import type {
  NamedTypeNode,
  NameNode,
  DirectiveNode,
  SelectionNode,
  SelectionSetNode,
  FieldNode,
  FragmentDefinitionNode,
} from '@0no-co/graphql.web';

import type { FormattedNode } from '@urql/core';

export type SelectionSet = readonly FormattedNode<SelectionNode>[];

const EMPTY_DIRECTIVES: Record<string, DirectiveNode | undefined> = {};

/** Returns the directives dictionary of a given node */
export const getDirectives = (node: {
  _directives?: Record<string, DirectiveNode | undefined>;
}) => node._directives || EMPTY_DIRECTIVES;

/** Returns the name of a given node */
export const getName = (node: { name: NameNode }): string => node.name.value;

export const getFragmentTypeName = (node: FragmentDefinitionNode): string =>
  node.typeCondition.name.value;

/** Returns either the field's name or the field's alias */
export const getFieldAlias = (node: FieldNode): string =>
  node.alias ? node.alias.value : node.name.value;

const emptySelectionSet: SelectionSet = [];

/** Returns the SelectionSet for a given inline or defined fragment node */
export const getSelectionSet = (node: {
  selectionSet?: FormattedNode<SelectionSetNode>;
}): FormattedNode<SelectionSet> =>
  (node.selectionSet
    ? node.selectionSet.selections
    : emptySelectionSet) as FormattedNode<SelectionSet>;

export const getTypeCondition = (node: {
  typeCondition?: NamedTypeNode;
}): string | null =>
  node.typeCondition ? node.typeCondition.name.value : null;