Add F-Droid updater

android/src/main/java/app/shosetsu/android/datasource/remote/impl/update/FDroidAppUpdateDataSource.kt

@@ -1,18 +1,89 @@
 package app.shosetsu.android.datasource.remote.impl.update
 
+import app.shosetsu.android.common.EmptyResponseBodyException
+import app.shosetsu.android.common.ext.quickie
 import app.shosetsu.android.datasource.remote.base.IRemoteAppUpdateDataSource
 import app.shosetsu.android.domain.model.local.AppUpdateEntity
+import app.shosetsu.lib.exceptions.HTTPException
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.decodeFromStream
+import okhttp3.OkHttpClient
+import java.io.IOException
 import java.io.InputStream
 
-class FDroidAppUpdateDataSource : IRemoteAppUpdateDataSource,
+/**
+ * Load app updates from F-Droid
+ */
+class FDroidAppUpdateDataSource(
+	private val okHttpClient: OkHttpClient
+) : IRemoteAppUpdateDataSource,
 	IRemoteAppUpdateDataSource.Downloadable {
+	companion object {
+		private const val FDROID_UPDATE_URL =
+			"https://f-droid.org/api/v1/packages/app.shosetsu.android"
 
+		private const val FDROID_DOWNLOAD_URL = "https://f-droid.org/repo/app.shosetsu.android_"
+
+		private val json = Json {
+			encodeDefaults = true
+		}
+	}
+
+	@Serializable
+	data class PackagesInfo(
+		val packageName: String = "",
+		val suggestedVersionCode: Int = -1,
+		val packages: List<PackageData> = emptyList(),
+		val error: String? = null
+	)
+
+	@Serializable
+	data class PackageData(
+		val versionName: String,
+		val versionCode: Int
+	)
+
+	@Throws(HTTPException::class, EmptyResponseBodyException::class, IOException::class)
+	@OptIn(ExperimentalSerializationApi::class)
 	override suspend fun loadAppUpdate(): AppUpdateEntity {
-		TODO("Add F-DROID update source")
+		okHttpClient.quickie(FDROID_UPDATE_URL).use { response ->
+			if (response.isSuccessful) {
+				return response.body?.use { responseBody ->
+					responseBody.byteStream().use { responseStream ->
+						val info = json.decodeFromStream<PackagesInfo>(responseStream)
+						if (info.error != null)
+							throw EmptyResponseBodyException(info.error)
+
+						var packageData = info.packages.firstOrNull {
+							it.versionCode == info.suggestedVersionCode
+						}
+
+						if (packageData == null)
+							packageData = info.packages.first()
+
+						AppUpdateEntity(
+							packageData.versionName,
+							packageData.versionCode,
+							url = FDROID_DOWNLOAD_URL + "${packageData.versionCode}.apk",
+							notes = emptyList()
+						)
+					}
+				} ?: throw EmptyResponseBodyException(FDROID_UPDATE_URL)
+			}
+			throw HTTPException(response.code)
+		}
 	}
 
+	@Throws(EmptyResponseBodyException::class, HTTPException::class, IOException::class)
 	override suspend fun downloadAppUpdate(update: AppUpdateEntity): InputStream {
-		TODO("Add F-DROID update source")
+		okHttpClient.quickie(update.url).let { response ->
+			if (response.isSuccessful) {
+				return response.body?.byteStream()
+					?: throw EmptyResponseBodyException(update.url)
+			} else throw HTTPException(response.code)
+		}
 	}
 
 }