Meteor.subscribe("users");

/**
 * Find the id of a chat between two users.
 *
 * @param {String} myId
 *   The current user id.
 * @param {String} otherUserId
 *   The id of an other user.
 *
 * @returns {String}
 *   The id of a chat between both users.
 */
const getChatId = function (myId, otherUserId) {
  let id1;
  let id2;
  // Ensure ordering as id1 <= id2. Equality should not happen, but handle it correctly nonetheless.
  if (myId <= otherUserId) {
    id1 = myId;
    id2 = otherUserId;
  }
  else {
    id1 = otherUserId;
    id2 = myId;
  }

  // Since ids are ordered, we do not need a $or.
  const filter = { user1Id: id1, user2Id: id2 };
  const chat = Chats.findOne(filter);
  // Meteor._debug(filter, chat);

  // No chat matching the filter - need to insert a new one.
  let chatId;
  if (!chat) {
    chatId = Chats.insert({
      user1Id: id1,
      user2Id: id2
    });
    console.log("--- No chat found between " + id1 + " and " + id2 + ". Created " + chatId);
  }
  // There is a chat going already - use that.
  else {
    chatId = chat._id;
    console.log("--- Chat " + chatId + " found between " + id1 + " and " + id2 + ".");
  }
  return chatId;
};

// set up the main template the the router will use to build pages
Router.configure({
  layoutTemplate: "ApplicationLayout"
});

// specify the top level route, the page users see when they arrive at the site
Router.route("/", function () {
  console.log("Routing root /");
  this.render("navbar", { to: "header" });
  this.render("lobby_page", { to: "main" });
});

// specify a route that allows the current user to chat to another users
Router.route("/chat/:_id", {
  subscriptions: function () {
    Meteor._debug("Subscriptions");
    return Meteor.subscribe("chats");
  },

  action: function (req, wtf, next) {
    Meteor._debug("Action", req.url);
    if (this.ready()) {
      console.log("- Now ready");

      // The user they want to chat to has id equal to the id sent in after /chat/...
      const otherUserId = this.params._id;
      const myId = Meteor.userId();
      const chatId = getChatId(myId, otherUserId);
      if (chatId) {
        // Looking good, save the id to the session.
        Session.set("chatId", chatId);
        this.render("navbar", { to: "header" });
        this.render("chat_page", {
          to: "main",
          data: function () {
            const other = Meteor.users.findOne({ _id: otherUserId });
            console.log("--- Routing data, other: " + (other ? other.profile.username : "not available"));
            return {
              other: other
            };
          }
        });
      }
      else {
        this.render("navbar", { to: "header" });
        this.render("Error", {
          to: "main",
          data: new Meteor.Error("no-chat", `Could not find a chat between ${myId} and ${otherUserId}.`)
        });
      }
    }
    else {
      console.log("- Not yet ready");
      this.render("Loading");
    }
  }
});