fix: use radiogroup for instance switcher (#1634)

* fix: use radiogroup for instance switcher

progress on #1633

* fixup

* add unique id

src/routes/_components/radio/RadioGroup.html

@@ -0,0 +1,43 @@
+<!-- Modeled after https://www.w3.org/TR/2016/WD-wai-aria-practices-1.1-20160317/examples/radio/radio.html -->
+<div class="radio-group focus-fix {className}"
+     role="radiogroup"
+     aria-label={label}
+     aria-owns={ariaOwns}
+     on:keydown="onKeyDown(event)"
+     ref:radiogroup
+>
+  <slot></slot>
+</div>
+<script>
+  import { times } from '../../_utils/lodash-lite'
+
+  export default {
+    methods: {
+      onKeyDown (e) {
+        // ArrowUp and ArrowDown should change the focused/checked radio button per
+        // https://www.w3.org/TR/2016/WD-wai-aria-practices-1.1-20160317/examples/radio/radio.html
+        const { key, target } = e
+        if (!['ArrowUp', 'ArrowDown'].includes(key)) {
+          return
+        }
+        if (!target.classList.contains('radio-group-button')) {
+          return
+        }
+        const buttons = Array.from(this.refs.radiogroup.getElementsByClassName('radio-group-button'))
+        const len = buttons.length
+        const index = Math.max(0, buttons.findIndex(button => button.getAttribute('aria-checked') === 'true'))
+        const newIndex = (len + (index + (key === 'ArrowUp' ? -1 : 1))) % len // increment/decrement and wrap around
+        buttons[newIndex].focus()
+        buttons[newIndex].click()
+      }
+    },
+    data: () => ({
+      className: ''
+    }),
+    computed: {
+      ariaOwns: ({ length, id }) => (
+        times(length, index => `radio-group-button-${id}-${index}`).join(' ')
+      )
+    }
+  }
+</script>

src/routes/_components/radio/RadioGroupButton.html

@@ -0,0 +1,17 @@
+<button id="radio-group-button-{id}-{index}"
+        class="radio-group-button {className}"
+        role="radio"
+        aria-label={label}
+        title={label}
+        aria-checked={checked}
+        on:click
+>
+  <slot></slot>
+</button>
+<script>
+  export default {
+    data: () => ({
+      className: ''
+    })
+  }
+</script>

src/routes/_pages/settings/instances/index.html

@@ -3,6 +3,7 @@
 
   {#if $isUserLoggedIn}
   <p>Instances you've logged in to:</p>
+  <RadioGroup id="instance-switch" label="Switch to instance" length={numInstances}>
     <SettingsList label="Instances">
       {#each instanceStates as instance}
       <SettingsListRow>
@@ -11,18 +12,21 @@
                             label={instance.name}
                             ariaLabel={instance.label} />
         <div class="instance-switcher-button-wrapper">
-        <button class="instance-switcher-button"
-                aria-label={instance.switchLabel}
-                title={instance.switchLabel}
-                aria-pressed={instance.current}
+          <RadioGroupButton
+                  id="instance-switch"
+                  className="instance-switcher-button"
+                  label={instance.switchLabel}
+                  checked={instance.current}
+                  index={instance.index}
                   on:click="onSwitchToThisInstance(event, instance.name)">
             <SvgIcon className="instance-switcher-button-svg"
                      href={instance.current ? '#fa-star' : '#fa-star-o'} />
-        </button>
+          </RadioGroupButton>
         </div>
       </SettingsListRow>
       {/each}
     </SettingsList>
+  </RadioGroup>
   <p><a rel="prefetch" href="/settings/instances/add">Add another instance</a></p>
   {:else}
   <p>You're not logged in to any instances.</p>
@@ -40,7 +44,7 @@
     border: 1px solid var(--settings-list-item-border);
     min-width: 44px;
   }
-  .instance-switcher-button {
+  :global(.instance-switcher-button) {
     display: flex;
     position: absolute;
     top: 0;
@@ -69,6 +73,8 @@
   import SettingsListRow from '../../../_components/settings/SettingsListRow.html'
   import SettingsListButton from '../../../_components/settings/SettingsListButton.html'
   import SvgIcon from '../../../_components/SvgIcon.html'
+  import RadioGroup from '../../../_components/radio/RadioGroup.html'
+  import RadioGroupButton from '../../../_components/radio/RadioGroupButton.html'
 
   export default {
     components: {
@@ -76,7 +82,9 @@
       SettingsList,
       SettingsListRow,
       SettingsListButton,
-      SvgIcon
+      SvgIcon,
+      RadioGroup,
+      RadioGroupButton
     },
     methods: {
       onSwitchToThisInstance (e, instanceName) {
@@ -88,13 +96,15 @@
     store: () => store,
     computed: {
       instanceStates: ({ $loggedInInstancesAsList }) => (
-        $loggedInInstancesAsList.map(({ name, current }) => ({
+        $loggedInInstancesAsList.map(({ name, current }, index) => ({
+          index,
           name,
           current,
           label: `${name} ${current ? '(current instance)' : ''}`,
-          switchLabel: current ? `${name} is the current instance` : `Switch to ${name}`
+          switchLabel: `Switch to ${name}`
         }))
-      )
+      ),
+      numInstances: ({ $loggedInInstancesAsList }) => $loggedInInstancesAsList.length
     }
   }
 </script>

src/routes/_utils/lodash-lite.js

@@ -36,3 +36,11 @@ export function sum (list) {
   }
   return total
 }
+
+export function times (n, func) {
+  const res = []
+  for (let i = 0; i < n; i++) {
+    res.push(func(i))
+  }
+  return res
+}