@aller/blink/src/persistenceMiddleware.ts

A library for tracking user behaviour.

import {
  ARTICLE_PREVIEW_SCREEN_ENTER,
  PAGE_INIT,
  CLICK,
  ARTICLE_PREVIEW_SCREEN_EXIT,
} from './actions';
import getInscreenTime from './selectors/get-inscreen-time';
import getPageState from './selectors/get-page-state';

export default function persistenceMiddleware(
  persistState: (key: string, value: any) => any,
) {
  return ({ getState }: { getState: any }) => (next: any) => (action: any) => {
    // Execute the action, which might mutate the state
    const returnValue = next(action);
    const page = getPageState(getState(), action.payload.pageId);

    switch (action.type) {
      case PAGE_INIT:
        persistState(`${page.id}::pageView`, page.state.general.pageView);
        break;

      case CLICK:
        persistState(`${page.id}::clicked::${action.payload.id}`, true);
        break;

      case ARTICLE_PREVIEW_SCREEN_ENTER:
      case ARTICLE_PREVIEW_SCREEN_EXIT:
        if (action.payload.url !== page.state.general.url) {
          const id = action.payload.id;
          const ap = page.state.articlePreview[id] || {};
          persistState(`${page.id}::impression::${id}`, {
            ...ap,
            inscreenTime: getInscreenTime(page.state, id, new Date()),
          });
        }
        break;
    }

    return returnValue;
  };
}