1 files changed, 218 insertions, 0 deletions
diff --git a/src/components/Menu.svelte b/src/components/Menu.svelte
new file mode 100644
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--- /dev/null
+++ b/src/components/Menu.svelte
@@ -0,0 +1,218 @@
+<script lang="ts" generics="T">
+    import { tick } from 'svelte';
+    import type { Opt } from '@jet/environment/types/optional';
+    import type { MouseEventHandler } from 'svelte/elements';
+    import { onDestroy, onMount } from 'svelte';
+    import { generateUuid } from '@amp/web-apps-utils/src';
+    import {
+        computePosition,
+        autoUpdate,
+        offset,
+        flip,
+        shift,
+    } from '@floating-ui/dom';
+
+    export let options: T[];
+    // Allows the developer the override the floating-ui calculated offset to a fixed number
+    export let forcedXPosition: number | null = null;
+
+    export let handleShowMenu: () => void = () => {};
+
+    let isMenuOpen = false;
+
+    /**
+     * Display the menu
+     *
+     * @example
+     * <script>
+     *   let menu;
+     *
+     *   function showMenu() {
+     *     menu.show();
+     *   }
+     * <\/script>
+     *
+     * <Menu bind:this={menu} />
+     */
+    export async function show() {
+        if (!menuEl) return;
+
+        isMenuOpen = true;
+
+        // Menu position should be updated *only* after the dialog has been shown
+        updateMenuPosition();
+
+        // Focuses the first link in the dropdown after the DOM updates
+        await tick();
+        menuEl.querySelector('a')?.focus();
+
+        // When the modal is open, track viewport changes and update the menu position
+        floatingUIAutoUpdatePositionCleanupCallback = autoUpdate(
+            trigger!,
+            menuEl!,
+            updateMenuPosition,
+        );
+    }
+
+    /**
+     * Close the menu
+     *
+     * @example
+     * <script>
+     *   let menu;
+     *
+     *   function closeMenu() {
+     *     menu.close();
+     *   }
+     * <\/script>
+     *
+     * <Menu bind:this={menu} />
+     */
+    export function close() {
+        if (!menuEl) return;
+
+        isMenuOpen = false;
+        cleanUpFloatingUIAutoPosition();
+    }
+
+    function toggle() {
+        if (isMenuOpen) {
+            close();
+        } else {
+            show();
+            handleShowMenu?.();
+        }
+    }
+
+    const menuId = generateUuid();
+
+    let menuEl: HTMLUListElement | undefined;
+    let trigger: HTMLButtonElement | undefined;
+
+    function handleKeyUp(event: KeyboardEvent) {
+        if (event.key === 'Escape') {
+            close();
+        }
+    }
+
+    /**
+     * Dismiss the dialog when clicking anywhere with the dialog open
+     */
+    const handleBodyClick: MouseEventHandler<HTMLElement> = (event) => {
+        const clickedElement = event.target as HTMLElement;
+
+        // Only close the dialog if the click is "outside" of the trigger
+        // Otherwise, it will be closed immediately
+        if (!trigger?.contains(clickedElement)) {
+            close();
+        }
+    };
+
+    /// MARK: Menu Positioning through `FloatingUI`
+
+    /**
+     * Update the position of the menu to align it with the trigger
+     */
+    async function updateMenuPosition() {
+        const { x, y } = await computePosition(trigger!, menuEl!, {
+            middleware: [
+                offset({
+                    mainAxis: 10,
+                }),
+
+                flip(),
+                shift(),
+            ],
+            placement: 'bottom-end',
+        });
+
+        Object.assign(menuEl!.style, {
+            left: `${forcedXPosition || x}px`,
+            top: `${y}px`,
+        });
+    }
+
+    let floatingUIAutoUpdatePositionCleanupCallback: Opt<() => void>;
+
+    /**
+     * Cleans up the `FloatingUI` auto-update listener, which should only be "active"
+     * while the menu is open
+     */
+    function cleanUpFloatingUIAutoPosition() {
+        floatingUIAutoUpdatePositionCleanupCallback?.();
+        floatingUIAutoUpdatePositionCleanupCallback = undefined;
+    }
+
+    onMount(() => {
+        // Ensures menu is hidden initially
+        if (menuEl) isMenuOpen = false;
+    });
+
+    onDestroy(function () {
+        cleanUpFloatingUIAutoPosition();
+    });
+</script>
+
+<svelte:body on:keyup={handleKeyUp} on:click={handleBodyClick} />
+
+<button
+    class="menu-trigger"
+    aria-controls={menuId}
+    aria-haspopup="menu"
+    aria-expanded={isMenuOpen}
+    bind:this={trigger}
+    on:click={toggle}
+>
+    <slot name="trigger" />
+</button>
+
+<ul
+    id={menuId}
+    hidden={!isMenuOpen}
+    tabindex="-1"
+    class="menu-popover focus-visible"
+    bind:this={menuEl}
+>
+    {#each options as option}
+        <li class="menu-item" role="presentation">
+            <slot name="option" {option} />
+        </li>
+    {/each}
+</ul>
+
+<style>
+    :root {
+        --menu-common-padding: 4px 8px;
+    }
+
+    .menu-trigger {
+        background-color: var(--menu-trigger-background-color);
+        border-radius: var(--menu-trigger-border-radius);
+        font: var(--menu-trigger-font);
+        padding: var(--menu-trigger-padding, var(--menu-common-padding));
+    }
+
+    .menu-popover {
+        background-color: var(--menu-popover-background-color, var(--pageBg));
+        padding: var(--menu-popover-padding, 0);
+        border: var(--menu-popover-border, none);
+        border-radius: var(
+            --menu-popover-border-radius,
+            var(--global-border-radius-large)
+        );
+        box-shadow: var(--menu-popover-box-shadow, var(--shadow-medium));
+        position: absolute;
+        inset: auto;
+        z-index: var(--menu-popover-z-index, 2);
+    }
+
+    .menu-popover::backdrop {
+        background: var(--menu-popover-backdrop-background, none);
+    }
+
+    .menu-item {
+        padding: var(--menu-item-padding, var(--menu-common-padding));
+        margin: var(--menu-item-margin, 0);
+        white-space: nowrap;
+    }
+</style>