index.js

const url = require("url");
const appUrl = "https://oliversgame.deals";
const appIcon = "https://oliversgame.deals/icons/icon-192x192.png";

// Setup Firebase SDK
const functions = require("firebase-functions");
const admin = require("firebase-admin");

const axios = require("axios");
const cors = require('cors')({ origin: true });

let emulated = process.env.FIREBASE_EMULATED === "true";

if (process.env.GOOGLE_APPLICATION_CREDENTIALS !== undefined) {
  var serviceAccount = require(process.env.GOOGLE_APPLICATION_CREDENTIALS);

  admin.initializeApp({
    credential: admin.credential.cert(serviceAccount),
  });
} else {
  admin.initializeApp();
}

const topic = emulated === true ? "deals-dev" : "deals";

const CHANNEL_MAIN = "main";

/**
 * Ensures the user who invoked the function is an admin.
 */
function ensureAdmin(context) {
  const uid = context.auth.uid;

  if (uid === null) {
    throw new functions.https.HttpsError("unauthenticated", "Not logged in");
  }

  return admin
    .firestore()
    .collection("admins")
    .doc(uid)
    .get()
    .catch(err => {
      console.error("Failed to get admins collection document", err);
      throw new functions.https.HttpsError(
        "internal",
        "Failed to determine admin status"
      );
    })
    .then(docRef => {
      if (docRef.exists === false) {
        throw new functions.https.HttpsError(
          "permission-denied",
          "Not an admin"
        );
      }

      return Promise.resolve();
    });
}

/**
 * Subscribe a client to the deals FCM topic.
 * Uses the request context to know the user's FCM token.
 * Data optionally { channel: string }, which can be used to augment which deals
 * topic to subscribe to. Only allowed to be used by admins.
 */
exports.subscribe = functions.https.onCall((data, context) => {
  const fcmToken = context.instanceIdToken;
  let channel = data && data.channel ? data.channel : CHANNEL_MAIN;

  const subTopic = `${topic}-${channel}`;
  var baseProm = Promise.resolve();

  if (channel !== CHANNEL_MAIN) {
    baseProm = ensureAdmin(context);
  }

  return baseProm
    .then(() => admin.messaging().subscribeToTopic(fcmToken, subTopic))
    .then(resp => {
      return Promise.resolve({});
    });
});

/**
 * Unsubscribe a client from the deals FCM topic.
 * Uses the request context to know the user's FCM token.
 * Data optionally { channel: string }, which can be used to augment which deals
 * topic to unsubscribe from. Only allowed to be used by admins.
 */
exports.unsubscribe = functions.https.onCall((data, context) => {
  const fcmToken = context.instanceIdToken;
  const channel = data && data.channel ? data.channel : CHANNEL_MAIN;

  const unsubTopic = `${topic}-${channel}`;
  var baseProm = Promise.resolve();

  if (channel !== CHANNEL_MAIN) {
    baseProm = ensureAdmin(context);
  }

  return baseProm
    .then(() => admin.messaging().unsubscribeFromTopic(fcmToken, unsubTopic))
    .then(resp => {
      return Promise.resolve({});
    });
});

/**
 * Send a notification about a new game deal to clients subscribed to the
 * deals topic.
 * Data must be { dealId: string, confirmResend: bool, channel: string }, where
 * dealId is the ID of the deals document and confirmResend is set to true if you
 * want to send a notification for a deal which has already had a notification
 * sent, this key is optional. The channel key can be used to augment which topic
 * to send the notification to.
 */
exports.notify = functions.https.onCall((data, context) => {
  const channel = data && data.channel ? data.channel : CHANNEL_MAIN;
  const notifyTopic = `${topic}-${channel}`;

  const dealId = data.dealId;
  const confirmResend = data.confirmResend || false;

  // Determine if admin
  return ensureAdmin(context)
    .then(() => {
      // Get deal from database
      return admin.firestore().collection("deals").doc(dealId).get();
    })
    .catch(error => {
      console.error("Failed to get deal to send notification for", error);
      throw new functions.https.HttpsError(
        "internal",
        "Failed to retrieve deal"
      );
    })
    .then(async docRef => {
      if (docRef.exists === false) {
        throw new functions.https.HttpsError(
          "not-found",
          "Deal does not exist"
        );
      }

      const deal = docRef.data();

      // Check if we are okay to resend the notification
      const notificationSent =
        channel in deal.notificationSent
          ? deal.notificationSent[channel]
          : false;
      if (notificationSent === true && confirmResend === false) {
        throw new functions.https.HttpsError(
          "already-exists",
          "Notification already sent for " + "this deal"
        );
      }

      // Send a Discord message
      const dealLink = url.parse(deal.link);
      const dealPrice = deal.isFree === true ? "free" : deal.price;

      const webhookData = {
        "content": "Hi there, it's me, totally not anti-Semitic Oliver, bringing you a brand new game deal!",
        "embeds": [
          {
            "title": deal.name,
            "type": "rich",
            "description": `${dealPrice === "free" ? "FREE" : "$" + dealPrice}! (click the title above to get the game)\nExpires ${deal.expires.toDate().toDateString()}`,
            "url": deal.link,
          }
        ]
      }

      if (deal.image) {
        webhookData.embeds[0].image = {
          "url": deal.image,
          "height": 100,
          "width": 100
        }
      }

      // eslint-disable-next-line promise/no-nesting
      await axios.post(functions.config().discord.webhook, webhookData)
      .catch(error => console.error(error));

      // Send notification to clients who subscribe
      return admin.messaging().send({
        topic: notifyTopic,
        webpush: {
          notification: {
            title: `Deal on ${deal.name} (${dealPrice})`,
            body:
              `${deal.name} is now available at ` +
              `${dealLink.hostname} for ${dealPrice}`,
            icon: appIcon,
            image: deal.image,
            requireInteraction: true,
          },
          fcmOptions: {
            link: appUrl,
          },
        },
        fcmOptions: {
          analyticsLabel: `${dealId}-${channel}`,
        },
      });
    })
    .then(() => {
      // Record that notification was sent on channel
      var sentUpdate = {};
      sentUpdate[`notificationSent.${channel}`] = true;
      return admin
        .firestore()
        .collection("deals")
        .doc(dealId)
        .update(sentUpdate);
    });
});

// !!!FOR LOCAL DEVELOPMENT USE ONLY!!!
// If firebase is being emulated expose some development utility functions
if (emulated === true) {
  /**
   * Makes the current user an admin. Useful for setting up the local database with
   * the correct admin users.
   * Data must be the user's ID (uid).
   */
  exports.devMakeUserAdmin = functions.https.onCall((data, context) => {
    return admin
      .firestore()
      .collection("admins")
      .doc(data)
      .set({
        admin: true,
      })
      .catch(error => {
        throw new functions.https.HttpsError(
          "internal",
          "Failed to make user " + data + " an admin: " + error
        );
      });
  });

  /**
   * Removes admin status from the current user. Useful for testing how pages will
   * behave for non-admin users.
   * Data must be the user's ID (uid).
   */
  exports.devRemoveUserAdmin = functions.https.onCall((data, context) => {
    return admin
      .firestore()
      .collection("admins")
      .doc(data)
      .delete()
      .catch(error => {
        throw new functions.https.HttpsError(
          "internal",
          "Failed to remove admin" +
            "priviledges from user " +
            data +
            ": " +
            error
        );
      });
  });
}