From 0273c08f2306b3268c33e78a06ea2539f52a17f3 Mon Sep 17 00:00:00 2001
From: Tianer Zhou <zhoutianer@huawei.com>
Date: Wed, 19 Feb 2025 17:14:11 +0800
Subject: [PATCH] handle LazyForEach hybrid scenario

Signed-off-by: Tianer Zhou <zhoutianer@huawei.com>
---
 arkoala-arkts/arkui/src/LazyForEach.ts        | 48 +++++++++++++++++--
 arkoala-arkts/arkui/src/generated/PeerNode.ts |  1 +
 2 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/arkoala-arkts/arkui/src/LazyForEach.ts b/arkoala-arkts/arkui/src/LazyForEach.ts
index 3acd403c2..d07b1b456 100644
--- a/arkoala-arkts/arkui/src/LazyForEach.ts
+++ b/arkoala-arkts/arkui/src/LazyForEach.ts
@@ -13,10 +13,10 @@
  * limitations under the License.
  */
 
-import { __context, contextNode, memoEntry2, remember, rememberMutableState, scheduleCallback } from "@koalaui/runtime"
-import { hashCodeFromString, int32 } from "@koalaui/common"
+import { __context, __id, contextNode, DataNode, IncrementalNode, memoEntry2, remember, rememberMutableState, scheduleCallback } from "@koalaui/runtime"
+import { hashCodeFromString, int32, KoalaCallsiteKey } from "@koalaui/common"
 import { nullptr, pointer } from "@koalaui/interop";
-import { PeerNode } from "./generated/PeerNode";
+import { LazyForEachType, PeerNode, PeerNodeType } from "./generated/PeerNode";
 import { LazyForEachOps } from "./generated/ArkLazyForEachOpsMaterialized"
 
 // TODO: proper import [DataChangeListener] from lazy_for_each.d.ts
@@ -109,6 +109,40 @@ class VisibleRange {
     }
 }
 
+class LazyForEachIdentifier {
+    constructor(id: KoalaCallsiteKey, totalCnt: int32, activeCnt: int32) {
+        this.id = id
+        this.totalCnt = totalCnt
+        this.activeCnt = activeCnt
+    }
+    readonly id: KoalaCallsiteKey
+    readonly totalCnt: int32
+    readonly activeCnt: int32
+}
+
+/**
+ * @param id unique identifier of LazyForEach
+ * @returns item offset of LazyForEach in parent's children
+ */
+/** @memo */
+function getOffset(parent: PeerNode, id: KoalaCallsiteKey): int32 {
+    let offset = 0
+    for (let child = parent.firstChild; child; child = child!.nextSibling) {
+        // corresponding DataNode is attached after the generated items
+        let info = DataNode.extract<LazyForEachIdentifier>(LazyForEachType, child!!)
+        if (info?.id === id) {
+            offset -= info!.activeCnt
+            console.log(`offset = ${offset}`)
+            return offset
+        } else if (info) {
+            offset += info!.totalCnt - info!.activeCnt // active nodes are already counted
+        } else if (child.isKind(PeerNodeType)) {
+            ++offset
+        }
+    }
+    throw Error(`key not found ${id}`)
+}
+
 /** @memo */
 export function LazyForEach<T>(dataSource: IDataSource<T>,
     /** @memo */
@@ -121,7 +155,9 @@ export function LazyForEach<T>(dataSource: IDataSource<T>,
 	console.log(`LazyForEach current=${current.value} version=${version.value} mark=${mark.value}`)
 
     let parent = contextNode<PeerNode>()
-    const visibleRange = new VisibleRange(parent, current.value, current.value)
+
+    const currentLocal = current.value - getOffset(parent, __id()); // translated to local index
+    const visibleRange = new VisibleRange(parent, currentLocal, currentLocal)
     remember(() => {
         LazyForEachManager.OnRangeUpdate(visibleRange.parent, dataSource.totalCount() as int32, (currentIndex: int32, currentMark: pointer, end: int32) => {
             console.log(`LazyForEach[${parent}]: current updated to ${currentIndex} ${currentMark} end=${end}`)
@@ -161,4 +197,8 @@ export function LazyForEach<T>(dataSource: IDataSource<T>,
         LazyForEachManager.SetInsertMark(parent, moreUp ? visibleRange.markUp : visibleRange.markDown, moreUp)
 	}
 	parent.setInsertMark(nullptr, false)
+
+    // create DataNode to provide count information to parent
+    const activeCnt = visibleRange.indexDown - visibleRange.indexUp + 1
+    DataNode.attach<LazyForEachIdentifier>(LazyForEachType, new LazyForEachIdentifier(__id(), dataSource.totalCount() as int32, activeCnt))
 }
diff --git a/arkoala-arkts/arkui/src/generated/PeerNode.ts b/arkoala-arkts/arkui/src/generated/PeerNode.ts
index 7a30ef6f0..4702ed7f8 100644
--- a/arkoala-arkts/arkui/src/generated/PeerNode.ts
+++ b/arkoala-arkts/arkui/src/generated/PeerNode.ts
@@ -5,6 +5,7 @@ import { nullptr, pointer } from "@koalaui/interop"
 import { ArkRootPeer } from "./peers/ArkStaticComponentsPeer"
 
 export const PeerNodeType = 11
+export const LazyForEachType = 13
 const InitialID = 999
 
 export class PeerNode extends IncrementalNode {
-- 
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