Revamp Jelly completion suggestions

src/main/java/io/jenkins/stapler/idea/jelly/NamespaceUtil.java

@@ -0,0 +1,51 @@
+package io.jenkins.stapler.idea.jelly;
+
+import com.intellij.openapi.project.Project;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.PsiManager;
+import com.intellij.psi.search.FileTypeIndex;
+import com.intellij.psi.search.GlobalSearchScope;
+import com.intellij.psi.xml.XmlTag;
+import java.util.HashMap;
+import java.util.Map;
+import org.kohsuke.stapler.idea.language.JellyFileType;
+import org.kohsuke.stapler.idea.psi.JellyFile;
+
+public class NamespaceUtil {
+
+    /** Collects all namespaces (and prefixes) from .jelly files in the project */
+    public static Map<String, String> collectProjectNamespaces(Project project) {
+        Map<String, String> namespaces = new HashMap<>();
+
+        FileTypeIndex.processFiles(
+                JellyFileType.INSTANCE,
+                file -> {
+                    PsiFile psiFile = PsiManager.getInstance(project).findFile(file);
+                    if (psiFile instanceof JellyFile jellyFile) {
+                        XmlTag rootTag = jellyFile.getRootTag();
+                        if (rootTag != null) {
+                            String[] uris = rootTag.knownNamespaces();
+
+                            for (String uri : uris) {
+                                String prefix = rootTag.getPrefixByNamespace(uri);
+
+                                if (prefix == null || prefix.isEmpty()) {
+                                    continue;
+                                }
+
+                                // Ignore local prefixes as they're not for global usage
+                                if (prefix.equals("local") || prefix.equals("this")) {
+                                    continue;
+                                }
+
+                                namespaces.put(prefix, uri);
+                            }
+                        }
+                    }
+                    return true;
+                },
+                GlobalSearchScope.projectScope(project));
+
+        return namespaces;
+    }
+}

src/main/java/io/jenkins/stapler/idea/jelly/suggestions/JellyElement.java

@@ -0,0 +1,8 @@
+package io.jenkins.stapler.idea.jelly.suggestions;
+
+import com.intellij.xml.XmlAttributeDescriptor;
+import java.util.List;
+import javax.swing.*;
+
+public record JellyElement(
+        String name, int contentType, List<XmlAttributeDescriptor> attributesDescriptors, Icon icon) {}

src/main/java/io/jenkins/stapler/idea/jelly/suggestions/XsdParser.java

@@ -0,0 +1,43 @@
+package io.jenkins.stapler.idea.jelly.suggestions;
+
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import javax.xml.parsers.DocumentBuilderFactory;
+import org.kohsuke.stapler.idea.JellyCompletionContributor;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.NodeList;
+
+public class XsdParser {
+
+    /**
+     * @param file The schema to load
+     * @return a list of tags from the schema definition
+     */
+    public static List<String> getTagsFromSchema(String file) {
+        List<String> response = new ArrayList<>();
+        try {
+            ClassLoader classLoader = JellyCompletionContributor.class.getClassLoader();
+            InputStream inputStream =
+                    classLoader.getResourceAsStream("org/kohsuke/stapler/idea/resources/schemas/" + file + ".xsd");
+
+            if (inputStream == null) {
+                throw new RuntimeException("Schema not found: " + file + ".xsd");
+            }
+
+            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+            Document document = factory.newDocumentBuilder().parse(inputStream);
+            NodeList attributeNodes = document.getElementsByTagName("xsd:element");
+
+            for (int i = 0; i < attributeNodes.getLength(); i++) {
+                Element element = (Element) attributeNodes.item(i);
+                String name = element.getAttribute("name");
+                response.add(name);
+            }
+        } catch (Exception e) {
+            System.out.println("Error parsing XSD: " + e.getMessage());
+        }
+        return response;
+    }
+}