import { listBranches } from "@/lib/storage";
import { getSession } from "@/lib/auth/session";
import { filterBranchesForSession } from "@/lib/auth/permissions";
import {
	withErrorHandling,
	json,
	unauthorized,
	ApiError,
} from "@/lib/api/errors";

/**
 * Next.js Route Handler caching configuration (RHL-006):
 *
 * We force this route to execute dynamically on every request.
 *
 * Reasons:
 * - NAS contents can change at any time (new scans).
 * - Auth/RBAC-protected responses must not be cached/shared across users.
 * - We rely on a small storage-layer TTL micro-cache instead of Next route caching.
 */
export const dynamic = "force-dynamic";

/**
 * GET /api/branches
 *
 * Returns the list of branches (e.g. ["NL01", "NL02", ...]) based on the
 * directory names under NAS_ROOT_PATH.
 *
 * RBAC:
 * - 401 if no session
 * - branch role: only returns its own branch
 * - admin/dev: returns all branches
 *
 * Happy-path response must remain unchanged:
 * { "branches": ["NL01", ...] }
 */
export const GET = withErrorHandling(
	async function GET() {
		const session = await getSession();

		if (!session) {
			throw unauthorized("AUTH_UNAUTHENTICATED", "Unauthorized");
		}

		try {
			const branches = await listBranches();
			const visibleBranches = filterBranchesForSession(session, branches);

			return json({ branches: visibleBranches }, 200);
		} catch (err) {
			// Treat any storage read failures as internal server errors.
			// We do NOT expose filesystem error messages to the client.
			throw new ApiError({
				status: 500,
				code: "FS_STORAGE_ERROR",
				message: "Internal server error",
				cause: err,
			});
		}
	},
	{ logPrefix: "[api/branches]" }
);