/*

Default list, single, and total resolvers

*/

import { Utils, debug, debugGroup, debugGroupEnd } from 'meteor/vulcan:core';
import { createError } from 'apollo-errors';

const defaultOptions = {
  cacheMaxAge: 300,
};

export const getDefaultResolvers = (collectionName, resolverOptions = defaultOptions) => {
  return {
    // resolver for returning a list of documents based on a set of query terms

    list: {
      name: `${collectionName}List`,

      description: `A list of ${collectionName} documents matching a set of query terms`,

      async resolver(root, { terms = {}, enableCache = false }, context, { cacheControl }) {
        debug('');
        debugGroup(`--------------- start \x1b[35m${collectionName} list\x1b[0m resolver ---------------`);
        debug(`Options: ${JSON.stringify(resolverOptions)}`);
        debug(`Terms: ${JSON.stringify(terms)}`);

        if (cacheControl && enableCache) {
          const maxAge = resolverOptions.cacheMaxAge || defaultOptions.cacheMaxAge;
          cacheControl.setCacheHint({ maxAge });
        }

        // get currentUser and Users collection from context
        const { currentUser, Users } = context;

        // get collection based on collectionName argument
        const collection = context[collectionName];

        // get selector and options from terms and perform Mongo query
        let { selector, options } = await collection.getParameters(terms, {}, context);
        options.skip = terms.offset;

        debug({ selector, options });

        const docs = collection.find(selector, options).fetch();

        // if collection has a checkAccess function defined, remove any documents that doesn't pass the check
        const viewableDocs = collection.checkAccess
          ? _.filter(docs, doc => collection.checkAccess(currentUser, doc))
          : docs;

        // take the remaining documents and remove any fields that shouldn't be accessible
        const restrictedDocs = Users.restrictViewableFields(currentUser, collection, viewableDocs);

        // prime the cache
        restrictedDocs.forEach(doc => collection.loader.prime(doc._id, doc));

        debug(`\x1b[33m=> ${restrictedDocs.length} documents returned\x1b[0m`);
        debugGroupEnd();
        debug(`--------------- end \x1b[35m${collectionName} list\x1b[0m resolver ---------------`);
        debug('');

        // return results
        return restrictedDocs;
      },
    },

    // resolver for returning a single document queried based on id or slug

    single: {
      name: `${collectionName}Single`,

      description: `A single ${collectionName} document fetched by ID or slug`,

      async resolver(root, { documentId, slug, enableCache = false }, context, { cacheControl }) {
        debug('');
        debugGroup(`--------------- start \x1b[35m${collectionName} single\x1b[0m resolver ---------------`);
        debug(`Options: ${JSON.stringify(resolverOptions)}`);
        debug(`DocumentId: ${documentId}`);

        if (cacheControl && enableCache) {
          const maxAge = resolverOptions.cacheMaxAge || defaultOptions.cacheMaxAge;
          cacheControl.setCacheHint({ maxAge });
        }

        const { currentUser, Users } = context;
        const collection = context[collectionName];

        // don't use Dataloader if doc is selected by slug
        const doc = documentId
          ? await collection.loader.load(documentId)
          : slug ? collection.findOne({ slug }) : collection.findOne();

        if (!doc) {
          const MissingDocumentError = createError('app.missing_document', { message: 'app.missing_document' });
          throw new MissingDocumentError({ data: { documentId, slug } });
        }

        // if collection has a checkAccess function defined, use it to perform a check on the current document
        // (will throw an error if check doesn't pass)
        if (collection.checkAccess) {
          Utils.performCheck(collection.checkAccess, currentUser, doc, collection, documentId);
        }

        const restrictedDoc = Users.restrictViewableFields(currentUser, collection, doc);

        debugGroupEnd();
        debug(`--------------- end \x1b[35m${collectionName} single\x1b[0m resolver ---------------`);
        debug('');

        // filter out disallowed properties and return resulting document
        return restrictedDoc;
      },
    },

    // resolver for returning the total number of documents matching a set of query terms

    total: {
      name: `${collectionName}Total`,

      description: `The total count of ${collectionName} documents matching a set of query terms`,

      async resolver(root, { terms, enableCache }, context, { cacheControl }) {
        if (cacheControl && enableCache) {
          const maxAge = resolverOptions.cacheMaxAge || defaultOptions.cacheMaxAge;
          cacheControl.setCacheHint({ maxAge });
        }

        const collection = context[collectionName];

        const { selector } = await collection.getParameters(terms, {}, context);

        const docs = collection.find(selector);

        // if collection has a checkAccess function defined, remove any documents that doesn't pass the check
        if (collection.checkAccess) {
          const { currentUser } = context;
          return docs.fetch().filter(doc => collection.checkAccess(currentUser, doc)).length;
        }

        return docs.count();
      },
    },
  };
};