avatar to main merge

I have completed the character creation screen on the avatar branch and am preparing to merge it into main.

lib/character/variant-validation.ts

@@ -0,0 +1,79 @@
+import type { CharacterLayerId } from "./presets";
+import { CHARACTER_LAYERS, NONE_VARIANT_ID } from "./presets";
+import type { LayerVariantState } from "./types";
+
+const STYLE_FIELD_BY_LAYER: Record<
+  Exclude<CharacterLayerId, "skin">,
+  keyof LayerVariantState
+> = {
+  pants: "pants",
+  shoes: "shoes",
+  torso: "torso",
+  eyes: "eyes",
+  head: "head",
+};
+
+const VALID_VARIANT_IDS: Record<CharacterLayerId, readonly string[]> = {
+  skin: ["skin-1"],
+  pants: ["none", "pants-1", "pants-2", "pants-3"],
+  shoes: ["none", "shoes-1", "shoes-2", "shoes-3"],
+  torso: ["none", "torso-1", "torso-2", "torso-3", "torso-4"],
+  eyes: ["none", "eyes-1", "eyes-2"],
+  head: [
+    "none",
+    "head-1",
+    "head-2",
+    "head-3",
+    "head-4",
+    "head-5",
+    "head-6",
+    "head-7",
+  ],
+};
+
+export function getValidVariantIds(layerId: CharacterLayerId): readonly string[] {
+  return VALID_VARIANT_IDS[layerId];
+}
+
+export function isValidVariantId(layerId: CharacterLayerId, variantId: string) {
+  return VALID_VARIANT_IDS[layerId].includes(variantId);
+}
+
+export function normalizeVariantId(
+  layerId: CharacterLayerId,
+  variantId: string | null | undefined,
+): string {
+  if (layerId === "skin") {
+    return "skin-1";
+  }
+
+  const trimmed = variantId?.trim();
+
+  if (trimmed && isValidVariantId(layerId, trimmed)) {
+    return trimmed;
+  }
+
+  return NONE_VARIANT_ID;
+}
+
+export function normalizeVariants(
+  variants: Partial<LayerVariantState> | null | undefined,
+): LayerVariantState {
+  return CHARACTER_LAYERS.reduce((state, layer) => {
+    state[layer.id] = normalizeVariantId(
+      layer.id,
+      variants?.[layer.id as keyof LayerVariantState],
+    );
+    return state;
+  }, {} as LayerVariantState);
+}
+
+export function assertValidVariants(variants: LayerVariantState) {
+  for (const layer of CHARACTER_LAYERS) {
+    if (!isValidVariantId(layer.id, variants[layer.id])) {
+      throw new Error(`Invalid ${layer.label.toLowerCase()} style selected.`);
+    }
+  }
+}
+
+export { STYLE_FIELD_BY_LAYER, VALID_VARIANT_IDS };