Signal a missing Rascal dependency during PathConfig calculation

src/org/rascalmpl/library/Messages.java

@@ -3,6 +3,7 @@
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -43,6 +44,33 @@ public class Messages {
     private static final io.usethesource.vallang.type.Type Message_warning = tf.constructor(ts, Message, "warning", tf.stringType(), "msg", tf.sourceLocationType(), "at");
     private static final io.usethesource.vallang.type.Type Message_error = tf.constructor(ts, Message, "error", tf.stringType(), "msg", tf.sourceLocationType(), "at");
 
+    // These declarations mirror the data definitions in the `util::IDEServices` module of the standard library
+    private static final io.usethesource.vallang.type.Type CodeAction = tf.abstractDataType(ts, "CodeAction");
+    public static final io.usethesource.vallang.type.Type CodeAction_action = tf.constructor(ts, CodeAction, "action");
+
+    public static final io.usethesource.vallang.type.Type Command = tf.abstractDataType(ts, "Command");
+    private static final io.usethesource.vallang.type.Type Command_noop = tf.constructor(ts, Command, "noop");
+
+    // These declarations mirror the data definition in the `analysis::diff::edits::FileSystemChanges` module of the standard library
+    private static final io.usethesource.vallang.type.Type FileSystemChange = tf.abstractDataType(ts, "FileSystemChange");
+    private static final io.usethesource.vallang.type.Type FileSystemChange_removed = tf.constructor(ts, FileSystemChange, "removed", tf.sourceLocationType(), "file");
+    private static final io.usethesource.vallang.type.Type FileSystemChange_created = tf.constructor(ts, FileSystemChange, "created", tf.sourceLocationType(), "file");
+    private static final io.usethesource.vallang.type.Type FileSystemChange_renamed = tf.constructor(ts, FileSystemChange, "renamed", tf.sourceLocationType(), "from", tf.sourceLocationType(), "to");
+    private static final io.usethesource.vallang.type.Type FileSystemChange_changed = tf.constructor(ts, FileSystemChange, "changed", tf.sourceLocationType(), "file");
+
+    static {
+        // data Message(list[CodeAction] fixes = []]);
+        ts.declareKeywordParameter(Message, "fixes", tf.listType(CodeAction));
+
+        // data CodeAction(list[FileSystemChange] edits = [], Command command = noop(), str title = command.title);
+        ts.declareKeywordParameter(CodeAction, "edits", tf.listType(FileSystemChange));
+        ts.declareKeywordParameter(CodeAction, "command", Command);
+        ts.declareKeywordParameter(CodeAction, "title", tf.stringType());
+
+        // data Command(str title="");
+        ts.declareKeywordParameter(CodeAction, "title", tf.stringType());
+    }
+
     public static IConstructor info(String message, ISourceLocation loc) {
         return message(Message_info, message, loc);
     }
@@ -73,6 +101,18 @@ public static IConstructor addCause(IConstructor msg, String cause, ISourceLocat
         return msg.asWithKeywordParameters().setParameter("causes", causes);
     }
 
+    public static IConstructor addFix(IConstructor msg, IConstructor fix) {
+        if (fix == null) {
+            return msg;
+        }
+
+        var kw = msg.asWithKeywordParameters();
+        IList fixes = (IList) kw.getParameter("fixes");
+        fixes = fixes == null ? vf.list(fix) : fixes.append(fix);
+
+        return kw.setParameter("fixes", fixes);
+    }
+
     public static boolean isError(IValue v) {
         return v instanceof IConstructor && ((IConstructor) v).getConstructorType() == Message_error;
     }

src/org/rascalmpl/library/util/PathConfig.java

@@ -520,7 +520,7 @@ private static void buildRascalSelfApplicationConfig(ISourceLocation workspaceRa
      * Configure paths for the rascal-lsp project when it's open in the IDE (the runtime inside rascal-lsp is not configured here)
      */
     private static void buildRascalLSPConfig(ISourceLocation manifestRoot, RascalConfigMode mode, List<Artifact> mavenClasspath, IListWriter srcs, IListWriter libs, IListWriter messages) throws IOException {
-        var rascalRuntime = getRelevantRascal(mavenClasspath, mode);
+        var rascalRuntime = getRelevantRascal(mavenClasspath, mode, manifestRoot, messages);
         var insideRascalJar = JarURIResolver.jarify(MavenRepositoryURIResolver.mavenize(rascalRuntime));
         var rascalLibrary = URIUtil.getChildLocation(insideRascalJar, "org/rascalmpl/library");
         var rascalCompiler = URIUtil.getChildLocation(insideRascalJar, "org/rascalmpl/compiler");
@@ -576,7 +576,7 @@ public static boolean isRascalArtifact(Artifact art) {
             && coord.getGroupId().equals("org.rascalmpl");
     }
 
-    private static ISourceLocation getRelevantRascal(List<Artifact> mavenClasspath, RascalConfigMode mode) throws IOException {
+    private static ISourceLocation getRelevantRascal(List<Artifact> mavenClasspath, RascalConfigMode mode, ISourceLocation manifestRoot, IListWriter messages) throws IOException {
         if (mode == RascalConfigMode.INTERPRETER_EXTERNAL || mode == RascalConfigMode.COMPILER) {
             var rascalFromPom = mavenClasspath.stream()
                 .filter(PathConfig::isRascalArtifact)
@@ -586,14 +586,34 @@ private static ISourceLocation getRelevantRascal(List<Artifact> mavenClasspath,
                 .map(vf::sourceLocation);
             if (rascalFromPom.isPresent()) {
                 return rascalFromPom.get();
+            } else {
+                messages.append(makeMissingRascalMessage(manifestRoot));
             }
         }
         return resolveCurrentRascalRuntime();
     }
 
+    // This declaration does not mirror a constructor from the standard library; it is here to be able to send the command, but the declaration must live in the implementing project (e.g., `rascal-lsp`)
+    private static final io.usethesource.vallang.type.Type Command_addRascalDependencyToPom = tf.constructor(store, Messages.Command, "addRascalDependencyToPom", tf.sourceLocationType(), "pomLoc");
+
+    private static IConstructor addAddRascalDependencyFix(IConstructor msg, ISourceLocation pomXml) {
+        var title = "Add Rascal dependency to pom.xml";
+        var codeAction = vf.constructor(Command_addRascalDependencyToPom, new IValue[] { pomXml }, Map.of("title", vf.string(title)));
+        var fix = vf.constructor(Messages.CodeAction_action, new IValue[]{}, Map.of("command", codeAction));
+        return Messages.addFix(msg, fix);
+    }
+
+    private static IConstructor makeMissingRascalMessage(ISourceLocation manifestRoot) {
+        // The `pomXml` location is given an artificial range on the second line to make sure that the hover remains within the bounds of the editor
+        // Otherwise, the quick-fix pop-up immediately disappears as the editor loses focus
+        var pomXml = vf.sourceLocation(URIUtil.getChildLocation(manifestRoot, "pom.xml"), 0, 0, 2, 2, 0, 8);
+        var msg = Messages.warning("Missing required Rascal dependency in project " + URIUtil.getLocationName(manifestRoot), pomXml);
+        return addAddRascalDependencyFix(msg, pomXml);
+    }
+
     private static void buildNormalProjectConfig(ISourceLocation manifestRoot, RascalConfigMode mode, List<Artifact> mavenClasspath, boolean isRoot, IListWriter srcs, IListWriter libs, IListWriter messages) throws IOException, URISyntaxException {
         if (isRoot) {
-            var rascal = getRelevantRascal(mavenClasspath, mode);
+            var rascal = getRelevantRascal(mavenClasspath, mode, manifestRoot, messages);
             var insideRascal = JarURIResolver.jarify(MavenRepositoryURIResolver.mavenize(rascal));
 
             libs.append(rascal);