import { z } from 'zod';

/**
 * sim/offline/events — OfflineEventBlock Zod runtime validator + pure
 * aggregator. Per CONTEXT D-19, D-10, D-11.
 *
 * Phase 2 ships the minimum slot vocabulary that the letter Ink template
 * (UX-02) needs: per-plant counts of plants bloomed, the list of
 * auto-harvested fragment ids, and a flag for any newly-unlocked Lura
 * beat queued for first-visit. Phase 4+ may add more if playtest
 * demands.
 *
 * Structurally compatible with the OfflineEventBlock interface declared
 * in src/save/migrations.ts (Plan 02-01) — that one is the type the
 * save layer carries; this file is the runtime validator + aggregator.
 *
 * Pure. Imports only zod. CORE-10 firewall + Phase-2 sim-purity rule
 * still apply: no Date.now, no setInterval, no DOM, no fetch.
 */
export const OfflineEventBlockSchema = z.object({
  plantsBloomedCount: z.record(z.string(), z.number().int().nonnegative()),
  harvestedFragmentIds: z.array(z.string().regex(/^season\d+\.[a-z0-9._-]+$/)),
  luraBeatPending: z.enum(['arrival', 'mid', 'farewell']).nullable(),
});

export type OfflineEventBlock = z.infer<typeof OfflineEventBlockSchema>;

/**
 * Frozen empty block. The boot path uses this as the seed for the silent
 * catch-up loop's offlineEvents accumulator. Object.freeze prevents
 * accidental mutation across catchup boundaries.
 */
export const EMPTY_OFFLINE_EVENTS: OfflineEventBlock = Object.freeze({
  plantsBloomedCount: Object.freeze({}) as Record<string, number>,
  harvestedFragmentIds: Object.freeze([]) as unknown as string[],
  luraBeatPending: null,
});

/**
 * aggregateOfflineEvent — pure combiner for a single auto-harvest event
 * during the silent-mode catchup loop.
 *
 * Returns a NEW OfflineEventBlock with:
 *   - plantsBloomedCount[plantTypeId] incremented by 1
 *   - fragmentId appended to harvestedFragmentIds
 *   - luraBeatPending: prev's value preserved unless the incoming
 *     `luraBeatPending` is non-null (in which case the most recent
 *     pending beat wins — Phase 2 has at most one pending beat at a
 *     time per advanceLuraBeatProgress's invariant in
 *     src/sim/narrative/lura-gate.ts).
 *
 * Per CONTEXT D-17/D-19 — this is the slot vocabulary the letter Ink
 * template renders.
 */
export function aggregateOfflineEvent(
  prev: OfflineEventBlock,
  plantTypeId: string,
  fragmentId: string,
  luraBeatPending: OfflineEventBlock['luraBeatPending'],
): OfflineEventBlock {
  const counts = { ...prev.plantsBloomedCount };
  counts[plantTypeId] = (counts[plantTypeId] ?? 0) + 1;
  return {
    plantsBloomedCount: counts,
    harvestedFragmentIds: [...prev.harvestedFragmentIds, fragmentId],
    luraBeatPending: luraBeatPending ?? prev.luraBeatPending,
  };
}