// Properties used internally by protobufjs on Namespace/ReflectionObject instances.
// A protobuf package component that happens to share one of these names must not be
// promoted to a direct property, or it would corrupt protobufjs's internal state.
// (Such types are still reachable via root.lookup() or root.nested traversal.)
const ROOT_PROPS = new Set([
  'options',
  'parsedOptions',
  'name',
  'parent',
  'resolved',
  'comment',
  'filename',
  'nested',
  '_nestedArray',
]);

/**
 * Create a version of `root` with non-nested namespaces to match the generated types.
 * For more information, see:
 * https://github.com/temporalio/sdk-typescript/blob/main/docs/protobuf-libraries.md#current-solution
 * @param root Generated by `pbjs -t json-module -w commonjs -o json-module.js *.proto`
 * @returns A new patched `root`
 */
export function patchProtobufRoot<T extends Record<string, unknown>>(root: T): T {
  const patched = _patchProtobufRoot(root);

  // Protobufjs >=7.5.2 added a fast-path cache in Namespace#lookup() that accesses
  // `this.root._fullyQualifiedObjects`. The `root` accessor is defined as a non-enumerable
  // getter on `ReflectionObject.prototype`, so it is not copied by `for...in` loops.
  // When the patched root is imported via `import * as proto from '@temporalio/proto'`,
  // TypeScript's `__importStar` helper wraps the CJS module in a plain object by iterating
  // own enumerable properties with `for...in` + `hasOwnProperty`. Because `root` is
  // non-enumerable, it is skipped, the wrapper's `root` is `undefined`, and any subsequent
  // `this.root._fullyQualifiedObjects` access crashes.
  // Defining `root` as an own **enumerable** getter ensures `__importStar` includes it in
  // the wrapper, so that `wrapper.root` delegates back to the patched root (which has the
  // proper `_fullyQualifiedObjects` map and full prototype chain).
  if (!Object.getOwnPropertyDescriptor(patched, 'root')) {
    Object.defineProperty(patched, 'root', {
      get(this: any) {
        // eslint-disable-next-line @typescript-eslint/no-this-alias
        let ptr = this;
        while (ptr.parent !== null) ptr = ptr.parent;
        return ptr;
      },
      enumerable: true,
      configurable: true,
    });
  }

  return patched;
}

function _patchProtobufRoot<T extends Record<string, unknown>>(root: T, name?: string): T {
  const newRoot = new (root.constructor as any)(isNamespace(root) ? name : {});
  for (const key in root) {
    // 'root' is a getter-only accessor defined on ReflectionObject.prototype. Trying to
    // assign it as a plain property on a new Root/Namespace instance throws in strict mode.
    // It is also safe to skip because each object correctly resolves its own root at runtime
    // by traversing the parent chain. The top-level own enumerable getter is added separately
    // by patchProtobufRoot() after recursion completes.
    if (key === 'root') continue;
    newRoot[key] = root[key];
  }

  if (isRecord(root.nested)) {
    for (const typeOrNamespace in root.nested) {
      // Skip names that protobufjs uses internally — overriding them would corrupt
      // the namespace object's internal state. Types/namespaces with these names are
      // still reachable via root.lookup() or by traversing root.nested manually.
      if (ROOT_PROPS.has(typeOrNamespace)) continue;

      const value = root.nested[typeOrNamespace];
      if (isNamespace(value)) {
        newRoot[typeOrNamespace] = _patchProtobufRoot(value, typeOrNamespace);
      } else if (isType(value)) {
        newRoot[typeOrNamespace] = value;
      }
    }
  }

  return newRoot;
}

type Type = Record<string, unknown>;
type Namespace = { nested: Record<string, unknown> };

function isType(value: unknown): value is Type {
  // constructor.name may get mangled by minifiers; thanksfuly protobufjs also sets a constructor.className property
  return isRecord(value) && (value.constructor as any).className === 'Type';
}

function isNamespace(value: unknown): value is Namespace {
  // constructor.name may get mangled by minifiers; thanksfuly protobufjs also sets a constructor.className property
  return isRecord(value) && (value.constructor as any).className === 'Namespace';
}

// Duplicate from type-helpers instead of importing in order to avoid circular dependency
function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null;
}