From 12e37184e1d24769bf807ff60f9a71151664dbdb Mon Sep 17 00:00:00 2001
From: InsanusMokrassar <ovsyannikov.alexey95@gmail.com>
Date: Mon, 14 Dec 2020 19:17:16 +0600
Subject: [PATCH] add selector

---
 CHANGELOG.md                                  |  3 +
 README.md                                     |  1 +
 gradle.properties                             |  2 +-
 selector/common/build.gradle                  | 17 ++++
 .../dev/inmo/micro_utils/selector/Selector.kt | 85 +++++++++++++++++++
 selector/common/src/main/AndroidManifest.xml  |  1 +
 settings.gradle                               |  1 +
 7 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 selector/common/build.gradle
 create mode 100644 selector/common/src/commonMain/kotlin/dev/inmo/micro_utils/selector/Selector.kt
 create mode 100644 selector/common/src/main/AndroidManifest.xml

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8840ee571d7..f356ff1c470 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 ## 0.4.12
 
+* `Selector`
+    * Project created
+
 ## 0.4.11
 
 * `Common`
diff --git a/README.md b/README.md
index 1c11fb08176..0686112a8cf 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ You always can look at the <a href="https://github.com/InsanusMokrassar/MicroUti
 ## Projects
 
 * `common` contains common tools for platform which usually are absent out-of-the-box when you starting project
+* `selector` contains tools to use `Selector` interface with things like `RecyclerView` in android or other selection needs
 * `coroutines` is a module for `Kotlin Coroutines` with different things like subscribing on flows (`onEach` + `launchIn` shortcut :) )
 * `ktor` is a set of modules for `client`s and `server`s
 * `mime_types` is NOT lightweight set of `MimeType`s with a lot of different objected and serializable (with `Kotlin Serialization`) mime types
diff --git a/gradle.properties b/gradle.properties
index 78fccfdb2b9..fad45ef5161 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -35,7 +35,7 @@ espresso_core=3.3.0
 
 # Dokka
 
-dokka_version=1.4.21
+dokka_version=1.4.20
 
 # Project data
 
diff --git a/selector/common/build.gradle b/selector/common/build.gradle
new file mode 100644
index 00000000000..74d1ba46f61
--- /dev/null
+++ b/selector/common/build.gradle
@@ -0,0 +1,17 @@
+plugins {
+    id "org.jetbrains.kotlin.multiplatform"
+    id "org.jetbrains.kotlin.plugin.serialization"
+    id "com.android.library"
+}
+
+apply from: "$mppProjectWithSerializationPresetPath"
+
+kotlin {
+    sourceSets {
+        commonMain {
+            dependencies {
+                api "org.jetbrains.kotlinx:kotlinx-coroutines-core:$kotlin_coroutines_version"
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/selector/common/src/commonMain/kotlin/dev/inmo/micro_utils/selector/Selector.kt b/selector/common/src/commonMain/kotlin/dev/inmo/micro_utils/selector/Selector.kt
new file mode 100644
index 00000000000..465b11d3167
--- /dev/null
+++ b/selector/common/src/commonMain/kotlin/dev/inmo/micro_utils/selector/Selector.kt
@@ -0,0 +1,85 @@
+package dev.inmo.micro_utils.selector
+
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.sync.Mutex
+
+interface Selector<T> {
+    val selectedItems: List<T>
+    val itemSelected: SharedFlow<T>
+    val itemUnselected: SharedFlow<T>
+
+    suspend fun toggleSelection(element: T)
+}
+
+@Suppress("NOTHING_TO_INLINE")
+inline operator fun <T> Selector<T>.contains(element: T) = selectedItems.contains(element)
+@Suppress("NOTHING_TO_INLINE")
+inline fun <T> Selector<T>.nothingSelected(): Boolean = selectedItems.isEmpty()
+
+class SingleSelector<T>(
+    selectedItem: T? = null,
+    useMutex: Boolean = true
+) : Selector<T> {
+    var selectedItem: T? = selectedItem
+        private set
+    override val selectedItems: List<T>
+        get() = selectedItem ?.let { listOf(it) } ?: emptyList()
+
+    private val _itemSelected = MutableSharedFlow<T>()
+    override val itemSelected: SharedFlow<T> = _itemSelected.asSharedFlow()
+    private val _itemUnselected = MutableSharedFlow<T>()
+    override val itemUnselected: SharedFlow<T> = _itemUnselected.asSharedFlow()
+
+    private val mutex = if (useMutex) {
+        Mutex()
+    } else {
+        null
+    }
+
+    override suspend fun toggleSelection(element: T) {
+        mutex ?.lock()
+        if (selectedItem == element) {
+            selectedItem = null
+            _itemUnselected.emit(element)
+        } else {
+            val previouslySelected = selectedItem
+            selectedItem = null
+            if (previouslySelected != null) {
+                _itemUnselected.emit(previouslySelected)
+            }
+            selectedItem = element
+            _itemSelected.emit(element)
+        }
+        mutex ?.unlock()
+    }
+}
+
+class MultipleSelector<T>(
+    selectedItems: List<T>,
+    useMutex: Boolean = true
+) : Selector<T> {
+    private val _selectedItems: MutableList<T> = selectedItems.toMutableList()
+    override val selectedItems: List<T> = _selectedItems
+
+    private val _itemSelected = MutableSharedFlow<T>()
+    override val itemSelected: SharedFlow<T> = _itemSelected.asSharedFlow()
+    private val _itemUnselected = MutableSharedFlow<T>()
+    override val itemUnselected: SharedFlow<T> = _itemUnselected.asSharedFlow()
+
+    private val mutex = if (useMutex) {
+        Mutex()
+    } else {
+        null
+    }
+
+    override suspend fun toggleSelection(element: T) {
+        mutex ?.lock()
+        if (_selectedItems.remove(element)) {
+            _itemUnselected.emit(element)
+        } else {
+            _selectedItems.add(element)
+            _itemSelected.emit(element)
+        }
+        mutex ?.unlock()
+    }
+}
diff --git a/selector/common/src/main/AndroidManifest.xml b/selector/common/src/main/AndroidManifest.xml
new file mode 100644
index 00000000000..af2679c3813
--- /dev/null
+++ b/selector/common/src/main/AndroidManifest.xml
@@ -0,0 +1 @@
+<manifest package="dev.inmo.micro_utils.selector"/>
\ No newline at end of file
diff --git a/settings.gradle b/settings.gradle
index 320b82da2da..c438c68de35 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -2,6 +2,7 @@ rootProject.name='micro_utils'
 
 String[] includes = [
     ":common",
+    ":selector:common",
     ":pagination:common",
     ":pagination:exposed",
     ":pagination:ktor:common",