export type ModelAssetFormat = "gltf" | "glb" | "usdz" | "fbx" | "obj" | "stl" | "3mf" | "3d";

export function normalizeModelAssetUrl(value: unknown): string | null {
  if (typeof value !== "string") return null;
  const normalized = value.trim();
  return normalized || null;
}

export function extractModelAssetFormat(modelUrl?: string | null): ModelAssetFormat {
  const value = String(modelUrl || "").toLowerCase();
  if (!value) return "3d";
  if (value.includes(".gltf")) return "gltf";
  if (value.includes(".glb")) return "glb";
  if (value.includes(".usdz")) return "usdz";
  if (value.includes(".fbx")) return "fbx";
  if (value.includes(".obj")) return "obj";
  if (value.includes(".stl")) return "stl";
  if (value.includes(".3mf")) return "3mf";
  return "3d";
}

export function resolvePreferredModelAssetUrl(params: {
  primaryUrl?: string | null;
  sourceUrl?: string | null;
  fallbackUrl?: string | null;
}) {
  const primaryUrl = normalizeModelAssetUrl(params.primaryUrl);
  const sourceUrl = normalizeModelAssetUrl(params.sourceUrl);
  const fallbackUrl = normalizeModelAssetUrl(params.fallbackUrl);

  if (sourceUrl) {
    if (!primaryUrl) return sourceUrl;
    if (primaryUrl !== sourceUrl) {
      const primaryFormat = extractModelAssetFormat(primaryUrl);
      const sourceFormat = extractModelAssetFormat(sourceUrl);

      if (primaryFormat === "gltf") return sourceUrl;
      if (primaryFormat !== "glb" && sourceFormat === "glb") return sourceUrl;
    }
  }

  return primaryUrl || sourceUrl || fallbackUrl || null;
}