'use strict';

const _ = require('lodash');
const loadConfigs = require('./load-config');

const attachMetadataToResolvers = (schema, { api, plugin }) => {
  const { resolver = {} } = schema;
  if (_.isEmpty(resolver)) return schema;

  Object.keys(resolver).forEach(type => {
    if (!_.isPlainObject(resolver[type])) return;

    Object.keys(resolver[type]).forEach(resolverName => {
      if (!_.isPlainObject(resolver[type][resolverName])) return;

      resolver[type][resolverName]['_metadatas'] = {
        api,
        plugin,
      };
    });
  });

  return schema;
};

module.exports = async ({ strapi }) => {
  const { appPath, installedPlugins } = strapi.config;

  // Try to inject this hook just after the others hooks to skip the router processing.
  if (!strapi.config.get('hook.load.after')) {
    strapi.config.hook.load.after = [];
  }

  strapi.config.hook.load.after.push('graphql');
  // Load core utils.

  const { api, plugins, extensions } = await loadConfigs({
    appPath,
    installedPlugins,
  });

  _.merge(strapi, { api, plugins });

  // Create a merge of all the GraphQL configuration.
  const apisSchemas = Object.keys(strapi.api || {}).map(key => {
    const schema = _.get(strapi.api[key], 'config.schema.graphql', {});
    return attachMetadataToResolvers(schema, { api: key });
  });

  const pluginsSchemas = Object.keys(strapi.plugins || {}).map(key => {
    const schema = _.get(strapi.plugins[key], 'config.schema.graphql', {});
    return attachMetadataToResolvers(schema, { plugin: key });
  });

  const extensionsSchemas = Object.keys(extensions || {}).map(key => {
    const schema = _.get(extensions[key], 'config.schema.graphql', {});
    return attachMetadataToResolvers(schema, { plugin: key });
  });

  const baseSchema = mergeSchemas([...pluginsSchemas, ...extensionsSchemas, ...apisSchemas]);

  // save the final schema in the plugin's config
  _.set(strapi.plugins.graphql, 'config._schema.graphql', baseSchema);
};

/**
 * Merges a  list of schemas
 * @param {Array<Object>} schemas - The list of schemas to merge
 */
const mergeSchemas = schemas => {
  return schemas.reduce((acc, el) => {
    const { definition, query, mutation, type, resolver } = el;

    return _.merge(acc, {
      definition: `${acc.definition || ''} ${definition || ''}`,
      query: `${acc.query || ''} ${query || ''}`,
      mutation: `${acc.mutation || ''} ${mutation || ''}`,
      type,
      resolver,
    });
  }, {});
};