datastore.js

const { Datastore } = require("@google-cloud/datastore");
const TRUCK = "Truck";

require("dotenv").config();

const datastore = new Datastore();
const fromDatastore = function (item) {
  item.id = item[Datastore.KEY].id;
  return item;
};

// returns an entity in a kind corresponding to the passed id
function getEntityByID(kind, id) {
  const key = datastore.key([kind, parseInt(id, 10)]);
  return datastore.get(key).then((entity) => {
    if (entity[0] === undefined || entity[0] === null) {
      return entity;
    } else {
      return entity.map(fromDatastore);
    }
  });
}

// returns list of entities in kind
function getUnprotectedEntitiesInKind(kind) {
  const q = datastore.createQuery(kind);
  return datastore.runQuery(q).then((entities) => {
    return entities[0].map(fromDatastore);
  });
}

// returns list of entities in kind that belong to specified owner
function getProtectedEntitiesInKind(kind, owner) {
  const q = datastore.createQuery(kind);
  return datastore.runQuery(q).then((entities) => {
    return entities[0]
      .map(fromDatastore)
      .filter((item) => item.owner === owner);
  });
}

// returns true is any of the values in the array are falsy;
// returns false otherwise
function hasFalsyValue(arr) {
  for (const el of arr) {
    if (!el) {
      return true;
    }
  }
  return false;
}

// returns true if any of the values in the array are truthy; false otherwise
function hasTruthyValue(arr) {
  for (const el of arr) {
    if (el) {
      return true;
    }
  }
  return false;
}

// return an object that contains the passed id and the corresponding self link
function convertIdToObjectWithSelfLink(id, endpoint, req) {
  return {
    id: id,
    self: `${req.protocol}://${req.get("host")}/${endpoint}/${id}`,
  };
}

// return a modified version of the object that has self links for the load and for its carrier
function addSelfLinksToLoad(load, req) {
  const loadWithSelfLinks = {
    ...load,
    self: `${req.protocol}://${req.get("host")}/loads/${load.id}`,
  };

  if (load.carrier) {
    loadWithSelfLinks.carrier = convertIdToObjectWithSelfLink(
      load.carrier,
      "trucks",
      req
    );
  }

  return loadWithSelfLinks;
}

// return a modified version of the object that has self links for the truck and for each of its loads
function addSelfLinksToTruck(truck, req) {
  const truckWithSelfLinks = {
    ...truck,
    self: `${req.protocol}://${req.get("host")}/trucks/${truck.id}`,
    loads: [],
  };

  for (let j = 0; j < truck.loads.length; j++) {
    const loadID = truck.loads[j];
    truckWithSelfLinks.loads.push(
      convertIdToObjectWithSelfLink(loadID, "loads", req)
    );
  }

  return truckWithSelfLinks;
}

// remove a load id from a truck's list of loads
function removeLoadFromTruck(truckID, loadID) {
  const l_key = datastore.key([TRUCK, parseInt(truckID, 10)]);
  return datastore.get(l_key).then((truck) => {
    truck[0].loads = truck[0].loads.filter((load) => load != loadID);
    return datastore.save({ key: l_key, data: truck[0] });
  });
}

// return true if the client accepts JSON responses; false otherwise
function hasJsonInAcceptHeader(req) {
  return req.accepts(["application/json"]);
}

// return true if the response is JSON; false otherwise
function hasValidContentType(req) {
  return req.get("content-type") === "application/json";
}

// return true if the client is authorized to view the entity
function ownerIsValid(req, entity) {
  return entity.owner === req.auth.sub;
}

module.exports.Datastore = Datastore;
module.exports.datastore = datastore;
module.exports.fromDatastore = fromDatastore;
module.exports.getEntityByID = getEntityByID;
module.exports.getUnprotectedEntitiesInKind = getUnprotectedEntitiesInKind;
module.exports.getProtectedEntitiesInKind = getProtectedEntitiesInKind;
module.exports.hasFalsyValue = hasFalsyValue;
module.exports.hasTruthyValue = hasTruthyValue;
module.exports.addSelfLinksToLoad = addSelfLinksToLoad;
module.exports.addSelfLinksToTruck = addSelfLinksToTruck;
module.exports.removeLoadFromTruck = removeLoadFromTruck;
module.exports.hasJsonInAcceptHeader = hasJsonInAcceptHeader;
module.exports.hasValidContentType = hasValidContentType;
module.exports.ownerIsValid = ownerIsValid;