From 051757adcabcf2912d0fcd24b089def8393291c7 Mon Sep 17 00:00:00 2001
From: y9vad9 <y9vad9@gmail.com>
Date: Wed, 10 Jan 2024 01:30:45 +0100
Subject: [PATCH] feat: `SmartValue` implementation for updatable multi-source
 values

---
 foundation/smart-value/build.gradle.kts       | 11 ++++
 .../io/timemates/remote/value/SmartValue.kt   | 66 +++++++++++++++++++
 .../remote/value/UpdatableSmartValue.kt       | 28 ++++++++
 settings.gradle.kts                           |  1 +
 4 files changed, 106 insertions(+)
 create mode 100644 foundation/smart-value/build.gradle.kts
 create mode 100644 foundation/smart-value/src/main/kotlin/io/timemates/remote/value/SmartValue.kt
 create mode 100644 foundation/smart-value/src/main/kotlin/io/timemates/remote/value/UpdatableSmartValue.kt

diff --git a/foundation/smart-value/build.gradle.kts b/foundation/smart-value/build.gradle.kts
new file mode 100644
index 0000000..7d7bc5e
--- /dev/null
+++ b/foundation/smart-value/build.gradle.kts
@@ -0,0 +1,11 @@
+plugins {
+    id(libs.plugins.configurations.multiplatform.library.get().pluginId)
+}
+
+kotlin {
+    explicitApi()
+}
+
+dependencies {
+    commonMainImplementation(libs.kotlinx.coroutines)
+}
\ No newline at end of file
diff --git a/foundation/smart-value/src/main/kotlin/io/timemates/remote/value/SmartValue.kt b/foundation/smart-value/src/main/kotlin/io/timemates/remote/value/SmartValue.kt
new file mode 100644
index 0000000..94bd86a
--- /dev/null
+++ b/foundation/smart-value/src/main/kotlin/io/timemates/remote/value/SmartValue.kt
@@ -0,0 +1,66 @@
+package io.timemates.remote.value
+
+import kotlinx.coroutines.channels.ReceiveChannel
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * A generic interface representing a remote value with local storage capabilities.
+ *
+ * This interface provides access to the current value, local value, and remote value.
+ * It also supports setting a listener to be notified when the value is received.
+ *
+ * @param T The type of the value.
+ */
+public interface SmartValue<T> {
+    /**
+     * A [Flow] representing the local value. This flow can emit multiple values if any change
+     * has occurred in the local storage (if watching for updates is supported).
+     *
+     * **Note**: Some [SmartValue]s can support remote only value meaning there's no
+     * value will be present.
+     *
+     * @see kotlinx.coroutines.flow.Flow
+     */
+    public val localValue: Flow<T?>
+
+    /**
+     * A [Flow] representing the remote value. This flow can have multiple outputs depending on the
+     * implementation, as it may receive updates from external sources, such as the server.
+     *
+     * **Note**: [remoteValue] shouldn't be considered as 'last actual source' as for specific cases
+     * [localValue] can receive updates that made on client that appears much faster than on server
+     * or actual 'update watching' system could be missing.
+     *
+     * @see kotlinx.coroutines.flow.Flow
+     */
+    public val remoteValue: Flow<T?>
+
+    public companion object {
+        /**
+         * A factory method for creating instances of [SmartValue].
+         *
+         * This method is used to construct a [SmartValue] instance with specified local and remote update
+         * logic, along with optional channels for receiving updates from local and remote sources.
+         *
+         * @param T The type of the value.
+         * @param local A suspending lambda representing the logic to retrieve the initial local value.
+         * @param remote A suspending lambda representing the logic to retrieve the initial remote value.
+         * @param localUpdates An optional [ReceiveChannel] to receive updates from local sources.
+         * @param remoteUpdates An optional [ReceiveChannel] to receive updates from remote sources.
+         * @return A [SmartValue] instance configured with the provided parameters.
+         *
+         * @see SmartValue
+         * @see kotlinx.coroutines.channels.ReceiveChannel
+         */
+        public fun <T> of(
+            local: suspend () -> T?,
+            remote: suspend () -> T?,
+            localUpdates: ReceiveChannel<T>? = null,
+            remoteUpdates: ReceiveChannel<T>? = null,
+        ): SmartValue<T> {
+            return UpdatableSmartValue(
+                local, remote, localUpdates, remoteUpdates
+            )
+        }
+    }
+}
\ No newline at end of file
diff --git a/foundation/smart-value/src/main/kotlin/io/timemates/remote/value/UpdatableSmartValue.kt b/foundation/smart-value/src/main/kotlin/io/timemates/remote/value/UpdatableSmartValue.kt
new file mode 100644
index 0000000..a039d6b
--- /dev/null
+++ b/foundation/smart-value/src/main/kotlin/io/timemates/remote/value/UpdatableSmartValue.kt
@@ -0,0 +1,28 @@
+package io.timemates.remote.value
+
+import kotlinx.coroutines.channels.ReceiveChannel
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.receiveAsFlow
+
+internal class UpdatableSmartValue<T>(
+    private val local: suspend () -> T?,
+    private val remote: suspend () -> T?,
+    private val localUpdates: ReceiveChannel<T>? = null,
+    private val remoteUpdates: ReceiveChannel<T>? = null,
+) : SmartValue<T> {
+    override val localValue: Flow<T?> = flow {
+        emit(local())
+
+        localUpdates?.receiveAsFlow()?.collect {
+            emit(it)
+        }
+    }
+    override val remoteValue: Flow<T?> = flow {
+        emit(remote())
+
+        remoteUpdates?.receiveAsFlow()?.collect {
+            emit(it)
+        }
+    }
+}
\ No newline at end of file
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 1764d51..c710f8d 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -40,6 +40,7 @@ include(
     ":foundation:system-tray",
     ":foundation:shimmer-compose",
     ":foundation:time",
+    ":foundation:smart-value",
 )
 
 include(