start working with fsm

fsm/core/build.gradle

@@ -0,0 +1,17 @@
+plugins {
+    id "org.jetbrains.kotlin.multiplatform"
+    id "org.jetbrains.kotlin.plugin.serialization"
+    id "com.android.library"
+}
+
+apply from: "$mppProjectWithSerializationPresetPath"
+
+kotlin {
+    sourceSets {
+        commonMain {
+            dependencies {
+                api "dev.inmo:micro_utils.coroutines:$micro_utils_version"
+            }
+        }
+    }
+}

fsm/core/src/commonMain/kotlin/dev/inmo/tgbotapi/libraries/fsm/core/State.kt

@@ -0,0 +1,17 @@
+package dev.inmo.tgbotapi.libraries.fsm.core
+
+sealed interface State {
+    val context: Any
+}
+
+/**
+ * Use this state as parent of your state in case you want to avoid saving of this state in queue for [context] if this
+ * queue is not empty
+ */
+interface ImmediateOrNeverState : State
+
+/**
+ * Use this state as parent of your state in case you want to keep saving of this state in queue for [context] if this
+ * queue is not empty
+ */
+interface QueueableState : State

fsm/core/src/commonMain/kotlin/dev/inmo/tgbotapi/libraries/fsm/core/StateHandlerHolder.kt

@@ -0,0 +1,15 @@
+package dev.inmo.tgbotapi.libraries.fsm.core
+
+import kotlin.reflect.KClass
+
+class StateHandlerHolder<I : State, O : State>(
+    private val inputKlass: KClass<I>,
+    private val delegateTo: StatesHandler<I, O>,
+    private val strict: Boolean = false
+) : StatesHandler<State, O> {
+    fun checkHandleable(state: State) = state::class == inputKlass || (!strict && inputKlass.isInstance(state))
+
+    override suspend fun handleState(state: State): O? {
+        return delegateTo.handleState(state as I)
+    }
+}

fsm/core/src/commonMain/kotlin/dev/inmo/tgbotapi/libraries/fsm/core/StatesHandler.kt

@@ -0,0 +1,5 @@
+package dev.inmo.tgbotapi.libraries.fsm.core
+
+fun interface StatesHandler<I : State, O : State> {
+    suspend fun handleState(state: I): O?
+}

fsm/core/src/commonMain/kotlin/dev/inmo/tgbotapi/libraries/fsm/core/StatesMachine.kt

@@ -0,0 +1,37 @@
+package dev.inmo.tgbotapi.libraries.fsm.core
+
+import dev.inmo.micro_utils.coroutines.*
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.asFlow
+
+private suspend fun <I : State, O : State> launchStateHandling(
+    state: State,
+    handlers: List<StateHandlerHolder<out I, out O>>
+): O? {
+    return handlers.firstOrNull { it.checkHandleable(state) } ?.handleState(
+        state
+    )
+}
+
+class StatesMachine<T : State, I : T, O : T>(
+    private val statesRepo: StatesRepo<T>,
+    private val statesQuotaManager: StatesQuotaManager,
+    private val handlers: List<StateHandlerHolder<out I, out O>>
+) : StatesHandler<T, O> {
+    override suspend fun handleState(state: T): O? {
+        return statesQuotaManager.doOnQuota(
+            state
+        ) {
+            launchStateHandling(state, handlers)
+        }
+    }
+
+    fun start(scope: CoroutineScope): Job = scope.launchSafelyWithoutExceptions {
+        val statesFlow = statesRepo.loadStates().asFlow() + statesRepo.onNewState
+        statesFlow.subscribeSafelyWithoutExceptions(this) {
+            val newState = handleState(it)
+            newState ?.also { statesRepo.saveState(newState) }
+            statesRepo.removeState(it)
+        }
+    }
+}

fsm/core/src/commonMain/kotlin/dev/inmo/tgbotapi/libraries/fsm/core/StatesQuotaManager.kt

@@ -0,0 +1,5 @@
+package dev.inmo.tgbotapi.libraries.fsm.core
+
+interface StatesQuotaManager {
+    suspend fun <T : State, O : State> doOnQuota(state: T, block: suspend (T) -> O?): O?
+}

fsm/core/src/commonMain/kotlin/dev/inmo/tgbotapi/libraries/fsm/core/StatesRepo.kt

@@ -0,0 +1,12 @@
+package dev.inmo.tgbotapi.libraries.fsm.core
+
+import kotlinx.coroutines.flow.Flow
+
+interface StatesRepo<T : State> {
+    val onNewState: Flow<T>
+    val onStateRemoved: Flow<T>
+
+    suspend fun saveState(state: T)
+    suspend fun removeState(state: T)
+    suspend fun loadStates(): List<T>
+}

fsm/core/src/main/AndroidManifest.xml

@@ -0,0 +1 @@
+<manifest package="dev.inmo.tgbotapi.libraries.fsm.core"/>

gradle.properties

@@ -8,6 +8,7 @@ android.enableJetifier=true
 
 kotlin_version=1.5.10
 kotlin_serialisation_core_version=1.2.1
+kotlin_coroutines_version=1.5.0
 
 github_release_plugin_version=2.2.12
 

settings.gradle

@@ -4,7 +4,9 @@ String[] includes = [
     ":cache:admins:common",
     ":cache:admins:micro_utils",
     ":cache:admins:plagubot",
-    ":cache:media"
+    ":cache:media",
+
+    ":fsm:core"
 ]