Add support for argument file #690

cli/harness/src/main/java/io/helidon/build/cli/harness/CommandParser.java

@@ -16,6 +16,11 @@
 package io.helidon.build.cli.harness;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -27,6 +32,7 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Properties;
+import java.util.stream.Collectors;
 
 import io.helidon.build.cli.harness.CommandModel.ArgumentInfo;
 import io.helidon.build.cli.harness.CommandModel.FlagInfo;
@@ -75,7 +81,8 @@ static CommandParser create(String... args) {
         Properties properties = new Properties();
         Map<String, Parameter> params = new HashMap<>();
         String error = null;
-        List<String> argsList = mapArgs(args);
+        String[] processedArgs = preProcessArgs(args);
+        List<String> argsList = mapArgs(processedArgs);
         Iterator<String> it = argsList.iterator();
         while (it.hasNext()) {
             String rawArg = it.next();
@@ -112,6 +119,31 @@ static CommandParser create(String... args) {
         return new CommandParser(argsList, commandName, new Resolver(params, properties), error);
     }
 
+    static String[] preProcessArgs(String[] args) {
+        List<String> result = new ArrayList<>();
+        for (int i = 0; i < args.length; i++) {
+            if ("--args-file".equals(args[i]) && (i < args.length - 1)) {
+                String argsFile = args[i + 1];
+                result.addAll(readArgsFile(argsFile));
+                i++;
+            } else {
+                result.add(args[i]);
+            }
+        }
+        return result.toArray(new String[0]);
+    }
+
+    static List<String> readArgsFile(String argsFile) {
+        try {
+            return Files.lines(Path.of(argsFile))
+                        .filter(line -> !line.startsWith("#"))
+                        .flatMap(line -> Arrays.stream(line.split("\\s+")))
+                        .collect(Collectors.toList());
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
     static List<String> mapArgs(String... args) {
         List<String> result = new LinkedList<>(Arrays.asList(args));
         // Map version flag to version command if first argument

cli/harness/src/test/java/io/helidon/build/cli/harness/CommandParserTest.java

@@ -15,12 +15,20 @@
  */
 package io.helidon.build.cli.harness;
 
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+import java.util.Map;
+import java.util.Properties;
+
 import io.helidon.build.cli.harness.CommandModel.KeyValueInfo;
 import io.helidon.build.cli.harness.CommandModel.FlagInfo;
 import io.helidon.build.cli.harness.CommandParser.CommandParserException;
 
 import org.junit.jupiter.api.Test;
 
+import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -271,4 +279,30 @@ public void testDuplicateOptions() {
         assertThat(resolver.resolve(verboseFlag1), is(true));
         assertThat(resolver.resolve(verboseFlag2), is(true));
     }
+
+    @Test
+    public void testArgsFileOptionWithExistingFile() throws URISyntaxException {
+        KeyValueInfo<String> param = new KeyValueInfo<>(String.class, "flavor", "flavor", null, false);
+        CommandParameters cmd = new CommandParameters(param);
+
+        URI argsFilePath = getClass().getResource("args.txt").toURI();
+        CommandParser parser = CommandParser.create("command", "--args-file", Paths.get(argsFilePath).toString());
+        CommandParser.Resolver resolver = parser.parseCommand(cmd);
+
+        Map<String, CommandParser.Parameter> params = resolver.params();
+        assertThat(params.containsKey("help"), is(true));
+        assertThat(((CommandParser.KeyValueParam) params.get("flavor")).value(), is("se"));
+
+        Properties properties = resolver.properties();
+        assertThat(properties.get("foo"), is("bar"));
+    }
+
+    @Test
+    public void testArgsFileOptionWithIncorrectFile() {
+        UncheckedIOException e = assertThrows(
+                UncheckedIOException.class,
+                () -> CommandParser.create("command", "--args-file", "not_existing_file.txt")
+        );
+        assertThat(e.getMessage(), containsString("java.nio.file.NoSuchFileException: not_existing_file.txt"));
+    }
 }

cli/harness/src/test/resources/io/helidon/build/cli/harness/args.txt

@@ -0,0 +1,4 @@
+# some comment
+--flavor se
+--help
+-Dfoo=bar