import type { BlockConfig, KsAppClientDataNoMeta } from '@knapsack/types';
import {
  type JSONContent,
  findUnrecognizedTiptapTypes,
  recognizedTiptapTypeNames,
} from '@knapsack/tiptap-utils';
import { getTiptapContentFields } from './tiptap-content-fields.js';

export type UnrecognizedTiptapContentReport = {
  blockId: string;
  blockType: BlockConfig['blockType'];
  /** Which JSONContent field on the block, e.g. 'content' or 'guidelines[2].content' */
  fieldPath: string;
  unrecognizedTypes: readonly string[];
};

// Immer's structural sharing means a block's JSONContent field reference is
// unchanged across appClientData versions unless that specific block was
// edited - so after any single edit, this cache is a hit for every other
// block, avoiding a full site-wide re-walk on every debounced content change.
// Keyed on `recognizedTypeNames` first (production always passes the same
// singleton default, so this outer lookup is effectively free) so that a
// caller passing a different set - e.g. tests - can never read back a
// result computed under a different set for the same content reference.
const unrecognizedTypesCache = new WeakMap<
  ReadonlySet<string>,
  WeakMap<JSONContent, readonly string[]>
>();

function findUnrecognizedTypesCached(
  content: JSONContent | null | undefined,
  recognizedTypeNames: ReadonlySet<string>,
): readonly string[] {
  if (!content) return [];
  let cacheForSet = unrecognizedTypesCache.get(recognizedTypeNames);
  if (!cacheForSet) {
    cacheForSet = new WeakMap();
    unrecognizedTypesCache.set(recognizedTypeNames, cacheForSet);
  }
  const cached = cacheForSet.get(content);
  if (cached) return cached;
  // Frozen before caching - this array is handed out by reference to every
  // caller sharing this content reference for the module's lifetime, so an
  // accidental downstream mutation must fail loudly instead of silently
  // corrupting results for every other block.
  const found = Object.freeze(
    findUnrecognizedTiptapTypes(content, recognizedTypeNames),
  );
  cacheForSet.set(content, found);
  return found;
}

/**
 * Non-mutating. Walks every block in appClientData.db.blocks.byId that can
 * carry JSONContent, and reports any unrecognized node/mark type names
 * found. Does NOT resolve page/pattern location - callers already have
 * buildBlockLocationMap()/BlockCollectionLocation for that (this package
 * cannot import from app-ui).
 */
export function detectUnrecognizedTiptapContent({
  appClientData,
  recognizedTypeNames = recognizedTiptapTypeNames,
}: {
  appClientData: KsAppClientDataNoMeta;
  recognizedTypeNames?: ReadonlySet<string>;
}): UnrecognizedTiptapContentReport[] {
  const reports: UnrecognizedTiptapContentReport[] = [];
  for (const block of Object.values(appClientData.db.blocks.byId)) {
    for (const { fieldPath, content } of getTiptapContentFields(block)) {
      const unrecognizedTypes = findUnrecognizedTypesCached(
        content,
        recognizedTypeNames,
      );
      if (unrecognizedTypes.length > 0) {
        reports.push({
          blockId: block.id,
          blockType: block.blockType,
          fieldPath,
          unrecognizedTypes,
        });
      }
    }
  }
  return reports;
}