fix: handle faulty imports

Do not throw silently for incompatible
import paths. Fix comment removal
for JS files to accept ' as string.

fixes #12765

flow-server/src/main/java/com/vaadin/flow/internal/StringUtil.java

@@ -34,7 +34,7 @@ public final class StringUtil {
      * Comment parser state enumeration.
      */
     private enum State {
-        NORMAL, IN_LINE_COMMENT, IN_BLOCK_COMMENT, IN_STRING
+        NORMAL, IN_LINE_COMMENT, IN_BLOCK_COMMENT, IN_STRING, IN_STRING_APOSTROPHE
     }
 
     /**
@@ -99,6 +99,78 @@ public final static String removeComments(String code) {
         return handled;
     }
 
+    /**
+     * Removes comments (block comments and line comments) from the JS code.
+     *
+     * @return the code with removed comments
+     */
+    public static String removeJsComments(String code) {
+        State state = State.NORMAL;
+        StringBuilder result = new StringBuilder();
+        Map<String, Character> replacements = new HashMap<>();
+        Scanner scanner = new Scanner(normalize(code, replacements));
+        scanner.useDelimiter("");
+        while (scanner.hasNext()) {
+            String character = scanner.next();
+            switch (state) {
+            case NORMAL:
+                if (character.equals("/") && scanner.hasNext()) {
+                    String nextCharacter = scanner.next();
+                    if (nextCharacter.equals("/")) {
+                        state = State.IN_LINE_COMMENT;
+                    } else if (nextCharacter.equals("*")) {
+                        state = State.IN_BLOCK_COMMENT;
+                    } else {
+                        result.append(character).append(nextCharacter);
+                    }
+                } else {
+                    result.append(character);
+                    if (character.equals("\"")) {
+                        state = State.IN_STRING;
+                    } else if (character.equals("\'")) {
+                        state = State.IN_STRING_APOSTROPHE;
+                    }
+                }
+                break;
+            case IN_STRING:
+                result.append(character);
+                if (character.equals("\"")) {
+                    state = State.NORMAL;
+                } else if (character.equals("\\") && scanner.hasNext()) {
+                    result.append(scanner.next());
+                }
+                break;
+            case IN_STRING_APOSTROPHE:
+                result.append(character);
+                if (character.equals("\'")) {
+                    state = State.NORMAL;
+                } else if (character.equals("\\") && scanner.hasNext()) {
+                    result.append(scanner.next());
+                }
+                break;
+            case IN_LINE_COMMENT:
+                if (character.equals("\n")) {
+                    result.append(character);
+                    state = State.NORMAL;
+                }
+                break;
+            case IN_BLOCK_COMMENT:
+                if (character.equals("*") && scanner.hasNext("/")) {
+                    scanner.next();
+                    state = State.NORMAL;
+                    break;
+                }
+            }
+        }
+        scanner.close();
+        String handled = result.toString();
+        for (Entry<String, Character> entry : replacements.entrySet()) {
+            handled = handled.replace(entry.getKey(),
+                    String.valueOf(entry.getValue()));
+        }
+        return handled;
+    }
+
     private static String normalize(String str,
             Map<String, Character> replacements) {
         StringBuilder builder = new StringBuilder();

flow-server/src/main/java/com/vaadin/flow/server/frontend/AbstractUpdateImports.java

@@ -22,6 +22,7 @@
 import java.nio.charset.MalformedInputException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.InvalidPathException;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -574,7 +575,10 @@ private void visitImportsRecursively(Path filePath, String path,
             if (file == null && !importedPath.startsWith("./")) {
                 // In case such file doesn't exist it may be external: inside
                 // node_modules folder
-                file = getFile(getNodeModulesDir(), resolvedPath);
+                file = getFile(getNodeModulesDir(), importedPath);
+                if (!file.exists()) {
+                    file = null;
+                }
                 resolvedPath = importedPath;
             }
             if (file == null) {
@@ -632,12 +636,19 @@ private String resolve(String importedPath, Path moduleFile, String path) {
         String pathPrefix = moduleFile.toString();
         pathPrefix = pathPrefix.substring(0,
                 pathPrefix.length() - path.length());
-        String resolvedPath = moduleFile.getParent().resolve(importedPath)
-                .toString();
-        if (resolvedPath.startsWith(pathPrefix)) {
-            resolvedPath = resolvedPath.substring(pathPrefix.length());
+        try {
+            String resolvedPath = moduleFile.getParent().resolve(importedPath)
+                    .toString();
+            if (resolvedPath.startsWith(pathPrefix)) {
+                resolvedPath = resolvedPath.substring(pathPrefix.length());
+            }
+            return resolvedPath;
+        } catch (InvalidPathException ipe) {
+            getLogger().error("Invalid import '{}' in file '{}'", importedPath,
+                    moduleFile);
+            getLogger().debug("Failed to resolve path.", ipe);
         }
-        return resolvedPath;
+        return importedPath;
     }
 
     private String normalizePath(String path) {

flow-server/src/main/java/com/vaadin/flow/server/frontend/ImportExtractor.java

@@ -86,7 +86,7 @@ List<String> getImportedPaths() {
      * @return the code with removed comments
      */
     String removeComments() {
-        return StringUtil.removeComments(content);
+        return StringUtil.removeJsComments(content);
     }
 
     /**

flow-server/src/test/java/com/vaadin/flow/internal/StringUtilTest.java

@@ -66,7 +66,44 @@ public void commentRemoval_emojiInString_removalDoesnotThrowResultIsTheSame() {
     @Test
     public void removeComments_commentsWithAsterisksInside_commentIsRemoved() {
         String result = StringUtil.removeComments("/* comment **/ ;");
-        Assert.assertEquals(result, " ;");
+        Assert.assertEquals(" ;", result);
     }
 
+    @Test
+    public void removeJsComments_handlesApostropheAsInString() {
+        String httpImport = "import 'http://localhost:56445/files/transformed/@vaadin/vaadin-text-field/vaadin-text-field.js';";
+
+        Assert.assertEquals("Nothing shoiuld be removed for import", httpImport,
+                StringUtil.removeJsComments(httpImport));
+
+        String result = StringUtil.removeJsComments("/* comment **/ ;");
+        Assert.assertEquals(" ;", result);
+
+        String singleLineBlock = StringUtil.removeJsComments(
+                "return html`/* single line block comment*/`;");
+
+        Assert.assertEquals("return html``;", singleLineBlock);
+
+        String blockComment = StringUtil
+                .removeJsComments("return html`/* block with new lines\n"
+                        + "* still in my/their block */`;");
+        Assert.assertEquals("return html``;", blockComment);
+
+        String newLineSingleBlock = StringUtil
+                .removeJsComments("return html`/* not here \n*/`;");
+        Assert.assertEquals("return html``;", newLineSingleBlock);
+
+        String noComments = "<vaadin-text-field label=\"Nats Url(s)\" placeholder=\"nats://server:port\" id=\"natsUrlTxt\" style=\"width:100%\"></vaadin-text-field>`";
+        Assert.assertEquals(noComments,
+                StringUtil.removeJsComments(noComments));
+
+        String lineComment = StringUtil
+                .removeJsComments("return html`// this line comment\n`;");
+        Assert.assertEquals("return html`\n`;", lineComment);
+
+        String mixedComments = StringUtil.removeJsComments(
+                "return html`/* not here \n*/\nCode;// neither this\n"
+                        + "/* this should // be fine\n* to remove / */`;");
+        Assert.assertEquals("return html`\nCode;\n`;", mixedComments);
+    }
 }