add local setting to auto reveal media behind cw

app/javascript/flavours/glitch/features/local_settings/page/index.js

@@ -328,6 +328,14 @@ export default class LocalSettingsPage extends React.PureComponent {
         >
           <FormattedMessage id='settings.inline_preview_cards' defaultMessage='Inline preview cards for external links' />
         </LocalSettingsPageItem>
+        <LocalSettingsPageItem
+          settings={settings}
+          item={['media', 'reveal_behind_cw']}
+          id='mastodon-settings--reveal-behind-cw'
+          onChange={onChange}
+        >
+          <FormattedMessage id='settings.media_reveal_behind_cw' defaultMessage='Reveal sensitive media behind a CW by default' />
+        </LocalSettingsPageItem>
       </div>
     ),
   ];

app/javascript/flavours/glitch/features/status/components/detailed_status.js

@@ -138,6 +138,7 @@ export default class DetailedStatus extends ImmutablePureComponent {
             preventPlayback={!expanded}
             onOpenVideo={this.handleOpenVideo}
             autoplay
+            revealed={settings.getIn(['media', 'reveal_behind_cw']) && !!status.get('spoiler_text') ? true : undefined}
           />
         );
         mediaIcon = 'video-camera';
@@ -151,6 +152,7 @@ export default class DetailedStatus extends ImmutablePureComponent {
             fullwidth={settings.getIn(['media', 'fullwidth'])}
             hidden={!expanded}
             onOpenMedia={this.props.onOpenMedia}
+            revealed={settings.getIn(['media', 'reveal_behind_cw']) && !!status.get('spoiler_text') ? true : undefined}
           />
         );
         mediaIcon = 'picture-o';

app/javascript/flavours/glitch/features/video/index.js

@@ -119,6 +119,12 @@ export default class Video extends React.PureComponent {
     revealed: this.props.revealed === undefined ? (displayMedia !== 'hide_all' && !this.props.sensitive || displayMedia === 'show_all') : this.props.revealed,
   };
 
+  componentWillReceiveProps (nextProps) {
+    if (nextProps.revealed === true) {
+      this.setState({ revealed: true });
+    }
+  }
+
   // hard coded in components.scss
   // any way to get ::before values programatically?
   volWidth = 50;