import { createStore, applyMiddleware } from "redux";
import thunk from "redux-thunk";
import actions from "./storeActions";
import update from "immutability-helper";

function reducer(previousState, action) {
  let newState;
  const createOrUpdateRoom = (room) => {
    if (!(room.id in newState.rooms)) {
      newState = update(newState, {
        rooms: { [room.id]: { devices: { $set: new Set() } } },
      });
    } else {
      newState = update(newState, {
        rooms: {
          [room.id]: {
            name: { $set: room.name },
            image: { $set: room.image },
            icon: { $set: room.icon },
          },
        },
      });
    }
  };

  let change;
  switch (action.type) {
    case "LOGIN_UPDATE":
      newState = update(previousState, { login: { $set: action.login } });
      break;
    case "USER_INFO_UPDATE":
      newState = update(previousState, { userInfo: { $set: action.user } });
      break;
    case "ROOMS_UPDATE":
      newState = previousState;
      for (const room of action.rooms) {
        createOrUpdateRoom(room);
      }
      break;
    case "DEVICES_UPDATE":
      change = null;

      // if room is given, delete all devices in that room
      // and remove any join between that room and deleted
      // devices
      if (action.roomId) {
        change = {
          rooms: { [action.roomId]: { devices: { $set: new Set() } } },
          devices: { $unset: [] },
        };

        const room = newState.rooms[action.roomId];
        for (const deviceId of room.devices) {
          change.devices.$unset.push(deviceId);
        }
      } else if (action.partial) {
        // if the update is partial and caused by an operation on an input
        // device (like /switch/operate), iteratively remove deleted
        // devices and their join with their corresponding room.
        change = {
          devices: { $unset: [] },
          rooms: {},
        };

        for (const device of action.devices) {
          const roomId = previousState.devices[device.id].roomId;
          change.rooms[roomId] = change.rooms[roomId] || {
            devices: { $remove: [] },
          };
          change.rooms[roomId].devices.$remove.push(device.id);
          change.devices.$unset.push(device.id);
        }
      } else {
        // otherwise, just delete all devices and all joins
        // between rooms and devices
        change = {
          devices: { $set: {} },
          rooms: {},
        };

        for (const room of newState.rooms) {
          change.rooms[room.id].devices = { $set: new Set() };
        }
      }
      newState = update(previousState, change);

      change = {
        devices: {},
        rooms: {},
      };
      for (const device of action.devices) {
        change.devices[device.id] = { $set: device };

        if (device.roomId in newState.rooms) {
          const devices = change.rooms[device.roomId].devices;
          devices.$add = devices.$add || [];
          devices.$add.push(device.id);
        } else {
          console.warn(
            "Cannot join device",
            device,
            `in room ${device.roomId} since that
                        room has not been fetched`
          );
        }
      }
      newState = update(newState, change);
      break;
    case "ROOM_SAVE":
      createOrUpdateRoom(action.room);
      break;
    case "ROOM_DELETE":
      if (!(actions.roomId in previousState.rooms)) {
        console.warn(`Room to delete ${actions.roomId} does not exist`);
        break;
      }

      // This update does not ensure the consistent update of switchId/dimmerId properties
      // on output devices connected to an input device in this room. Please manually request
      // all devices again if consistent update is desired
      change = { devices: { $unset: [] } };

      for (const id of previousState.rooms[action.roomId].devices) {
        change.devices.$unset.push(id);
      }

      change.rooms = { $unset: actions.roomId };
      newState = update(previousState, change);
      break;
    case "DEVICE_DELETE":
      if (!(actions.deviceId in previousState.devices)) {
        console.warn(`Device to delete ${actions.deviceId} does not exist`);
        break;
      }

      newState = update(previousState, {
        devices: { $unset: actions.deviceId },
        rooms: {
          [previousState.devices[actions.deviceId].roomId]: {
            devices: { $remove: actions.deviceId },
          },
        },
      });
      break;
    case "LOGOUT":
      newState = {
        login: { loggedIn: false, token: null },
        rooms: [],
        devices: [],
        userInfo: null,
      };
      break;
    default:
      console.warn(`Action type ${action.type} unknown`, action);
      return previousState;
  }

  console.log("new state: ", newState);
  return newState;
}

function createSmartHutStore() {
  const token = localStorage.getItem("token");
  const exp = localStorage.getItem("exp");

  const initialState = {
    errors: {},
    login: {
      token: token,
    },
    userInfo: null,
    /** @type {[integer]Room} */
    rooms: {},
    /** @type {[integer]Device} */
    devices: {},
  };

  initialState.login.loggedIn = !!(token && exp > new Date().getTime());
  if (!initialState.login.loggedIn) {
    localStorage.removeItem("token");
    localStorage.removeItem("exp");
    initialState.login.token = null;
  }

  return createStore(reducer, initialState, applyMiddleware(thunk));
}

const smartHutStore = createSmartHutStore();
export default smartHutStore;