graphql_utils.ts

import { ApolloClient } from 'apollo-boost';
import { get as lodashGet } from 'lodash';

interface INode<T> {
  node: T;
}

interface IHaveNextPage {
  pageInfo: {
    hasNextPage: boolean;
  };
}

export interface IConnectionPartial<T> {
  edges: INode<T>[];
}

export interface IConnection<T> {
  edges: INode<T>[];
  pageInfo: {
    hasNextPage: boolean;
    endCursor: string | null;
  };
}

export type IArrayOrConnection<T> = T[] | IConnectionPartial<T>;


export function map<T, R>(
  list: IArrayOrConnection<T>,
  fn: (node: T, i: number) => R,
) {
  return Array.isArray(list)
    ? list.map(fn)
    : list.edges.map(({ node }, i) => fn(node, i));
}

export function forEach<T>(
  list: IArrayOrConnection<T>,
  fn: (node: T, i: number) => void,
) {
  return Array.isArray(list)
    ? list.forEach(fn)
    : list.edges.forEach(({ node }, i) => fn(node, i));
}

export function toArray<T>(list: IArrayOrConnection<T>): T[] {
  return map(list, (node) => node);
}

export function length(list: IArrayOrConnection<any>) {
  return Array.isArray(list) ? list.length : list.edges.length;
}

export function get<T>(list: IArrayOrConnection<T>, i: number): T | null {
  if (Array.isArray(list)) {
    return list[i] || null;
  }
  return list.edges[i] ? list.edges[i].node : null;
}

export function first<T>(list: IArrayOrConnection<T>): T | null {
  return get(list, 0);
}

export function isEmpty(list: IArrayOrConnection<any>) {
  return length(list) === 0;
}

export function isPresent(list: IArrayOrConnection<any>) {
  return length(list) > 0;
}

export function hasNextPage(connection: IHaveNextPage) {
  return connection.pageInfo.hasNextPage;
}

export function polymorphicInput(
  name: string,
  subject: { id: string; __typename: string },
) {
  return {
    [`${name}Id`]: subject.id,
    [`${name}Type`]: subject.__typename,
  };
}

export function responseNode(response: any) {
  return response?.data?.response?.node;
}

export function responseErrors(response: any) {
  if (
    !response ||
    !response.data ||
    !response.data.response ||
    !response.data.response.errors ||
    response.data.response.errors.length === 0
  ) {
    return null;
  }

  return response.data.response.errors.reduce((acc: any, error: any) => {
    acc[error.field] = error.message;
    return acc;
  }, {});
}