Store and restore session

app/src/main/java/io/element/android/x/MainActivity.kt

@@ -4,8 +4,11 @@ import android.content.Intent
 import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.activity.viewModels
+import androidx.lifecycle.lifecycleScope
 import io.element.android.x.ui.screen.login.LoginActivity
 import io.element.android.x.ui.screen.login.RoomListActivity
+import kotlinx.coroutines.launch
 
 class MainActivity : ComponentActivity() {
     private val launcher =
@@ -18,11 +21,17 @@ class MainActivity : ComponentActivity() {
             }
         }
 
+    private val viewModel: MainViewModel by viewModels()
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        // Just start the LoginActivity for now.
-        // TODO if a session exist, start the room list
-        launcher.launch(Intent(this, LoginActivity::class.java))
+        lifecycleScope.launch {
+            if (viewModel.hasSession()) {
+                startRoomActivityAndFinish()
+            } else {
+                launcher.launch(Intent(this@MainActivity, LoginActivity::class.java))
+            }
+        }
     }
 
     private fun startRoomActivityAndFinish() {

app/src/main/java/io/element/android/x/MainViewModel.kt

@@ -0,0 +1,12 @@
+package io.element.android.x
+
+import androidx.lifecycle.ViewModel
+import io.element.android.x.sdk.matrix.MatrixInstance
+
+class MainViewModel : ViewModel() {
+    private val matrix = MatrixInstance.getInstance()
+
+    suspend fun hasSession(): Boolean {
+        return matrix.restoreSession() != null
+    }
+}

libraries/sdk/matrix/build.gradle

@@ -30,4 +30,6 @@ android {
 dependencies {
     implementation(name: 'matrix-rust-sdk', ext: 'aar')
     implementation "net.java.dev.jna:jna:5.10.0@aar"
+    implementation 'androidx.datastore:datastore-core:1.0.0'
+    implementation 'androidx.datastore:datastore-preferences:1.0.0'
 }

libraries/sdk/matrix/src/main/java/io/element/android/x/sdk/matrix/Matrix.kt

@@ -1,18 +1,35 @@
 package io.element.android.x.sdk.matrix
 
 import android.content.Context
+import io.element.android.x.sdk.matrix.store.SessionStore
 import org.matrix.rustcomponents.sdk.AuthenticationService
+import org.matrix.rustcomponents.sdk.ClientBuilder
 import java.io.File
 
 class Matrix(
     context: Context,
 ) {
     private val authFolder = File(context.filesDir, "auth")
+    private val sessionStore = SessionStore(context)
 
-    fun login(homeserver: String, username: String, password: String): MatrixClient {
+    suspend fun restoreSession(): MatrixClient? {
+        return sessionStore.getStoredData()
+            ?.let { sessionData ->
+                val client = ClientBuilder()
+                    .username(sessionData.userId)
+                    .build()
+                client.restoreLogin(sessionData.restoreToken)
+                client
+            }?.let {
+                MatrixClient(it)
+            }
+    }
+
+    suspend fun login(homeserver: String, username: String, password: String): MatrixClient {
         val authService = AuthenticationService(authFolder.absolutePath)
         authService.configureHomeserver(homeserver)
         val client = authService.login(username, password, "MatrixRustSDKSample", null)
+        sessionStore.storeData(SessionStore.SessionData(username, client.restoreToken()))
         return MatrixClient(client)
     }
 }

libraries/sdk/matrix/src/main/java/io/element/android/x/sdk/matrix/store/SessionStore.kt

@@ -0,0 +1,48 @@
+package io.element.android.x.sdk.matrix.store
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.preferencesDataStore
+import kotlinx.coroutines.flow.firstOrNull
+
+
+private val Context.dataStore: DataStore<Preferences> by preferencesDataStore(name = "elementx_sessions")
+
+internal class SessionStore(
+    context: Context
+) {
+    data class SessionData(
+        val userId: String,
+        val restoreToken: String,
+    )
+
+    private val store = context.dataStore
+
+    private val userIdPreference = stringPreferencesKey("userId")
+    private val restoreTokenPreference = stringPreferencesKey("restoreToken")
+
+    suspend fun storeData(sessionData: SessionData) {
+        store.edit { prefs ->
+            prefs[userIdPreference] = sessionData.userId
+            prefs[restoreTokenPreference] = sessionData.restoreToken
+        }
+    }
+
+    suspend fun getStoredData(): SessionData? {
+        return store.data.firstOrNull()?.let { prefs ->
+            val userId = prefs[userIdPreference] ?: return@let null
+            val restoreToken = prefs[restoreTokenPreference] ?: return@let null
+            SessionData(
+                userId = userId,
+                restoreToken = restoreToken,
+            )
+        }
+    }
+
+    suspend fun reset() {
+        store.edit { it.clear() }
+    }
+}