Checks for the server version

app/src/main/java/chat/rocket/android/fragment/server_config/InputHostnameFragment.java

@@ -2,11 +2,14 @@ package chat.rocket.android.fragment.server_config;
 
 import android.support.design.widget.Snackbar;
 import android.widget.TextView;
+import android.widget.Toast;
 import org.json.JSONObject;
 
 import chat.rocket.android.R;
 import chat.rocket.android.RocketChatCache;
 import chat.rocket.android.helper.LogcatIfError;
+import chat.rocket.android.helper.OkHttpHelper;
+import chat.rocket.android.helper.ServerHelper;
 import chat.rocket.android.helper.TextUtils;
 import chat.rocket.android.model.ServerConfig;
 import chat.rocket.android.realm_helper.RealmObjectObserver;
@@ -37,11 +40,42 @@ public class InputHostnameFragment extends AbstractServerConfigFragment {
   }
 
   private void handleConnect() {
+    final String hostname = ServerHelper.enforceHostname(getHostname());
+
+    ServerHelper.isApiVersionValid(OkHttpHelper.getClientForUploadFile(), hostname,
+        new ServerHelper.Callback() {
+          @Override
+          public void isValid() {
+            getActivity().runOnUiThread(() -> onServerValid(hostname));
+          }
+
+          @Override
+          public void isNotValid() {
+            getActivity().runOnUiThread(() ->
+                Toast.makeText(getActivity(), R.string.input_hostname_invalid_server_message,
+                    Toast.LENGTH_SHORT).show());
+          }
+        });
+  }
+
+  @Override
+  public void onResume() {
+    super.onResume();
+  }
+
+  @Override
+  public void onDestroyView() {
+    serverConfigObserver.unsub();
+    super.onDestroyView();
+  }
+
+  private String getHostname() {
     final TextView editor = (TextView) rootView.findViewById(R.id.editor_hostname);
 
-    final String hostname =
-        TextUtils.or(TextUtils.or(editor.getText(), editor.getHint()), "").toString();
+    return TextUtils.or(TextUtils.or(editor.getText(), editor.getHint()), "").toString();
+  }
 
+  private void onServerValid(String hostname) {
     RocketChatCache.get(getContext()).edit()
         .putString(RocketChatCache.KEY_SELECTED_SERVER_CONFIG_ID, serverConfigId)
         .apply();
@@ -55,17 +89,6 @@ public class InputHostnameFragment extends AbstractServerConfigFragment {
                 .put("state", ServerConfig.STATE_READY))).continueWith(new LogcatIfError());
   }
 
-  @Override
-  public void onResume() {
-    super.onResume();
-  }
-
-  @Override
-  public void onDestroyView() {
-    serverConfigObserver.unsub();
-    super.onDestroyView();
-  }
-
   private void showError(String errString) {
     Snackbar.make(rootView, errString, Snackbar.LENGTH_LONG).show();
   }

app/src/main/java/chat/rocket/android/helper/ServerHelper.java

+package chat.rocket.android.helper;
+
+import android.support.annotation.NonNull;
+
+import org.json.JSONObject;
+
+import java.io.IOException;
+import okhttp3.Call;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+import okhttp3.ResponseBody;
+
+public class ServerHelper {
+
+  private static final String DEFAULT_HOST = ".rocket.chat";
+  private static final String API_INFO_PATH = "/api/info";
+  private static final String VERSION_PROPERTY = "version";
+
+  public static String enforceHostname(String hostname) {
+    if (hostname == null) {
+      return "demo.rocket.chat";
+    }
+
+    return removeProtocol(enforceDefaultHost(hostname));
+  }
+
+  public static void isApiVersionValid(@NonNull OkHttpClient client, @NonNull String host,
+                                       @NonNull Callback callback) {
+    Request request;
+    try {
+      request = new Request.Builder()
+          .url("https://" + host + API_INFO_PATH)
+          .get()
+          .build();
+    } catch (Exception e) {
+      callback.isNotValid();
+      return;
+    }
+
+    client.newCall(request).enqueue(new okhttp3.Callback() {
+      @Override
+      public void onFailure(Call call, IOException e) {
+        // some connection error
+        callback.isNotValid();
+      }
+
+      @Override
+      public void onResponse(Call call, Response response) throws IOException {
+        if (!response.isSuccessful() || !isValid(response.body())) {
+          callback.isNotValid();
+          return;
+        }
+
+        callback.isValid();
+      }
+    });
+  }
+
+  @NonNull
+  private static String enforceDefaultHost(String hostname) {
+    if (hostname.indexOf('.') == -1) {
+      hostname = hostname + DEFAULT_HOST;
+    }
+    return hostname;
+  }
+
+  @NonNull
+  private static String removeProtocol(String hostname) {
+    // yep. cheap.
+    return hostname.replace("http://", "").replace("https://", "");
+  }
+
+  private static boolean isValid(ResponseBody body) {
+    if (body == null || body.contentLength() == 0) {
+      return false;
+    }
+
+    try {
+      final JSONObject jsonObject = new JSONObject(body.string());
+
+      return jsonObject.has(VERSION_PROPERTY)
+          && isVersionValid(jsonObject.getString(VERSION_PROPERTY));
+    } catch (Exception e) {
+      return false;
+    }
+  }
+
+  private static boolean isVersionValid(String version) {
+    if (version == null || version.length() == 0) {
+      return false;
+    }
+
+    String[] versionParts = version.split("\\.");
+    return versionParts.length >= 3 && Integer.valueOf(versionParts[1]) >= 49;
+  }
+
+  public interface Callback {
+    void isValid();
+
+    void isNotValid();
+  }
+}

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

@@ -39,4 +39,6 @@
     <string name="image_upload_message_spec_title">Attach image</string>
     <string name="audio_upload_message_spec_title">Attach audio</string>
     <string name="video_upload_message_spec_title">Attach video</string>
+
+    <string name="input_hostname_invalid_server_message">Invalid server version</string>
 </resources>