/**
 * Local (optimistic) admin-moderation store.
 *
 * WHY THIS EXISTS
 * ---------------
 * An admin verdict publishes a kind:1985 label so it applies across devices (see
 * `useAdminModeration`). But publishing requires an Amber approval, which can be
 * slow. We must not make the admin UI wait on it, so every verdict is ALSO
 * mirrored here and merged in, so it takes effect on this device instantly.
 *
 * VERDICTS (latest wins)
 * ----------------------
 * A target has ONE current verdict, and the newest one wins — both here and on
 * the relay side. That is what makes moderation reversible:
 *   • `hidden`   — out of the app;
 *   • `verified` — admin-vouched (badge, and cleared from the review queue);
 *   • `cleared`  — UNDO: back to neutral, as if nobody had said anything.
 *
 * Entries carry a timestamp so a device-local verdict (just now) can be compared
 * against a relay label (created_at) instead of blindly winning forever.
 */

/** A moderation verdict about one target. */
export type LocalVerdict = 'hidden' | 'verified' | 'cleared';

export interface LocalVerdictEntry {
  verdict: LocalVerdict;
  /** Unix seconds. */
  at: number;
}

const STORAGE_KEY = 'skatespots_local_admin_verdicts_v1';
// Older versions stored hidden and confirmed as two separate arrays.
const LEGACY_HIDDEN_KEY = 'skatespots_local_admin_hidden_v1';
const LEGACY_CONFIRMED_KEY = 'skatespots_local_admin_confirmed_v1';

type Store = Record<string, LocalVerdictEntry>;

/** One key per target: the addressable coord, or `e:<id>` for a concrete event. */
export function targetKey(opts: { coord?: string; id?: string }): string | null {
  if (opts.coord) return opts.coord;
  if (opts.id) return `e:${opts.id}`;
  return null;
}

function readLegacy(key: string): string[] {
  try {
    const raw = localStorage.getItem(key);
    if (!raw) return [];
    const parsed = JSON.parse(raw) as { coords?: unknown; ids?: unknown };
    const coords = Array.isArray(parsed.coords) ? (parsed.coords as string[]) : [];
    const ids = Array.isArray(parsed.ids) ? (parsed.ids as string[]) : [];
    return [...coords, ...ids.map((id) => `e:${id}`)];
  } catch {
    return [];
  }
}

function read(): Store {
  try {
    const raw = localStorage.getItem(STORAGE_KEY);
    if (raw) return JSON.parse(raw) as Store;
    // Migrate the legacy two-array format. `at: 0` means "no idea when", so any
    // real relay label supersedes it — but it still applies while the label
    // hasn't propagated.
    const migrated: Store = {};
    for (const key of readLegacy(LEGACY_HIDDEN_KEY)) migrated[key] = { verdict: 'hidden', at: 0 };
    for (const key of readLegacy(LEGACY_CONFIRMED_KEY)) migrated[key] = { verdict: 'verified', at: 0 };
    if (Object.keys(migrated).length > 0) write(migrated);
    return migrated;
  } catch {
    return {};
  }
}

function write(store: Store): void {
  try {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(store));
  } catch {
    /* storage full / unavailable — the optimistic mirror is best-effort */
  }
}

/** Record the admin's verdict for a target (device-local, newest wins). */
export function setLocalVerdict(
  opts: { coord?: string; id?: string },
  verdict: LocalVerdict,
): void {
  const key = targetKey(opts);
  if (!key) return;
  const store = read();
  store[key] = { verdict, at: Math.floor(Date.now() / 1000) };
  write(store);
}

/** Read every locally-recorded verdict, keyed by `targetKey`. */
export function getLocalVerdicts(): Map<string, LocalVerdictEntry> {
  return new Map(Object.entries(read()));
}

// ─── Thin wrappers, kept for existing callers ────────────────────────────────

/** @see setLocalVerdict */
export function addLocalHidden(opts: { coord?: string; id?: string }): void {
  setLocalVerdict(opts, 'hidden');
}

/** @see setLocalVerdict */
export function addLocalConfirmed(opts: { coord?: string; id?: string }): void {
  setLocalVerdict(opts, 'verified');
}