From bdb7fa6aa8db06c906b2b404d1ed1a6947983b6c Mon Sep 17 00:00:00 2001
From: Allan Wang <me@allanwang.ca>
Date: Thu, 22 Jun 2023 02:11:29 -0700
Subject: [PATCH] Add onDrop event

---
 .../frost/compose/draggable/DraggableState.kt | 20 +++++++++++++------
 .../frost/tabselector/TabSelectorScreen.kt    | 11 ++++++++--
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/app-compose/src/main/kotlin/com/pitchedapps/frost/compose/draggable/DraggableState.kt b/app-compose/src/main/kotlin/com/pitchedapps/frost/compose/draggable/DraggableState.kt
index a3f3db4b4..b04f79795 100644
--- a/app-compose/src/main/kotlin/com/pitchedapps/frost/compose/draggable/DraggableState.kt
+++ b/app-compose/src/main/kotlin/com/pitchedapps/frost/compose/draggable/DraggableState.kt
@@ -27,12 +27,16 @@ import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Rect
 import androidx.compose.ui.unit.IntSize
 
-@Composable
-fun <T> rememberDraggableState(): DraggableState<T> {
-  return remember { DraggableStateImpl() }
+typealias DraggableComposeContent = @Composable (isDragging: Boolean) -> Unit
+
+fun interface OnDrop<T> {
+  fun onDrop(dragTarget: String, dragData: T, dropTarget: String)
 }
 
-typealias DraggableComposeContent = @Composable (isDragging: Boolean) -> Unit
+@Composable
+fun <T> rememberDraggableState(onDrop: OnDrop<T>): DraggableState<T> {
+  return remember(onDrop) { DraggableStateImpl(onDrop) }
+}
 
 interface DraggableState<T> {
 
@@ -58,7 +62,7 @@ interface DraggableState<T> {
   @Composable fun rememberDropTarget(key: String): DropTargetState<T>
 }
 
-class DraggableStateImpl<T> : DraggableState<T> {
+class DraggableStateImpl<T>(private val onDrop: OnDrop<T>) : DraggableState<T> {
   private val activeDragTargets = mutableStateMapOf<String, DragTargetState<T>>()
 
   private val dropTargets = mutableStateMapOf<String, DropTargetState<T>>()
@@ -79,9 +83,13 @@ class DraggableStateImpl<T> : DraggableState<T> {
   }
 
   override fun onDragEnd(key: String) {
-    activeDragTargets.remove(key)
+    val dragTarget = activeDragTargets.remove(key)
     for ((dropKey, dropTarget) in dropTargets) {
       if (dropTarget.hoverKey == key) {
+        if (dragTarget != null) {
+          onDrop.onDrop(dragTarget = key, dragData = dragTarget.data, dropTarget = dropKey)
+        }
+
         setHover(dragKey = null, dropKey)
         // Check other drag targets in case one meets drag requirements
         checkForDrop(dropKey)
diff --git a/app-compose/src/main/kotlin/com/pitchedapps/frost/tabselector/TabSelectorScreen.kt b/app-compose/src/main/kotlin/com/pitchedapps/frost/tabselector/TabSelectorScreen.kt
index 7a0ce7b1d..8855c5258 100644
--- a/app-compose/src/main/kotlin/com/pitchedapps/frost/tabselector/TabSelectorScreen.kt
+++ b/app-compose/src/main/kotlin/com/pitchedapps/frost/tabselector/TabSelectorScreen.kt
@@ -100,7 +100,14 @@ fun TabSelector(
   unselected: List<TabData>,
   onSelect: (List<TabData>) -> Unit
 ) {
-  val draggableState = rememberDraggableState<TabData>()
+  val draggableState =
+    rememberDraggableState<TabData>(
+      onDrop = { _, dragData, dropTarget ->
+        onSelect(
+          selected.map { if (it.key == dropTarget) dragData else it },
+        )
+      },
+    )
 
   DragContainer(modifier = modifier, draggableState = draggableState) {
     Column(modifier = Modifier.statusBarsPadding()) {
@@ -196,7 +203,7 @@ fun DraggingTabItem(
     transition.animateColor(label = "Background") {
       if (it)
         MaterialTheme.colorScheme.surfaceVariant.copy(
-          LocalRippleTheme.current.rippleAlpha().pressedAlpha
+          LocalRippleTheme.current.rippleAlpha().pressedAlpha,
         )
       else MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.85f)
     }