instrumental/app/javascript/mastodon/actions/timelines.js

import { importFetchedStatus, importFetchedStatuses } from './importer';
import api, { getLinks } from 'mastodon/api';
import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
import compareId from 'mastodon/compare_id';
import { usePendingItems as preferPendingItems } from 'mastodon/initial_state';

export const TIMELINE_UPDATE  = 'TIMELINE_UPDATE';
export const TIMELINE_DELETE  = 'TIMELINE_DELETE';
export const TIMELINE_CLEAR   = 'TIMELINE_CLEAR';

export const TIMELINE_EXPAND_REQUEST = 'TIMELINE_EXPAND_REQUEST';
export const TIMELINE_EXPAND_SUCCESS = 'TIMELINE_EXPAND_SUCCESS';
export const TIMELINE_EXPAND_FAIL    = 'TIMELINE_EXPAND_FAIL';

export const TIMELINE_SCROLL_TOP   = 'TIMELINE_SCROLL_TOP';
export const TIMELINE_LOAD_PENDING = 'TIMELINE_LOAD_PENDING';
export const TIMELINE_DISCONNECT   = 'TIMELINE_DISCONNECT';
export const TIMELINE_CONNECT      = 'TIMELINE_CONNECT';

export const CURRENTLY_VIEWING = 'CURRENTLY_VIEWING';

export const updateCurrentlyViewing = (timeline, id) => ({
  type: CURRENTLY_VIEWING,
  timeline,
  id,
});

export const loadPending = timeline => ({
  type: TIMELINE_LOAD_PENDING,
  timeline,
});

export function updateTimeline(timeline, status, accept) {
  return dispatch => {
    if (typeof accept === 'function' && !accept(status)) {
      return;
    }

    dispatch(importFetchedStatus(status));

    dispatch({
      type: TIMELINE_UPDATE,
      timeline,
      status,
      usePendingItems: preferPendingItems,
    });
  };
};

export function deleteFromTimelines(id) {
  return (dispatch, getState) => {
    const accountId  = getState().getIn(['statuses', id, 'account']);
    const references = getState().get('statuses').filter(status => status.get('reblog') === id).map(status => [status.get('id'), status.get('account')]);
    const reblogOf   = getState().getIn(['statuses', id, 'reblog'], null);

    dispatch({
      type: TIMELINE_DELETE,
      id,
      accountId,
      references,
      reblogOf,
    });
  };
};

export function clearTimeline(timeline) {
  return (dispatch) => {
    dispatch({ type: TIMELINE_CLEAR, timeline });
  };
};

const noOp = () => {};

const parseTags = (tags = {}, mode) => {
  return (tags[mode] || []).map((tag) => {
    return tag.value;
  });
};

export function expandTimeline(timelineId, path, params = {}, done = noOp) {
  return (dispatch, getState) => {
    const timeline = getState().getIn(['timelines', timelineId], ImmutableMap());
    const isLoadingMore = !!params.max_id;

    if (timeline.get('isLoading')) {
      done();
      return;
    }

    if (!params.max_id && !params.pinned && (timeline.get('items', ImmutableList()).size + timeline.get('pendingItems', ImmutableList()).size) > 0) {
      const a = timeline.getIn(['pendingItems', 0]);
      const b = timeline.getIn(['items', 0]);

      if (a && b && compareId(a, b) > 0) {
        params.since_id = a;
      } else {
        params.since_id = b || a;
      }
    }

    const isLoadingRecent = !!params.since_id;

    dispatch(expandTimelineRequest(timelineId, isLoadingMore));

    api(getState).get(path, { params }).then(response => {
      const next = getLinks(response).refs.find(link => link.rel === 'next');
      dispatch(importFetchedStatuses(response.data));
      dispatch(expandTimelineSuccess(timelineId, response.data, next ? next.uri : null, response.status === 206, isLoadingRecent, isLoadingMore, isLoadingRecent && preferPendingItems));
      done();
    }).catch(error => {
      dispatch(expandTimelineFail(timelineId, error, isLoadingMore));
      done();
    });
  };
};

export const expandHomeTimeline            = ({ maxId } = {}, done = noOp) => expandTimeline('home', '/api/v1/timelines/home', { max_id: maxId }, done);
export const expandPublicTimeline          = ({ maxId, onlyMedia } = {}, done = noOp) => expandTimeline(`public${onlyMedia ? ':media' : ''}`, '/api/v1/timelines/public', { max_id: maxId, only_media: !!onlyMedia }, done);
export const expandCommunityTimeline       = ({ maxId, onlyMedia } = {}, done = noOp) => expandTimeline(`community${onlyMedia ? ':media' : ''}`, '/api/v1/timelines/public', { local: true, max_id: maxId, only_media: !!onlyMedia }, done);
export const expandAccountTimeline         = (accountId, { maxId, withReplies } = {}) => expandTimeline(`account:${accountId}${withReplies ? ':with_replies' : ''}`, `/api/v1/accounts/${accountId}/statuses`, { exclude_replies: !withReplies, max_id: maxId });
export const expandAccountFeaturedTimeline = accountId => expandTimeline(`account:${accountId}:pinned`, `/api/v1/accounts/${accountId}/statuses`, { pinned: true });
export const expandAccountMediaTimeline    = (accountId, { maxId } = {}) => expandTimeline(`account:${accountId}:media`, `/api/v1/accounts/${accountId}/statuses`, { max_id: maxId, only_media: true, limit: 40 });
export const expandListTimeline            = (id, { maxId } = {}, done = noOp) => expandTimeline(`list:${id}`, `/api/v1/timelines/list/${id}`, { max_id: maxId }, done);
export const expandHashtagTimeline         = (hashtag, { maxId, tags } = {}, done = noOp) => {
  return expandTimeline(`hashtag:${hashtag}`, `/api/v1/timelines/tag/${hashtag}`, {
    max_id: maxId,
    any:    parseTags(tags, 'any'),
    all:    parseTags(tags, 'all'),
    none:   parseTags(tags, 'none'),
  }, done);
};

export function expandTimelineRequest(timeline, isLoadingMore) {
  return {
    type: TIMELINE_EXPAND_REQUEST,
    timeline,
    skipLoading: !isLoadingMore,
  };
};

export function expandTimelineSuccess(timeline, statuses, next, partial, isLoadingRecent, isLoadingMore, usePendingItems) {
  return {
    type: TIMELINE_EXPAND_SUCCESS,
    timeline,
    statuses,
    next,
    partial,
    isLoadingRecent,
    usePendingItems,
    skipLoading: !isLoadingMore,
  };
};

export function expandTimelineFail(timeline, error, isLoadingMore) {
  return {
    type: TIMELINE_EXPAND_FAIL,
    timeline,
    error,
    skipLoading: !isLoadingMore,
  };
};

export function scrollTopTimeline(timeline, top) {
  return {
    type: TIMELINE_SCROLL_TOP,
    timeline,
    top,
  };
};

export function connectTimeline(timeline) {
  return {
    type: TIMELINE_CONNECT,
    timeline,
  };
};

export const disconnectTimeline = timeline => ({
  type: TIMELINE_DISCONNECT,
  timeline,
  usePendingItems: preferPendingItems,
});