From 9afc1491934c3dcb6cdfa2b2387b05b3e807905a Mon Sep 17 00:00:00 2001
From: Eric Liu <ericyl.us@gmail.com>
Date: Fri, 20 Dec 2019 16:35:48 -0800
Subject: [PATCH] feat(components): add ContentSwitcher, Switch

Closes #33
---
 README.md                                     |  2 +
 .../ContentSwitcher.Story.svelte              | 23 ++++++++
 .../ContentSwitcher.stories.js                | 19 +++++++
 .../ContentSwitcher/ContentSwitcher.svelte    | 54 +++++++++++++++++++
 src/components/ContentSwitcher/Switch.svelte  | 50 +++++++++++++++++
 src/components/ContentSwitcher/index.js       |  4 ++
 src/index.js                                  |  3 ++
 7 files changed, 155 insertions(+)
 create mode 100644 src/components/ContentSwitcher/ContentSwitcher.Story.svelte
 create mode 100644 src/components/ContentSwitcher/ContentSwitcher.stories.js
 create mode 100644 src/components/ContentSwitcher/ContentSwitcher.svelte
 create mode 100644 src/components/ContentSwitcher/Switch.svelte
 create mode 100644 src/components/ContentSwitcher/index.js

diff --git a/README.md b/README.md
index ef980b7f..2a2d53ef 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,8 @@ Currently, the following components are supported:
   - CheckboxSkeleton
 - CodeSnippet
   - CodeSnippetSkeleton
+- ContentSwitcher
+  - Switch
 - Copy
 - CopyButton
 - DataTableSkeleton
diff --git a/src/components/ContentSwitcher/ContentSwitcher.Story.svelte b/src/components/ContentSwitcher/ContentSwitcher.Story.svelte
new file mode 100644
index 00000000..b8ff1961
--- /dev/null
+++ b/src/components/ContentSwitcher/ContentSwitcher.Story.svelte
@@ -0,0 +1,23 @@
+<script>
+  export let story = undefined;
+
+  import Layout from '../../internal/ui/Layout.svelte';
+  import ContentSwitcher from './ContentSwitcher.svelte';
+  import Switch from './Switch.svelte';
+</script>
+
+<Layout>
+  {#if story === 'selected'}
+    <ContentSwitcher>
+      <Switch {...$$props} text="First section" />
+      <Switch {...$$props} text="Second section" selected />
+      <Switch {...$$props} text="Third section" />
+    </ContentSwitcher>
+  {:else}
+    <ContentSwitcher>
+      <Switch {...$$props} text="First section" />
+      <Switch {...$$props} text="Second section" />
+      <Switch {...$$props} text="Third section" />
+    </ContentSwitcher>
+  {/if}
+</Layout>
diff --git a/src/components/ContentSwitcher/ContentSwitcher.stories.js b/src/components/ContentSwitcher/ContentSwitcher.stories.js
new file mode 100644
index 00000000..b25659a3
--- /dev/null
+++ b/src/components/ContentSwitcher/ContentSwitcher.stories.js
@@ -0,0 +1,19 @@
+import { withKnobs, boolean } from '@storybook/addon-knobs';
+import Component from './ContentSwitcher.Story.svelte';
+
+export default { title: 'ContentSwitcher', decorators: [withKnobs] };
+
+export const Default = () => ({
+  Component,
+  props: {
+    disabled: boolean('Disabled (disabled)', false)
+  }
+});
+
+export const Selected = () => ({
+  Component,
+  props: {
+    story: 'selected',
+    disabled: boolean('Disabled (disabled)', false)
+  }
+});
diff --git a/src/components/ContentSwitcher/ContentSwitcher.svelte b/src/components/ContentSwitcher/ContentSwitcher.svelte
new file mode 100644
index 00000000..c9216d0a
--- /dev/null
+++ b/src/components/ContentSwitcher/ContentSwitcher.svelte
@@ -0,0 +1,54 @@
+<script>
+  export let className = undefined;
+  export { className as class };
+  export let selectedIndex = 0;
+  export let style = undefined;
+
+  import { createEventDispatcher, setContext } from 'svelte';
+  import { writable } from 'svelte/store';
+  import { cx } from '../../lib';
+
+  const dispatch = createEventDispatcher();
+  const _class = cx('--content-switcher', className);
+  let currentId = writable(null);
+  let currentIndex = selectedIndex;
+  let switches = [];
+
+  setContext('ContentSwitcher', {
+    currentId,
+    add: ({ id, text, selected }) => {
+      switches = [...switches, { id, text, selected }];
+
+      if (selected) {
+        currentIndex = switches.length;
+      }
+    },
+    update: id => {
+      currentIndex = switches.map(({ id }) => id).indexOf(id);
+    },
+    change: direction => {
+      let index = currentIndex + direction;
+
+      if (index < 0) {
+        index = switches.length - 1;
+      } else if (index >= switches.length) {
+        index = 0;
+      }
+
+      currentIndex = index;
+    }
+  });
+
+  $: if (switches[currentIndex]) {
+    selectedIndex = currentIndex;
+    currentId.set(switches[currentIndex].id);
+    switches = switches.map((_, i) => ({ ..._, selected: i === currentIndex }));
+
+    const { id, ...rest } = switches[currentIndex];
+    dispatch('change', { ...rest, index: currentIndex });
+  }
+</script>
+
+<div role="tablist" on:click on:mouseover on:mouseenter on:mouseleave class={_class} {style}>
+  <slot />
+</div>
diff --git a/src/components/ContentSwitcher/Switch.svelte b/src/components/ContentSwitcher/Switch.svelte
new file mode 100644
index 00000000..821316df
--- /dev/null
+++ b/src/components/ContentSwitcher/Switch.svelte
@@ -0,0 +1,50 @@
+<script>
+  let className = undefined;
+  export { className as class };
+  export let selected = false;
+  export let text = 'Provide text';
+  export let style = undefined;
+  export let disabled = false;
+
+  import { cx } from '../../lib';
+  import { getContext } from 'svelte';
+
+  const id = Math.random();
+  const { currentId, add, update, change } = getContext('ContentSwitcher');
+
+  let buttonRef = undefined;
+
+  add({ id, text, selected });
+
+  $: selected = $currentId === id;
+  $: if (selected && buttonRef) {
+    buttonRef.focus();
+  }
+  $: _class = cx('--content-switcher-btn', selected && '--content-switcher--selected', className);
+</script>
+
+<button
+  bind:this={buttonRef}
+  role="tab"
+  tabindex={selected ? '0' : '-1'}
+  aria-selected={selected}
+  class={_class}
+  on:click
+  on:click|preventDefault={() => {
+    update(id);
+  }}
+  on:mouseover
+  on:mouseenter
+  on:mouseleave
+  on:keydown
+  on:keydown={event => {
+    if (event.key === 'ArrowRight') {
+      change(1);
+    } else if (event.key === 'ArrowLeft') {
+      change(-1);
+    }
+  }}
+  {disabled}
+  {style}>
+  <span class={cx('--content-switcher__label')}>{text}</span>
+</button>
diff --git a/src/components/ContentSwitcher/index.js b/src/components/ContentSwitcher/index.js
new file mode 100644
index 00000000..273931c9
--- /dev/null
+++ b/src/components/ContentSwitcher/index.js
@@ -0,0 +1,4 @@
+import ContentSwitcher from './ContentSwitcher.svelte';
+
+export default ContentSwitcher;
+export { default as Switch } from './Switch.svelte';
diff --git a/src/index.js b/src/index.js
index e7d843bb..3fa2aa64 100644
--- a/src/index.js
+++ b/src/index.js
@@ -2,6 +2,7 @@ import Accordion, { AccordionItem, AccordionSkeleton } from './components/Accord
 import Breadcrumb, { BreadcrumbItem, BreadcrumbSkeleton } from './components/Breadcrumb';
 import Button, { ButtonSkeleton } from './components/Button';
 import Checkbox, { CheckboxSkeleton } from './components/Checkbox';
+import ContentSwitcher, { Switch } from './components/ContentSwitcher';
 import Copy from './components/Copy';
 import CopyButton from './components/CopyButton';
 import CodeSnippet, { CodeSnippetSkeleton } from './components/CodeSnippet';
@@ -46,6 +47,7 @@ export {
   ClickableTile,
   CodeSnippet,
   CodeSnippetSkeleton,
+  ContentSwitcher,
   Copy,
   CopyButton,
   DataTableSkeleton,
@@ -63,6 +65,7 @@ export {
   SelectableTile,
   SkeletonPlaceholder,
   SkeletonText,
+  Switch,
   Tag,
   TagSkeleton,
   TextArea,