0xDC00 && d <= 0xDFFF) i++;
+        }
+        n++;
+    }
+    return n === 1;
+}
+
+// The map as stored: an invalid generic falls back, invalid scenes drop.
+function normalize(map) {
+    const src = map || {};
+    const out = {
+        generic: validGlyph(src.generic) ? src.generic : defaults.generic,
+        scenes: {},
+    };
+    const sc = src.scenes || {};
+    for (const k in sc) if (validGlyph(sc[k])) out.scenes[k] = sc[k];
+    return out;
+}
+
+// A missing or unparseable file is the starter map; a valid file is used as-is.
+function parse(text) {
+    let v = null;
+    try { v = JSON.parse(text); } catch (e) {}
+    if (!v || typeof v !== "object" || Array.isArray(v)) return normalize(defaults);
+    return normalize(v);
+}
+
+function serialize(map) {
+    return JSON.stringify({ generic: map.generic, scenes: map.scenes }, null, 2) + "\n";
+}
+
+function iconFor(map, name) {
+    return (map && map.scenes && map.scenes[name]) || (map && map.generic) || defaults.generic;
+}
+
+// A draft may leave the generic empty; Save substitutes the default.
+function validMap(map) {
+    if (!map || typeof map !== "object") return false;
+    if (map.generic !== "" && !validGlyph(map.generic)) return false;
+    const sc = map.scenes || {};
+    for (const k in sc) if (!validGlyph(sc[k])) return false;
+    return true;
+}