Fix ChatApp time (#4381)

Fix time of message in ChatApp sample.
Added library kotlinx-datetime.

It resolves issue:
 - https://github.com/JetBrains/compose-multiplatform/issues/4378

examples/chat/shared/build.gradle.kts

@@ -53,6 +53,7 @@ kotlin {
                 implementation(compose.material)
                 @OptIn(org.jetbrains.compose.ExperimentalComposeLibrary::class)
                 implementation(compose.components.resources)
+                implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.5.0")
             }
         }
         val androidMain by getting {

examples/chat/shared/src/androidMain/kotlin/currentTime.android.kt

@@ -1,3 +0,0 @@
-actual fun timestampMs(): Long {
-    return System.currentTimeMillis()
-}

examples/chat/shared/src/commonMain/kotlin/ChatApp.kt

@@ -77,7 +77,7 @@ fun ChatApp(displayTextField: Boolean = true) {
                         SendMessage { text ->
                             store.send(
                                 Action.SendMessage(
-                                    Message(myUser, timeMs = timestampMs(), text)
+                                    Message(myUser, text)
                                 )
                             )
                         }
@@ -100,7 +100,6 @@ fun ChatApp(displayTextField: Boolean = true) {
                 Action.SendMessage(
                     message = Message(
                         user = thisFriend,
-                        timeMs = timestampMs(),
                         text = thisMessage
                     )
                 )

examples/chat/shared/src/commonMain/kotlin/ChatMessage.kt

@@ -96,7 +96,7 @@ inline fun ChatMessage(isMyMessage: Boolean, message: Message) {
                             modifier = Modifier.align(Alignment.End)
                         ) {
                             Text(
-                                text = timeToString(message.timeMs),
+                                text = timeToString(message.seconds),
                                 textAlign = TextAlign.End,
                                 style = MaterialTheme.typography.subtitle1.copy(fontSize = 10.sp),
                                 color = ChatColors.TIME_TEXT

examples/chat/shared/src/commonMain/kotlin/Data.kt

@@ -1,21 +1,21 @@
 import androidx.compose.ui.graphics.Color
+import kotlinx.datetime.Clock
 import kotlin.random.Random
 import kotlin.random.nextInt
 
-data class Message private constructor(
+data class Message(
     val user: User,
-    val timeMs: Long,
     val text: String,
+    val seconds: Long,
     val id: Long
 ) {
     constructor(
         user: User,
-        timeMs: Long,
         text: String
     ) : this(
         user = user,
-        timeMs = timeMs,
         text = text,
+        seconds = Clock.System.now().epochSeconds,
         id = Random.nextLong()
     )
 }

examples/chat/shared/src/commonMain/kotlin/currentTime.common.kt

@@ -1,10 +1,15 @@
-fun timeToString(timestampMs: Long): String {
-    val seconds = timestampMs
-    val minutes = seconds / 1000 / 60
-    val hours = minutes / 24
+import kotlinx.datetime.Clock
+import kotlinx.datetime.Instant
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toLocalDateTime
 
-    val m = minutes % 60
-    val h = hours % 24
+
+fun timeToString(seconds: Long): String {
+    val instant: Instant = Instant.fromEpochSeconds(seconds)
+    val localTime = instant.toLocalDateTime(TimeZone.currentSystemDefault())
+    val m = localTime.minute
+    val h = localTime.hour
 
     val mm = if (m < 10) {
         "0$m"
@@ -19,4 +24,3 @@ fun timeToString(timestampMs: Long): String {
     return "$hh:$mm"
 }
 
-expect fun timestampMs(): Long

examples/chat/shared/src/desktopMain/kotlin/currentTime.desktop.kt

@@ -1,3 +0,0 @@
-actual fun timestampMs(): Long {
-    return System.currentTimeMillis()
-}

examples/chat/shared/src/iosMain/kotlin/currentTime.ios.kt

@@ -1,6 +0,0 @@
-import platform.Foundation.NSDate
-import platform.Foundation.timeIntervalSince1970
-
-actual fun timestampMs(): Long {
-    return (NSDate().timeIntervalSince1970() * 1000).toLong()
-}

examples/chat/shared/src/iosMain/kotlin/main.ios.kt

@@ -6,7 +6,7 @@ fun ChatViewController(): UIViewController = ComposeUIViewController {
 }
 
 fun sendMessage(text: String) {
-    store.send(Action.SendMessage(Message(myUser, timestampMs(), text)))
+    store.send(Action.SendMessage(Message(myUser, text)))
 }
 
 fun gradient3Colors() = ChatColors.GRADIENT_3

examples/chat/shared/src/jsMain/kotlin/currentTime.js.kt

@@ -1,5 +0,0 @@
-import kotlin.js.Date
-
-actual fun timestampMs(): Long {
-    return Date.now().toLong()
-}

examples/chat/shared/src/macosMain/kotlin/currentTime.macos.kt

@@ -1,6 +0,0 @@
-import platform.Foundation.NSDate
-import platform.Foundation.timeIntervalSince1970
-
-actual fun timestampMs(): Long {
-    return NSDate().timeIntervalSince1970().toLong()
-}