feat: implement add mode in PlaylistEditPage; add drag-and-drop functionality for managing available sounds

src/pages/PlaylistEditPage.tsx

@@ -2,7 +2,9 @@ import { useEffect, useState, useCallback } from 'react'
 import { useParams, useNavigate } from 'react-router'
 import {
   DndContext,
-  DragEndEvent,
+  type DragEndEvent,
+  type DragStartEvent,
+  type DragOverEvent,
   closestCenter,
   PointerSensor,
   useSensor,
@@ -13,9 +15,11 @@ import {
   verticalListSortingStrategy,
   useSortable,
 } from '@dnd-kit/sortable'
+import { useDroppable } from '@dnd-kit/core'
 import { CSS } from '@dnd-kit/utilities'
 import { AppLayout } from '@/components/AppLayout'
 import { playlistsService, type Playlist, type PlaylistSound } from '@/lib/api/services/playlists'
+import { soundsService, type Sound } from '@/lib/api/services/sounds'
 import { Skeleton } from '@/components/ui/skeleton'
 import { Input } from '@/components/ui/input'
 import { Button } from '@/components/ui/button'
@@ -24,7 +28,7 @@ import { Label } from '@/components/ui/label'
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
 import { Badge } from '@/components/ui/badge'
 import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from '@/components/ui/table'
-import { AlertCircle, Save, Music, Clock, ChevronUp, ChevronDown, Trash2, RefreshCw, Edit, X, ArrowLeft } from 'lucide-react'
+import { AlertCircle, Save, Music, Clock, ChevronUp, ChevronDown, Trash2, RefreshCw, Edit, X, Plus, Minus } from 'lucide-react'
 import { toast } from 'sonner'
 import { formatDuration } from '@/utils/format-duration'
 
@@ -137,6 +141,173 @@ function SortableTableRow({
   )
 }
 
+// Simplified sortable row component for add mode
+interface SimpleSortableRowProps {
+  sound: PlaylistSound
+  index: number
+  onRemoveSound: (soundId: number) => void
+}
+
+function SimpleSortableRow({ sound, index, onRemoveSound }: SimpleSortableRowProps) {
+  const {
+    attributes,
+    listeners,
+    setNodeRef,
+    transform,
+    transition,
+    isDragging,
+  } = useSortable({ id: `playlist-sound-${sound.id}` })
+
+  const style = {
+    transform: CSS.Transform.toString(transform),
+    transition,
+    opacity: isDragging ? 0.8 : 1,
+  }
+
+  return (
+    <div
+      ref={setNodeRef}
+      style={style}
+      className="flex items-center justify-between p-3 border rounded-lg hover:bg-muted/50 group"
+    >
+      <div className="flex items-center gap-3 flex-1 min-w-0">
+        <div 
+          className="flex items-center justify-center cursor-grab active:cursor-grabbing"
+          {...attributes}
+          {...listeners}
+        >
+          <div className="flex flex-col gap-0.5">
+            <div className="w-1 h-1 bg-muted-foreground/60 rounded-full"></div>
+            <div className="w-1 h-1 bg-muted-foreground/60 rounded-full"></div>
+            <div className="w-1 h-1 bg-muted-foreground/60 rounded-full"></div>
+          </div>
+        </div>
+        
+        <span className="text-sm font-mono text-muted-foreground w-6 text-center">
+          {index + 1}
+        </span>
+        
+        <Music className="h-4 w-4 text-muted-foreground flex-shrink-0" />
+        
+        <div className="min-w-0 flex-1">
+          <div className="font-medium truncate">
+            {sound.name}
+          </div>
+        </div>
+      </div>
+
+      <Button
+        size="sm"
+        variant="ghost"
+        onClick={() => onRemoveSound(sound.id)}
+        className="h-8 w-8 p-0 text-destructive hover:text-destructive opacity-0 group-hover:opacity-100 transition-opacity"
+        title="Remove from playlist"
+      >
+        <X className="h-4 w-4" />
+      </Button>
+    </div>
+  )
+}
+
+// Available sound component for dragging
+interface AvailableSoundProps {
+  sound: Sound
+}
+
+function AvailableSound({ sound }: AvailableSoundProps) {
+  const {
+    attributes,
+    listeners,
+    setNodeRef,
+    transform,
+    transition,
+    isDragging,
+  } = useSortable({ id: `available-sound-${sound.id}` })
+
+  const style = {
+    transform: CSS.Transform.toString(transform),
+    transition,
+    opacity: isDragging ? 0.8 : 1,
+  }
+
+  return (
+    <div
+      ref={setNodeRef}
+      style={style}
+      className="flex items-center gap-3 p-3 border rounded-lg hover:bg-muted/50 cursor-grab active:cursor-grabbing"
+      {...attributes}
+      {...listeners}
+    >
+      <Music className="h-4 w-4 text-muted-foreground flex-shrink-0" />
+      
+      <div className="min-w-0 flex-1">
+        <div className="font-medium truncate">
+          {sound.name}
+        </div>
+      </div>
+    </div>
+  )
+}
+
+// Drop zone component for inserting sounds at specific positions
+interface DropZoneProps {
+  index: number
+  isActive: boolean
+}
+
+function DropZone({ index, isActive }: DropZoneProps) {
+  const { isOver, setNodeRef } = useDroppable({ 
+    id: `drop-zone-${index}`,
+    data: { type: 'dropzone', index }
+  })
+
+  return (
+    <div
+      ref={setNodeRef}
+      className={`h-2 transition-colors ${
+        isActive || isOver 
+          ? 'bg-primary/30 border-2 border-dashed border-primary' 
+          : 'transparent'
+      }`}
+    />
+  )
+}
+
+// Inline preview component that shows where the sound will be dropped
+interface InlinePreviewProps {
+  sound: Sound | PlaylistSound
+  position: number
+}
+
+function InlinePreview({ sound, position }: InlinePreviewProps) {
+  return (
+    <div className="flex items-center gap-3 p-3 border-2 border-dashed border-primary rounded-lg bg-primary/10 animate-pulse">
+      <div className="flex items-center justify-center">
+        <div className="flex flex-col gap-0.5">
+          <div className="w-1 h-1 bg-primary/60 rounded-full"></div>
+          <div className="w-1 h-1 bg-primary/60 rounded-full"></div>
+          <div className="w-1 h-1 bg-primary/60 rounded-full"></div>
+        </div>
+      </div>
+      
+      <span className="text-sm font-mono text-primary w-6 text-center">
+        {position + 1}
+      </span>
+      
+      <Music className="h-4 w-4 text-primary flex-shrink-0" />
+      
+      <div className="min-w-0 flex-1">
+        <div className="font-medium truncate text-primary">
+          {sound.name}
+        </div>
+        <div className="text-xs text-primary/70">
+          Will be added here
+        </div>
+      </div>
+    </div>
+  )
+}
+
 
 export function PlaylistEditPage() {
   const { id } = useParams<{ id: string }>()
@@ -151,6 +322,14 @@ export function PlaylistEditPage() {
   const [saving, setSaving] = useState(false)
   const [isEditMode, setIsEditMode] = useState(false)
   
+  // Add mode state
+  const [isAddMode, setIsAddMode] = useState(false)
+  const [availableSounds, setAvailableSounds] = useState<Sound[]>([])
+  const [availableSoundsLoading, setAvailableSoundsLoading] = useState(false)
+  const [draggedItem, setDraggedItem] = useState<string | null>(null)
+  const [draggedSound, setDraggedSound] = useState<Sound | PlaylistSound | null>(null)
+  const [dropPosition, setDropPosition] = useState<number | null>(null)
+  
   
   // dnd-kit sensors
   const sensors = useSensors(
@@ -204,6 +383,30 @@ export function PlaylistEditPage() {
     }
   }, [playlistId])
 
+  const fetchAvailableSounds = useCallback(async () => {
+    try {
+      setAvailableSoundsLoading(true)
+      const soundsData = await soundsService.getSoundsByType('EXT')
+      // Filter out sounds that are already in the playlist
+      const playlistSoundIds = new Set(sounds.map(s => s.id))
+      const filteredSounds = soundsData.filter(sound => !playlistSoundIds.has(sound.id))
+      setAvailableSounds(filteredSounds)
+    } catch (err) {
+      const errorMessage = err instanceof Error ? err.message : 'Failed to fetch available sounds'
+      toast.error(errorMessage)
+    } finally {
+      setAvailableSoundsLoading(false)
+    }
+  }, [sounds])
+
+  const toggleAddMode = async () => {
+    if (!isAddMode) {
+      // Entering add mode - fetch available sounds
+      await fetchAvailableSounds()
+    }
+    setIsAddMode(!isAddMode)
+  }
+
   useEffect(() => {
     if (!isNaN(playlistId)) {
       fetchPlaylist()
@@ -324,10 +527,28 @@ export function PlaylistEditPage() {
 
   const handleRemoveSound = async (soundId: number) => {
     try {
+      // Find the sound being removed to check if it's EXT type
+      const removedSound = sounds.find(s => s.id === soundId)
+      
       await playlistsService.removeSoundFromPlaylist(playlistId, soundId)
       setSounds(prev => prev.filter(sound => sound.id !== soundId))
       toast.success('Sound removed from playlist')
       
+      // If it's an EXT sound and we're in add mode, add it back to available sounds
+      if (isAddMode && removedSound && removedSound.type === 'EXT') {
+        // Get the full sound data from the API to add back to available sounds
+        try {
+          const allExtSounds = await soundsService.getSoundsByType('EXT')
+          const soundToAddBack = allExtSounds.find(s => s.id === soundId)
+          if (soundToAddBack) {
+            setAvailableSounds(prev => [...prev, soundToAddBack].sort((a, b) => a.name.localeCompare(b.name)))
+          }
+        } catch (err) {
+          // If we can't fetch the sound data, just refresh the available sounds
+          await fetchAvailableSounds()
+        }
+      }
+      
       // Refresh playlist data to update counts
       await fetchPlaylist()
     } catch (err) {
@@ -337,19 +558,78 @@ export function PlaylistEditPage() {
   }
 
 
-  // dnd-kit drag handler
+  const handleDragStart = (event: DragStartEvent) => {
+    const draggedId = event.active.id.toString()
+    setDraggedItem(draggedId)
+    setDropPosition(null) // Clear any previous drop position
+    
+    // Find the sound being dragged
+    if (draggedId.startsWith('available-sound-')) {
+      const soundId = parseInt(draggedId.replace('available-sound-', ''), 10)
+      const sound = availableSounds.find(s => s.id === soundId)
+      setDraggedSound(sound || null)
+    } else if (draggedId.startsWith('playlist-sound-') || draggedId.startsWith('table-sound-')) {
+      const soundId = parseInt(
+        draggedId.replace('playlist-sound-', '').replace('table-sound-', ''), 10
+      )
+      const sound = sounds.find(s => s.id === soundId)
+      setDraggedSound(sound || null)
+    }
+  }
+
   const handleDragEnd = async (event: DragEndEvent) => {
     const { active, over } = event
+    setDraggedItem(null)
+    setDraggedSound(null)
+    setDropPosition(null)
     
     if (!over) return
     
     const activeId = active.id as string
     const overId = over.id as string
     
-    // Only handle table-sound reordering
-    if (overId.startsWith('table-sound-')) {
-      const draggedSoundId = parseInt(activeId.replace('table-sound-', ''), 10)
-      const targetSoundId = parseInt(overId.replace('table-sound-', ''), 10)
+    // Handle adding sound from available list to playlist
+    if (activeId.startsWith('available-sound-') && (overId.startsWith('playlist-sound-') || overId.startsWith('drop-zone-'))) {
+      const soundId = parseInt(activeId.replace('available-sound-', ''), 10)
+      
+      let position = sounds.length // Default to end
+      
+      if (overId.startsWith('playlist-sound-')) {
+        const targetSoundId = parseInt(overId.replace('playlist-sound-', ''), 10)
+        const targetIndex = sounds.findIndex(s => s.id === targetSoundId)
+        position = targetIndex
+      } else if (overId.startsWith('drop-zone-')) {
+        position = parseInt(overId.replace('drop-zone-', ''), 10)
+      }
+      
+      try {
+        await playlistsService.addSoundToPlaylist(playlistId, soundId, position)
+        toast.success('Sound added to playlist')
+        
+        // Refresh playlist sounds first
+        await fetchSounds()
+        
+        // Immediately remove the added sound from available sounds
+        if (isAddMode) {
+          setAvailableSounds(prev => prev.filter(s => s.id !== soundId))
+        }
+      } catch (err) {
+        const errorMessage = err instanceof Error ? err.message : 'Failed to add sound to playlist'
+        toast.error(errorMessage)
+      }
+      return
+    }
+    
+    // Handle reordering sounds within playlist (both table and simple view)
+    if ((activeId.startsWith('table-sound-') && overId.startsWith('table-sound-')) || 
+        (activeId.startsWith('playlist-sound-') && overId.startsWith('playlist-sound-'))) {
+      
+      const draggedSoundId = parseInt(
+        activeId.replace('table-sound-', '').replace('playlist-sound-', ''), 10
+      )
+      const targetSoundId = parseInt(
+        overId.replace('table-sound-', '').replace('playlist-sound-', ''), 10
+      )
       
       const draggedIndex = sounds.findIndex(s => s.id === draggedSoundId)
       const targetIndex = sounds.findIndex(s => s.id === targetSoundId)
@@ -375,6 +655,29 @@ export function PlaylistEditPage() {
     }
   }
 
+  const handleDragOver = (event: DragOverEvent) => {
+    const { active, over } = event
+    
+    // Only show preview when dragging available sounds
+    if (!active.id.toString().startsWith('available-sound-') || !over) {
+      setDropPosition(null)
+      return
+    }
+    
+    const overId = over.id.toString()
+    
+    if (overId.startsWith('playlist-sound-')) {
+      const targetSoundId = parseInt(overId.replace('playlist-sound-', ''), 10)
+      const targetIndex = sounds.findIndex(s => s.id === targetSoundId)
+      setDropPosition(targetIndex)
+    } else if (overId.startsWith('drop-zone-')) {
+      const position = parseInt(overId.replace('drop-zone-', ''), 10)
+      setDropPosition(position)
+    } else {
+      setDropPosition(null)
+    }
+  }
+
   if (loading) {
     return (
       <AppLayout 
@@ -429,7 +732,9 @@ export function PlaylistEditPage() {
     <DndContext
       sensors={sensors}
       collisionDetection={closestCenter}
+      onDragStart={handleDragStart}
       onDragEnd={handleDragEnd}
+      onDragOver={handleDragOver}
     >
       <AppLayout 
         breadcrumb={{
@@ -624,6 +929,14 @@ export function PlaylistEditPage() {
                 Playlist Sounds ({sounds.length})
               </CardTitle>
               <div className="flex items-center gap-2">
+                <Button
+                  variant={isAddMode ? "default" : "outline"}
+                  size="sm"
+                  onClick={toggleAddMode}
+                  title={isAddMode ? "Exit add mode" : "Enter add mode to add EXT sounds"}
+                >
+                  {isAddMode ? <Minus className="h-4 w-4" /> : <Plus className="h-4 w-4" />}
+                </Button>
                 <Button
                   variant="outline"
                   size="sm"
@@ -647,7 +960,79 @@ export function PlaylistEditPage() {
                 <Music className="h-8 w-8 mx-auto mb-2 opacity-50" />
                 <p>No sounds in this playlist</p>
               </div>
+            ) : isAddMode ? (
+              // Add Mode: Split layout with simplified playlist and available sounds
+              <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
+                {/* Current Playlist Sounds - Simplified */}
+                <div className="space-y-2">
+                  <h4 className="font-medium text-sm text-muted-foreground mb-3">Current Playlist</h4>
+                  <SortableContext 
+                    items={sounds.map(sound => `playlist-sound-${sound.id}`)}
+                    strategy={verticalListSortingStrategy}
+                  >
+                    <div className="space-y-1">
+                      <DropZone index={0} isActive={draggedItem?.startsWith('available-sound-') || false} />
+                      {sounds.map((sound, index) => {
+                        const adjustedIndex = dropPosition !== null && dropPosition <= index ? index + 1 : index
+                        return (
+                          <div key={sound.id}>
+                            {/* Show inline preview if this is the drop position */}
+                            {dropPosition === index && draggedSound && draggedItem?.startsWith('available-sound-') && (
+                              <InlinePreview sound={draggedSound} position={dropPosition} />
+                            )}
+                            <SimpleSortableRow
+                              sound={sound}
+                              index={adjustedIndex}
+                              onRemoveSound={handleRemoveSound}
+                            />
+                            <DropZone index={index + 1} isActive={draggedItem?.startsWith('available-sound-') || false} />
+                          </div>
+                        )
+                      })}
+                      {/* Show inline preview at the end if that's the drop position */}
+                      {dropPosition === sounds.length && draggedSound && draggedItem?.startsWith('available-sound-') && (
+                        <InlinePreview sound={draggedSound} position={dropPosition} />
+                      )}
+                    </div>
+                  </SortableContext>
+                </div>
+
+                {/* Available Sounds */}
+                <div className="space-y-2">
+                  <h4 className="font-medium text-sm text-muted-foreground mb-3">
+                    Available EXT Sounds ({availableSounds.length})
+                  </h4>
+                  {availableSoundsLoading ? (
+                    <div className="space-y-2">
+                      {Array.from({ length: 3 }).map((_, i) => (
+                        <Skeleton key={i} className="h-16 w-full" />
+                      ))}
+                    </div>
+                  ) : availableSounds.length === 0 ? (
+                    <div className="text-center py-8 text-muted-foreground">
+                      <Music className="h-8 w-8 mx-auto mb-2 opacity-50" />
+                      <p className="text-sm">No EXT sounds available</p>
+                      <p className="text-xs mt-1">All EXT sounds are already in this playlist</p>
+                    </div>
                   ) : (
+                    <SortableContext 
+                      items={availableSounds.map(sound => `available-sound-${sound.id}`)}
+                      strategy={verticalListSortingStrategy}
+                    >
+                      <div className="space-y-2 max-h-96 overflow-y-auto">
+                        {availableSounds.map((sound) => (
+                          <AvailableSound
+                            key={sound.id}
+                            sound={sound}
+                          />
+                        ))}
+                      </div>
+                    </SortableContext>
+                  )}
+                </div>
+              </div>
+            ) : (
+              // Normal Mode: Full table view
               <div className="rounded-md border">
                 <SortableContext 
                   items={sounds.map(sound => `table-sound-${sound.id}`)}