/**
 * outbox-log — read-only diagnostic inspection of `@ng-org/web`'s offline write
 * outbox, at session bootstrap (polyfill-era, low-level-data-path trace).
 *
 * ── What this surfaces ──────────────────────────────────────────────────────
 * `@ng-org/web` (the real injected SDK) queues writes made while offline/
 * disconnected in an "outbox", persisted client-side in `sessionStorage` by the
 * WASM verifier (see `sdk/rust/src/local_broker.rs` `JsStorageConfig::
 * get_js_storage_config` in the `nextgraph-rs` core repo — read-only reference,
 * NOT vendored here). A non-empty outbox at session start is an ANOMALY worth
 * surfacing unconditionally: it means writes from a previous (disconnected)
 * session are still queued and haven't reached the broker yet.
 *
 * ── sessionStorage key shapes (verified in the core repo, not guessed) ──────
 * The outbox is keyed per LOCAL PEER id (`peer_id`, the persistent local peer's
 * pubkey — NOT the ng-eventually shim's `account`/`identity` concept), via two
 * key families written by `session_write`/read by `session_read`:
 *   - `ng_peer_last_seq@<peerId>`         — the peer's last reserved seq number.
 *   - `ng_outboxes@<peerId>@start`        — the seq number the outbox starts at.
 *   - `ng_outboxes@<peerId>@<00000-idx>`  — one queued (base64url + BARE-encoded)
 *     event per zero-padded index, contiguous from 0 until the first miss (the
 *     exact shape `outbox_read_function` walks — see `local_broker.rs`).
 * We don't know `peerId` ahead of time (it's internal to the injected SDK), so
 * we DISCOVER it by scanning `sessionStorage` for `@start` markers instead of
 * requiring it to be passed in — this also means the probe works unchanged
 * however many peers/wallets the browser session has touched.
 *
 * ── Read-only, defensive, best-effort ────────────────────────────────────────
 * This NEVER writes or deletes a key (unlike the real `outbox_read_function`,
 * which drains on read) — it only counts. The queued event bytes are opaque
 * (BARE-encoded Rust structs, base64url'd); decoding them to report concrete
 * write TARGETS (topics/docs) would mean duplicating the WASM verifier's wire
 * format in this polyfill, which is explicitly out of scope (SDK internals live
 * in the `@ng-eventually/client`-independent core repo, per this repo's
 * doctrine) — so only the pending COUNT is reported, never fabricated targets.
 * `sessionStorage` access itself can throw (sandboxed iframe, disabled storage —
 * see the exact error string handled in the core repo's `main.ts`
 * `convert_error`), so the whole probe is wrapped in one try/catch: unavailable
 * → skip silently, never throw into the caller.
 *
 * Polyfill-era; removed at the real multi-store migration alongside the rest of
 * this low-level trace instrumentation.
 */

import { accessLogPrefix, logStage } from "./access-log";

/** Matches an outbox "start" marker key, capturing the peer id. */
const OUTBOX_START_KEY = /^ng_outboxes@(.+)@start$/;

/** Safety bound on the per-peer index walk, so a corrupted/mocked storage
 *  (e.g. a `@start` marker with no matching index gaps) can't spin forever.
 *  Real outboxes are queued-while-offline writes — nowhere near this size. */
const MAX_SCAN_PER_PEER = 10_000;

/**
 * Inspect the outbox NOW and log its state — count only, never targets (see
 * module doc). Non-empty → `console.warn`, ALWAYS printed (anomaly, not gated
 * by the access-log flag). Empty → a normal {@link logStage} line, gated by the
 * access-log flag like the rest of the low-level trace. Read-only: never
 * mutates `sessionStorage`. Never throws.
 */
export function inspectOutbox(): void {
  try {
    const storage = (globalThis as any)?.sessionStorage;
    if (!storage) return;

    const peers = new Set<string>();
    const length: number = storage.length ?? 0;
    for (let i = 0; i < length; i++) {
      const key = storage.key?.(i);
      if (!key) continue;
      const m = OUTBOX_START_KEY.exec(key);
      const peerId = m?.[1];
      if (peerId) peers.add(peerId);
    }

    let total = 0;
    for (const peer of peers) {
      let idx = 0;
      while (idx < MAX_SCAN_PER_PEER) {
        const idxKey = "ng_outboxes@" + peer + "@" + String(idx).padStart(5, "0");
        if (storage.getItem(idxKey) === null) break;
        total++;
        idx++;
      }
    }

    if (total > 0) {
      // Anomaly: ALWAYS visible, regardless of the access-log flag.
      console.warn(accessLogPrefix() + " OUTBOX " + total + " pending write(s)");
    } else {
      logStage("OUTBOX empty");
    }
  } catch {
    // sessionStorage unavailable / access denied — skip silently. Diagnostic
    // only, never a hard dependency of the read/write path.
  }
}