From 9ea4a03f21b415fa9cf4ec2f2e87a59390027d67 Mon Sep 17 00:00:00 2001
From: Alex Tran <alex.tran1502@gmail.com>
Date: Wed, 20 May 2026 14:57:34 -0500
Subject: [PATCH] drag and drop

---
 i18n/en.json                                  |   1 +
 .../workflows/[workflowId]/+page.svelte       | 233 +++++++++++++-----
 .../[workflowId]/WorkflowStepDragImage.svelte |  43 ++++
 3 files changed, 217 insertions(+), 60 deletions(-)
 create mode 100644 web/src/routes/(user)/workflows/[workflowId]/WorkflowStepDragImage.svelte

diff --git a/i18n/en.json b/i18n/en.json
index 054408dff9..05fb92fc8c 100644
--- a/i18n/en.json
+++ b/i18n/en.json
@@ -976,6 +976,7 @@
   "downloading_asset_filename": "Downloading asset {filename}",
   "downloading_from_icloud": "Downloading from iCloud",
   "downloading_media": "Downloading media",
+  "drag_to_reorder": "Drag to reorder",
   "drop_files_to_upload": "Drop files anywhere to upload",
   "duplicates": "Duplicates",
   "duplicates_description": "Resolve each group by indicating which, if any, are duplicates.",
diff --git a/web/src/routes/(user)/workflows/[workflowId]/+page.svelte b/web/src/routes/(user)/workflows/[workflowId]/+page.svelte
index 227ec46d49..e80c564f5a 100644
--- a/web/src/routes/(user)/workflows/[workflowId]/+page.svelte
+++ b/web/src/routes/(user)/workflows/[workflowId]/+page.svelte
@@ -39,6 +39,7 @@
     mdiAutoFix,
     mdiCodeJson,
     mdiContentSave,
+    mdiDragVertical,
     mdiFilterVariant,
     mdiFlashOutline,
     mdiFormatListBulletedSquare,
@@ -48,9 +49,11 @@
     mdiTrashCanOutline,
   } from '@mdi/js';
   import { cloneDeep, isEqual } from 'lodash-es';
+  import { flushSync } from 'svelte';
   import { t } from 'svelte-i18n';
   import type { PageData } from './$types';
   import WorkflowJsonEditor from './WorkflowJsonEditor.svelte';
+  import WorkflowStepDragImage from './WorkflowStepDragImage.svelte';
   import WorkflowSummary from './WorkflowSummary.svelte';
 
   type WorkflowJsonContent = Required<
@@ -58,6 +61,12 @@
   >;
 
   type EditMode = 'visual' | 'json';
+  type StepDragImage = {
+    description?: string;
+    isFilter: boolean;
+    label: string;
+    stepNumber: number;
+  };
 
   type Props = {
     data: PageData;
@@ -71,6 +80,11 @@
   let isShowingNavigationDialog = $state(false);
   let isSaving = $state(false);
   let editMode = $state<EditMode>('visual');
+  let draggedIndex = $state<number | null>(null);
+  let dragHandleHoverIndex = $state<number | null>(null);
+  let dragImageElement = $state<HTMLElement | null>(null);
+  let dragImage = $state<StepDragImage>({ isFilter: false, label: '', stepNumber: 1 });
+  let dropTargetIndex = $state<number | null>(null);
 
   const workflowSummary = $derived({ name, description, trigger, steps });
   const workflowJsonContent = $derived<WorkflowJsonContent>({ description, enabled, name, steps, trigger });
@@ -112,6 +126,66 @@
     }
   };
 
+  const handleDragStart = (index: number) => (event: DragEvent) => {
+    draggedIndex = index;
+    if (event.dataTransfer) {
+      event.dataTransfer.effectAllowed = 'move';
+      event.dataTransfer.setData('text/plain', String(index));
+
+      const step = steps[index];
+      const method = step ? pluginManager.getMethod(step.method) : undefined;
+      dragImage = {
+        description: method?.description,
+        isFilter: method?.uiHints?.includes('filter') ?? false,
+        label: step ? pluginManager.getMethodLabel(step.method) : '',
+        stepNumber: index + 1,
+      };
+      flushSync();
+
+      if (dragImageElement) {
+        event.dataTransfer.setDragImage(dragImageElement, 16, 22);
+      }
+    }
+  };
+
+  const handleDragOver = (index: number) => (event: DragEvent) => {
+    if (draggedIndex === null) {
+      return;
+    }
+    event.preventDefault();
+    if (event.dataTransfer) {
+      event.dataTransfer.dropEffect = 'move';
+    }
+    if (dropTargetIndex !== index) {
+      dropTargetIndex = index;
+    }
+  };
+
+  const handleDragLeave = (index: number) => () => {
+    if (dropTargetIndex === index) {
+      dropTargetIndex = null;
+    }
+  };
+
+  const handleDrop = (index: number) => (event: DragEvent) => {
+    event.preventDefault();
+    const from = draggedIndex;
+    draggedIndex = null;
+    dropTargetIndex = null;
+    if (from === null || from === index) {
+      return;
+    }
+    const next = [...steps];
+    [next[from], next[index]] = [next[index], next[from]];
+    steps = next;
+  };
+
+  const handleDragEnd = () => {
+    draggedIndex = null;
+    dragHandleHoverIndex = null;
+    dropTargetIndex = null;
+  };
+
   const handleDeleteStep = async (index: number) => {
     const confirmed = await modalManager.showDialog({ title: $t('step_delete'), prompt: $t('step_delete_confirm') });
     if (confirmed) {
@@ -364,70 +438,102 @@
         {#each stepsWithConfigEntries as { step, configEntries }, index (index)}
           {@const method = pluginManager.getMethod(step.method)}
           {@const isFilter = method?.uiHints?.includes('filter') ?? false}
+          {@const isDragging = draggedIndex === index}
+          {@const isDragHandleHovered = dragHandleHoverIndex === index}
+          {@const isDropTarget = dropTargetIndex === index && draggedIndex !== null && draggedIndex !== index}
           {@render sequenceConnector()}
-          <Card class="{isFilter ? '' : ''} shadow-none">
-            <CardHeader>
-              <div class="flex items-center gap-3">
-                <div
-                  class="flex size-10 shrink-0 items-center justify-center rounded-lg"
-                  class:bg-primary-50={isFilter}
-                  class:bg-warning-50={!isFilter}
-                >
-                  <Icon
-                    icon={isFilter ? mdiFilterVariant : mdiAutoFix}
-                    size="20"
-                    class={isFilter ? 'text-primary' : 'text-warning'}
-                  />
-                </div>
-                <div class="flex min-w-0 flex-1 flex-col">
-                  <CardTitle class="truncate">
-                    <span class="mr-1 font-bold text-light-500">{index + 1}</span>
-                    {pluginManager.getMethodLabel(step.method)}
-                  </CardTitle>
-                  {#if method?.description}
-                    <CardDescription class="truncate">{method.description}</CardDescription>
-                  {/if}
-                </div>
-                <div class="flex shrink-0 items-center gap-1">
-                  <IconButton
-                    icon={mdiPencilOutline}
-                    aria-label={$t('edit')}
-                    variant="ghost"
-                    shape="round"
-                    color="secondary"
-                    size="small"
-                    onclick={() => handleEditStep(index)}
-                  />
-                  <IconButton
-                    icon={mdiTrashCanOutline}
-                    aria-label={$t('delete')}
-                    variant="ghost"
-                    shape="round"
-                    color="danger"
-                    size="small"
-                    onclick={() => handleDeleteStep(index)}
-                  />
-                </div>
-              </div>
-            </CardHeader>
-
-            {#if configEntries.length > 0}
-              <CardBody class="py-3">
-                <div class="flex flex-wrap items-center gap-1.5">
-                  {#each configEntries as [key, value] (key)}
-                    <Badge
-                      color={isFilter ? 'info' : 'warning'}
+          <div
+            class="w-full transition-all"
+            class:opacity-40={isDragging}
+            class:scale-[0.99]={isDragging}
+            ondragover={handleDragOver(index)}
+            ondragleave={handleDragLeave(index)}
+            ondrop={handleDrop(index)}
+            role="listitem"
+          >
+            <Card
+              class="shadow-none transition-colors {isDropTarget
+                ? 'border-primary ring-2 ring-primary-200'
+                : isDragHandleHovered
+                  ? 'border-dashed border-primary'
+                  : ''}"
+            >
+              <CardHeader>
+                <div class="flex items-center gap-2">
+                  <!-- svelte-ignore a11y_no_static_element_interactions -->
+                  <div
+                    class="flex shrink-0 cursor-grab items-center justify-center rounded-md border border-transparent p-1 text-light-400 select-none hover:border-primary-200 hover:bg-primary-50 hover:text-primary active:cursor-grabbing"
+                    aria-label={$t('drag_to_reorder')}
+                    draggable="true"
+                    onmouseenter={() => (dragHandleHoverIndex = index)}
+                    onmouseleave={() => (dragHandleHoverIndex = null)}
+                    ondragstart={handleDragStart(index)}
+                    ondragend={handleDragEnd}
+                    title={$t('drag_to_reorder')}
+                  >
+                    <Icon icon={mdiDragVertical} size="20" />
+                  </div>
+                  <div
+                    class="flex size-10 shrink-0 items-center justify-center rounded-lg"
+                    class:bg-primary-50={isFilter}
+                    class:bg-warning-50={!isFilter}
+                  >
+                    <Icon
+                      icon={isFilter ? mdiFilterVariant : mdiAutoFix}
+                      size="20"
+                      class={isFilter ? 'text-primary' : 'text-warning'}
+                    />
+                  </div>
+                  <div class="flex min-w-0 flex-1 flex-col">
+                    <CardTitle class="truncate">
+                      <span class="mr-1 font-bold text-light-500">{index + 1}</span>
+                      {pluginManager.getMethodLabel(step.method)}
+                    </CardTitle>
+                    {#if method?.description}
+                      <CardDescription class="truncate">{method.description}</CardDescription>
+                    {/if}
+                  </div>
+                  <div class="flex shrink-0 items-center gap-1">
+                    <IconButton
+                      icon={mdiPencilOutline}
+                      aria-label={$t('edit')}
+                      variant="ghost"
                       shape="round"
+                      color="secondary"
                       size="small"
-                      class="border font-mono {isFilter ? 'border-primary-200' : 'border-warning-200'}"
-                    >
-                      <span class="opacity-60">{key}</span>{formatConfigValue(value)}
-                    </Badge>
-                  {/each}
+                      onclick={() => handleEditStep(index)}
+                    />
+                    <IconButton
+                      icon={mdiTrashCanOutline}
+                      aria-label={$t('delete')}
+                      variant="ghost"
+                      shape="round"
+                      color="danger"
+                      size="small"
+                      onclick={() => handleDeleteStep(index)}
+                    />
+                  </div>
                 </div>
-              </CardBody>
-            {/if}
-          </Card>
+              </CardHeader>
+
+              {#if configEntries.length > 0}
+                <CardBody class="py-3">
+                  <div class="flex flex-wrap items-center gap-1.5">
+                    {#each configEntries as [key, value] (key)}
+                      <Badge
+                        color={isFilter ? 'info' : 'warning'}
+                        shape="round"
+                        size="small"
+                        class="border font-mono {isFilter ? 'border-primary-200' : 'border-warning-200'}"
+                      >
+                        <span class="opacity-60">{key}</span>{formatConfigValue(value)}
+                      </Badge>
+                    {/each}
+                  </div>
+                </CardBody>
+              {/if}
+            </Card>
+          </div>
         {/each}
 
         <Button
@@ -446,5 +552,12 @@
     </VStack>
   </Container>
 
+  <WorkflowStepDragImage
+    bind:ref={dragImageElement}
+    description={dragImage.description}
+    isFilter={dragImage.isFilter}
+    label={dragImage.label}
+    stepNumber={dragImage.stepNumber}
+  />
   <WorkflowSummary workflow={workflowSummary} />
 </AppShell>
diff --git a/web/src/routes/(user)/workflows/[workflowId]/WorkflowStepDragImage.svelte b/web/src/routes/(user)/workflows/[workflowId]/WorkflowStepDragImage.svelte
new file mode 100644
index 0000000000..adee9a5866
--- /dev/null
+++ b/web/src/routes/(user)/workflows/[workflowId]/WorkflowStepDragImage.svelte
@@ -0,0 +1,43 @@
+<script lang="ts">
+  import { Icon } from '@immich/ui';
+  import { mdiAutoFix, mdiFilterVariant } from '@mdi/js';
+
+  type Props = {
+    ref?: HTMLElement | null;
+    description?: string;
+    isFilter: boolean;
+    label: string;
+    stepNumber: number;
+  };
+
+  let { ref = $bindable(null), description, isFilter, label, stepNumber }: Props = $props();
+</script>
+
+<div
+  bind:this={ref}
+  aria-hidden="true"
+  class="pointer-events-none fixed top-[-1000px] left-0 flex w-80 items-center gap-2.5 rounded-lg border border-light-200 bg-light px-3 py-2.5 text-sm/5 text-dark shadow-2xl"
+>
+  <div
+    class="flex size-8 shrink-0 items-center justify-center rounded-lg"
+    class:bg-primary-50={isFilter}
+    class:bg-warning-50={!isFilter}
+  >
+    <Icon
+      icon={isFilter ? mdiFilterVariant : mdiAutoFix}
+      size="18"
+      class={isFilter ? 'text-primary' : 'text-warning'}
+    />
+  </div>
+
+  <div class="min-w-0 flex-1">
+    <div class="flex min-w-0 items-center gap-2">
+      <span class="shrink-0 font-bold text-light-500">#{stepNumber}</span>
+      <span class="truncate font-bold">{label}</span>
+    </div>
+
+    {#if description}
+      <div class="mt-0.5 truncate text-xs/4 text-light-500">{description}</div>
+    {/if}
+  </div>
+</div>