Check server version against app minimum api version

app/src/main/java/com/jerboa/MainActivity.kt

@@ -14,6 +14,8 @@ import androidx.activity.viewModels
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.livedata.observeAsState
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
 import androidx.compose.ui.platform.LocalContext
 import androidx.navigation.NavType
 import androidx.navigation.compose.NavHost
@@ -22,6 +24,8 @@ import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navArgument
 import androidx.navigation.navDeepLink
 import arrow.core.Either
+import com.jerboa.api.ApiState
+import com.jerboa.api.MINIMUM_API_VERSION
 import com.jerboa.datatypes.types.GetCommunity
 import com.jerboa.datatypes.types.GetPersonDetails
 import com.jerboa.datatypes.types.GetPersonMentions
@@ -43,6 +47,7 @@ import com.jerboa.ui.components.comment.reply.CommentReplyActivity
 import com.jerboa.ui.components.comment.reply.CommentReplyViewModel
 import com.jerboa.ui.components.common.MarkdownHelper
 import com.jerboa.ui.components.common.ShowChangelog
+import com.jerboa.ui.components.common.ShowOutdatedServerDialog
 import com.jerboa.ui.components.common.getCurrentAccount
 import com.jerboa.ui.components.common.getCurrentAccountSync
 import com.jerboa.ui.components.community.CommunityActivity
@@ -126,6 +131,7 @@ class MainActivity : ComponentActivity() {
             ) {
                 val navController = rememberNavController()
                 val ctx = LocalContext.current
+                var serverVersionOutdatedViewed = remember { mutableStateOf(false) }
 
                 MarkdownHelper.init(
                     navController,
@@ -135,6 +141,19 @@ class MainActivity : ComponentActivity() {
 
                 ShowChangelog(appSettingsViewModel = appSettingsViewModel)
 
+                when (val siteRes = siteViewModel.siteRes) {
+                    is ApiState.Success -> {
+                        val siteVersion = siteRes.data.version
+                        if (compareVersions(siteVersion, MINIMUM_API_VERSION) < 0 && !serverVersionOutdatedViewed.value) {
+                            ShowOutdatedServerDialog(
+                                siteVersion = siteVersion,
+                                onConfirm = { serverVersionOutdatedViewed.value = true },
+                            )
+                        }
+                    }
+                    else -> {}
+                }
+
                 NavHost(
                     navController = navController,
                     startDestination = "home",

app/src/main/java/com/jerboa/Utils.kt

@@ -46,6 +46,7 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.lerp
 import androidx.core.util.PatternsCompat
 import androidx.navigation.NavController
+import arrow.core.compareTo
 import com.google.gson.Gson
 import com.google.gson.reflect.TypeToken
 import com.jerboa.api.API
@@ -1229,3 +1230,21 @@ fun scrollToPreviousParentComment(
             }
     }
 }
+
+/**
+ * Compare two version strings.
+ *
+ * This attempts to do a natural comparison assuming it's a typical semver (e.g. x.y.z),
+ * but it ignores anything it doesn't understand. Since we're highly confident that these verisons
+ * will be properly formed, this is safe enough without overcomplicating it.
+ */
+fun compareVersions(a: String, b: String): Int {
+    val versionA: List<Int> = a.split('.').mapNotNull { it.toIntOrNull() }
+    val versionB: List<Int> = b.split('.').mapNotNull { it.toIntOrNull() }
+
+    val comparison = versionA.compareTo(versionB)
+    if (comparison == 0) {
+        return a.compareTo(b)
+    }
+    return comparison
+}

app/src/main/java/com/jerboa/api/Http.kt

@@ -18,6 +18,7 @@ import java.io.InputStream
 
 const val VERSION = "v3"
 const val DEFAULT_INSTANCE = "lemmy.ml"
+const val MINIMUM_API_VERSION: String = "0.18"
 
 interface API {
     @GET("site")

app/src/main/java/com/jerboa/ui/components/common/Dialogs.kt

@@ -39,6 +39,7 @@ import androidx.compose.ui.tooling.preview.Preview
 import com.jerboa.PostViewMode
 import com.jerboa.R
 import com.jerboa.UnreadOrAll
+import com.jerboa.api.MINIMUM_API_VERSION
 import com.jerboa.datatypes.types.CommentSortType
 import com.jerboa.datatypes.types.ListingType
 import com.jerboa.datatypes.types.SortType
@@ -368,3 +369,27 @@ fun ShowChangelog(appSettingsViewModel: AppSettingsViewModel) {
         }
     }
 }
+
+@Composable
+fun ShowOutdatedServerDialog(siteVersion: String, onConfirm: () -> Unit) {
+    AlertDialog(
+        text = {
+            Text(
+                stringResource(
+                    R.string.dialogs_server_version_outdated,
+                    siteVersion,
+                    MINIMUM_API_VERSION,
+                ),
+            )
+        },
+        onDismissRequest = { },
+        confirmButton = {
+            Button(
+                onClick = onConfirm,
+                content = {
+                    Text(stringResource(id = R.string.input_fields_ok))
+                },
+            )
+        },
+    )
+}

app/src/main/java/com/jerboa/ui/components/login/LoginViewModel.kt

@@ -12,8 +12,10 @@ import androidx.navigation.NavController
 import com.jerboa.R
 import com.jerboa.api.API
 import com.jerboa.api.ApiState
+import com.jerboa.api.MINIMUM_API_VERSION
 import com.jerboa.api.apiWrapper
 import com.jerboa.api.retrofitErrorHandler
+import com.jerboa.compareVersions
 import com.jerboa.datatypes.types.GetPosts
 import com.jerboa.datatypes.types.GetSite
 import com.jerboa.datatypes.types.Login
@@ -93,32 +95,49 @@ class LoginViewModel : ViewModel() {
                     ).show()
                 }
                 is ApiState.Success -> {
-                    val luv = siteRes.data.my_user!!.local_user_view
-                    val account = Account(
-                        id = luv.person.id,
-                        name = luv.person.name,
-                        current = true,
-                        instance = instance,
-                        jwt = jwt,
-                        defaultListingType = luv.local_user.default_listing_type.ordinal,
-                        defaultSortType = luv.local_user.default_sort_type.ordinal,
-                    )
+                    val siteVersion = siteRes.data.version
+                    if (compareVersions(siteVersion, MINIMUM_API_VERSION) < 0) {
+                        val message = ctx.resources.getString(
+                            R.string.dialogs_server_version_outdated_short,
+                            siteVersion,
+                        )
+                        Toast.makeText(ctx, message, Toast.LENGTH_SHORT).show()
+                    }
 
-                    homeViewModel.resetPage()
-                    homeViewModel.getPosts(
-                        GetPosts(
-                            type_ = luv.local_user.default_listing_type,
-                            sort = luv.local_user.default_sort_type,
-                            page = homeViewModel.page,
-                            auth = account.jwt,
-                        ),
-                    )
+                    try {
+                        val luv = siteRes.data.my_user!!.local_user_view
+                        val account = Account(
+                            id = luv.person.id,
+                            name = luv.person.name,
+                            current = true,
+                            instance = instance,
+                            jwt = jwt,
+                            defaultListingType = luv.local_user.default_listing_type.ordinal,
+                            defaultSortType = luv.local_user.default_sort_type.ordinal,
+                        )
+
+                        homeViewModel.resetPage()
+                        homeViewModel.getPosts(
+                            GetPosts(
+                                type_ = luv.local_user.default_listing_type,
+                                sort = luv.local_user.default_sort_type,
+                                page = homeViewModel.page,
+                                auth = account.jwt,
+                            ),
+                        )
 
-                    // Remove the default account
-                    accountViewModel.removeCurrent()
+                        // Remove the default account
+                        accountViewModel.removeCurrent()
 
-                    // Save that info in the DB
-                    accountViewModel.insert(account)
+                        // Save that info in the DB
+                        accountViewModel.insert(account)
+                    } catch (e: Exception) {
+                        loading = false
+                        Log.e("login", e.toString())
+                        API.changeLemmyInstance(originalInstance)
+                        this.cancel()
+                        return@launch
+                    }
 
                     loading = false
 

app/src/main/res/values/strings.xml

@@ -140,6 +140,8 @@
     <string name="dialogs_top_year">Top Year</string>
     <string name="dialogs_old">Old</string>
     <string name="dialogs_unread">Unread</string>
+    <string name="dialogs_server_version_outdated">Server version (%1$s) is under the minimum supported version (%2$s).\n\nPlease inform your administrator and login to another instance, or sign out and use the default instance.</string>
+    <string name="dialogs_server_version_outdated_short">Server version (%1$s) too low.</string>
     <string name="floating_createPost">Create post</string>
     <string name="form_submit">Submit</string>
     <string name="homeHeader_filter">Select feed</string>

app/src/test/java/com/jerboa/UtilsKtTest.kt

@@ -179,4 +179,14 @@ class UtilsKtTest {
         val durationString = formatDuration(date, true)
         assertEquals("1 day", durationString)
     }
+
+    @Test
+    fun compareVersions() {
+        assertEquals(-1, compareVersions("0.0.1", "0.0.2"))
+        assertEquals(1, compareVersions("0.0.10", "0.0.2"))
+        assertEquals(1, compareVersions("0.1.10", "0.1.2"))
+        assertEquals(0, compareVersions("0.1.2", "0.1.2"))
+        assertEquals(-1, compareVersions("0.1.2-alpha1", "0.1.2-beta1"))
+        assertEquals(1, compareVersions("0.1.2-beta1", "0.1.2-alpha2"))
+    }
 }