import type { Plugin } from "vite";

// The design lab (`src/design-lab/`) is a dev-only page: main.tsx reaches it behind
// `import.meta.env.DEV`, which Vite folds to `false` in a production build, so the dynamic import
// is dead code and the chunk is never emitted. That rule used to be a sentence; this makes it a
// build failure. If a future edit imports the lab unguarded (a static import, a shared helper, a
// re-export), the production build refuses instead of shipping the lab to every visitor.
const DEV_ONLY_DIR = "/src/design-lab/";

export function devOnlyGuard(): Plugin {
  return {
    name: "siftlode-dev-only-guard",
    apply: "build",
    generateBundle(_options, bundle) {
      for (const [fileName, output] of Object.entries(bundle)) {
        if (output.type !== "chunk") continue;
        const leaked = Object.keys(output.modules).find((id) =>
          id.replaceAll("\\", "/").includes(DEV_ONLY_DIR),
        );
        if (leaked) {
          this.error(
            `dev-only module ${leaked} reached the production bundle (${fileName}). ` +
              "Import src/design-lab only behind `import.meta.env.DEV`.",
          );
        }
      }
    },
  };
}