// Hash routing for admin sections (SD-0002 §5). The URL is the durable handle on a
// section (PUC-8: run detail can be left and returned to); the SD-0001 entry-routing
// rule (routing.ts) still decides whether the admin renders at all.
export type AdminView =
  | { view: "home" }
  | { view: "products" }
  | { view: "import-upload" }
  | { view: "import-preview"; draftId: number }
  | { view: "run-detail"; runId: number };

export function adminViewFor(hash: string): AdminView {
  const parts = hash.replace(/^#\/?/, "").split("/").filter(Boolean);
  if (parts[0] !== "products") return { view: "home" };
  if (parts.length === 1) return { view: "products" };
  if (parts[1] === "import" && parts.length === 2) return { view: "import-upload" };
  if (parts[1] === "imports" && parts[2] === "drafts" && /^\d+$/.test(parts[3] ?? ""))
    return { view: "import-preview", draftId: Number(parts[3]) };
  if (parts[1] === "imports" && parts[2] === "runs" && /^\d+$/.test(parts[3] ?? ""))
    return { view: "run-detail", runId: Number(parts[3]) };
  return { view: "products" };
}

export function hashFor(v: AdminView): string {
  switch (v.view) {
    case "home": return "#/";
    case "products": return "#/products";
    case "import-upload": return "#/products/import";
    case "import-preview": return `#/products/imports/drafts/${v.draftId}`;
    case "run-detail": return `#/products/imports/runs/${v.runId}`;
  }
}