Allow using dark / light theme as indicated by prefers-color-scheme media feature

changes/changelog.d/auto-darkmode.enhancement

@@ -0,0 +1 @@
+Allow using default browser dark mode and update UI dynamically on change

front/src/App.vue

@@ -129,6 +129,12 @@ export default {
         return this.$store.state.instance.frontSettings.additionalStylesheets || []
       }
       return null
+    },
+    matchDarkColorScheme () {
+      if (window.matchMedia) {
+        return window.matchMedia('(prefers-color-scheme: dark)')
+      }
+      return null
     }
   },
   watch: {
@@ -138,10 +144,21 @@ export default {
     },
     '$store.state.ui.theme': {
       immediate: true,
-      handler (newValue, oldValue) {
-        const oldTheme = oldValue || 'light'
-        document.body.classList.remove(`theme-${oldTheme}`)
-        document.body.classList.add(`theme-${newValue}`)
+      handler (newValue) {
+        const matchesDark = this.matchDarkColorScheme
+        if (matchesDark) {
+          if (newValue === 'system') {
+            newValue = matchesDark.matches ? 'dark' : 'light'
+            matchesDark.addEventListener('change', this.handleThemeChange)
+          } else {
+            matchesDark.removeEventListener('change', this.handleThemeChange)
+          }
+        } else {
+          if (newValue === 'system') {
+            newValue = 'light'
+          }
+        }
+        this.setTheme(newValue)
       }
     },
     '$store.state.auth.authenticated' (newValue) {
@@ -451,6 +468,14 @@ export default {
     },
     handleResize () {
       this.width = window.innerWidth
+    },
+    handleThemeChange (event) {
+      this.setTheme(event.matches ? 'dark' : 'light')
+    },
+    setTheme (theme) {
+      const oldTheme = (theme === 'light') ? 'dark' : 'light'
+      document.body.classList.remove(`theme-${oldTheme}`)
+      document.body.classList.add(`theme-${theme}`)
     }
   }
 }

front/src/components/Footer.vue

@@ -212,9 +212,11 @@
 
 <script>
 import { mapState } from 'vuex'
+import ThemesMixin from '@/components/mixins/Themes'
 import _ from '@/lodash'
 
 export default {
+  mixins: [ThemesMixin],
   props: { version: { type: String, required: true } },
   computed: {
     ...mapState({
@@ -229,18 +231,6 @@ export default {
       const parser = document.createElement('a')
       parser.href = url
       return parser.hostname
-    },
-    themes () {
-      return [
-        {
-          name: this.$pgettext('Footer/Settings/Dropdown.Label/Theme name', 'Light'),
-          key: 'light'
-        },
-        {
-          name: this.$pgettext('Footer/Settings/Dropdown.Label/Theme name', 'Dark'),
-          key: 'dark'
-        }
-      ]
     }
   }
 }

front/src/components/Sidebar.vue

@@ -475,6 +475,7 @@ import { mapState, mapActions, mapGetters } from 'vuex'
 import UserModal from '@/components/common/UserModal'
 import Logo from '@/components/Logo'
 import SearchBar from '@/components/audio/SearchBar'
+import ThemesMixin from '@/components/mixins/Themes'
 import UserMenu from '@/components/common/UserMenu'
 import Modal from '@/components/semantic/Modal'
 
@@ -489,6 +490,7 @@ export default {
     UserModal,
     Modal
   },
+  mixins: [ThemesMixin],
   props: {
     width: { type: Number, required: true }
   },
@@ -589,18 +591,6 @@ export default {
     },
     production () {
       return process.env.NODE_ENV === 'production'
-    },
-    themes () {
-      return [
-        {
-          name: this.$pgettext('Sidebar/Settings/Dropdown.Label/Theme name', 'Light'),
-          key: 'light'
-        },
-        {
-          name: this.$pgettext('Sidebar/Settings/Dropdown.Label/Theme name', 'Dark'),
-          key: 'dark'
-        }
-      ]
     }
   },
   watch: {

front/src/components/common/UserMenu.vue

@@ -155,7 +155,10 @@
 
 import { mapGetters } from 'vuex'
 
+import ThemesMixin from '@/components/mixins/Themes'
+
 export default {
+  mixins: [ThemesMixin],
   computed: {
     labels () {
       return {
@@ -176,20 +179,6 @@ export default {
         notifications: this.$pgettext('*/Notifications/*', 'Notifications')
       }
     },
-    themes () {
-      return [
-        {
-          icon: 'sun icon',
-          name: this.$pgettext('Footer/Settings/Dropdown.Label/Theme name', 'Light'),
-          key: 'light'
-        },
-        {
-          icon: 'moon icon',
-          name: this.$pgettext('Footer/Settings/Dropdown.Label/Theme name', 'Dark'),
-          key: 'dark'
-        }
-      ]
-    },
     ...mapGetters({
       additionalNotifications: 'ui/additionalNotifications'
     })

front/src/components/common/UserModal.vue

@@ -175,12 +175,14 @@
 
 <script>
 import Modal from '@/components/semantic/Modal'
+import ThemesMixin from '@/components/mixins/Themes'
 import { mapGetters } from 'vuex'
 
 export default {
   components: {
     Modal
   },
+  mixins: [ThemesMixin],
   props: {
     show: { type: Boolean, required: true }
   },
@@ -216,26 +218,6 @@ export default {
         )
       }
     },
-    themes () {
-      return [
-        {
-          icon: 'sun icon',
-          name: this.$pgettext(
-            'Footer/Settings/Dropdown.Label/Theme name',
-            'Light'
-          ),
-          key: 'light'
-        },
-        {
-          icon: 'moon icon',
-          name: this.$pgettext(
-            'Footer/Settings/Dropdown.Label/Theme name',
-            'Dark'
-          ),
-          key: 'dark'
-        }
-      ]
-    },
     ...mapGetters({
       additionalNotifications: 'ui/additionalNotifications'
     })

front/src/components/mixins/Themes.vue

@@ -0,0 +1,25 @@
+<script>
+export default {
+  computed: {
+    themes () {
+      return [
+        {
+          icon: 'palette icon',
+          name: this.$pgettext('*/Settings/Dropdown.Label/Theme name', 'Browser default'),
+          key: 'system'
+        },
+        {
+          icon: 'sun icon',
+          name: this.$pgettext('*/Settings/Dropdown.Label/Theme name', 'Light'),
+          key: 'light'
+        },
+        {
+          icon: 'moon icon',
+          name: this.$pgettext('*/Settings/Dropdown.Label/Theme name', 'Dark'),
+          key: 'dark'
+        }
+      ]
+    }
+  }
+}
+</script>

front/src/store/ui.js

@@ -13,7 +13,7 @@ export default {
     messageDisplayDuration: 5 * 1000,
     supportedExtensions: ['flac', 'ogg', 'mp3', 'opus', 'aac', 'm4a', 'aiff', 'aif'],
     messages: [],
-    theme: 'light',
+    theme: 'system',
     window: {
       height: 0,
       width: 0