save comments collapsed state

closes #43

web/app/common/constants.js

@@ -12,6 +12,7 @@ const PROVIDER_NAMES = {
   facebook: 'Facebook',
   github: 'GitHub',
 };
+const LS_COLLAPSE_KEY = '__remarkCollapsed';
 
 module.exports = {
   BASE_URL,
@@ -24,4 +25,5 @@ module.exports = {
   DEFAULT_MAX_COMMENT_SIZE,
   PROVIDER_NAMES,
   DEFAULT_SORT,
+  LS_COLLAPSE_KEY,
 };

web/app/components/thread/thread.jsx

@@ -1,21 +1,51 @@
 import { h, Component } from 'preact';
 
+import { LS_COLLAPSE_KEY } from 'common/constants';
+import { siteId, url } from 'common/settings';
+
 import Comment from 'components/comment';
 
 export default class Thread extends Component {
   constructor(props) {
     super(props);
 
-    this.state = {
-      collapsed: false,
-    };
+    if (this.props.data && this.props.data.comment) {
+      this.updateCollapsedState(this.props.data.comment);
+    }
 
     this.onCollapseToggle = this.onCollapseToggle.bind(this);
   }
 
+  componentWillReceiveProps(nextProps) {
+    if (nextProps.data && nextProps.data.comment) {
+      this.updateCollapsedState(nextProps.data.comment);
+    }
+  }
+
+  updateCollapsedState(comment) {
+    this.lsCollapsedID = `${siteId}_${url}_${comment.id}`;
+
+    this.state = {
+      collapsed: getCollapsedComments().includes(this.lsCollapsedID),
+    };
+  }
 
   onCollapseToggle() {
+    const collapsed = !this.state.collapsed;
+
     this.setState({ collapsed: !this.state.collapsed });
+
+    let collapsedComments = getCollapsedComments();
+
+    if (collapsed) {
+      if (!collapsedComments.includes(this.lsCollapsedID)) {
+        collapsedComments = collapsedComments.concat(this.lsCollapsedID);
+      }
+    } else {
+      collapsedComments = collapsedComments.filter(id => id !== this.lsCollapsedID);
+    }
+
+    saveCollapsedComments(collapsedComments);
   }
 
   render(props, { collapsed }) {
@@ -49,3 +79,11 @@ export default class Thread extends Component {
     );
   }
 }
+
+function getCollapsedComments() {
+  return JSON.parse(localStorage.getItem(LS_COLLAPSE_KEY) || '[]');
+}
+
+function saveCollapsedComments(comments) {
+  localStorage.setItem(LS_COLLAPSE_KEY, JSON.stringify(comments));
+}