Merge pull request #8 from arkivanov/save-state-web

State saving and restoration on web

README.md

@@ -8,6 +8,7 @@ Tech stack:
 - [Compose Multiplatform](https://github.com/JetBrains/compose-multiplatform) - declarative UI
 - [Decompose](https://github.com/arkivanov/Decompose) - navigation and lifecycle
 - [MVIKotlin](https://github.com/arkivanov/MVIKotlin) - state management
+- [kotlinx-serialization](https://github.com/Kotlin/kotlinx.serialization) - state saving and restoration
 
 Supported targets: Desktop (JVM) and Wasm Browser.
 

composeApp/build.gradle.kts

@@ -40,6 +40,7 @@ kotlin {
             implementation(libs.mvikotlin.timetravel)
             implementation(libs.decompose)
             implementation(libs.decompose.extensions.compose)
+            implementation(libs.serialization.json)
         }
 
         commonTest.dependencies {

composeApp/src/commonMain/kotlin/com/arkivanov/minesweeper/Serialization.kt

@@ -0,0 +1,19 @@
+package com.arkivanov.minesweeper
+
+import com.arkivanov.essenty.statekeeper.SerializableContainer
+import kotlinx.serialization.json.Json
+
+private val json =
+    Json {
+        allowStructuredMapKeys = true
+    }
+
+internal fun SerializableContainer.encodeToString(): String =
+    json.encodeToString(SerializableContainer.serializer(), this)
+
+internal fun String.decodeSerializableContainer(): SerializableContainer? =
+    try {
+        json.decodeFromString(SerializableContainer.serializer(), this)
+    } catch (e: Exception) {
+        null
+    }

composeApp/src/commonMain/kotlin/com/arkivanov/minesweeper/game/DefaultGameComponent.kt

@@ -15,15 +15,16 @@ internal class DefaultGameComponent(
     private val store =
         instanceKeeper.getStore {
             storeFactory.gameStore(
-                newGameState(
-                    width = settings.width,
-                    height = settings.height,
-                    maxMines = settings.maxMines,
-                )
+                state = stateKeeper.consume(key = KEY_SAVED_STATE, strategy = GameState.serializer())
+                    ?: newGameState(width = settings.width, height = settings.height, maxMines = settings.maxMines),
             )
         }
 
-    override val state: Value<State> = store.asValue()
+    override val state: Value<GameState> = store.asValue()
+
+    init {
+        stateKeeper.register(key = KEY_SAVED_STATE, strategy = GameState.serializer()) { store.state }
+    }
 
     override fun onCellTouchedPrimary(x: Int, y: Int) {
         store.accept(Intent.PressCell(x = x, y = y))
@@ -44,4 +45,8 @@ internal class DefaultGameComponent(
     override fun onRestartClicked() {
         store.accept(Intent.Restart)
     }
+
+    private companion object {
+        private const val KEY_SAVED_STATE = "saved_state"
+    }
 }

composeApp/src/commonMain/kotlin/com/arkivanov/minesweeper/game/GameComponent.kt

@@ -5,7 +5,7 @@ import com.arkivanov.decompose.value.Value
 
 internal interface GameComponent {
 
-    val state: Value<State>
+    val state: Value<GameState>
 
     fun onCellTouchedPrimary(x: Int, y: Int)
     fun onCellPressedSecondary(x: Int, y: Int)

composeApp/src/commonMain/kotlin/com/arkivanov/minesweeper/game/GameContent.kt

@@ -255,9 +255,9 @@ internal fun GameContentPreview() {
 }
 
 internal class PreviewGameComponent : GameComponent {
-    override val state: Value<State> =
+    override val state: Value<GameState> =
         MutableValue(
-            State(
+            GameState(
                 grid = buildMap {
                     var number = 1
                     var isFlagged = false

composeApp/src/commonMain/kotlin/com/arkivanov/minesweeper/game/GameState.kt

@@ -0,0 +1,99 @@
+package com.arkivanov.minesweeper.game
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+internal data class GameState(
+    val grid: Grid,
+    val width: Int = grid.keys.maxOf { it.x } + 1,
+    val height: Int = grid.keys.maxOf { it.y } + 1,
+    val maxMines: Int = grid.values.count { it.value.isMine },
+    val gameStatus: GameStatus = GameStatus.INITIALIZED,
+    val pressMode: PressMode = PressMode.NONE,
+) {
+    init {
+        require(grid.size == width * height) { "Grid size must be equal to width * height" }
+    }
+}
+
+internal enum class GameStatus {
+    INITIALIZED,
+    STARTED,
+    WIN,
+    FAILED,
+}
+
+internal enum class PressMode {
+    NONE,
+    SINGLE,
+    MULTIPLE,
+}
+
+internal val GameStatus.isOver: Boolean
+    get() =
+        when (this) {
+            GameStatus.INITIALIZED,
+            GameStatus.STARTED -> false
+
+            GameStatus.WIN,
+            GameStatus.FAILED -> true
+        }
+
+internal typealias Grid = Map<Location, Cell>
+internal typealias MutableGrid = MutableMap<Location, Cell>
+
+@Serializable
+internal data class Cell(
+    val value: CellValue = CellValue.None,
+    val status: CellStatus = CellStatus.Closed(),
+)
+
+@Serializable
+sealed interface CellValue {
+
+    @Serializable
+    data object None : CellValue
+
+    @Serializable
+    data object Mine : CellValue
+
+    @Serializable
+    data class Number(val number: Int) : CellValue
+}
+
+@Serializable
+sealed interface CellStatus {
+
+    @Serializable
+    data class Closed(
+        val isFlagged: Boolean = false,
+        val isPressed: Boolean = false,
+    ) : CellStatus
+
+    @Serializable
+    data object Open : CellStatus
+}
+
+internal val CellValue.isNone: Boolean
+    get() = this is CellValue.None
+
+internal val CellValue.isMine: Boolean
+    get() = this is CellValue.Mine
+
+internal val CellValue.isNumber: Boolean
+    get() = asNumber() != null
+
+internal fun CellValue.asNumber(): CellValue.Number? =
+    this as? CellValue.Number
+
+internal val CellStatus.isClosed: Boolean
+    get() = this is CellStatus.Closed
+
+internal val CellStatus.isOpen: Boolean
+    get() = this is CellStatus.Open
+
+internal val CellStatus.isFlagged: Boolean
+    get() = (this as? CellStatus.Closed)?.isFlagged == true
+
+internal fun Cell.open(): Cell =
+    copy(status = CellStatus.Open)