Automatically update rates

closes #31

build-logic/convention/src/main/java/com/sadellie/unitto/ConfigureKotlinAndroid.kt

@@ -74,7 +74,8 @@ internal fun Project.configureKotlinAndroid(
                 "-opt-in=androidx.compose.animation.ExperimentalAnimationApi",
                 "-opt-in=androidx.compose.foundation.ExperimentalFoundationApi",
                 "-opt-in=androidx.compose.ui.unit.ExperimentalUnitApi",
-                "-opt-in=androidx.lifecycle.compose.ExperimentalLifecycleComposeApi"
+                "-opt-in=androidx.lifecycle.compose.ExperimentalLifecycleComposeApi",
+                "-opt-in=kotlinx.coroutines.ExperimentalCoroutinesApi",
             )
             jvmTarget = JavaVersion.VERSION_11.toString()
         }

feature/converter/src/main/AndroidManifest.xml

@@ -17,6 +17,7 @@
   ~ along with this program.  If not, see <https://www.gnu.org/licenses/>.
   -->
 
-<manifest>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 </manifest>

feature/converter/src/main/java/com/sadellie/unitto/feature/converter/ConverterScreen.kt

@@ -45,6 +45,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -75,6 +76,7 @@ import com.sadellie.unitto.core.ui.common.textfield.ExpressionTextField
 import com.sadellie.unitto.core.ui.common.textfield.FormatterSymbols
 import com.sadellie.unitto.core.ui.common.textfield.UnformattedTextField
 import com.sadellie.unitto.data.common.format
+import com.sadellie.unitto.data.model.UnitGroup
 import com.sadellie.unitto.data.model.unit.AbstractUnit
 import com.sadellie.unitto.feature.converter.components.DefaultKeyboard
 import com.sadellie.unitto.feature.converter.components.NumberBaseKeyboard
@@ -282,6 +284,15 @@ private fun Default(
         )
     }
 
+    val connection by connectivityState()
+
+    LaunchedEffect(connection) {
+        if ((connection == ConnectionState.Available) and (uiState.result == ConverterResult.Error)) {
+            val unitFrom = uiState.unitFrom
+            if (unitFrom.group == UnitGroup.CURRENCY) refreshCurrencyRates(unitFrom)
+        }
+    }
+
     PortraitLandscape(
         modifier = modifier.fillMaxSize(),
         content1 = { contentModifier ->

feature/converter/src/main/java/com/sadellie/unitto/feature/converter/NetworkUtils.kt

@@ -0,0 +1,66 @@
+/*
+ * Unitto is a unit converter for Android
+ * Copyright (c) 2023 Elshan Agaev
+ *
+ * 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 com.sadellie.unitto.feature.converter
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.Network
+import android.net.NetworkCapabilities
+import android.net.NetworkRequest
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
+import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.callbackFlow
+
+// https://github.com/PatilShreyas/NotyKT/pull/210/files#diff-88d0c098edd51dfdd06d871b22de23efe0935234fe80b2b54592583262fbe846
+
+internal sealed class ConnectionState {
+    data object Available : ConnectionState()
+    data object Unavailable : ConnectionState()
+}
+
+private fun Context.observeConnectivityAsFlow() = callbackFlow {
+    val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
+
+    val callback = object : ConnectivityManager.NetworkCallback() {
+        override fun onAvailable(network: Network) { trySend(ConnectionState.Available) }
+        override fun onLost(network: Network) { trySend(ConnectionState.Unavailable) }
+    }
+
+    val networkRequest = NetworkRequest.Builder()
+        .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
+        .build()
+
+    connectivityManager.registerNetworkCallback(networkRequest, callback)
+
+    awaitClose {
+        connectivityManager.unregisterNetworkCallback(callback)
+    }
+}
+
+@Composable
+internal fun connectivityState(): State<ConnectionState> {
+    val context = LocalContext.current
+
+    return context
+        .observeConnectivityAsFlow()
+        .collectAsStateWithLifecycle(ConnectionState.Unavailable)
+}