Fix #3665 - Refactor timelines reducer (#3686)

* Move ancestors/descendants out of timelines reducer

* Refactor timelines reducer

All types of timelines now have a flat structure and use the same
reducer functions and actions

* Reintroduce some missing behaviours

* Fix wrong import in reports

* Fix includes typo

* Fix issue related to "next" pagination in timelines and notifications

* Fix bug with timeline's initial state, expandNotifications

6 files changed, 103 insertions, 272 deletions

diff --git a/app/javascript/mastodon/reducers/accounts.js b/app/javascript/mastodon/reducers/accounts.js
index d4d9ad62e..7b7074317 100644
--- a/app/javascript/mastodon/reducers/accounts.js
+++ b/app/javascript/mastodon/reducers/accounts.js
@@ -4,8 +4,6 @@ import {
   FOLLOWERS_EXPAND_SUCCESS,
   FOLLOWING_FETCH_SUCCESS,
   FOLLOWING_EXPAND_SUCCESS,
-  ACCOUNT_TIMELINE_FETCH_SUCCESS,
-  ACCOUNT_TIMELINE_EXPAND_SUCCESS,
   FOLLOW_REQUESTS_FETCH_SUCCESS,
   FOLLOW_REQUESTS_EXPAND_SUCCESS,
 } from '../actions/accounts';
@@ -113,8 +111,6 @@ export default function accounts(state = initialState, action) {
     return normalizeAccountsFromStatuses(normalizeAccounts(state, action.accounts), action.statuses);
   case TIMELINE_REFRESH_SUCCESS:
   case TIMELINE_EXPAND_SUCCESS:
-  case ACCOUNT_TIMELINE_FETCH_SUCCESS:
-  case ACCOUNT_TIMELINE_EXPAND_SUCCESS:
   case CONTEXT_FETCH_SUCCESS:
   case FAVOURITED_STATUSES_FETCH_SUCCESS:
   case FAVOURITED_STATUSES_EXPAND_SUCCESS:
diff --git a/app/javascript/mastodon/reducers/accounts_counters.js b/app/javascript/mastodon/reducers/accounts_counters.js
index ea631ceca..eb8a4f83d 100644
--- a/app/javascript/mastodon/reducers/accounts_counters.js
+++ b/app/javascript/mastodon/reducers/accounts_counters.js
@@ -4,8 +4,6 @@ import {
   FOLLOWERS_EXPAND_SUCCESS,
   FOLLOWING_FETCH_SUCCESS,
   FOLLOWING_EXPAND_SUCCESS,
-  ACCOUNT_TIMELINE_FETCH_SUCCESS,
-  ACCOUNT_TIMELINE_EXPAND_SUCCESS,
   FOLLOW_REQUESTS_FETCH_SUCCESS,
   FOLLOW_REQUESTS_EXPAND_SUCCESS,
   ACCOUNT_FOLLOW_SUCCESS,
@@ -115,8 +113,6 @@ export default function accountsCounters(state = initialState, action) {
     return normalizeAccountsFromStatuses(normalizeAccounts(state, action.accounts), action.statuses);
   case TIMELINE_REFRESH_SUCCESS:
   case TIMELINE_EXPAND_SUCCESS:
-  case ACCOUNT_TIMELINE_FETCH_SUCCESS:
-  case ACCOUNT_TIMELINE_EXPAND_SUCCESS:
   case CONTEXT_FETCH_SUCCESS:
   case FAVOURITED_STATUSES_FETCH_SUCCESS:
   case FAVOURITED_STATUSES_EXPAND_SUCCESS:
diff --git a/app/javascript/mastodon/reducers/contexts.js b/app/javascript/mastodon/reducers/contexts.js
new file mode 100644
index 000000000..8a24f5f7a
--- /dev/null
+++ b/app/javascript/mastodon/reducers/contexts.js
@@ -0,0 +1,43 @@
+import { CONTEXT_FETCH_SUCCESS } from '../actions/statuses';
+import { TIMELINE_DELETE } from '../actions/timelines';
+import Immutable from 'immutable';
+
+const initialState = Immutable.Map({
+  ancestors: Immutable.Map(),
+  descendants: Immutable.Map(),
+});
+
+const normalizeContext = (state, id, ancestors, descendants) => {
+  const ancestorsIds   = ancestors.map(ancestor => ancestor.get('id'));
+  const descendantsIds = descendants.map(descendant => descendant.get('id'));
+
+  return state.withMutations(map => {
+    map.setIn(['ancestors', id], ancestorsIds);
+    map.setIn(['descendants', id], descendantsIds);
+  });
+};
+
+const deleteFromContexts = (state, id) => {
+  state.getIn(['descendants', id], Immutable.List()).forEach(descendantId => {
+    state = state.updateIn(['ancestors', descendantId], Immutable.List(), list => list.filterNot(itemId => itemId === id));
+  });
+
+  state.getIn(['ancestors', id], Immutable.List()).forEach(ancestorId => {
+    state = state.updateIn(['descendants', ancestorId], Immutable.List(), list => list.filterNot(itemId => itemId === id));
+  });
+
+  state = state.deleteIn(['descendants', id]).deleteIn(['ancestors', id]);
+
+  return state;
+};
+
+export default function contexts(state = initialState, action) {
+  switch(action.type) {
+  case CONTEXT_FETCH_SUCCESS:
+    return normalizeContext(state, action.id, Immutable.fromJS(action.ancestors), Immutable.fromJS(action.descendants));
+  case TIMELINE_DELETE:
+    return deleteFromContexts(state, action.id);
+  default:
+    return state;
+  }
+};
diff --git a/app/javascript/mastodon/reducers/index.js b/app/javascript/mastodon/reducers/index.js
index c4fe28ea7..be402a16b 100644
--- a/app/javascript/mastodon/reducers/index.js
+++ b/app/javascript/mastodon/reducers/index.js
@@ -17,6 +17,7 @@ import settings from './settings';
 import status_lists from './status_lists';
 import cards from './cards';
 import reports from './reports';
+import contexts from './contexts';
 
 export default combineReducers({
   timelines,
@@ -37,4 +38,5 @@ export default combineReducers({
   settings,
   cards,
   reports,
+  contexts,
 });
diff --git a/app/javascript/mastodon/reducers/statuses.js b/app/javascript/mastodon/reducers/statuses.js
index 7bc3710c4..691135ff7 100644
--- a/app/javascript/mastodon/reducers/statuses.js
+++ b/app/javascript/mastodon/reducers/statuses.js
@@ -21,10 +21,6 @@ import {
   TIMELINE_EXPAND_SUCCESS,
 } from '../actions/timelines';
 import {
-  ACCOUNT_TIMELINE_FETCH_SUCCESS,
-  ACCOUNT_TIMELINE_EXPAND_SUCCESS,
-  ACCOUNT_MEDIA_TIMELINE_FETCH_SUCCESS,
-  ACCOUNT_MEDIA_TIMELINE_EXPAND_SUCCESS,
   ACCOUNT_BLOCK_SUCCESS,
 } from '../actions/accounts';
 import {
@@ -113,10 +109,6 @@ export default function statuses(state = initialState, action) {
     return state.setIn([action.id, 'muted'], false);
   case TIMELINE_REFRESH_SUCCESS:
   case TIMELINE_EXPAND_SUCCESS:
-  case ACCOUNT_TIMELINE_FETCH_SUCCESS:
-  case ACCOUNT_TIMELINE_EXPAND_SUCCESS:
-  case ACCOUNT_MEDIA_TIMELINE_FETCH_SUCCESS:
-  case ACCOUNT_MEDIA_TIMELINE_EXPAND_SUCCESS:
   case CONTEXT_FETCH_SUCCESS:
   case NOTIFICATIONS_REFRESH_SUCCESS:
   case NOTIFICATIONS_EXPAND_SUCCESS:
diff --git a/app/javascript/mastodon/reducers/timelines.js b/app/javascript/mastodon/reducers/timelines.js
index ab756b854..2bc1c8050 100644
--- a/app/javascript/mastodon/reducers/timelines.js
+++ b/app/javascript/mastodon/reducers/timelines.js
@@ -18,228 +18,79 @@ import {
   UNFAVOURITE_SUCCESS,
 } from '../actions/interactions';
 import {
-  ACCOUNT_TIMELINE_FETCH_REQUEST,
-  ACCOUNT_TIMELINE_FETCH_SUCCESS,
-  ACCOUNT_TIMELINE_FETCH_FAIL,
-  ACCOUNT_TIMELINE_EXPAND_REQUEST,
-  ACCOUNT_TIMELINE_EXPAND_SUCCESS,
-  ACCOUNT_TIMELINE_EXPAND_FAIL,
-  ACCOUNT_MEDIA_TIMELINE_FETCH_REQUEST,
-  ACCOUNT_MEDIA_TIMELINE_FETCH_SUCCESS,
-  ACCOUNT_MEDIA_TIMELINE_FETCH_FAIL,
-  ACCOUNT_MEDIA_TIMELINE_EXPAND_REQUEST,
-  ACCOUNT_MEDIA_TIMELINE_EXPAND_SUCCESS,
-  ACCOUNT_MEDIA_TIMELINE_EXPAND_FAIL,
   ACCOUNT_BLOCK_SUCCESS,
   ACCOUNT_MUTE_SUCCESS,
 } from '../actions/accounts';
-import {
-  CONTEXT_FETCH_SUCCESS,
-} from '../actions/statuses';
 import Immutable from 'immutable';
 
-const initialState = Immutable.Map({
-  home: Immutable.Map({
-    path: () => '/api/v1/timelines/home',
-    next: null,
-    isLoading: false,
-    online: false,
-    loaded: false,
-    top: true,
-    unread: 0,
-    items: Immutable.List(),
-  }),
-
-  public: Immutable.Map({
-    path: () => '/api/v1/timelines/public',
-    next: null,
-    isLoading: false,
-    online: false,
-    loaded: false,
-    top: true,
-    unread: 0,
-    items: Immutable.List(),
-  }),
-
-  community: Immutable.Map({
-    path: () => '/api/v1/timelines/public',
-    next: null,
-    params: { local: true },
-    isLoading: false,
-    online: false,
-    loaded: false,
-    top: true,
-    unread: 0,
-    items: Immutable.List(),
-  }),
+const initialState = Immutable.Map();
 
-  tag: Immutable.Map({
-    path: (id) => `/api/v1/timelines/tag/${id}`,
-    next: null,
-    isLoading: false,
-    id: null,
-    loaded: false,
-    top: true,
-    unread: 0,
-    items: Immutable.List(),
-  }),
-
-  accounts_timelines: Immutable.Map(),
-  accounts_media_timelines: Immutable.Map(),
-  ancestors: Immutable.Map(),
-  descendants: Immutable.Map(),
+const initialTimeline = Immutable.Map({
+  unread: 0,
+  online: false,
+  top: true,
+  loaded: false,
+  isLoading: false,
+  next: false,
+  items: Immutable.List(),
 });
 
-const normalizeStatus = (state, status) => {
-  return state;
-};
-
 const normalizeTimeline = (state, timeline, statuses, next) => {
-  let ids      = Immutable.List();
-  const loaded = state.getIn([timeline, 'loaded']);
-
-  statuses.forEach((status, i) => {
-    state = normalizeStatus(state, status);
-    ids   = ids.set(i, status.get('id'));
-  });
-
-  state = state.setIn([timeline, 'loaded'], true);
-  state = state.setIn([timeline, 'isLoading'], false);
-
-  if (state.getIn([timeline, 'next']) === null) {
-    state = state.setIn([timeline, 'next'], next);
-  }
-
-  return state.updateIn([timeline, 'items'], Immutable.List(), list => (loaded ? ids.concat(list) : ids));
+  const ids       = Immutable.List(statuses.map(status => status.get('id')));
+  const wasLoaded = state.getIn([timeline, 'loaded']);
+  const hadNext   = state.getIn([timeline, 'next']);
+  const oldIds    = state.getIn([timeline, 'items'], Immutable.List());
+
+  return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
+    mMap.set('loaded', true);
+    mMap.set('isLoading', false);
+    if (!hadNext) mMap.set('next', next);
+    mMap.set('items', wasLoaded ? ids.concat(oldIds) : ids);
+  }));
 };
 
 const appendNormalizedTimeline = (state, timeline, statuses, next) => {
-  let moreIds = Immutable.List();
-
-  statuses.forEach((status, i) => {
-    state   = normalizeStatus(state, status);
-    moreIds = moreIds.set(i, status.get('id'));
-  });
-
-  state = state.setIn([timeline, 'isLoading'], false);
-  state = state.setIn([timeline, 'next'], next);
-
-  return state.updateIn([timeline, 'items'], Immutable.List(), list => list.concat(moreIds));
-};
-
-const normalizeAccountTimeline = (state, accountId, statuses, replace, next) => {
-  let ids = Immutable.List();
-
-  statuses.forEach((status, i) => {
-    state = normalizeStatus(state, status);
-    ids   = ids.set(i, status.get('id'));
-  });
-
-  return state.updateIn(['accounts_timelines', accountId], Immutable.Map(), map => map
-    .set('isLoading', false)
-    .set('loaded', true)
-    .update('next', null, v => replace ? next : v)
-    .update('items', Immutable.List(), list => (replace ? ids : ids.concat(list))));
-};
-
-const normalizeAccountMediaTimeline = (state, accountId, statuses, replace, next) => {
-  let ids = Immutable.List();
-
-  statuses.forEach((status, i) => {
-    state = normalizeStatus(state, status);
-    ids   = ids.set(i, status.get('id'));
-  });
-
-  return state.updateIn(['accounts_media_timelines', accountId], Immutable.Map(), map => map
-    .set('isLoading', false)
-    .update('next', null, v => replace ? next : v)
-    .update('items', Immutable.List(), list => (replace ? ids : ids.concat(list))));
-};
-
-const appendNormalizedAccountTimeline = (state, accountId, statuses, next) => {
-  let moreIds = Immutable.List([]);
-
-  statuses.forEach((status, i) => {
-    state   = normalizeStatus(state, status);
-    moreIds = moreIds.set(i, status.get('id'));
-  });
-
-  return state.updateIn(['accounts_timelines', accountId], Immutable.Map(), map => map
-    .set('isLoading', false)
-    .set('next', next)
-    .update('items', list => list.concat(moreIds)));
-};
-
-const appendNormalizedAccountMediaTimeline = (state, accountId, statuses, next) => {
-  let moreIds = Immutable.List([]);
-
-  statuses.forEach((status, i) => {
-    state   = normalizeStatus(state, status);
-    moreIds = moreIds.set(i, status.get('id'));
-  });
-
-  return state.updateIn(['accounts_media_timelines', accountId], Immutable.Map(), map => map
-    .set('isLoading', false)
-    .set('next', next)
-    .update('items', list => list.concat(moreIds)));
+  const ids    = Immutable.List(statuses.map(status => status.get('id')));
+  const oldIds = state.getIn([timeline, 'items'], Immutable.List());
+
+  return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
+    mMap.set('isLoading', false);
+    mMap.set('next', next);
+    mMap.set('items', oldIds.concat(ids));
+  }));
 };
 
 const updateTimeline = (state, timeline, status, references) => {
-  const top = state.getIn([timeline, 'top']);
+  const top        = state.getIn([timeline, 'top']);
+  const ids        = state.getIn([timeline, 'items'], Immutable.List());
+  const includesId = ids.includes(status.get('id'));
+  const unread     = state.getIn([timeline, 'unread'], 0);
 
-  state = normalizeStatus(state, status);
-
-  if (!top) {
-    state = state.updateIn([timeline, 'unread'], unread => unread + 1);
+  if (includesId) {
+    return state;
   }
 
-  state = state.updateIn([timeline, 'items'], Immutable.List(), list => {
-    if (top && list.size > 40) {
-      list = list.take(20);
-    }
-
-    if (list.includes(status.get('id'))) {
-      return list;
-    }
-
-    const reblogOfId = status.getIn(['reblog', 'id'], null);
+  let newIds = ids;
 
-    if (reblogOfId !== null) {
-      list = list.filterNot(itemId => references.includes(itemId));
-    }
-
-    return list.unshift(status.get('id'));
-  });
-
-  return state;
+  return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
+    if (!top) mMap.set('unread', unread + 1);
+    if (top && ids.size > 40) newIds = newIds.take(20);
+    if (status.getIn(['reblog', 'id'], null) !== null) newIds = newIds.filterNot(item => references.includes(item));
+    mMap.set('items', newIds.unshift(status.get('id')));
+  }));
 };
 
 const deleteStatus = (state, id, accountId, references, reblogOf) => {
-  if (reblogOf) {
-    // If we are deleting a reblog, just replace reblog with its original
-    return state.updateIn(['home', 'items'], list => list.map(item => item === id ? reblogOf : item));
-  }
-
-  // Remove references from timelines
-  ['home', 'public', 'community', 'tag'].forEach(function (timeline) {
-    state = state.updateIn([timeline, 'items'], list => list.filterNot(item => item === id));
+  state.keySeq().forEach(timeline => {
+    state = state.updateIn([timeline, 'items'], list => {
+      if (reblogOf && !list.includes(reblogOf)) {
+        return list.map(item => item === id ? reblogOf : item);
+      } else {
+        return list.filterNot(item => item === id);
+      }
+    });
   });
 
-  // Remove references from account timelines
-  state = state.updateIn(['accounts_timelines', accountId, 'items'], Immutable.List([]), list => list.filterNot(item => item === id));
-  state = state.updateIn(['accounts_media_timelines', accountId, 'items'], Immutable.List([]), list => list.filterNot(item => item === id));
-
-  // Remove references from context
-  state.getIn(['descendants', id], Immutable.List()).forEach(descendantId => {
-    state = state.updateIn(['ancestors', descendantId], Immutable.List(), list => list.filterNot(itemId => itemId === id));
-  });
-
-  state.getIn(['ancestors', id], Immutable.List()).forEach(ancestorId => {
-    state = state.updateIn(['descendants', ancestorId], Immutable.List(), list => list.filterNot(itemId => itemId === id));
-  });
-
-  state = state.deleteIn(['descendants', id]).deleteIn(['ancestors', id]);
-
   // Remove reblogs of deleted status
   references.forEach(ref => {
     state = deleteStatus(state, ref[0], ref[1], []);
@@ -257,54 +108,27 @@ const filterTimelines = (state, relationship, statuses) => {
     }
 
     references = statuses.filter(item => item.get('reblog') === status.get('id')).map(item => [item.get('id'), item.get('account')]);
-    state = deleteStatus(state, status.get('id'), status.get('account'), references);
-  });
-
-  return state;
-};
-
-const normalizeContext = (state, id, ancestors, descendants) => {
-  const ancestorsIds   = ancestors.map(ancestor => ancestor.get('id'));
-  const descendantsIds = descendants.map(descendant => descendant.get('id'));
-
-  return state.withMutations(map => {
-    map.setIn(['ancestors', id], ancestorsIds);
-    map.setIn(['descendants', id], descendantsIds);
+    state      = deleteStatus(state, status.get('id'), status.get('account'), references);
   });
-};
-
-const resetTimeline = (state, timeline, id) => {
-  if (timeline === 'tag' && typeof id !== 'undefined' && state.getIn([timeline, 'id']) !== id) {
-    state = state.update(timeline, map => map
-        .set('id', id)
-        .set('isLoading', true)
-        .set('loaded', false)
-        .set('next', null)
-        .set('top', true)
-        .update('items', list => list.clear()));
-  } else {
-    state = state.setIn([timeline, 'isLoading'], true);
-  }
 
   return state;
 };
 
 const updateTop = (state, timeline, top) => {
-  if (top) {
-    state = state.setIn([timeline, 'unread'], 0);
-  }
-
-  return state.setIn([timeline, 'top'], top);
+  return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
+    if (top) mMap.set('unread', 0);
+    mMap.set('top', top);
+  }));
 };
 
 export default function timelines(state = initialState, action) {
   switch(action.type) {
   case TIMELINE_REFRESH_REQUEST:
   case TIMELINE_EXPAND_REQUEST:
-    return resetTimeline(state, action.timeline, action.id);
+    return state.update(action.timeline, initialTimeline, map => map.set('isLoading', true));
   case TIMELINE_REFRESH_FAIL:
   case TIMELINE_EXPAND_FAIL:
-    return state.setIn([action.timeline, 'isLoading'], false);
+    return state.update(action.timeline, initialTimeline, map => map.set('isLoading', false));
   case TIMELINE_REFRESH_SUCCESS:
     return normalizeTimeline(state, action.timeline, Immutable.fromJS(action.statuses), action.next);
   case TIMELINE_EXPAND_SUCCESS:
@@ -313,37 +137,15 @@ export default function timelines(state = initialState, action) {
     return updateTimeline(state, action.timeline, Immutable.fromJS(action.status), action.references);
   case TIMELINE_DELETE:
     return deleteStatus(state, action.id, action.accountId, action.references, action.reblogOf);
-  case CONTEXT_FETCH_SUCCESS:
-    return normalizeContext(state, action.id, Immutable.fromJS(action.ancestors), Immutable.fromJS(action.descendants));
-  case ACCOUNT_TIMELINE_FETCH_REQUEST:
-  case ACCOUNT_TIMELINE_EXPAND_REQUEST:
-    return state.updateIn(['accounts_timelines', action.id], Immutable.Map(), map => map.set('isLoading', true));
-  case ACCOUNT_TIMELINE_FETCH_FAIL:
-  case ACCOUNT_TIMELINE_EXPAND_FAIL:
-    return state.updateIn(['accounts_timelines', action.id], Immutable.Map(), map => map.set('isLoading', false));
-  case ACCOUNT_TIMELINE_FETCH_SUCCESS:
-    return normalizeAccountTimeline(state, action.id, Immutable.fromJS(action.statuses), action.replace, action.next);
-  case ACCOUNT_TIMELINE_EXPAND_SUCCESS:
-    return appendNormalizedAccountTimeline(state, action.id, Immutable.fromJS(action.statuses), action.next);
-  case ACCOUNT_MEDIA_TIMELINE_FETCH_REQUEST:
-  case ACCOUNT_MEDIA_TIMELINE_EXPAND_REQUEST:
-    return state.updateIn(['accounts_media_timelines', action.id], Immutable.Map(), map => map.set('isLoading', true));
-  case ACCOUNT_MEDIA_TIMELINE_FETCH_FAIL:
-  case ACCOUNT_MEDIA_TIMELINE_EXPAND_FAIL:
-    return state.updateIn(['accounts_media_timelines', action.id], Immutable.Map(), map => map.set('isLoading', false));
-  case ACCOUNT_MEDIA_TIMELINE_FETCH_SUCCESS:
-    return normalizeAccountMediaTimeline(state, action.id, Immutable.fromJS(action.statuses), action.replace, action.next);
-  case ACCOUNT_MEDIA_TIMELINE_EXPAND_SUCCESS:
-    return appendNormalizedAccountMediaTimeline(state, action.id, Immutable.fromJS(action.statuses), action.next);
   case ACCOUNT_BLOCK_SUCCESS:
   case ACCOUNT_MUTE_SUCCESS:
     return filterTimelines(state, action.relationship, action.statuses);
   case TIMELINE_SCROLL_TOP:
     return updateTop(state, action.timeline, action.top);
   case TIMELINE_CONNECT:
-    return state.setIn([action.timeline, 'online'], true);
+    return state.update(action.timeline, initialTimeline, map => map.set('online', true));
   case TIMELINE_DISCONNECT:
-    return state.setIn([action.timeline, 'online'], false);
+    return state.update(action.timeline, initialTimeline, map => map.set('online', false));
   default:
     return state;
   }