From 543545d93dfcaeda47ebaa29bb114c1063d3ace5 Mon Sep 17 00:00:00 2001
From: Abdelilah El Aissaoui <aeab13@gmail.com>
Date: Mon, 23 May 2022 19:36:06 +0200
Subject: [PATCH] Changed commited changes load block to avoid changing the
 state to loading when is not necessary

---
 .../app/extensions/StateManagementUtils.kt    | 26 +++++++++++++++++++
 .../app/viewmodels/CommitChangesViewModel.kt  | 15 +++++++----
 2 files changed, 36 insertions(+), 5 deletions(-)
 create mode 100644 src/main/kotlin/app/extensions/StateManagementUtils.kt

diff --git a/src/main/kotlin/app/extensions/StateManagementUtils.kt b/src/main/kotlin/app/extensions/StateManagementUtils.kt
new file mode 100644
index 0000000..93f477c
--- /dev/null
+++ b/src/main/kotlin/app/extensions/StateManagementUtils.kt
@@ -0,0 +1,26 @@
+package app.extensions
+
+import kotlinx.coroutines.*
+
+/**
+ * Calls a code [onDelayTriggered] if [block] has not completed before the time specified in [delayMs].
+ * Use case: Sometimes is not worth updating the UI with a state to "loading" if the load code executed afterwards is really
+ * fast.
+ */
+suspend fun delayedStateChange(delayMs: Long, onDelayTriggered: suspend () -> Unit, block: suspend () -> Unit) {
+    val scope = CoroutineScope(Dispatchers.IO)
+    var completed = false
+
+    scope.launch {
+        delay(delayMs)
+        if(!completed) {
+            onDelayTriggered()
+        }
+    }
+    try {
+        block()
+        scope.cancel()
+    } finally {
+        completed = true
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/app/viewmodels/CommitChangesViewModel.kt b/src/main/kotlin/app/viewmodels/CommitChangesViewModel.kt
index 2e5da4b..d89ab89 100644
--- a/src/main/kotlin/app/viewmodels/CommitChangesViewModel.kt
+++ b/src/main/kotlin/app/viewmodels/CommitChangesViewModel.kt
@@ -1,5 +1,6 @@
 package app.viewmodels
 
+import app.extensions.delayedStateChange
 import app.git.DiffManager
 import app.git.RefreshType
 import app.git.TabState
@@ -9,6 +10,8 @@ import org.eclipse.jgit.diff.DiffEntry
 import org.eclipse.jgit.revwalk.RevCommit
 import javax.inject.Inject
 
+private const val MIN_TIME_IN_MS_TO_SHOW_LOAD = 300L
+
 class CommitChangesViewModel @Inject constructor(
     private val tabState: TabState,
     private val diffManager: DiffManager,
@@ -19,15 +22,17 @@ class CommitChangesViewModel @Inject constructor(
     fun loadChanges(commit: RevCommit) = tabState.runOperation(
         refreshType = RefreshType.NONE,
     ) { git ->
-        _commitChangesStatus.value = CommitChangesStatus.Loading
+        delayedStateChange(
+            delayMs = MIN_TIME_IN_MS_TO_SHOW_LOAD,
+            onDelayTriggered = { _commitChangesStatus.value = CommitChangesStatus.Loading }
+        ) {
+            val changes = diffManager.commitDiffEntries(git, commit)
 
-        val changes = diffManager.commitDiffEntries(git, commit)
-
-        _commitChangesStatus.value = CommitChangesStatus.Loaded(commit, changes)
+            _commitChangesStatus.value = CommitChangesStatus.Loaded(commit, changes)
+        }
     }
 }
 
-
 sealed class CommitChangesStatus {
     object Loading : CommitChangesStatus()
     data class Loaded(val commit: RevCommit, val changes: List<DiffEntry>) : CommitChangesStatus()