import { createContext, useCallback, useContext, useEffect, useMemo, useState } from 'react';
import { useSocket } from './SocketContext.jsx';

const SessionContext = createContext({
  connected: false,
  session: null,
  logs: [],
  login: async () => {},
  setRole: async () => {},
  requestControl: async () => {},
  releaseControl: async () => {},
  subscribeAll: async () => {},
});

function useAckEmitter(socket) {
  return useCallback(
    (event, payload = {}) =>
      new Promise((resolve, reject) => {
        socket.emit(event, payload, (resp = {}) => {
          if (resp.error) {
            reject(new Error(resp.error));
          } else {
            resolve(resp);
          }
        });
      }),
    [socket],
  );
}

export function SessionProvider({ children }) {
  const socket = useSocket();
  const emitWithAck = useAckEmitter(socket);
  const [session, setSession] = useState(null);
  const [logs, setLogs] = useState([]);
  const [connected, setConnected] = useState(socket.connected);

  useEffect(() => {
    const onConnect = () => setConnected(true);
    const onDisconnect = () => setConnected(false);
    socket.on('connect', onConnect);
    socket.on('disconnect', onDisconnect);
    return () => {
      socket.off('connect', onConnect);
      socket.off('disconnect', onDisconnect);
    };
  }, [socket]);

  useEffect(() => {
    function handleSession(payload) {
      setSession(payload);
    }
    function handleLogInit(entries = []) {
      setLogs(entries);
    }
    function handleLogEntry(entry) {
      setLogs((prev) => [...prev.slice(-199), entry]);
    }
    socket.on('session:sync', handleSession);
    socket.on('log:init', handleLogInit);
    socket.on('log:entry', handleLogEntry);
    return () => {
      socket.off('session:sync', handleSession);
      socket.off('log:init', handleLogInit);
      socket.off('log:entry', handleLogEntry);
    };
  }, [socket]);

  const actions = useMemo(
    () => ({
      login: (username, password) => emitWithAck('auth:login', { username, password }),
      setRole: (role) => emitWithAck('session:setRole', { role }),
      requestControl: (roverId, options = {}) =>
        emitWithAck('session:requestControl', { roverId, ...options }),
      releaseControl: (roverId) => emitWithAck('session:releaseControl', { roverId }),
      subscribeAll: () => emitWithAck('session:subscribeAll'),
    }),
    [emitWithAck],
  );

  const value = useMemo(
    () => ({
      connected,
      session,
      logs,
      ...actions,
    }),
    [actions, connected, logs, session],
  );

  return <SessionContext.Provider value={value}>{children}</SessionContext.Provider>;
}

export function useSession() {
  return useContext(SessionContext);
}