web: add dark mode and theme selection

This adds a theme selection in the preferences in the
config modal and adds a new dark theme.

Removes the line.png image and instead uses CSS
linear-gradient that is available in all browsers
since around 2018, also fixes the 15 pixels spacing
issue that is there today.

You can select between three different themes.

Auto will use your system preference to choose either the
light or dark theme, changes dynamically based on your
system preference.

Light is the current theme.

Dark is the theme added by this patch series.

The UX this changes is that if somebody has their system
preferences set to dark, for example in Mac OS X that is
in System Settings -> Appearance -> Dark the user will
get the Zuul web UI in dark by default and same for the
opposite.

This uses a poor man's dark mode for swagger-ui
as per the comment in [1].

[1] https://github.com/swagger-api/swagger-ui/issues/5327#issuecomment-742375520

Change-Id: I01cf32f3decdb885307a76eb79d644667bbbf9a3

1 files changed, 13 insertions, 10 deletions

diff --git a/web/src/reducers/preferences.js b/web/src/reducers/preferences.js
index 1fba8eacf..0a2755257 100644
--- a/web/src/reducers/preferences.js
+++ b/web/src/reducers/preferences.js
@@ -15,13 +15,14 @@
 import {
   PREFERENCE_SET,
 } from '../actions/preferences'
-
+import { resolveDarkMode, setDarkMode } from '../Misc'
 
 const stored_prefs = localStorage.getItem('preferences')
 let default_prefs
 if (stored_prefs === null) {
   default_prefs = {
-    autoReload: true
+    autoReload: true,
+    theme: 'Auto'
   }
 } else {
   default_prefs = JSON.parse(stored_prefs)
@@ -30,13 +31,15 @@ if (stored_prefs === null) {
 export default (state = {
   ...default_prefs
 }, action) => {
-  let newstate
-  switch (action.type) {
-    case PREFERENCE_SET:
-      newstate = { ...state, [action.key]: action.value }
-      localStorage.setItem('preferences', JSON.stringify(newstate))
-      return newstate
-    default:
-      return state
+  if (action.type === PREFERENCE_SET) {
+    let newstate = { ...state, [action.key]: action.value }
+    delete newstate.darkMode
+    localStorage.setItem('preferences', JSON.stringify(newstate))
+    let darkMode = resolveDarkMode(newstate.theme)
+    setDarkMode(darkMode)
+    return { ...newstate, darkMode: darkMode }
   }
+  let darkMode = resolveDarkMode(state.theme)
+  setDarkMode(darkMode)
+  return { ...state, darkMode: darkMode }
 }