🌐(frontend) add a language selector in the header

this will be better in an options page later i think, as we don't pass
our life changing language and we already have a language detector at
load.

this adds a PopoverList primitive to easily create buttons triggering
popovers containing list of actionable items.

src/frontend/src/i18n/LanguageSelector.tsx

@@ -0,0 +1,28 @@
+import { useTranslation } from 'react-i18next'
+import { Button, Popover, PopoverList } from '@/primitives'
+import { useLanguageLabels } from './useLanguageLabels'
+
+export const LanguageSelector = () => {
+  const { t, i18n } = useTranslation()
+  const { languagesList, currentLanguage } = useLanguageLabels()
+  return (
+    <Popover aria-label={t('languageSelector.popoverLabel')}>
+      <Button
+        aria-label={t('languageSelector.buttonLabel', {
+          currentLanguage,
+        })}
+        size="sm"
+        variant="primary"
+        outline
+      >
+        {i18n.language}
+      </Button>
+      <PopoverList
+        items={languagesList}
+        onAction={(lang) => {
+          i18n.changeLanguage(lang)
+        }}
+      />
+    </Popover>
+  )
+}

src/frontend/src/i18n/useLanguageLabels.ts

@@ -0,0 +1,20 @@
+import { useTranslation } from 'react-i18next'
+
+const langageLabels: Record<string, string> = {
+  en: 'English',
+  fr: 'Français',
+  de: 'Deutsch',
+}
+
+export const useLanguageLabels = () => {
+  const { i18n } = useTranslation()
+  // cimode is a testing value from i18next, don't include it
+  const supportedLanguages = (i18n.options.supportedLngs || []).filter(
+    (lang) => lang !== 'cimode'
+  )
+  const languagesList = supportedLanguages.map((lang) => ({
+    value: lang,
+    label: langageLabels[lang],
+  }))
+  return { languagesList, currentLanguage: langageLabels[i18n.language] }
+}

src/frontend/src/layout/Header.tsx

@@ -1,9 +1,11 @@
-import { useTranslation } from 'react-i18next'
+import { Link } from 'wouter'
 import { css } from '@/styled-system/css'
 import { flex } from '@/styled-system/patterns'
+import { Stack } from '@/styled-system/jsx'
+import { useTranslation } from 'react-i18next'
+import { LanguageSelector } from '@/i18n/LanguageSelector'
 import { A, Badge, Text } from '@/primitives'
 import { authUrl, logoutUrl, useUser } from '@/features/auth'
-import { Link } from 'wouter'
 
 export const Header = () => {
   const { t } = useTranslation()
@@ -21,29 +23,27 @@ export const Header = () => {
         boxShadow: 'box',
       })}
     >
-      <header
-        className={flex({
-          justify: 'space-between',
-          align: 'center',
-        })}
-      >
-        <div>
+      <Stack direction="row" justify="space-between" align="center">
+        <header>
           <Text bold variant="h1" margin={false}>
             <Link to="/">{t('app')}</Link>
           </Text>
-        </div>
-        <div>
-          {isLoggedIn === false && <A href={authUrl()}>{t('login')}</A>}
-          {!!user && (
-            <p className={flex({ gap: 1, align: 'center' })}>
-              <Badge>{user.email}</Badge>
-              <A href={logoutUrl()} size="small">
-                {t('logout')}
-              </A>
-            </p>
-          )}
-        </div>
-      </header>
+        </header>
+        <nav>
+          <Stack gap={1} direction="row" align="center">
+            <LanguageSelector />
+            {isLoggedIn === false && <A href={authUrl()}>{t('login')}</A>}
+            {!!user && (
+              <p className={flex({ gap: 1, align: 'center' })}>
+                <Badge>{user.email}</Badge>
+                <A href={logoutUrl()} size="small">
+                  {t('logout')}
+                </A>
+              </p>
+            )}
+          </Stack>
+        </nav>
+      </Stack>
     </div>
   )
 }

src/frontend/src/locales/de/global.json

@@ -9,6 +9,10 @@
   "app": "Meet",
   "login": "Anmelden",
   "logout": "",
+  "languageSelector": {
+    "popoverLabel": "",
+    "buttonLabel": ""
+  },
   "loading": "",
   "notFound": {
     "heading": ""

src/frontend/src/locales/en/global.json

@@ -9,6 +9,10 @@
   "app": "Meet",
   "login": "Login",
   "logout": "Logout",
+  "languageSelector": {
+    "popoverLabel": "Choose language",
+    "buttonLabel": "Change language (currently {{currentLanguage}})"
+  },
   "loading": "Loading…",
   "notFound": {
     "heading": ""

src/frontend/src/locales/fr/global.json

@@ -9,6 +9,10 @@
   "app": "Meet",
   "login": "Se connecter",
   "logout": "Se déconnecter",
+  "languageSelector": {
+    "popoverLabel": "Choix de la langue",
+    "buttonLabel": "Changer de langue (actuellement {{currentLanguage}})"
+  },
   "loading": "Chargement…",
   "notFound": {
     "heading": "Page introuvable"

src/frontend/src/primitives/Button.tsx

@@ -9,44 +9,69 @@ import { cva, type RecipeVariantProps } from '@/styled-system/css'
 const button = cva({
   base: {
     display: 'inline-block',
-    paddingX: '1',
-    paddingY: '0.625',
-    transition: 'all 200ms',
-    borderRadius: 8,
+    transition: 'background 200ms',
     cursor: 'pointer',
+    border: '1px solid transparent',
+    color: 'colorPalette.text',
+    backgroundColor: 'colorPalette',
+    '_ra-hover': {
+      backgroundColor: 'colorPalette.hover',
+    },
+    '_ra-pressed': {
+      backgroundColor: 'colorPalette.active',
+    },
   },
   variants: {
+    size: {
+      default: {
+        borderRadius: 8,
+        paddingX: '1',
+        paddingY: '0.625',
+      },
+      sm: {
+        borderRadius: 4,
+        paddingX: '0.5',
+        paddingY: '0.25',
+      },
+    },
     variant: {
       default: {
-        color: 'control.text',
-        backgroundColor: 'control',
-        '_ra-hover': {
-          backgroundColor: 'control.hover',
-        },
-        '_ra-pressed': {
-          backgroundColor: 'control.active',
-        },
+        colorPalette: 'control',
       },
       primary: {
-        color: 'primary.text',
-        backgroundColor: 'primary',
+        colorPalette: 'primary',
+      },
+    },
+    outline: {
+      true: {
+        color: 'colorPalette',
+        backgroundColor: 'transparent!',
+        borderColor: 'currentcolor!',
         '_ra-hover': {
-          backgroundColor: 'primary.hover',
+          backgroundColor: 'colorPalette.subtle!',
         },
         '_ra-pressed': {
-          backgroundColor: 'primary.active',
+          backgroundColor: 'colorPalette.subtle!',
         },
       },
     },
   },
+  defaultVariants: {
+    size: 'default',
+    variant: 'default',
+    outline: false,
+  },
 })
 
-type ButtonProps = RecipeVariantProps<typeof button> &
-  (RACButtonsProps | LinkProps)
+export type ButtonProps = RecipeVariantProps<typeof button> & RACButtonsProps
 
-export const Button = (props: ButtonProps) => {
+type LinkButtonProps = RecipeVariantProps<typeof button> & LinkProps
+
+type ButtonOrLinkProps = ButtonProps | LinkButtonProps
+
+export const Button = (props: ButtonOrLinkProps) => {
   const [variantProps, componentProps] = button.splitVariantProps(props)
-  if ((props as LinkProps).href !== undefined) {
+  if ((props as LinkButtonProps).href !== undefined) {
     return <Link className={button(variantProps)} {...componentProps} />
   }
   return (

src/frontend/src/primitives/PopoverList.tsx

@@ -0,0 +1,61 @@
+import { ReactNode, useContext } from 'react'
+import {
+  ButtonProps,
+  Button,
+  OverlayTriggerStateContext,
+} from 'react-aria-components'
+import { styled } from '@/styled-system/jsx'
+
+const ListItem = styled(Button, {
+  base: {
+    paddingY: 0.125,
+    paddingX: 0.5,
+    textAlign: 'left',
+    width: 'full',
+    borderRadius: 4,
+    cursor: 'pointer',
+    color: 'primary',
+    '_ra-hover': {
+      color: 'primary.subtle-text',
+      backgroundColor: 'primary.subtle',
+    },
+  },
+})
+
+/**
+ * render a Button primitive that shows a popover showing a list of pressable items
+ */
+export const PopoverList = <T extends string | number = string>({
+  onAction,
+  closeOnAction = true,
+  items = [],
+}: {
+  closeOnAction?: boolean
+  onAction: (key: T) => void
+  items: Array<string | { value: T; label: ReactNode }>
+} & ButtonProps) => {
+  const popoverState = useContext(OverlayTriggerStateContext)!
+  return (
+    <ul>
+      {items.map((item) => {
+        const value = typeof item === 'string' ? item : item.value
+        const label = typeof item === 'string' ? item : item.label
+        return (
+          <li>
+            <ListItem
+              key={value}
+              onPress={() => {
+                onAction(value as T)
+                if (closeOnAction) {
+                  popoverState.close()
+                }
+              }}
+            >
+              {label}
+            </ListItem>
+          </li>
+        )
+      })}
+    </ul>
+  )
+}