OSM: implement progress indicator for full download

app/src/main/java/net/vonforst/evmap/api/ChargepointApi.kt

@@ -78,15 +78,8 @@ interface ChargepointApi<out T : ReferenceData> {
      * Fetches all available chargers from this API.
      *
      * This may take a long time and should only be used when the user explicitly wants to download all chargers.
-     *
-     * TODO: add an optional callback parameter to this function to be able to receive updates on the download progress?
-     * TODO: Should this also include getting the ReferenceData, instead of taking it as an argument?
-     *       ReferenceData typically includes information that is needed to create the filter options, e.g.
-     *       mappings between IDs and readable names (for operators etc.). So probably for OSM it makes sense
-     *       to generate that within this function (e.g. build the list of available operators using all the
-     *       operators found in the dataset).
      */
-    suspend fun fullDownload(referenceData: ReferenceData): Sequence<ChargeLocation>
+    suspend fun fullDownload(): FullDownloadResult<T>
 }
 
 interface StringProvider {
@@ -135,4 +128,10 @@ data class ChargepointList(val items: List<ChargepointListItem>, val isComplete:
     companion object {
         fun empty() = ChargepointList(emptyList(), true)
     }
+}
+
+interface FullDownloadResult<out T : ReferenceData> {
+    val chargers: Sequence<ChargeLocation>
+    val progress: Float
+    val referenceData: T
 }

app/src/main/java/net/vonforst/evmap/api/Utils.kt

@@ -11,6 +11,7 @@ import okhttp3.Response
 import org.json.JSONArray
 import java.io.IOException
 import kotlin.coroutines.resumeWithException
+import kotlin.experimental.ExperimentalTypeInference
 import kotlin.math.abs
 
 operator fun <T> JSONArray.iterator(): Iterator<T> =

app/src/main/java/net/vonforst/evmap/api/goingelectric/GoingElectricApi.kt

@@ -136,7 +136,7 @@ class GoingElectricApiWrapper(
     override val supportsOnlineQueries = true
     override val supportsFullDownload = false
 
-    override suspend fun fullDownload(referenceData: ReferenceData): Sequence<ChargeLocation> {
+    override suspend fun fullDownload(): FullDownloadResult<GEReferenceData> {
         throw NotImplementedError()
     }
 

app/src/main/java/net/vonforst/evmap/api/openchargemap/OpenChargeMapApi.kt

@@ -115,7 +115,7 @@ class OpenChargeMapApiWrapper(
     override val supportsOnlineQueries = true
     override val supportsFullDownload = false
 
-    override suspend fun fullDownload(referenceData: ReferenceData): Sequence<ChargeLocation> {
+    override suspend fun fullDownload(): FullDownloadResult<OCMReferenceData> {
         throw NotImplementedError()
     }
 

app/src/main/java/net/vonforst/evmap/api/openstreetmap/OpenStreetMapApi.kt

@@ -3,15 +3,14 @@ package net.vonforst.evmap.api.openstreetmap
 import android.database.DatabaseUtils
 import com.car2go.maps.model.LatLng
 import com.car2go.maps.model.LatLngBounds
-import com.squareup.moshi.JsonAdapter
-import com.squareup.moshi.JsonReader
 import com.squareup.moshi.Moshi
 import net.vonforst.evmap.BuildConfig
 import net.vonforst.evmap.R
 import net.vonforst.evmap.addDebugInterceptors
 import net.vonforst.evmap.api.ChargepointApi
 import net.vonforst.evmap.api.ChargepointList
 import net.vonforst.evmap.api.FiltersSQLQuery
+import net.vonforst.evmap.api.FullDownloadResult
 import net.vonforst.evmap.api.StringProvider
 import net.vonforst.evmap.api.mapPower
 import net.vonforst.evmap.api.mapPowerInverse
@@ -32,14 +31,11 @@ import net.vonforst.evmap.model.getMultipleChoiceValue
 import net.vonforst.evmap.model.getSliderValue
 import net.vonforst.evmap.viewmodel.Resource
 import okhttp3.OkHttpClient
-import okhttp3.Request
 import retrofit2.Response
 import retrofit2.Retrofit
-import retrofit2.converter.moshi.MoshiConverterFactory
 import retrofit2.http.GET
 import java.io.IOException
 import java.time.Duration
-import java.time.Instant
 
 interface OpenStreetMapApi {
     @GET("charging-stations-osm.json")
@@ -108,7 +104,7 @@ class OpenStreetMapApiWrapper(baseurl: String = "https://evmap-dev.vonforst.net"
     }
 
     override suspend fun getReferenceData(): Resource<OSMReferenceData> {
-        TODO("Not yet implemented")
+        throw NotImplementedError()
     }
 
     override fun getFilters(
@@ -215,20 +211,34 @@ class OpenStreetMapApiWrapper(baseurl: String = "https://evmap-dev.vonforst.net"
         return true
     }
 
-    override suspend fun fullDownload(referenceData: ReferenceData): Sequence<ChargeLocation> {
+    override suspend fun fullDownload(): FullDownloadResult<OSMReferenceData> {
         val response = api.getAllChargingStations()
         if (!response.isSuccessful) {
             throw IOException(response.message())
         } else {
             val body = response.body()!!
+            return OSMFullDownloadResult(body)
+        }
+    }
+}
+
+data class OSMReferenceData(val test: String) : ReferenceData()
+
+class OSMFullDownloadResult(private val body: OSMDocument) : FullDownloadResult<OSMReferenceData> {
+    private var downloadProgress = 0f
+    override val chargers: Sequence<ChargeLocation>
+        get() {
             val time = body.timestamp
             return sequence {
-                body.elements.forEach {
+                body.elements.forEachIndexed { i, it ->
                     yield(it.convert(time))
+                    downloadProgress = i.toFloat() / body.count
                 }
             }
         }
-    }
-}
+    override val progress: Float
+        get() = downloadProgress
+    override val referenceData: OSMReferenceData
+        get() = TODO("Not yet implemented")
 
-data class OSMReferenceData(val test: String) : ReferenceData()
+}

app/src/main/java/net/vonforst/evmap/storage/ChargeLocationsDao.kt

@@ -11,6 +11,13 @@ import com.car2go.maps.model.LatLngBounds
 import com.car2go.maps.util.SphericalUtil
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancelAndJoin
+import kotlinx.coroutines.flow.FlowCollector
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.cancel
+import kotlinx.coroutines.launch
 import net.vonforst.evmap.api.ChargepointApi
 import net.vonforst.evmap.api.ChargepointList
 import net.vonforst.evmap.api.StringProvider
@@ -154,6 +161,8 @@ class ChargeLocationsRepository(
 
     private val chargeLocationsDao = db.chargeLocationsDao()
     private val savedRegionDao = db.savedRegionDao()
+    private var fullDownloadJob: Job? = null
+    private var fullDownloadProgress: MutableStateFlow<Float?> = MutableStateFlow(null)
 
     fun getChargepoints(
         bounds: LatLngBounds,
@@ -225,7 +234,16 @@ class ChargeLocationsRepository(
         } else {
             return liveData {
                 if (!savedRegionResult.await()) {
-                    fullDownload()
+                    val job = fullDownloadJob ?: scope.launch {
+                        fullDownload()
+                    }.also { fullDownloadJob = it }
+                    val progressJob = scope.launch {
+                        fullDownloadProgress.collect {
+                            emit(Resource.loading(null, it))
+                        }
+                    }
+                    job.join()
+                    progressJob.cancelAndJoin()
                 }
                 emit(Resource.success(dbResult.await()))
             }
@@ -307,7 +325,16 @@ class ChargeLocationsRepository(
         } else {
             return liveData {
                 if (!savedRegionResult.await()) {
-                    fullDownload()
+                    val job = fullDownloadJob ?: scope.launch {
+                        fullDownload()
+                    }.also { fullDownloadJob = it }
+                    val progressJob = scope.launch {
+                        fullDownloadProgress.collect {
+                            emit(Resource.loading(null, it))
+                        }
+                    }
+                    job.join()
+                    progressJob.cancelAndJoin()
                 }
                 emit(Resource.success(dbResult.await()))
             }
@@ -470,25 +497,29 @@ class ChargeLocationsRepository(
         val api = api.value!!
         if (!api.supportsFullDownload) return
 
-        val refData = referenceData.await()
         val time = Instant.now()
-        val result = api.fullDownload(refData)
-        result.chunked(100).forEach {
-            chargeLocationsDao.insert(*it.toTypedArray())
-        }
-        val region = Mbr(
-            -180.0,
-            -90.0,
-            180.0,
-            90.0, 4326
-        ).asPolygon()
-        savedRegionDao.insert(
-            SavedRegion(
-                region, api.id, time,
-                null,
-                true
+        val result = api.fullDownload()
+        try {
+            result.chargers.chunked(100).forEach {
+                chargeLocationsDao.insert(*it.toTypedArray())
+                fullDownloadProgress.value = result.progress
+            }
+            val region = Mbr(
+                -180.0,
+                -90.0,
+                180.0,
+                90.0, 4326
+            ).asPolygon()
+            savedRegionDao.insert(
+                SavedRegion(
+                    region, api.id, time,
+                    null,
+                    true
+                )
             )
-        )
+        } finally {
+            fullDownloadProgress.value = null
+        }
     }
 
 

app/src/main/java/net/vonforst/evmap/viewmodel/Utils.kt

@@ -39,19 +39,24 @@ enum class Status {
  * trying to write it to a Parcel if the type parameter does not implement Parcelable.
  */
 @Parcelize
-data class Resource<out T>(val status: Status, val data: @RawValue T?, val message: String?) :
+data class Resource<out T>(
+    val status: Status,
+    val data: @RawValue T?,
+    val message: String?,
+    val progress: Float? = null
+) :
     Parcelable {
     companion object {
         fun <T> success(data: T?): Resource<T> {
-            return Resource(Status.SUCCESS, data, null)
+            return Resource(Status.SUCCESS, data, null, null)
         }
 
         fun <T> error(msg: String?, data: T?): Resource<T> {
-            return Resource(Status.ERROR, data, msg)
+            return Resource(Status.ERROR, data, msg, null)
         }
 
-        fun <T> loading(data: T?): Resource<T> {
-            return Resource(Status.LOADING, data, null)
+        fun <T> loading(data: T?, progress: Float? = null): Resource<T> {
+            return Resource(Status.LOADING, data, null, progress)
         }
     }
 }

app/src/main/res/layout/fragment_map.xml

@@ -131,7 +131,9 @@
                         android:layout_height="wrap_content"
                         android:layout_marginTop="-10dp"
                         android:layout_marginBottom="-7dp"
-                        android:indeterminate="true"
+                        android:indeterminate="@{ vm.chargepoints.progress == null }"
+                        android:progress="@{ vm.chargepoints.progress != null ? Math.round(vm.chargepoints.progress * 100f) : 0 }"
+                        android:max="100"
                         android:visibility="visible"
                         app:goneUnless="@{ vm.chargepoints.status == Status.LOADING }" />