Add PagerBuilder, DefaultReducerBuilder, and default paging strategies

paging/core/src/commonMain/kotlin/org/mobilenativefoundation/paging/core/DefaultReducerBuilder.kt

@@ -0,0 +1,103 @@
+package org.mobilenativefoundation.paging.core
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.flow.StateFlow
+import org.mobilenativefoundation.paging.core.impl.DefaultAggregatingStrategy
+import org.mobilenativefoundation.paging.core.impl.DefaultFetchingStrategy
+import org.mobilenativefoundation.paging.core.impl.DefaultReducer
+import org.mobilenativefoundation.paging.core.impl.Dispatcher
+import org.mobilenativefoundation.paging.core.impl.Injector
+import org.mobilenativefoundation.paging.core.impl.JobCoordinator
+import org.mobilenativefoundation.paging.core.impl.OptionalInjector
+import org.mobilenativefoundation.paging.core.impl.RetriesManager
+
+/**
+ * A builder class for creating a default [Reducer] instance.
+ *
+ * It enables configuring error handling strategy, aggregating strategy, fetching strategy, custom action reducer, and paging buffer size.
+ *
+ * @param Id The type of the unique identifier for each item in the paged data.
+ * @param K The type of the key used for paging.
+ * @param P The type of the parameters associated with each page of data.
+ * @param D The type of the data items.
+ * @param E The type of errors that can occur during the paging process.
+ * @param A The type of custom actions that can be dispatched to modify the paging state.
+ * @param initialKey The initial [PagingKey] used as the starting point for paging.
+ * @param childScope The [CoroutineScope] in which the reducer will operate.
+ * @param dispatcherInjector The [Injector] used to provide the [Dispatcher] instance.
+ * @param loggerInjector The [OptionalInjector] used to provide the optional [Logger] instance.
+ * @param pagingConfigInjector The [Injector] used to provide the [PagingConfig] instance.
+ * @param anchorPosition The [StateFlow] representing the anchor position for paging.
+ */
+class DefaultReducerBuilder<Id : Comparable<Id>, K : Any, P : Any, D : Any, E : Any, A : Any> internal constructor(
+    private val initialKey: PagingKey<K, P>,
+    private val childScope: CoroutineScope,
+    private val dispatcherInjector: Injector<Dispatcher<Id, K, P, D, E, A>>,
+    private val loggerInjector: OptionalInjector<Logger>,
+    private val pagingConfigInjector: Injector<PagingConfig>,
+    private val anchorPosition: StateFlow<PagingKey<K, P>>,
+    private val mutablePagingBufferInjector: Injector<MutablePagingBuffer<Id, K, P, D>>,
+    private val jobCoordinator: JobCoordinator
+) {
+
+    private var errorHandlingStrategy: ErrorHandlingStrategy = ErrorHandlingStrategy.RetryLast()
+    private var aggregatingStrategy: AggregatingStrategy<Id, K, P, D> = DefaultAggregatingStrategy()
+    private var fetchingStrategy: FetchingStrategy<Id, K, P, D> = DefaultFetchingStrategy()
+    private var customActionReducer: UserCustomActionReducer<Id, K, P, D, E, A>? = null
+
+    /**
+     * Sets the [ErrorHandlingStrategy] to be used by the reducer.
+     *
+     * @param errorHandlingStrategy The [ErrorHandlingStrategy] to be used.
+     * @return The [DefaultReducerBuilder] instance for chaining.
+     */
+    fun errorHandlingStrategy(errorHandlingStrategy: ErrorHandlingStrategy) = apply { this.errorHandlingStrategy = errorHandlingStrategy }
+
+    /**
+     * Sets the [AggregatingStrategy] to be used by the reducer.
+     *
+     * @param aggregatingStrategy The [AggregatingStrategy] to be used.
+     * @return The [DefaultReducerBuilder] instance for chaining.
+     */
+    fun aggregatingStrategy(aggregatingStrategy: AggregatingStrategy<Id, K, P, D>) = apply { this.aggregatingStrategy = aggregatingStrategy }
+
+    /**
+     * Sets the [FetchingStrategy] to be used by the reducer.
+     *
+     * @param fetchingStrategy The [FetchingStrategy] to be used.
+     * @return The [DefaultReducerBuilder] instance for chaining.
+     */
+    fun fetchingStrategy(fetchingStrategy: FetchingStrategy<Id, K, P, D>) = apply { this.fetchingStrategy = fetchingStrategy }
+
+    /**
+     * Sets the custom action reducer to be used by the reducer.
+     *
+     * @param customActionReducer The [UserCustomActionReducer] to be used.
+     * @return The [DefaultReducerBuilder] instance for chaining.
+     */
+    fun customActionReducer(customActionReducer: UserCustomActionReducer<Id, K, P, D, E, A>) = apply { this.customActionReducer = customActionReducer }
+
+    /**
+     * Builds and returns the configured default [Reducer] instance.
+     *
+     * @return The built default [Reducer] instance.
+     */
+    fun build(): Reducer<Id, K, P, D, E, A> {
+        val mutablePagingBuffer = mutablePagingBufferInjector.inject()
+
+        return DefaultReducer(
+            childScope = childScope,
+            dispatcherInjector = dispatcherInjector,
+            pagingConfigInjector = pagingConfigInjector,
+            userCustomActionReducer = customActionReducer,
+            anchorPosition = anchorPosition,
+            loggerInjector = loggerInjector,
+            mutablePagingBuffer = mutablePagingBuffer,
+            aggregatingStrategy = aggregatingStrategy,
+            initialKey = initialKey,
+            retriesManager = RetriesManager(),
+            errorHandlingStrategy = errorHandlingStrategy,
+            jobCoordinator = jobCoordinator
+        )
+    }
+}