import { createContext, useEffect, useState } from "react";

/**
 * constants
 */
export const Constants = {
  API_ADDRESS: "http://localhost:8080/v1",
  WS_ADDRESS: "ws://localhost:8080/ws",
};

/**
 * user session
 */
export function UseUserSession() {
  const getUserSession = () => {
    return JSON.parse(localStorage.getItem("session"));
  };

  const [userSession, setUserSession] = useState(getUserSession());

  const saveUserSession = (session) => {
    setUserSession(session);

    if (session === undefined) {
      localStorage.removeItem("session");
    } else {
      localStorage.setItem("session", JSON.stringify(session));
    }
  };

  return {
    setUserSession: saveUserSession,
    userSession,
  };
}

/**
 * websocket
 */
let l = "loading...";

let webSocketContextPreview = {
  User: {
    Username: l,
    Email: l,
  },
  ConnectionBadgeStatus: "error",
  ConnectedWebSocketUsersCount: 0,
  CategoryGroups: [],
};

export const WebSocketContext = createContext(webSocketContextPreview);

// commands received from the backend server
const ReceivedMessagesCommands = {
  InitUserSocketConnection: 1,
  UpdateConnectedUsers: 2,
};

export function WebSocketProvider({ children, userSession, setUserSession }) {
  const [isReady, setIsReady] = useState(false);
  const [connectionBadgeStatus, setConnectionBadgeStatus] = useState(
    webSocketContextPreview.ConnectionBadgeStatus
  );
  const [connectedWebSocketUsersCount, setConnectedWebSocketUsersCount] =
    useState(0);
  const [user, setUser] = useState(webSocketContextPreview.User);
  const [categoryGroups, setCategoryGroups] = useState(
    webSocketContextPreview.CategoryGroups
  );

  let socket = null;

  const connect = () => {
    socket = new WebSocket(Constants.WS_ADDRESS + "?auth=" + userSession);

    socket.onopen = () => {
      console.log("connected");
      setConnectionBadgeStatus("success");
      setIsReady(true);
    };

    socket.onmessage = (event) => {
      const data = JSON.parse(event.data);
      console.log("received message", data);

      const cmd = data.Cmd;
      const body = data.Body;

      switch (cmd) {
        case ReceivedMessagesCommands.InitUserSocketConnection:
          setUser(body.User);
          setCategoryGroups(body.CategoryGroups);
          break;
        case ReceivedMessagesCommands.UpdateConnectedUsers:
          setConnectedWebSocketUsersCount(body);
          break;
      }
    };

    socket.onclose = (event) => {
      setIsReady(false);
      setConnectionBadgeStatus("error");
      console.log("closed", event);

      // custom code defined by the backend server
      if (event.code === 4001) {
        setUserSession();
        window.location.href = "/";
        return;
      }

      if (event.reason.code === 1005) return;

      console.log("reconnecting...");

      setTimeout(() => connect(), 1000);
    };
  };

  useEffect(() => {
    connect();

    return () => socket.close();
  }, []);

  return (
    <WebSocketContext.Provider
      value={{
        ConnectionBadgeStatus: connectionBadgeStatus,
        ConnectedWebSocketUsersCount: connectedWebSocketUsersCount,
        CategoryGroups: categoryGroups,
        User: user,
      }}
    >
      {children}
    </WebSocketContext.Provider>
  );
}