Mismatched SDK checking and service plumbing (#54,#61).

* adds an inspection that checks for mismatched SDKs and pops up an editor notification (#54)
* introduces `FlutterSettings` for persisting settings
* adds a new `FlutterSdkService` with Small and IDEA IDE implementations (#61)

resources/META-INF/idea-contribs.xml

@@ -0,0 +1,8 @@
+<!-- Defines IDEA IDE-specific contributions and implementations. -->
+<idea-plugin version="2">
+  <extensions defaultExtensionNs="com.intellij">
+    <projectService serviceInterface="io.flutter.sdk.FlutterSdkService" serviceImplementation="io.flutter.sdk.FlutterIdeaSdkService"
+                    overrides="true"/>
+    <editorNotificationProvider implementation="io.flutter.inspections.WrongDartSdkConfigurationNotificationProvider"/>
+  </extensions>
+</idea-plugin>

resources/META-INF/plugin.xml

@@ -1,26 +1,38 @@
 <idea-plugin version="2">
   <id>io.flutter</id>
   <name>flutter-intellij</name>
+  <description><![CDATA[
+      Flutter-specific extensions for Dart.
+    ]]></description>
+
   <vendor>flutter.io</vendor>
 
   <depends>Dart</depends>
 
-  <description><![CDATA[
-      Flutter-specific extensions for Dart.
-    ]]></description>
+  <!-- Contributes IDEA-specific features and implementations. -->
+  <depends optional="true" config-file="idea-contribs.xml">com.intellij.modules.java</depends>
 
+  <!-- Everything following should be SmallIDE-friendly.-->
+  <!-- See: http://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/plugin_compatibility.html -->
 
   <extensions defaultExtensionNs="com.intellij">
     <configurationType implementation="io.flutter.run.FlutterRunConfigurationType"/>
     <runConfigurationProducer implementation="io.flutter.run.FlutterRunConfigurationProducer"/>
     <programRunner implementation="io.flutter.run.FlutterRunner"/>
+
     <moduleType id="FLUTTER_MODULE_TYPE" implementationClass="io.flutter.module.FlutterModuleType"/>
 
+    <projectService serviceInterface="io.flutter.settings.FlutterSettings" serviceImplementation="io.flutter.settings.FlutterSettings"/>
+
     <!-- SDK type support WIP; see: #55 /-->
     <!--sdkType implementation="io.flutter.sdk.FlutterSdkType"/-->
 
+    <!-- Plugin service with SmallIDE default, optionally overridden by product-specific implementations -->
+    <projectService serviceInterface="io.flutter.sdk.FlutterSdkService" serviceImplementation="io.flutter.sdk.FlutterSmallIDESdkService"
+                    overrides="false"/>
+
     <applicationConfigurable groupId="language" instance="io.flutter.sdk.FlutterSettingsConfigurable"
-                         id="flutter.settings" key="flutter.title" bundle="io.flutter.FlutterBundle" nonDefaultProject="true"/>
+                             id="flutter.settings" key="flutter.title" bundle="io.flutter.FlutterBundle" nonDefaultProject="true"/>
   </extensions>
 
 </idea-plugin>

src/io/flutter/FlutterBundle.properties

@@ -20,3 +20,5 @@ no.project.dir=Project directory not given
 flutter.sdk.name=Flutter SDK
 flutter.sdk.label.0=Flutter {0}
 flutter.sdk.label.unknown.0=Unknown Flutter version at {0}
+dart.sdk.configuration.action.label=Configure Dart SDK
+flutter.wrong.dart.sdk.warning=The Dart SDK for this module is not the same as Flutter's.  Setting Dart to use the Flutter vended SDK is strongly recommended.

src/io/flutter/inspections/WrongDartSdkConfigurationNotificationProvider.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2016 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter.inspections;
+
+import com.intellij.execution.ExecutionException;
+import com.intellij.openapi.fileEditor.FileEditor;
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.module.ModuleType;
+import com.intellij.openapi.module.ModuleUtilCore;
+import com.intellij.openapi.project.DumbAware;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.Key;
+import com.intellij.openapi.util.text.StringUtil;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.PsiManager;
+import com.intellij.ui.EditorNotificationPanel;
+import com.intellij.ui.EditorNotifications;
+import com.jetbrains.lang.dart.DartFileType;
+import com.jetbrains.lang.dart.DartLanguage;
+import com.jetbrains.lang.dart.sdk.DartSdk;
+import io.flutter.FlutterBundle;
+import io.flutter.module.FlutterModuleType;
+import io.flutter.sdk.FlutterSdk;
+import io.flutter.sdk.FlutterSdkService;
+import io.flutter.settings.FlutterSettings;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class WrongDartSdkConfigurationNotificationProvider extends EditorNotifications.Provider<EditorNotificationPanel>
+  implements DumbAware {
+  private static final Key<EditorNotificationPanel> KEY = Key.create("Setup Dart SDK");
+
+  private final Project project;
+
+  public WrongDartSdkConfigurationNotificationProvider(@NotNull Project project, @NotNull EditorNotifications notifications) {
+    this.project = project;
+  }
+
+  @NotNull
+  private static EditorNotificationPanel createWrongSdkPanel(@NotNull Project project, @Nullable Module module) {
+
+    final FlutterSettings settings = FlutterSettings.getInstance(project);
+    if (settings.ignoreMismatchedDartSdks()) return null;
+
+    EditorNotificationPanel panel = new EditorNotificationPanel();
+    panel.setText(FlutterBundle.message("flutter.wrong.dart.sdk.warning"));
+    panel.createActionLabel(FlutterBundle.message("dart.sdk.configuration.action.label"),
+                            () -> FlutterSdkService.getInstance(project).configureDartSdk(module));
+    panel.createActionLabel("Dismiss", () -> {
+      settings.setIgnoreMismatchedDartSdks(true);
+      panel.setVisible(false);
+    });
+
+    return panel;
+  }
+
+  @NotNull
+  @Override
+  public Key<EditorNotificationPanel> getKey() {
+    return KEY;
+  }
+
+  @Override
+  public EditorNotificationPanel createNotificationPanel(@NotNull VirtualFile file, @NotNull FileEditor fileEditor) {
+    if (file.getFileType() != DartFileType.INSTANCE) return null;
+
+    PsiFile psiFile = PsiManager.getInstance(project).findFile(file);
+    if (psiFile == null) return null;
+
+    if (psiFile.getLanguage() != DartLanguage.INSTANCE) return null;
+
+    Module module = ModuleUtilCore.findModuleForPsiElement(psiFile);
+    if (module == null) return null;
+
+    if (!ModuleType.is(module, FlutterModuleType.getInstance())) return null;
+
+    try {
+      final String flutterDartSdkPath = FlutterSdk.getFlutterSdk(project).getDartSdkPath();
+      final String dartSdkPath = DartSdk.getDartSdk(project).getHomePath();
+      if (!StringUtil.equals(flutterDartSdkPath, dartSdkPath)) {
+        return createWrongSdkPanel(project, module);
+      }
+    }
+    catch (ExecutionException e) {
+      //TODO(pq): add panel for unconfigured Flutter SDK.
+    }
+
+    return null;
+  }
+}

src/io/flutter/sdk/FlutterIdeaSdkService.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2016 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter.sdk;
+
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.project.Project;
+import com.jetbrains.lang.dart.sdk.DartConfigurable;
+import org.jetbrains.annotations.NotNull;
+
+public class FlutterIdeaSdkService extends FlutterSdkService {
+  public FlutterIdeaSdkService(Project project) {
+    super(project);
+  }
+
+  @Override
+  public void configureDartSdk(@NotNull Module module) {
+    //TODO(pq): consider a service that sets this value or seeds the dialog with a proposed path
+    DartConfigurable.openDartSettings(module.getProject());
+  }
+
+}

src/io/flutter/sdk/FlutterSdk.java

@@ -179,6 +179,11 @@ public String getVersion() {
     return myVersion;
   }
 
+  @NotNull
+  public String getDartSdkPath() throws ExecutionException {
+    return FlutterSdkUtil.pathToDartSdk(getHomePath());
+  }
+
   public enum Command {
 
     CREATE("create", "Flutter: Create") {

src/io/flutter/sdk/FlutterSdkService.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2016 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter.sdk;
+
+
+import com.intellij.openapi.components.ServiceManager;
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.project.Project;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A service to coordinate SDK configuration with specific IDEA and SmallIDE
+ * implementations.
+ */
+public abstract class FlutterSdkService {
+
+  @NotNull
+  protected final Project project;
+
+  protected FlutterSdkService(@NotNull Project project) {
+    this.project = project;
+  }
+
+  public static FlutterSdkService getInstance(@NotNull Project project) {
+    return ServiceManager.getService(project, FlutterSdkService.class);
+  }
+
+  public abstract void configureDartSdk(@Nullable Module module);
+}

src/io/flutter/sdk/FlutterSdkUtil.java

@@ -64,18 +64,30 @@ private static void updateKnownPaths(@NotNull final String propertyKey, @Nullabl
     }
   }
 
-
   @NotNull
   public static String pathToFlutterTool(@NotNull String sdkPath) throws ExecutionException {
-    VirtualFile sdk = LocalFileSystem.getInstance().findFileByPath(sdkPath);
-    if (sdk == null) throw new ExecutionException(FlutterBundle.message("flutter.sdk.is.not.configured"));
-    VirtualFile bin = sdk.findChild("bin");
-    if (bin == null) throw new ExecutionException(FlutterBundle.message("flutter.sdk.is.not.configured"));
-    VirtualFile exec = bin.findChild("flutter"); // TODO Use flutter.bat on Windows
-    if (exec == null) throw new ExecutionException(FlutterBundle.message("flutter.sdk.is.not.configured"));
-    return exec.getPath();
+    return sdkRelativePathTo(sdkPath, "bin", "flutter"); // TODO Use flutter.bat on Windows
+  }
+
+  @NotNull
+  public static String pathToDartSdk(@NotNull String sdkPath) throws ExecutionException {
+    return sdkRelativePathTo(sdkPath, "bin", "cache", "dart-sdk");
   }
 
+  @NotNull
+  private static String sdkRelativePathTo(@NotNull String sdkPath, @NotNull String... segments) throws ExecutionException {
+    VirtualFile child = LocalFileSystem.getInstance().findFileByPath(sdkPath);
+    if (child == null) throw new ExecutionException(FlutterBundle.message("flutter.sdk.is.not.configured"));
+    for (String segment : segments) {
+      child = child.findChild(segment);
+      if (child == null) {
+        throw new ExecutionException(FlutterBundle.message("flutter.sdk.is.not.configured"));
+      }
+    }
+    return child.getPath();
+  }
+
+
   public static boolean isFlutterSdkLibRoot(@Nullable VirtualFile sdk) {
     if (sdk == null) return false;
     VirtualFile bin = sdk.findChild("bin");

src/io/flutter/sdk/FlutterSmallIDESdkService.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2016 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter.sdk;
+
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.project.Project;
+import org.jetbrains.annotations.NotNull;
+
+public class FlutterSmallIDESdkService extends FlutterSdkService {
+
+  public FlutterSmallIDESdkService(Project project) {
+    super(project);
+  }
+
+  @Override
+  public void configureDartSdk(@NotNull Module module) {
+      //TODO(pq): implement
+  }
+
+}

src/io/flutter/settings/FlutterSettings.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2016 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter.settings;
+
+import com.intellij.openapi.components.PersistentStateComponent;
+import com.intellij.openapi.components.ServiceManager;
+import com.intellij.openapi.components.State;
+import com.intellij.openapi.components.Storage;
+import com.intellij.openapi.project.Project;
+import com.intellij.util.xmlb.XmlSerializerUtil;
+import org.jetbrains.annotations.Nullable;
+
+
+/**
+ * Persists Flutter settings.
+ */
+@State(
+  name = "FlutterSettings",
+  storages = {
+    @Storage("FlutterSettings.xml")}
+)
+public class FlutterSettings implements PersistentStateComponent<FlutterSettings> {
+
+  private boolean ignoreMismatchedDartSdks;
+
+  @Nullable
+  public static FlutterSettings getInstance(Project project) {
+    return ServiceManager.getService(project, FlutterSettings.class);
+  }
+
+  @Nullable
+  @Override
+  public FlutterSettings getState() {
+    return this;
+  }
+
+  @Override
+  public void loadState(FlutterSettings settings) {
+    XmlSerializerUtil.copyBean(settings, this);
+  }
+
+  public boolean ignoreMismatchedDartSdks() {
+    return ignoreMismatchedDartSdks;
+  }
+
+  public void setIgnoreMismatchedDartSdks(boolean ignoreMismatchedDartSdks) {
+    this.ignoreMismatchedDartSdks = ignoreMismatchedDartSdks;
+  }
+}