Filter history: foundation (feature flag + Room persistence)

WooCommerce/src/main/kotlin/com/woocommerce/android/ui/filters/FilterHistoryRepository.kt

@@ -0,0 +1,86 @@
+package com.woocommerce.android.ui.filters
+
+import com.woocommerce.android.tools.SelectedSite
+import dagger.Reusable
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import org.wordpress.android.fluxc.model.LocalOrRemoteId.LocalId
+import org.wordpress.android.fluxc.persistence.dao.FilterHistoryDao
+import org.wordpress.android.fluxc.persistence.entity.FilterHistoryEntity
+import org.wordpress.android.fluxc.utils.CurrentTimeProvider
+import javax.inject.Inject
+
+/**
+ * Per-site store for "filter history" — the previously applied filter selections on the order and
+ * product lists, gated by [com.woocommerce.android.util.FeatureFlag.FILTER_HISTORY].
+ *
+ * History is unlimited, deduped and newest-first (matching iOS): [save] upserts by [SavedFilter.payload],
+ * so re-saving an identical selection bumps it to the top instead of creating a duplicate.
+ *
+ * Callers own the [SavedFilter.payload] contract: it must be a canonical, normalized serialization of
+ * the active (non-empty) selection so that logically-identical filters dedup reliably across app
+ * versions. The per-surface encoders/decoders live with the order and product filter screens.
+ */
+@Reusable
+class FilterHistoryRepository @Inject constructor(
+    private val filterHistoryDao: FilterHistoryDao,
+    private val selectedSite: SelectedSite,
+    private val currentTimeProvider: CurrentTimeProvider
+) {
+    fun observeHistory(type: FilterHistoryType): Flow<List<SavedFilter>> =
+        filterHistoryDao.observeForSite(currentSiteId(), type.name)
+            .map { entities -> entities.map { it.toSavedFilter() } }
+
+    suspend fun save(
+        type: FilterHistoryType,
+        payload: String,
+        readableString: String
+    ) {
+        filterHistoryDao.insertOrReplace(
+            FilterHistoryEntity(
+                localSiteId = currentSiteId(),
+                filterType = type.name,
+                payload = payload,
+                readableString = readableString,
+                dateModified = currentTimeProvider.currentDate().time
+            )
+        )
+    }
+
+    suspend fun remove(filter: SavedFilter) {
+        filterHistoryDao.delete(filter.id)
+    }
+
+    suspend fun clear(type: FilterHistoryType) {
+        filterHistoryDao.clear(currentSiteId(), type.name)
+    }
+
+    private fun currentSiteId() = LocalId(selectedSite.get().id)
+
+    private fun FilterHistoryEntity.toSavedFilter() = SavedFilter(
+        id = id,
+        readableString = readableString,
+        payload = payload
+    )
+}
+
+/**
+ * Which list a filter history entry belongs to. Persisted as the entity's `filterType` column.
+ */
+enum class FilterHistoryType {
+    ORDERS,
+    PRODUCTS
+}
+
+/**
+ * A single persisted filter history entry.
+ *
+ * @param id database id, used to [FilterHistoryRepository.remove] a specific entry.
+ * @param readableString human-readable summary of the filter, shown in the history list.
+ * @param payload canonical serialization of the selection, decoded by the per-surface consumer.
+ */
+data class SavedFilter(
+    val id: Long,
+    val readableString: String,
+    val payload: String
+)

WooCommerce/src/main/kotlin/com/woocommerce/android/util/FeatureFlag.kt

@@ -41,4 +41,5 @@ enum class FeatureFlag(
     AI_SUPPORT_CHAT("ai_support_chat"),
     SMARTER_NOTIFICATIONS("smarter_notifications", localValue = PackageUtils.isDebugBuild()),
     QR_LOGIN("woo_qr_code_login"),
+    FILTER_HISTORY("woo_filter_history", localValue = PackageUtils.isDebugBuild()),
 }