PLT-6215 Major post list refactor (#6501)

* Major post list refactor

* Fix post and thread deletion

* Fix preferences not selecting correctly

* Fix military time displaying

* Fix UP key for editing posts

* Fix ESLint error

* Various fixes and updates per feedback

* Fix for permalink view

* Revert to old scrolling method and various fixes

* Add floating timestamp, new message indicator, scroll arrows

* Update post loading for focus mode and add visibility limit

* Fix pinning posts and a react warning

* Add loading UI updates from Asaad

* Fix refreshing loop

* Temporarily bump post visibility limit

* Update infinite scrolling

* Remove infinite scrolling

4 files changed, 152 insertions, 0 deletions

diff --git a/webapp/reducers/index.js b/webapp/reducers/index.js
new file mode 100644
index 000000000..ff2eb0d50
--- /dev/null
+++ b/webapp/reducers/index.js
@@ -0,0 +1,8 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import views from './views';
+
+export default {
+    views
+};
diff --git a/webapp/reducers/views/channel.js b/webapp/reducers/views/channel.js
new file mode 100644
index 000000000..0deb2389e
--- /dev/null
+++ b/webapp/reducers/views/channel.js
@@ -0,0 +1,69 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import {combineReducers} from 'redux';
+import {ActionTypes, Constants} from 'utils/constants.jsx';
+import {ChannelTypes, PostTypes} from 'mattermost-redux/action_types';
+
+function postVisibility(state = {}, action) {
+    switch (action.type) {
+    case ChannelTypes.SELECT_CHANNEL: {
+        const nextState = {...state};
+        nextState[action.data] = Constants.POST_CHUNK_SIZE / 2;
+        return nextState;
+    }
+    case ActionTypes.INCREASE_POST_VISIBILITY: {
+        const nextState = {...state};
+        nextState[action.data] += action.amount;
+        return nextState;
+    }
+    case ActionTypes.RECEIVED_FOCUSED_POST: {
+        const nextState = {...state};
+        nextState[action.channelId] = Constants.POST_CHUNK_SIZE / 2;
+        return nextState;
+    }
+    case PostTypes.RECEIVED_POST: {
+        if (action.data && state[action.data.channel_id]) {
+            const nextState = {...state};
+            nextState[action.data.channel_id] += 1;
+            return nextState;
+        }
+        return state;
+    }
+    default:
+        return state;
+    }
+}
+
+function lastChannelViewTime(state = {}, action) {
+    switch (action.type) {
+    case ChannelTypes.SELECT_CHANNEL: {
+        if (action.member) {
+            const nextState = {...state};
+            nextState[action.data] = action.member.last_viewed_at;
+            return nextState;
+        }
+        return state;
+    }
+    default:
+        return state;
+    }
+}
+
+function loadingPosts(state = {}, action) {
+    switch (action.type) {
+    case ActionTypes.LOADING_POSTS: {
+        const nextState = {...state};
+        nextState[action.channelId] = action.data;
+        return nextState;
+    }
+    default:
+        return state;
+    }
+}
+
+export default combineReducers({
+    postVisibility,
+    lastChannelViewTime,
+    loadingPosts
+});
diff --git a/webapp/reducers/views/index.js b/webapp/reducers/views/index.js
new file mode 100644
index 000000000..98eb7dac9
--- /dev/null
+++ b/webapp/reducers/views/index.js
@@ -0,0 +1,12 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import {combineReducers} from 'redux';
+
+import rhs from './rhs';
+import channel from './channel';
+
+export default combineReducers({
+    rhs,
+    channel
+});
diff --git a/webapp/reducers/views/rhs.js b/webapp/reducers/views/rhs.js
new file mode 100644
index 000000000..1e6480743
--- /dev/null
+++ b/webapp/reducers/views/rhs.js
@@ -0,0 +1,63 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import {combineReducers} from 'redux';
+import {ActionTypes} from 'utils/constants.jsx';
+import {PostTypes} from 'mattermost-redux/action_types';
+
+function selectedPostId(state = '', action) {
+    switch (action.type) {
+    case ActionTypes.SELECT_POST:
+        return action.postId;
+    case PostTypes.REMOVE_POST:
+        if (action.data && action.data.id === state) {
+            return '';
+        }
+        return state;
+    default:
+        return state;
+    }
+}
+
+function fromSearch(state = '', action) {
+    switch (action.type) {
+    case ActionTypes.SELECT_POST:
+        if (action.from_search) {
+            return action.from_search;
+        }
+        return '';
+    default:
+        return state;
+    }
+}
+
+function fromFlaggedPosts(state = false, action) {
+    switch (action.type) {
+    case ActionTypes.SELECT_POST:
+        if (action.from_flagged_posts) {
+            return action.from_flagged_posts;
+        }
+        return false;
+    default:
+        return state;
+    }
+}
+
+function fromPinnedPosts(state = false, action) {
+    switch (action.type) {
+    case ActionTypes.SELECT_POST:
+        if (action.from_pinned_posts) {
+            return action.from_pinned_posts;
+        }
+        return false;
+    default:
+        return state;
+    }
+}
+
+export default combineReducers({
+    selectedPostId,
+    fromSearch,
+    fromFlaggedPosts,
+    fromPinnedPosts
+});