From 71d6b91f0da79e55f4a5478c8b9f3748b22f3797 Mon Sep 17 00:00:00 2001
From: Arkadii Ivanov <arkann1985@gmail.com>
Date: Tue, 10 Aug 2021 01:09:22 +0100
Subject: [PATCH] Added Navigator.bringToFront extension function

---
 .../com/arkivanov/decompose/NavigatorExt.kt   | 10 +++
 .../router/NavigatorBringToFrontTest.kt       | 87 +++++++++++++++++++
 .../decompose/router/TestNavigator.kt         | 12 +++
 3 files changed, 109 insertions(+)
 create mode 100644 decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/NavigatorBringToFrontTest.kt
 create mode 100644 decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/TestNavigator.kt

diff --git a/decompose/src/commonMain/kotlin/com/arkivanov/decompose/NavigatorExt.kt b/decompose/src/commonMain/kotlin/com/arkivanov/decompose/NavigatorExt.kt
index d19845ad..f6d41d12 100644
--- a/decompose/src/commonMain/kotlin/com/arkivanov/decompose/NavigatorExt.kt
+++ b/decompose/src/commonMain/kotlin/com/arkivanov/decompose/NavigatorExt.kt
@@ -15,3 +15,13 @@ inline fun <C : Any> Navigator<C>.popWhile(crossinline predicate: (C) -> Boolean
 fun <C : Any> Navigator<C>.replaceCurrent(configuration: C) {
     navigate { it.dropLast(1) + configuration }
 }
+
+/**
+ * Removes all components with configurations of [configuration]'s class, and adds the provided [configuration] to the top of the stack.
+ * The operation is performed as one transaction. If there is already a component with the same configuration, it will not be recreated.
+ */
+fun <C : Any> Navigator<C>.bringToFront(configuration: C) {
+    navigate { stack ->
+        stack.filterNot { it::class == configuration::class } + configuration
+    }
+}
diff --git a/decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/NavigatorBringToFrontTest.kt b/decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/NavigatorBringToFrontTest.kt
new file mode 100644
index 00000000..090b3468
--- /dev/null
+++ b/decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/NavigatorBringToFrontTest.kt
@@ -0,0 +1,87 @@
+package com.arkivanov.decompose.router
+
+import com.arkivanov.decompose.bringToFront
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+@Suppress("TestFunctionName")
+class NavigatorBringToFrontTest {
+
+    @Test
+    fun WHEN_does_not_contain_THEN_new_configuration_pushed() {
+        val navigator = TestNavigator(listOf(Config.A, Config.B))
+
+        navigator.bringToFront(Config.C(0))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(0)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_exists_with_same_value_at_start_THEN_existing_configuration_moved_to_end() {
+        val navigator = TestNavigator(listOf(Config.C(0), Config.A, Config.B))
+
+        navigator.bringToFront(Config.C(0))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(0)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_exists_with_same_value_in_the_middle_THEN_existing_configuration_moved_to_end() {
+        val navigator = TestNavigator(listOf(Config.A, Config.C(0), Config.B))
+
+        navigator.bringToFront(Config.C(0))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(0)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_exists_with_same_value_at_the_end_THEN_existing_configuration_moved_to_end() {
+        val navigator = TestNavigator(listOf(Config.A, Config.B, Config.C(0)))
+
+        navigator.bringToFront(Config.C(0))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(0)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_exists_with_different_value_at_start_THEN_removed_and_new_added_to_end() {
+        val navigator = TestNavigator(listOf(Config.C(0), Config.A, Config.B))
+
+        navigator.bringToFront(Config.C(1))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(1)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_exists_with_different_value_in_the_middle_THEN_removed_and_new_added_to_end() {
+        val navigator = TestNavigator(listOf(Config.A, Config.C(0), Config.B))
+
+        navigator.bringToFront(Config.C(1))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(1)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_exists_with_different_value_at_the_end_THEN_removed_and_new_added_to_end() {
+        val navigator = TestNavigator(listOf(Config.A, Config.B, Config.C(0)))
+
+        navigator.bringToFront(Config.C(1))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(1)), navigator.stack)
+    }
+
+    @Test
+    fun WHEN_multiple_exist_THEN_all_removed_and_new_added_to_end() {
+        val navigator = TestNavigator(listOf(Config.C(0), Config.A, Config.C(1), Config.B))
+
+        navigator.bringToFront(Config.C(1))
+
+        assertEquals(listOf(Config.A, Config.B, Config.C(1)), navigator.stack)
+    }
+
+    private sealed class Config {
+        object A : Config()
+        object B : Config()
+        data class C(val value: Int) : Config()
+    }
+}
diff --git a/decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/TestNavigator.kt b/decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/TestNavigator.kt
new file mode 100644
index 00000000..17307872
--- /dev/null
+++ b/decompose/src/commonTest/kotlin/com/arkivanov/decompose/router/TestNavigator.kt
@@ -0,0 +1,12 @@
+package com.arkivanov.decompose.router
+
+import com.arkivanov.decompose.Navigator
+
+class TestNavigator<C : Any>(
+    var stack: List<C> = emptyList()
+) : Navigator<C> {
+
+    override fun navigate(transformer: (stack: List<C>) -> List<C>) {
+        stack = stack.let(transformer)
+    }
+}