Add backend module

backend/.gitignore

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+/build

backend/build.gradle.kts

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+plugins {
+    id("kotlin-platform-jvm")
+    id("application")
+    id("com.github.johnrengelman.shadow")
+}
+
+group = "net.underdesk"
+version = "0.0.1"
+
+dependencies {
+    implementation(project(":shared"))
+    implementation(Dependencies.Kotlin.core)
+    implementation(Dependencies.Kotlin.coroutinesCore)
+
+    implementation(Dependencies.Ktor.ktorCore)
+
+    implementation(Dependencies.Firebase.adminSDK)
+}
+
+application {
+    mainClass.set("net.underdesk.circolapp.backend.ServerKt")
+    mainClassName = "net.underdesk.circolapp.backend.ServerKt"
+}

backend/src/main/java/net/underdesk/circolapp/backend/JavaDatabase.kt

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+/*
+ * Circolapp
+ * Copyright (C) 2019-2020  Matteo Schiff
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.underdesk.circolapp.backend
+
+import net.underdesk.circolapp.shared.data.AppDatabase
+import net.underdesk.circolapp.shared.data.CircularDao
+import net.underdesk.circolapp.shared.data.DatabaseDriverFactory
+
+object JavaDatabase {
+
+    @Volatile
+    private var instance: AppDatabase? = null
+
+    private fun getInstance(): AppDatabase {
+        return instance ?: synchronized(this) {
+            instance ?: AppDatabase(
+                DatabaseDriverFactory().createDriver()
+            ).also { instance = it }
+        }
+    }
+
+    fun getDaoInstance(): CircularDao {
+        return CircularDao(getInstance())
+    }
+}

backend/src/main/java/net/underdesk/circolapp/backend/PushNotificationUtils.kt

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+/*
+ * Circolapp
+ * Copyright (C) 2019-2020  Matteo Schiff
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.underdesk.circolapp.backend
+
+import com.google.firebase.messaging.FirebaseMessaging
+import com.google.firebase.messaging.Message
+import com.google.firebase.messaging.Notification
+import java.time.LocalDateTime
+
+object PushNotificationUtils {
+    fun createPushNotification(topic: String) {
+        val message = Message.builder()
+            .putData("fetchCircular", "true")
+            .setTopic(topic)
+            .build()
+
+        val response = FirebaseMessaging.getInstance().send(message)
+
+        val current = LocalDateTime.now()
+
+        print("Sent data push notification for topic $topic with response $response at time $current \n")
+    }
+
+    fun createPushNotificationiOS(topic: String) {
+        val realTopic = topic + "IOS"
+
+        val message = Message.builder()
+            .setNotification(
+                Notification.builder()
+                    .setTitle("Nuove circolari")
+                    .setBody("La tua scuola ha pubblicato nuove circolari")
+                    .build()
+            )
+            .setTopic(realTopic)
+            .build()
+
+        val response = FirebaseMessaging.getInstance().send(message)
+
+        val current = LocalDateTime.now()
+
+        print("Sent managed push notification for topic $realTopic with response $response at time $current \n")
+    }
+}

backend/src/main/java/net/underdesk/circolapp/backend/Server.kt

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+/*
+ * Circolapp
+ * Copyright (C) 2019-2020  Matteo Schiff
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.underdesk.circolapp.backend
+
+import com.google.auth.oauth2.GoogleCredentials
+import com.google.firebase.FirebaseApp
+import com.google.firebase.FirebaseOptions
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.runBlocking
+
+const val CHECK_DELAY_MILLIS = 900000L
+
+fun main(args: Array<String>) {
+    print("Starting Circolapp Push microservice \n")
+    val options = FirebaseOptions.builder()
+        .setCredentials(GoogleCredentials.getApplicationDefault())
+        .build()
+
+    FirebaseApp.initializeApp(options)
+
+    val serverUtils = ServerUtils()
+
+    print("Microservice started! \n")
+    runBlocking {
+        while (true) {
+            serverUtils.checkServers()
+
+            delay(CHECK_DELAY_MILLIS)
+        }
+    }
+}

backend/src/main/java/net/underdesk/circolapp/backend/ServerUtils.kt

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+/*
+ * Circolapp
+ * Copyright (C) 2019-2020  Matteo Schiff
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.underdesk.circolapp.backend
+
+import net.underdesk.circolapp.shared.data.Circular
+import net.underdesk.circolapp.shared.server.KtorFactory
+import net.underdesk.circolapp.shared.server.Server
+import net.underdesk.circolapp.shared.server.ServerAPI
+
+class ServerUtils {
+    private val serverList: MutableList<Server> = mutableListOf()
+    private val ktorClient = KtorFactory().createClient()
+    private val circularDao = JavaDatabase.getDaoInstance()
+
+    init {
+        for (serverId in ServerAPI.Companion.Servers.values()) {
+            serverList.add(ServerAPI.createServer(serverId, ktorClient))
+        }
+    }
+
+    suspend fun checkServers() {
+        for (server in serverList) {
+            checkServer(server)
+        }
+    }
+
+    private suspend fun updateCirculars(server: Server): Pair<List<Circular>, Int> {
+        var onlyNewCirculars = listOf<Circular>()
+
+        var errorCode = 0
+        val result = server.getCircularsFromServer()
+        if (result.second == ServerAPI.Companion.Result.ERROR)
+            return Pair(emptyList(), -1)
+
+        val oldCirculars = circularDao.getCirculars(server.serverID)
+        val newCirculars = result.first
+
+        if (newCirculars.size != oldCirculars.size) {
+            if (newCirculars.size < oldCirculars.size) {
+                circularDao.deleteAll()
+                errorCode = 1
+            }
+
+            val oldCircularsSize =
+                if (newCirculars.size < oldCirculars.size) 0 else oldCirculars.size
+
+            val circularCount = newCirculars.size - oldCircularsSize
+            onlyNewCirculars = newCirculars.subList(0, circularCount)
+
+            circularDao.insertAll(newCirculars)
+        }
+        return Pair(onlyNewCirculars, errorCode)
+    }
+
+    private suspend fun checkServer(server: Server) {
+        val newCirculars = updateCirculars(server)
+
+        if (newCirculars.second != -1 && newCirculars.first.isNotEmpty()) {
+            PushNotificationUtils.createPushNotification(ServerAPI.getServerTopic(server.serverID))
+            PushNotificationUtils.createPushNotificationiOS(ServerAPI.getServerTopic(server.serverID))
+        }
+    }
+}