/**
 * Manifest health — pure checks over a raw `.nwire/manifest.json` payload.
 *
 * The manifest is generated by `@nwire/scan` and its schema evolves. A Studio
 * served against a manifest built by an older scanner must not crash; pages
 * that depend on a not-yet-present field render an empty state, and the operator
 * gets a "rebuild" hint naming exactly what's missing.
 *
 * Reports against the native manifest directly so App.vue can drive the
 * stale-manifest banner from the deep manifest, no flat reshape in between.
 */
import type { Manifest } from "./manifest";

/**
 * Top-level array fields the *current* `@nwire/scan` emits on every manifest
 * (always present, empty when a kind is unused — verified against real
 * `buildManifest` output). A field that's absent (or not an array) means the
 * manifest was built by an older scanner; we name it in the rebuild hint.
 *
 * Deliberately NOT the old flat-cache set: the deep manifest keeps apps,
 * resolvers, routes, hooks, plugins, sinks, bindings under `topology`/`model`,
 * not as top-level arrays — checking for them here false-flagged every real
 * manifest. `generatedAt` isn't emitted at top level either, so it's dropped.
 */
const ARRAY_FIELDS = [
  "events",
  "actions",
  "actors",
  "projections",
  "queries",
  "workflows",
  "commands",
  "crons",
  "externalCalls",
  "inboundWebhooks",
  "outboxes",
  "inboxes",
  "resources",
  "errors",
  "schemas",
] as const;

/**
 * The field paths a manifest is missing relative to the current schema. Empty
 * when the manifest is current-shape. Pure — no DOM, unit-testable.
 *
 * Order matches the schema declaration so the banner reads predictably
 * (`resolvers`, `workflows`, …).
 */
export function missingFields(manifest: Manifest | null | undefined): string[] {
  if (manifest === null || typeof manifest !== "object" || Array.isArray(manifest)) {
    return [];
  }

  const input = manifest as unknown as Record<string, unknown>;
  const missing: string[] = [];

  for (const field of ARRAY_FIELDS) {
    if (!Array.isArray(input[field])) missing.push(field);
  }

  // graph.events — nested arrays.
  const rawGraph = input.graph as { events?: unknown } | undefined;
  if (!rawGraph || typeof rawGraph !== "object") {
    missing.push("graph");
  } else if (!Array.isArray(rawGraph.events)) {
    missing.push("graph.events");
  }

  return missing;
}