import { useMemo } from 'react';
import { ApolloClient } from 'apollo-client';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { SchemaLink } from 'apollo-link-schema';
import { makeExecutableSchema } from 'graphql-tools';

let apolloClient;

const typeDefs = `
  type Query {
    search(query: SearchQuery!): Response!
  }

  type SearchQuery {
    q: String!
    fq: String!
    sort: String!
    rows: Int!
    start: Int!
    facet: String!
    include_drafts: Boolean!
    include_private: Boolean!
    use_default_schema: Boolean!
  }

  type Response {
    success: Boolean!
    result: Result!
  }

  type Result {
    count: Int!
    sort: String!
    facets: String!
    search_facets: String!
    results: [Package!]!
  }

  type Package {
    name: String!
    title: String!
    notes: String!
    resources: [Resource!]!
    organization: Organization!
    metadata_created: String!
    metadata_modified: String!
  }

  type Resource {
    name: String!
    id: String!
    title: String!
    format: String!
    created: String!
    last_modified: String!
    datastore_active: Boolean!
    url: String!
  }

  type Organization {
    name: String!
    title: String!
    description: String!
    created: String!
    image_url: String!
  }
`;

const resolvers = {
  Query: {
    search: (parent, { query }) => ({
      success: true,
      result: {
        count: 2,
        sort: 'score desc, metadata_modified desc',
        facets: {},
        results: [
          {
            name: 'gdp',
            title: 'Country, Regional and World GDP (Gross Domestic Product)',
            notes:
              'Country, regional and world GDP in current US Dollars ($). Regional means collections of countries e.g. Europe & Central Asia. Data is sourced from the World Bank and turned into a standard normalized CSV.',
            resources: [
              {
                name: 'gdp',
                id: 'gdp',
                title: 'GDP data',
                format: 'csv',
                created: '2019-03-07T12:00:36.273495',
                last_modified: '2020-05-07T12:00:36.273495',
                datastore_active: false,
                url: 'http://mock.filestore/gdp.csv',
              },
            ],
            organization: {
              title: 'World Bank',
              name: 'world-bank',
              description:
                'The World Bank is an international financial institution that provides loans and grants to the governments of poorer countries for the purpose of pursuing capital projects.',
              created: '2019-03-07T11:51:13.758844',
              image_url:
                'https://github.com/datahq/frontend/raw/master/public/img/avatars/world-bank.jpg',
            },
            metadata_created: '2019-03-07T11:56:19.696257',
            metadata_modified: '2019-03-07T12:03:58.817280',
          },
          {
            name: 'population',
            title: 'World population data',
            notes:
              'Population figures for countries, regions (e.g. Asia) and the world. Data comes originally from World Bank and has been converted into standard CSV.',
            resources: [
              {
                name: 'population',
                id: 'population',
                title: 'Population data',
                format: 'csv',
                created: '2019-03-07T12:00:36.273495',
                last_modified: '2020-05-07T12:00:36.273495',
                datastore_active: true,
                url: 'http://mock.filestore/population.csv',
              },
            ],
            organization: {
              title: 'World Bank',
              name: 'world-bank',
              description:
                'The World Bank is an international financial institution that provides loans and grants to the governments of poorer countries for the purpose of pursuing capital projects.',
              created: '2019-03-07T11:51:13.758844',
              image_url:
                'https://github.com/datahq/frontend/raw/master/public/img/avatars/world-bank.jpg',
            },
          },
        ],
        search_facets: {},
      },
    }),
  },
};

const executableSchema = makeExecutableSchema({
  typeDefs,
  resolvers,
});

const link = new SchemaLink({ schema: executableSchema });

function createApolloClient() {
  return new ApolloClient({
    ssrMode: typeof window === 'undefined',
    link,
    cache: new InMemoryCache(),
  });
}

export function initializeApollo(initialState = null) {
  const _apolloClient = apolloClient ?? createApolloClient();

  // If your page has Next.js data fetching methods that use Apollo Client, the initial state
  // gets hydrated here
  if (initialState) {
    _apolloClient.cache.restore(initialState);
  }
  // For SSG and SSR always create a new Apollo Client
  if (typeof window === 'undefined') return _apolloClient;
  // Create the Apollo Client once in the client
  if (!apolloClient) apolloClient = _apolloClient;

  return _apolloClient;
}

export function useApollo(initialState) {
  const store = useMemo(() => initializeApollo(initialState), [initialState]);
  return store;
}