'use strict';

/**
 * Module dependencies
 */

// Public node modules.
const _ = require('lodash');
const path = require('path');
const glob = require('glob');
const { ApolloServer } = require('apollo-server-koa');
const depthLimit = require('graphql-depth-limit');

module.exports = strapi => {
  return {
    beforeInitialize: async function() {
      // Try to inject this hook just after the others hooks to skip the router processing.
      if (!_.get(strapi.config.hook.load, 'after')) {
        _.set(strapi.config.hook.load, 'after', []);
      }

      strapi.config.hook.load.after.push('graphql');

      // Load core utils.
      const utils = require(path.resolve(
        strapi.config.appPath,
        'node_modules',
        'strapi',
        'lib',
        'utils',
      ));

      // Set '*.graphql' files configurations in the global variable.
      await Promise.all([
        // Load root configurations.
        new Promise((resolve, reject) => {
          glob(
            './config/*.graphql?(.js)',
            {
              cwd: strapi.config.appPath,
            },
            (err, files) => {
              if (err) {
                return reject(err);
              }

              utils.loadConfig
                .call(strapi, files, true)
                .then(resolve)
                .catch(reject);
            },
          );
        }),
        // Load APIs configurations.
        new Promise((resolve, reject) => {
          glob(
            './api/*/config/*.graphql?(.js)',
            {
              cwd: strapi.config.appPath,
            },
            (err, files) => {
              if (err) {
                return reject(err);
              }

              utils.loadConfig
                .call(strapi, files, true)
                .then(resolve)
                .catch(reject);
            },
          );
        }),
        // Load plugins configurations.
        new Promise((resolve, reject) => {
          glob(
            './plugins/*/config/*.graphql?(.js)',
            {
              cwd: strapi.config.appPath,
            },
            (err, files) => {
              if (err) {
                return reject(err);
              }

              utils.loadConfig
                .call(strapi, files, true)
                .then(resolve)
                .catch(reject);
            },
          );
        }),
      ]);

      /*
       * Create a merge of all the GraphQL configuration.
       */

      // Set path with initial state.
      _.set(strapi.plugins.graphql, 'config._schema.graphql', {
        definition: '',
        query: '',
        mutation: '',
        type: {},
        resolver: {},
      });

      // Merge user API.
      Object.keys(strapi.api || {}).reduce((acc, current) => {
        const { definition, query, mutation, type, resolver } = _.get(
          strapi.api[current],
          'config.schema.graphql',
          {},
        );

        acc.definition += definition || '';
        acc.query += query || '';
        acc.mutation += mutation || '';

        return _.merge(acc, {
          type,
          resolver,
        });
      }, strapi.plugins.graphql.config._schema.graphql);

      // Merge plugins API.
      Object.keys(strapi.plugins || {}).reduce((acc, current) => {
        const { definition, query, mutation, type, resolver } = _.get(
          strapi.plugins[current],
          'config.schema.graphql',
          {},
        );

        acc.definition += definition || '';
        acc.query += query || '';
        acc.mutation += mutation || '';

        return _.merge(acc, {
          type,
          resolver,
        });
      }, strapi.plugins.graphql.config._schema.graphql);
    },

    initialize: function(cb) {
      const {
        typeDefs,
        resolvers,
      } = strapi.plugins.graphql.services.schema.generateSchema();

      if (_.isEmpty(typeDefs)) {
        strapi.log.warn(
          'GraphQL schema has not been generated because it\'s empty',
        );

        return cb();
      }

      const serverParams = {
        typeDefs,
        resolvers,
        context: async ({ ctx }) => ({
          context: ctx,
        }),
        validationRules: [depthLimit(strapi.plugins.graphql.config.depthLimit)],
        tracing: _.get(strapi.plugins.graphql, 'config.tracing', false),
        playground: false,
      };

      // Disable GraphQL Playground in production environment.
      if (
        strapi.config.environment !== 'production' ||
        strapi.plugins.graphql.config.playgroundAlways
      ) {
        serverParams.playground = {
          endpoint: strapi.plugins.graphql.config.endpoint,
        };
      }

      const server = new ApolloServer(serverParams);

      server.applyMiddleware({
        app: strapi.app,
        path: strapi.plugins.graphql.config.endpoint,
      });

      cb();
    },
  };
};