From e2d1c5d6a1e1de99a02dc1d522bee067c3626c3b Mon Sep 17 00:00:00 2001
From: InsanusMokrassar <ovsyannikov.alexey95@gmail.com>
Date: Wed, 28 Oct 2020 14:17:39 +0600
Subject: [PATCH] corotoutines actualization

---
 CHANGELOG.md                                  |  2 +
 .../coroutines/BroadcastStateFlow.kt          | 46 ++++++++++++++-----
 2 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d9b508e394..c94ef7aaeeb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@
     * `K/JS`
         * Add several extensions for `Element` objects to detect that object is on screen viewport
         * Add several extensions for `Element` objects to detect object visibility
+* `Coroutines`
+    * `BroadcastStateFlow` now use different strategy for getting of state and implements `replayCache`
 
 ## 0.2.2
 
diff --git a/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/BroadcastStateFlow.kt b/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/BroadcastStateFlow.kt
index f8d54aab376..48b22b4f431 100644
--- a/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/BroadcastStateFlow.kt
+++ b/coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/BroadcastStateFlow.kt
@@ -5,29 +5,51 @@ import kotlinx.coroutines.channels.BroadcastChannel
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.*
 
+const val defaultBroadcastStateFlowReplayCacheSize = 1
+
 class BroadcastStateFlow<T> internal constructor(
     parentFlow: Flow<T>,
-    private val stateGetter: () -> T
+    initial: T,
+    replayCacheSize: Int = defaultBroadcastStateFlowReplayCacheSize,
+    replayScope: CoroutineScope
 ) : StateFlow<T>, Flow<T> by parentFlow {
+    private val deque = ArrayDeque<T>(1).also {
+        it.add(initial)
+    }
+    override val replayCache: List<T>
+        get() = deque.toList()
     override val value: T
-        get() = stateGetter()
-}
+        get() = deque.last()
 
-fun <T> BroadcastChannel<T>.asStateFlow(value: T, scope: CoroutineScope): StateFlow<T> = asFlow().let {
-    var state: T = value
-    it.onEach { state = it }.launchIn(scope)
-    BroadcastStateFlow(it) {
-        state
+    init {
+        if (replayCacheSize < 1) {
+            error("Replay cache size can't be less than 1, but was $replayCacheSize")
+        }
+        parentFlow.onEach {
+            deque.addLast(it)
+            if (deque.size > replayCacheSize) {
+                deque.removeFirst()
+            }
+        }.launchIn(replayScope)
     }
 }
 
-fun <T> BroadcastChannel<T?>.asStateFlow(scope: CoroutineScope): StateFlow<T?> = asStateFlow(null, scope)
+fun <T> BroadcastChannel<T>.asStateFlow(
+    value: T,
+    scope: CoroutineScope,
+    replayCacheSize: Int = defaultBroadcastStateFlowReplayCacheSize
+): StateFlow<T> = BroadcastStateFlow(asFlow(), value, replayCacheSize, scope)
 
-fun <T> broadcastStateFlow(initial: T, scope: CoroutineScope, channelSize: Int = Channel.BUFFERED) = BroadcastChannel<T>(
+fun <T> BroadcastChannel<T?>.asStateFlow(
+    scope: CoroutineScope,
+    replayCacheSize: Int = defaultBroadcastStateFlowReplayCacheSize
+): StateFlow<T?> = asStateFlow(null, scope, replayCacheSize)
+
+fun <T> broadcastStateFlow(initial: T, scope: CoroutineScope, channelSize: Int = Channel.BUFFERED, replayCacheSize: Int = defaultBroadcastStateFlowReplayCacheSize) = BroadcastChannel<T>(
     channelSize
 ).let {
-    it to it.asStateFlow(initial, scope)
+    it to it.asStateFlow(initial, scope, replayCacheSize)
 }
 
-fun <T> broadcastStateFlow(scope: CoroutineScope, channelSize: Int = Channel.BUFFERED) = broadcastStateFlow<T?>(null, scope, channelSize)
+fun <T> broadcastStateFlow(scope: CoroutineScope, channelSize: Int = Channel.BUFFERED, replayCacheSize: Int = defaultBroadcastStateFlowReplayCacheSize) = broadcastStateFlow<T?>(null, scope, channelSize, replayCacheSize)