Let space icons be dragged to reorder in the sidebar

e2e/USER_STORIES.md

@@ -153,8 +153,8 @@ Acceptance:
 - Typing a term filters both sections live, matching name, url, or description.
 - Clicking a joined space opens it; clicking one she hasn't joined opens a join
   prompt instead.
-- Dragging a joined space above another reorders the list immediately, and the
-  order survives a reload.
+- Dragging a joined space above another, on the page or in the sidebar rail,
+  reorders the list immediately, and the order survives a reload.
 
 ### US-010 — Join a space from an invite link
 

e2e/specs/spaces.spec.ts

@@ -83,6 +83,24 @@ test("US-009 browse, search, and reorder your spaces", async ({seed, as}) => {
   // starts the drag and moves it, but never delivers the drop the reorder is committed in, so the
   // row would snap back to where it came from.
   const dataTransfer = await page.evaluateHandle(() => new DataTransfer())
+
+  // The sidebar rail is the same list and reorders the same way. It shows icons and no text, so
+  // its rows are named by position and the list on the page is where the result is read.
+  const rail = page.locator(".primary-nav [draggable=true]")
+
+  await rail.nth(0).dispatchEvent("dragstart", {dataTransfer})
+  await rail.nth(1).dispatchEvent("drop", {dataTransfer})
+
+  await expect(joined.first()).toContainText(other.url)
+
+  await rail.nth(1).dispatchEvent("dragstart", {dataTransfer})
+  await rail.nth(0).dispatchEvent("drop", {dataTransfer})
+
+  await expect(joined.first()).toContainText(space.url)
+
+  // Dragging in the page's own list moves the same room list. It goes last because it shows the new
+  // order the moment it is dropped, ahead of the room list it publishes, so a drag in the rail
+  // straight afterwards would be working from the order it replaced.
   const source = joined.filter({hasText: other.url})
   const target = joined.filter({hasText: space.url})
 

src/app/components/PrimaryNavSpaces.svelte

@@ -5,9 +5,10 @@
   import Divider from "@lib/components/Divider.svelte"
   import Tippy from "@lib/components/Tippy.svelte"
   import PrimaryNavItem from "@lib/components/PrimaryNavItem.svelte"
+  import DragList from "@lib/components/DragList.svelte"
   import PrimaryNavItemSpace from "@app/components/PrimaryNavItemSpace.svelte"
   import PrimaryNavSpacesOverflow from "@app/components/PrimaryNavSpacesOverflow.svelte"
-  import {userSpaceUrls} from "@app/rooms"
+  import {reorderSpaceUrls, userSpaceUrls} from "@app/rooms"
   import {PLATFORM_RELAYS, PLATFORM_LOGO} from "@app/env"
   import {notifications} from "@app/notifications"
   import {makeSpacePath} from "@app/routes"
@@ -48,9 +49,14 @@
       <ImageIcon alt="Home" src={PLATFORM_LOGO} class="rounded-full" size={10} />
     </PrimaryNavItem>
     <Divider />
-    {#each primarySpaceUrls as url (url)}
-      <PrimaryNavItemSpace {url} />
-    {/each}
+    <DragList
+      class="flex flex-col items-center"
+      items={primarySpaceUrls}
+      onReorder={reorderSpaceUrls}>
+      {#snippet item(url)}
+        <PrimaryNavItemSpace {url} />
+      {/snippet}
+    </DragList>
     {#snippet allSpaces(title: string)}
       <PrimaryNavItem
         href="/spaces"

src/app/rooms.ts

@@ -1,10 +1,10 @@
 import * as nip19 from "nostr-tools/nip19"
-import {derived} from "svelte/store"
+import {derived, get} from "svelte/store"
 import {formatTimestampAsDate, int, sortBy, uniq, MINUTE} from "@welshman/lib"
 import type {Maybe} from "@welshman/lib"
 import {MESSAGE, makeEvent, outbox, seen, toNostrURI} from "@welshman/util"
 import type {EventContent, TrustedEvent} from "@welshman/util"
-import {MembershipStatus, RoomLists, makeRoomKey, createSearch} from "@welshman/app"
+import {MembershipStatus, RoomLists, makeRoomKey, createSearch, publish} from "@welshman/app"
 import type {Room, RoomMeta} from "@welshman/app"
 import {
   deriveUserItem,
@@ -126,6 +126,16 @@ export const userRoomList = deriveUserItem(RoomLists)
 
 export const userSpaceUrls = derived(userRoomList, $userRoomList => $userRoomList?.urls() ?? [])
 
+// Spaces get reordered from lists that show only some of them, so the urls given here go back
+// in the slots the ones they replace occupied.
+export const reorderSpaceUrls = (urls: string[]) => {
+  let index = 0
+
+  const nextUrls = get(userSpaceUrls).map(url => (urls.includes(url) ? urls[index++] : url))
+
+  return roomLists.get().setRelays(nextUrls).then(publish)
+}
+
 // Rooms in the space the user has joined, limited to those the relay still advertises.
 export const deriveUserRooms = (url: string) =>
   derived(

src/lib/components/DragList.svelte

@@ -0,0 +1,118 @@
+<script lang="ts">
+  import cx from "classnames"
+  import type {Snippet} from "svelte"
+  import {flip} from "svelte/animate"
+  import {cubicOut} from "svelte/easing"
+  import {insertAt, removeAt} from "@welshman/lib"
+
+  type Props = {
+    items: string[]
+    onReorder: (items: string[]) => void
+    item: Snippet<[string]>
+    class?: string
+    itemClass?: string
+    role?: string
+    itemRole?: string
+  }
+
+  const {
+    items,
+    onReorder,
+    item,
+    class: className = "",
+    itemClass = "",
+    role = undefined,
+    itemRole = undefined,
+  }: Props = $props()
+
+  const isSameOrder = (a: string[], b: string[]) =>
+    a.length === b.length && a.every((item, index) => item === b[index])
+
+  const moveTo = (source: string, target: string) => {
+    const from = order.indexOf(source)
+    const to = order.indexOf(target)
+
+    if (from >= 0 && to >= 0 && from !== to) {
+      preview = insertAt(to, order[from], removeAt(from, order))
+    }
+  }
+
+  const onDragStart = (e: DragEvent, value: string) => {
+    dragged = value
+    dropped = false
+
+    if (e.dataTransfer) {
+      e.dataTransfer.effectAllowed = "move"
+    }
+  }
+
+  const onDragOver = (e: DragEvent) => {
+    e.preventDefault()
+  }
+
+  const onDragEnter = (e: DragEvent, value: string) => {
+    e.preventDefault()
+
+    if (dragged) {
+      moveTo(dragged, value)
+    }
+  }
+
+  const onDrop = (e: DragEvent, value: string) => {
+    e.preventDefault()
+
+    if (dragged) {
+      moveTo(dragged, value)
+    }
+
+    dragged = undefined
+    dropped = true
+
+    if (preview) {
+      onReorder(preview)
+    }
+  }
+
+  const onDragEnd = () => {
+    if (!dropped) {
+      preview = undefined
+    }
+
+    dragged = undefined
+  }
+
+  let preview = $state<string[] | undefined>()
+  let lastItems = $state<string[]>([])
+  let dragged = $state<string | undefined>()
+  let dropped = $state(false)
+
+  // Reordering is previewed locally, so a drag reads as movement without the caller hearing about
+  // every position the item passes through. It hears about it once, on drop.
+  const order = $derived(preview ?? items)
+
+  // The preview outlives the drop, since the caller takes a moment to publish the new order, and
+  // is dropped as soon as the items it was built from change.
+  $effect(() => {
+    if (!isSameOrder(items, lastItems)) {
+      lastItems = items
+      preview = undefined
+    }
+  })
+</script>
+
+<div class={className} {role}>
+  {#each order as value (value)}
+    <div
+      animate:flip={{duration: 300, easing: cubicOut}}
+      class={cx("transition-opacity duration-200", itemClass, {"opacity-50": dragged === value})}
+      draggable="true"
+      role={itemRole}
+      ondragstart={e => onDragStart(e, value)}
+      ondragover={onDragOver}
+      ondragenter={e => onDragEnter(e, value)}
+      ondrop={e => onDrop(e, value)}
+      ondragend={onDragEnd}>
+      {@render item(value)}
+    </div>
+  {/each}
+</div>

src/routes/spaces/+page.svelte

@@ -1,13 +1,11 @@
 <script lang="ts">
   import {onMount} from "svelte"
-  import {flip} from "svelte/animate"
-  import {cubicOut} from "svelte/easing"
   import {derived as _derived} from "svelte/store"
-  import {addToMapKey, dec, insertAt, removeAt, sleep, spec} from "@welshman/lib"
+  import {addToMapKey, dec, sleep, spec} from "@welshman/lib"
   import {ROOMS} from "@welshman/util"
   import type {Relay} from "@welshman/domain"
   import {throttled} from "@welshman/store"
-  import {Sync, createSearch, publish} from "@welshman/app"
+  import {Sync, createSearch} from "@welshman/app"
   import {createScroller, isMobile} from "@lib/html"
   import {fly} from "@lib/transition"
   import DragHandle from "@assets/icons/drag-handle.svg?dataurl"
@@ -16,6 +14,7 @@
   import Magnifier from "@assets/icons/magnifier.svg?dataurl"
   import Icon from "@lib/components/Icon.svelte"
   import Button from "@lib/components/Button.svelte"
+  import DragList from "@lib/components/DragList.svelte"
   import Page from "@lib/components/Page.svelte"
   import PageBar from "@lib/components/PageBar.svelte"
   import PageContent from "@lib/components/PageContent.svelte"
@@ -27,7 +26,7 @@
   import SpaceInviteAccept from "@app/components/SpaceInviteAccept.svelte"
   import SpaceJoin from "@app/components/SpaceJoin.svelte"
   import {app, relays, roomLists, user} from "@app/core"
-  import {userSpaceUrls} from "@app/rooms"
+  import {reorderSpaceUrls, userSpaceUrls} from "@app/rooms"
   import {PLATFORM_RELAYS, DEFAULT_RELAYS} from "@app/env"
   import {bootstrapPubkeys} from "@app/social"
   import {parseInviteLink} from "@app/access"
@@ -85,108 +84,15 @@
     }
   }
 
-  const reconcileUrls = (currentUrls: string[], nextUrls: string[]) => {
-    const mergedUrls = currentUrls.filter(url => nextUrls.includes(url))
-
-    for (const url of nextUrls) {
-      if (!mergedUrls.includes(url)) {
-        mergedUrls.push(url)
-      }
-    }
-
-    return mergedUrls
-  }
-
-  const isSameOrder = (a: string[], b: string[]) =>
-    a.length === b.length && a.every((url, index) => url === b[index])
-
-  const reorderSpaceUrls = (targetUrl: string) => {
-    if (!draggedUrl) return
-
-    const sourceIndex = orderedSpaceUrls.indexOf(draggedUrl)
-    const targetIndex = orderedSpaceUrls.indexOf(targetUrl)
-
-    if (sourceIndex === -1 || targetIndex === -1 || sourceIndex === targetIndex) return
-
-    orderedSpaceUrls = insertAt(
-      targetIndex,
-      orderedSpaceUrls[sourceIndex],
-      removeAt(sourceIndex, orderedSpaceUrls),
-    )
-  }
-
-  const onDragStart = (e: DragEvent, url: string) => {
-    draggedUrl = url
-    dragStartOrder = [...orderedSpaceUrls]
-    lastDragTarget = undefined
-    didDrop = false
-
-    if (e.dataTransfer) {
-      e.dataTransfer.effectAllowed = "move"
-      e.dataTransfer.setData("text/plain", url)
-    }
-  }
-
-  const onDragOver = (e: DragEvent) => {
-    e.preventDefault()
-  }
-
-  const onDragEnter = (e: DragEvent, targetUrl: string) => {
-    e.preventDefault()
-
-    if (lastDragTarget === targetUrl) return
-
-    lastDragTarget = targetUrl
-    reorderSpaceUrls(targetUrl)
-  }
-
-  const onDrop = (e: DragEvent, targetUrl: string) => {
-    e.preventDefault()
-    reorderSpaceUrls(targetUrl)
-    didDrop = true
-    draggedUrl = undefined
-    lastDragTarget = undefined
-
-    if (dragStartOrder && !isSameOrder(dragStartOrder, orderedSpaceUrls)) {
-      void $roomLists.setRelays(orderedSpaceUrls).then(publish).catch(console.error)
-    }
-
-    dragStartOrder = undefined
-  }
-
-  const onDragEnd = () => {
-    if (!didDrop && dragStartOrder && !isSameOrder(dragStartOrder, orderedSpaceUrls)) {
-      orderedSpaceUrls = dragStartOrder
-    }
-
-    draggedUrl = undefined
-    dragStartOrder = undefined
-    lastDragTarget = undefined
-    didDrop = false
-  }
-
-  $effect(() => {
-    const nextUrls = reconcileUrls(orderedSpaceUrls, $userSpaceUrls)
-
-    if (!isSameOrder(nextUrls, orderedSpaceUrls)) {
-      orderedSpaceUrls = nextUrls
-    }
-  })
-
   let term = $state("")
   let limit = $state(20)
   let element: Element
-  let orderedSpaceUrls = $state<string[]>([])
-  let draggedUrl = $state<string | undefined>()
-  let dragStartOrder = $state<string[] | undefined>()
-  let lastDragTarget = $state<string | undefined>()
-  let didDrop = $state(false)
 
   const inviteData = $derived(parseInviteLink(term))
   const searchResults = $derived($relaySearch.searchOptions(term))
   const userSpaceSet = $derived(new Set($userSpaceUrls))
   const filteredUserUrls = $derived(
-    term ? orderedSpaceUrls.filter(url => searchResults.some(spec({url}))) : orderedSpaceUrls,
+    term ? $userSpaceUrls.filter(url => searchResults.some(spec({url}))) : $userSpaceUrls,
   )
   const otherSpaces = $derived(
     searchResults.filter(r => !userSpaceSet.has(r.url) && r.url !== inviteData?.url),
@@ -267,17 +173,13 @@
               {/if}
               {#if filteredUserUrls.length > 0}
                 <Divider>Your spaces</Divider>
-                {#each filteredUserUrls as url (url)}
-                  <div
-                    animate:flip={{duration: 300, easing: cubicOut}}
-                    class="transition-opacity duration-200 {draggedUrl === url ? 'opacity-50' : ''}"
-                    draggable="true"
-                    role="listitem"
-                    ondragstart={e => onDragStart(e, url)}
-                    ondragover={onDragOver}
-                    ondragenter={e => onDragEnter(e, url)}
-                    ondrop={e => onDrop(e, url)}
-                    ondragend={onDragEnd}>
+                <DragList
+                  class="flex flex-col gap-2"
+                  role="list"
+                  itemRole="listitem"
+                  items={filteredUserUrls}
+                  onReorder={reorderSpaceUrls}>
+                  {#snippet item(url)}
                     <Button
                       class="group card card-interactive w-full relative min-w-0"
                       onclick={() => openSpace(url)}>
@@ -294,8 +196,8 @@
                         </div>
                       {/if}
                     </Button>
-                  </div>
-                {/each}
+                  {/snippet}
+                </DragList>
               {:else if !term}
                 <p class="py-12 text-center">You haven't joined any spaces yet.</p>
               {/if}