From 5fa993392bea12670e8ccaf5ad7ed426d74c0503 Mon Sep 17 00:00:00 2001
From: cketti <cketti@thunderbird.net>
Date: Wed, 15 Mar 2023 15:20:35 +0100
Subject: [PATCH] Message Details: Use stable IDs for list items

---
 .../fsck/k9/ui/messagedetails/EmptyItem.kt    | 25 ++++++++++++
 .../messagedetails/MessageDetailsFragment.kt  | 38 +++++++++++++------
 .../main/res/values/message_details_ids.xml   |  1 +
 3 files changed, 52 insertions(+), 12 deletions(-)
 create mode 100644 app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/EmptyItem.kt

diff --git a/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/EmptyItem.kt b/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/EmptyItem.kt
new file mode 100644
index 000000000..30bcea9f6
--- /dev/null
+++ b/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/EmptyItem.kt
@@ -0,0 +1,25 @@
+package com.fsck.k9.ui.messagedetails
+
+import android.content.Context
+import android.view.View
+import android.view.ViewGroup
+import com.fsck.k9.ui.R
+import com.mikepenz.fastadapter.FastAdapter
+import com.mikepenz.fastadapter.items.AbstractItem
+
+internal class EmptyItem : AbstractItem<EmptyItem.ViewHolder>() {
+    override val type: Int = R.id.message_details_empty
+    override val layoutRes = 0
+
+    override fun createView(ctx: Context, parent: ViewGroup?): View {
+        return View(ctx)
+    }
+
+    override fun getViewHolder(v: View) = ViewHolder(v)
+
+    class ViewHolder(view: View) : FastAdapter.ViewHolder<EmptyItem>(view) {
+        override fun bindView(item: EmptyItem, payloads: List<Any>) = Unit
+
+        override fun unbindView(item: EmptyItem) = Unit
+    }
+}
diff --git a/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/MessageDetailsFragment.kt b/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/MessageDetailsFragment.kt
index a6f5d20c5..98672c2b3 100644
--- a/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/MessageDetailsFragment.kt
+++ b/app/ui/legacy/src/main/java/com/fsck/k9/ui/messagedetails/MessageDetailsFragment.kt
@@ -144,9 +144,7 @@ class MessageDetailsFragment : ToolbarBottomSheetDialogFragment() {
         val items = buildList {
             add(MessageDateItem(details.date ?: getString(R.string.message_details_missing_date)))
 
-            if (details.cryptoDetails != null) {
-                add(CryptoStatusItem(details.cryptoDetails))
-            }
+            addCryptoStatus(details)
 
             addParticipants(details.from, R.string.message_details_from_section_title, appearance)
             addParticipants(details.sender, R.string.message_details_sender_section_title, appearance)
@@ -158,14 +156,26 @@ class MessageDetailsFragment : ToolbarBottomSheetDialogFragment() {
             addParticipants(details.cc, R.string.message_details_cc_section_title, appearance)
             addParticipants(details.bcc, R.string.message_details_bcc_section_title, appearance)
 
-            if (details.folder != null) {
-                addFolderName(details.folder)
-            }
+            addFolderName(details.folder)
+        }
+
+        // Use list index as stable identifier. This means changes to the list may only update existing items or add
+        // new items to the end of the list. Use place holder items (EmptyItem) if necessary.
+        items.forEachIndexed { index, item ->
+            item.identifier = index.toLong()
         }
 
         itemAdapter.setNewList(items)
     }
 
+    private fun MutableList<GenericItem>.addCryptoStatus(details: MessageDetailsUi) {
+        if (details.cryptoDetails != null) {
+            add(CryptoStatusItem(details.cryptoDetails))
+        } else {
+            add(EmptyItem())
+        }
+    }
+
     private fun MutableList<GenericItem>.addParticipants(
         participants: List<Participant>,
         @StringRes title: Int,
@@ -188,12 +198,16 @@ class MessageDetailsFragment : ToolbarBottomSheetDialogFragment() {
         }
     }
 
-    private fun MutableList<GenericItem>.addFolderName(folder: FolderInfoUi) {
-        val folderNameItem = FolderNameItem(
-            displayName = folder.displayName,
-            iconResourceId = folderIconProvider.getFolderIcon(folder.type),
-        )
-        add(folderNameItem)
+    private fun MutableList<GenericItem>.addFolderName(folder: FolderInfoUi?) {
+        if (folder != null) {
+            val folderNameItem = FolderNameItem(
+                displayName = folder.displayName,
+                iconResourceId = folderIconProvider.getFolderIcon(folder.type),
+            )
+            add(folderNameItem)
+        } else {
+            add(EmptyItem())
+        }
     }
 
     private val cryptoStatusClickEventHook = object : ClickEventHook<CryptoStatusItem>() {
diff --git a/app/ui/legacy/src/main/res/values/message_details_ids.xml b/app/ui/legacy/src/main/res/values/message_details_ids.xml
index bc2f6e35f..82ef7db6e 100644
--- a/app/ui/legacy/src/main/res/values/message_details_ids.xml
+++ b/app/ui/legacy/src/main/res/values/message_details_ids.xml
@@ -6,4 +6,5 @@
     <item type="id" name="message_details_participant"/>
     <item type="id" name="message_details_folder_name"/>
     <item type="id" name="message_details_divider"/>
+    <item type="id" name="message_details_empty"/>
 </resources>