// balanceLanding.ts — pure landing-state helper for the /balance page.
//
// Issue #244. Decouples the old boolean empty-state guard
// (`accountsCount === 0 || !hasAnySnapshot`) into three explicit states so the
// UI can stop conflating "no account yet" with "accounts but no snapshot yet":
//
//   - "empty":                no active account at all → offer account creation
//                             (StarterAccountsModal + a "Manage accounts" tile).
//   - "accounts-no-snapshot": at least one account but no snapshot → offer BOTH
//                             "Manage accounts" and "New snapshot" tiles, without
//                             forcing the user toward the snapshot flow.
//   - "populated":            at least one account with at least one snapshot →
//                             render the full dashboard (overview + chart +
//                             accounts table) plus the navigation tiles.
//
// Extracted as a pure, DOM-free helper because this project has no
// @testing-library/react or jsdom configured — UI branching is unit-tested via
// pure helpers (same convention as `deriveOnboardingSteps` / `computeBalanceDateRange`).

export type BalanceLandingState = "empty" | "accounts-no-snapshot" | "populated";

/**
 * Derive the landing state from the two independent signals the balance page
 * already computes: the number of active accounts and whether ANY snapshot
 * exists (probed across accounts, independent of the active period filter).
 *
 * @param accountsCount  number of active (non-archived) accounts
 * @param hasAnySnapshot true when at least one account carries a snapshot date
 */
export function deriveLandingState(
  accountsCount: number,
  hasAnySnapshot: boolean
): BalanceLandingState {
  if (accountsCount <= 0) return "empty";
  if (!hasAnySnapshot) return "accounts-no-snapshot";
  return "populated";
}