message.
 */
const getSelectedMessage = createSelector(
  state => state.messages,
  ({ selectedMessage }) => (selectedMessage ? selectedMessage : undefined)
);

/**
 * Returns summary data of the list of messages that are visible to the user.
 * Filtered messages by types and text are factored in.
 */
const getDisplayedMessagesSummary = createSelector(
  getDisplayedMessages,
  displayedMessages => {
    let firstStartedMs = +Infinity;
    let lastEndedMs = -Infinity;
    let sentSize = 0;
    let receivedSize = 0;
    let totalSize = 0;

    displayedMessages.forEach(message => {
      if (message.type == "received") {
        receivedSize += message.payload.length;
      } else if (message.type == "sent") {
        sentSize += message.payload.length;
      }
      totalSize += message.payload.length;
      if (message.timeStamp < firstStartedMs) {
        firstStartedMs = message.timeStamp;
      }
      if (message.timeStamp > lastEndedMs) {
        lastEndedMs = message.timeStamp;
      }
    });

    return {
      count: displayedMessages.length,
      totalMs: (lastEndedMs - firstStartedMs) / 1000,
      sentSize,
      receivedSize,
      totalSize,
    };
  }
);

/**
 * Returns if the currentChannelId is closed
 */
const isCurrentChannelClosed = createSelector(
  state => state.messages,
  ({ closedConnections, currentChannelId }) =>
    closedConnections.has(currentChannelId)
);

/**
 * Returns the closed connection details of the currentChannelId
 * Null, if the connection is still open
 */
const getClosedConnectionDetails = createSelector(
  state => state.messages,
  ({ closedConnections, currentChannelId }) =>
    closedConnections.get(currentChannelId)
);

module.exports = {
  getSelectedMessage,
  isSelectedMessageVisible,
  getDisplayedMessages,
  getDisplayedMessagesSummary,
  isCurrentChannelClosed,
  getClosedConnectionDetails,
};
PK