import {createSessionCache, type SessionCache} from '$lib/sessionCache';

/**
 * Persists the source ('old') and destination ('new') login sessions of an in-progress
 * migration in localStorage so a page refresh can offer to resume it instead of forcing the
 * user to re-enter credentials and re-trigger 2FA. All persistence policy lives in the generic
 * `sessionCache` factory; the `@pds-moover/moover` package only exposes generic hooks
 * (onSessionUpdate / restoreSessions).
 *
 * Security note: this stores access + refresh JWTs in localStorage. Acceptable for this SPA,
 * mitigated by clearing on completion / start-over and by PasswordSession.resume() invalidating
 * dead sessions.
 */

const STORAGE_KEY = 'pdsmoover:migration-sessions:v1';

export type MigrationSessionCache = SessionCache<'old' | 'new'>;

// Resume is only offered when BOTH sides are present (an old-side-only entry means no destination
// account was ever logged into — nothing to resume), so an orphaned single side is cleared.
const cache = createSessionCache<'old' | 'new'>(STORAGE_KEY, ['old', 'new']);

/**
 * Persist (data) or drop (null) one side of the migration. When both sides end up gone the
 * whole key is removed so we never leave an orphaned entry behind.
 */
export const saveSide = cache.saveSide;

/**
 * Read the cached sessions. Resume is only offered when BOTH sides are present (an old-side-only
 * entry means no destination account was ever logged into — nothing to resume), so an orphaned
 * single side is cleared and null is returned.
 */
export const load = cache.load;

/** Remove the whole cache entry (completion / start-over / expired sessions). */
export const clear = cache.clear;