Setup basics for new code completion feature

src/main/java/de/marhali/easyi18n/ui/editor/I18nCompletionContributor.java

@@ -0,0 +1,14 @@
+package de.marhali.easyi18n.ui.editor;
+
+import com.intellij.codeInsight.completion.CompletionContributor;
+import com.intellij.codeInsight.completion.CompletionType;
+import com.intellij.patterns.*;
+import com.intellij.psi.PsiLiteralValue;
+
+public class I18nCompletionContributor extends CompletionContributor {
+
+    public I18nCompletionContributor() {
+        extend(CompletionType.BASIC, PlatformPatterns.psiElement().inside(PsiLiteralValue.class),
+                new I18nCompletionProvider());
+    }
+}

src/main/java/de/marhali/easyi18n/ui/editor/I18nCompletionProvider.java

@@ -0,0 +1,43 @@
+package de.marhali.easyi18n.ui.editor;
+
+import com.intellij.codeInsight.completion.CompletionParameters;
+import com.intellij.codeInsight.completion.CompletionProvider;
+import com.intellij.codeInsight.completion.CompletionResultSet;
+import com.intellij.codeInsight.lookup.LookupElementBuilder;
+import com.intellij.ide.DataManager;
+import com.intellij.openapi.actionSystem.PlatformDataKeys;
+import com.intellij.openapi.project.Project;
+import com.intellij.util.ProcessingContext;
+import de.marhali.easyi18n.model.LocalizedNode;
+import de.marhali.easyi18n.service.DataStore;
+import org.jetbrains.annotations.NotNull;
+
+public class I18nCompletionProvider extends CompletionProvider<CompletionParameters> {
+
+    Project project;
+
+    public I18nCompletionProvider() {
+        DataManager.getInstance().getDataContextFromFocusAsync().onSuccess(data -> {
+           project = PlatformDataKeys.PROJECT.getData(data);
+        });
+    }
+
+    @Override
+    protected void addCompletions(@NotNull CompletionParameters parameters, @NotNull ProcessingContext context, @NotNull CompletionResultSet result) {
+        String query = result.getPrefixMatcher().getPrefix();
+
+        LocalizedNode node = query.contains(".") ?
+                DataStore.getInstance(project).getTranslations().getNode(query)
+                : DataStore.getInstance(project).getTranslations().getNodes();
+
+        if(node == null) {
+            return;
+        }
+
+        for(LocalizedNode children : node.getChildren()) {
+            result.addElement(LookupElementBuilder.create(children.getKey()).appendTailText("I18n", true));
+        }
+
+        System.out.println(result.getPrefixMatcher().getPrefix()); // Debug
+    }
+}

src/main/resources/META-INF/plugin.xml

@@ -10,5 +10,8 @@
     <extensions defaultExtensionNs="com.intellij">
         <toolWindow id="Easy I18n" anchor="bottom" factoryClass="de.marhali.easyi18n.TranslatorToolWindowFactory" />
         <projectService serviceImplementation="de.marhali.easyi18n.service.SettingsService" />
+
+        <completion.contributor language="any"
+                                implementationClass="de.marhali.easyi18n.ui.editor.I18nCompletionContributor" />
     </extensions>
 </idea-plugin>