Add a LocalChangeFetcher

engine/src/main/java/com/google/android/fhir/FhirEngine.kt

@@ -19,6 +19,7 @@ package com.google.android.fhir
 import com.google.android.fhir.db.ResourceNotFoundException
 import com.google.android.fhir.search.Search
 import com.google.android.fhir.sync.ConflictResolver
+import com.google.android.fhir.sync.upload.LocalChangesFetchMode
 import java.time.OffsetDateTime
 import kotlinx.coroutines.flow.Flow
 import org.hl7.fhir.r4.model.Resource
@@ -53,7 +54,8 @@ interface FhirEngine {
    * api caller should [Flow.collect] it.
    */
   suspend fun syncUpload(
-    upload: (suspend (List<LocalChange>) -> Flow<Pair<LocalChangeToken, Resource>>)
+    localChangesFetchMode: LocalChangesFetchMode,
+    upload: (suspend (List<LocalChange>) -> Flow<Pair<LocalChangeToken, Resource>>),
   )
 
   /**
@@ -62,7 +64,7 @@ interface FhirEngine {
    */
   suspend fun syncDownload(
     conflictResolver: ConflictResolver,
-    download: suspend () -> Flow<List<Resource>>
+    download: suspend () -> Flow<List<Resource>>,
   )
 
   /**
@@ -87,29 +89,32 @@ interface FhirEngine {
    * Retrieves a list of [LocalChange]s for [Resource] with given type and id, which can be used to
    * purge resource from database. If there is no local change for given [resourceType] and
    * [Resource.id], return an empty list.
+   *
    * @param type The [ResourceType]
    * @param id The resource id [Resource.id]
    * @return [List]<[LocalChange]> A list of local changes for given [resourceType] and
-   * [Resource.id] . If there is no local change for given [resourceType] and [Resource.id], return
-   * an empty list.
+   *   [Resource.id] . If there is no local change for given [resourceType] and [Resource.id],
+   *   return an empty list.
    */
   suspend fun getLocalChanges(type: ResourceType, id: String): List<LocalChange>
 
   /**
    * Purges a resource from the database based on resource type and id without any deletion of data
    * from the server.
+   *
    * @param type The [ResourceType]
    * @param id The resource id [Resource.id]
    * @param isLocalPurge default value is false here resource will not be deleted from
-   * LocalChangeEntity table but it will throw IllegalStateException("Resource has local changes
-   * either sync with server or FORCE_PURGE required") if local change exists. If true this API will
-   * delete resource entry from LocalChangeEntity table.
+   *   LocalChangeEntity table but it will throw IllegalStateException("Resource has local changes
+   *   either sync with server or FORCE_PURGE required") if local change exists. If true this API
+   *   will delete resource entry from LocalChangeEntity table.
    */
   suspend fun purge(type: ResourceType, id: String, forcePurge: Boolean = false)
 }
 
 /**
  * Returns a FHIR resource of type [R] with [id] from the local storage.
+ *
  * @param <R> The resource type which should be a subtype of [Resource].
  * @throws ResourceNotFoundException if the resource is not found
  */
@@ -120,6 +125,7 @@ suspend inline fun <reified R : Resource> FhirEngine.get(id: String): R {
 
 /**
  * Deletes a FHIR resource of type [R] with [id] from the local storage.
+ *
  * @param <R> The resource type which should be a subtype of [Resource].
  */
 suspend inline fun <reified R : Resource> FhirEngine.delete(id: String) {
@@ -138,7 +144,7 @@ data class SearchResult<R : Resource>(
   /** Matching referenced resources as per the [Search.include] criteria in the query. */
   val included: Map<SearchParamName, List<Resource>>?,
   /** Matching referenced resources as per the [Search.revInclude] criteria in the query. */
-  val revIncluded: Map<Pair<ResourceType, SearchParamName>, List<Resource>>?
+  val revIncluded: Map<Pair<ResourceType, SearchParamName>, List<Resource>>?,
 ) {
   override fun equals(other: Any?) =
     other is SearchResult<*> &&
@@ -155,7 +161,7 @@ data class SearchResult<R : Resource>(
 
   private fun equalsShallow(
     first: Map<SearchParamName, List<Resource>>?,
-    second: Map<SearchParamName, List<Resource>>?
+    second: Map<SearchParamName, List<Resource>>?,
   ) =
     if (first != null && second != null && first.size == second.size) {
       first.entries.asSequence().zip(second.entries.asSequence()).all { (x, y) ->
@@ -168,7 +174,7 @@ data class SearchResult<R : Resource>(
   @JvmName("equalsShallowRevInclude")
   private fun equalsShallow(
     first: Map<Pair<ResourceType, SearchParamName>, List<Resource>>?,
-    second: Map<Pair<ResourceType, SearchParamName>, List<Resource>>?
+    second: Map<Pair<ResourceType, SearchParamName>, List<Resource>>?,
   ) =
     if (first != null && second != null && first.size == second.size) {
       first.entries.asSequence().zip(second.entries.asSequence()).all { (x, y) ->

engine/src/main/java/com/google/android/fhir/db/Database.kt

@@ -58,7 +58,7 @@ internal interface Database {
     resourceId: String,
     resourceType: ResourceType,
     versionId: String,
-    lastUpdated: Instant
+    lastUpdated: Instant,
   )
 
   /**
@@ -105,6 +105,9 @@ internal interface Database {
    */
   suspend fun getAllLocalChanges(): List<LocalChange>
 
+  /** Retrieves the count of [LocalChange]s stored in the database. */
+  suspend fun getLocalChangesCount(): Int
+
   /** Remove the [LocalChangeEntity] s with given ids. Call this after a successful sync. */
   suspend fun deleteUpdates(token: LocalChangeToken)
 
@@ -127,23 +130,25 @@ internal interface Database {
    * Retrieve a list of [LocalChange] for [Resource] with given type and id, which can be used to
    * purge resource from database. If there is no local change for given [resourceType] and
    * [Resource.id], return an empty list.
+   *
    * @param type The [ResourceType]
    * @param id The resource id [Resource.id]
    * @return [List]<[LocalChange]> A list of local changes for given [resourceType] and
-   * [Resource.id] . If there is no local change for given [resourceType] and [Resource.id], return
-   * empty list.
+   *   [Resource.id] . If there is no local change for given [resourceType] and [Resource.id],
+   *   return empty list.
    */
   suspend fun getLocalChanges(type: ResourceType, id: String): List<LocalChange>
 
   /**
    * Purge resource from database based on resource type and id without any deletion of data from
    * the server.
+   *
    * @param type The [ResourceType]
    * @param id The resource id [Resource.id]
    * @param isLocalPurge default value is false here resource will not be deleted from
-   * LocalChangeEntity table but it will throw IllegalStateException("Resource has local changes
-   * either sync with server or FORCE_PURGE required") if local change exists. If true this API will
-   * delete resource entry from LocalChangeEntity table.
+   *   LocalChangeEntity table but it will throw IllegalStateException("Resource has local changes
+   *   either sync with server or FORCE_PURGE required") if local change exists. If true this API
+   *   will delete resource entry from LocalChangeEntity table.
    */
   suspend fun purge(type: ResourceType, id: String, forcePurge: Boolean = false)
 }

engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt

@@ -46,7 +46,7 @@ internal class DatabaseImpl(
   private val context: Context,
   private val iParser: IParser,
   databaseConfig: DatabaseConfig,
-  private val resourceIndexer: ResourceIndexer
+  private val resourceIndexer: ResourceIndexer,
 ) : com.google.android.fhir.db.Database {
 
   val db: ResourceDatabase
@@ -88,8 +88,10 @@ internal class DatabaseImpl(
             openHelperFactory {
               SQLCipherSupportHelper(
                 it,
-                databaseErrorStrategy = databaseConfig.databaseErrorStrategy
-              ) { DatabaseEncryptionKeyProvider.getOrCreatePassphrase(DATABASE_PASSPHRASE_NAME) }
+                databaseErrorStrategy = databaseConfig.databaseErrorStrategy,
+              ) {
+                DatabaseEncryptionKeyProvider.getOrCreatePassphrase(DATABASE_PASSPHRASE_NAME)
+              }
             }
           }
 
@@ -115,7 +117,7 @@ internal class DatabaseImpl(
           val timeOfLocalChange = Instant.now()
           localChangeDao.addInsert(it, timeOfLocalChange)
           resourceDao.insertLocalResource(it, timeOfLocalChange)
-        }
+        },
       )
     }
     return logicalIds
@@ -140,14 +142,14 @@ internal class DatabaseImpl(
     resourceId: String,
     resourceType: ResourceType,
     versionId: String,
-    lastUpdated: Instant
+    lastUpdated: Instant,
   ) {
     db.withTransaction {
       resourceDao.updateAndIndexRemoteVersionIdAndLastUpdate(
         resourceId,
         resourceType,
         versionId,
-        lastUpdated
+        lastUpdated,
       )
     }
   }
@@ -174,12 +176,13 @@ internal class DatabaseImpl(
           null
         }
       val rowsDeleted = resourceDao.deleteResource(resourceId = id, resourceType = type)
-      if (rowsDeleted > 0)
+      if (rowsDeleted > 0) {
         localChangeDao.addDelete(
           resourceId = id,
           resourceType = type,
-          remoteVersionId = remoteVersionId
+          remoteVersionId = remoteVersionId,
         )
+      }
     }
   }
 
@@ -200,7 +203,7 @@ internal class DatabaseImpl(
           IndexedIdAndResource(
             it.matchingIndex,
             it.idOfBaseResourceOnWhichThisMatchedInc ?: it.idOfBaseResourceOnWhichThisMatchedRev!!,
-            iParser.parseResource(it.serializedResource) as Resource
+            iParser.parseResource(it.serializedResource) as Resource,
           )
         }
     }
@@ -216,6 +219,10 @@ internal class DatabaseImpl(
     return db.withTransaction { localChangeDao.getAllLocalChanges().map { it.toLocalChange() } }
   }
 
+  override suspend fun getLocalChangesCount(): Int {
+    return db.withTransaction { localChangeDao.getLocalChangesCount() }
+  }
+
   override suspend fun deleteUpdates(token: LocalChangeToken) {
     db.withTransaction { localChangeDao.discardLocalChanges(token) }
   }
@@ -265,12 +272,12 @@ internal class DatabaseImpl(
         if (forcePurge) {
           resourceDao.deleteResource(resourceId = id, resourceType = type)
           localChangeDao.discardLocalChanges(
-            token = LocalChangeToken(localChangeEntityList.map { it.id })
+            token = LocalChangeToken(localChangeEntityList.map { it.id }),
           )
         } else {
           // local change is available but FORCE_PURGE = false then throw exception
           throw IllegalStateException(
-            "Resource with type $type and id $id has local changes, either sync with server or FORCE_PURGE required"
+            "Resource with type $type and id $id has local changes, either sync with server or FORCE_PURGE required",
           )
         }
       }
@@ -301,5 +308,5 @@ internal class DatabaseImpl(
 data class DatabaseConfig(
   val inMemory: Boolean,
   val enableEncryption: Boolean,
-  val databaseErrorStrategy: DatabaseErrorStrategy
+  val databaseErrorStrategy: DatabaseErrorStrategy,
 )