import moment from 'moment';
import {RootState} from '../store/rootReducer';
import {ChannelGroupedType} from '../types';

/**
 * Finds the difference in time in minutes
 * @param lastActive given time e.g. "2021-04-08T19:07:09.361300983Z"
 * @returns diff in minutes
 */
const _diffInMinutes = (lastActive: string | undefined) => {
  if (!lastActive) {
    return undefined;
  }
  return moment().diff(moment(lastActive), 'minutes');
};

/**
 * Formats the last activity status.
 *  - "Active now"          (≤ 5 minutes)
 *  - "Seen X minutes ago"  (5 > x ≥ 59 minutes)
 *  - "Seen X hours ago"    (x = [1, 2])
 *  - "Offline"
 * @param lastActive given time e.g. "2021-04-08T19:07:09.361300983Z"
 * @returns
 */
export const formatLastSeenText = (lastActive: string | undefined) => {
  const diff = _diffInMinutes(lastActive);
  if (!diff) {
    return 'Offline';
  }
  if (diff <= 5) {
    return 'Active now';
  }
  if (diff <= 59) {
    return `Seen ${diff} minutes ago`;
  }
  if (diff <= 180) {
    const hours = Math.floor(diff / 60);
    return `Seen ${hours} hours ago`;
  }
  return 'Offline';
};

/**
 * Checks if a lastActive timestamp is considered Online or not.
 *
 * A user is online if last active is ≤ 15 minutes.
 *
 * @param lastActive given time e.g. "2021-04-08T19:07:09.361300983Z"
 * @returns True if active
 */
export const isOnline = (lastActive: string | undefined) => {
  if (!lastActive) {
    return false;
  }
  const diff = _diffInMinutes(lastActive);
  if (!diff) {
    return false;
  }
  return diff <= 15;
};

/**
 * Gets the other member in the channel.
 * @param channel the current chat channel
 * @param state the current redux state
 * @returns other member or undefined
 */
export const getMember = (
  channel: ChannelGroupedType | undefined,
  state: RootState,
) => {
  if (!channel) {
    return undefined;
  }
  const loggedInUserId = state.user.user.userId;
  const otherMembers = channel
    ? Object.values(channel.state.members).filter(
        (member) => member.user?.id !== loggedInUserId,
      )
    : [];
  return otherMembers.length === 1 ? otherMembers[0] : undefined;
};