[cli] config-help writes doc-compat output (#1239)

This updates config-help to have more control over how the output is
written for the user. We dump config-help output for per-generator
documentation, and this cleans up some cross-platform compatibility
issues that might arise from tweaking the output for clarity in the
target file.

Previously, we'd pipe config-help output to sed, then insert the
generator name, which we then redirected to an output file. The sed
syntax had to include a trailing newline so our tabbed configs would
automatically become code tags in markdown. Inserting newlines into sed
replacement strings doesn't work the same across platforms, mostly
because of Apple's customizations to GNU programs.

This commit moves the generator name and newline insertion into the
command itself. It also includes a new --output option, allowing the
user to specify the output location of the config-help.

Currently, we only dump in plain-text, and it is only coincidental that
our plaintext output results in a desirable Markdown output. If
tabbed lines did not automatically convert to a code style block, some
generators like C# would end up with broken text (`List<T>` would become
just `List`, for example).

I had previously discussed extending config-help to output to other
formats like asciidoc. This commit does not introduce any steps toward
that end.

bin/utils/export_docs_generators.sh

@@ -1,11 +1,11 @@
 #!/bin/bash
 
 SCRIPT="$0"
-echo "# START SCRIPT: $SCRIPT"
+echo "# START SCRIPT: ${SCRIPT}"
 
 executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
 
-for GENERATOR in $(java -jar $executable list --short | sed -e 's/,/\'$'\n''/g')
+for GENERATOR in $(java -jar ${executable} list --short | sed -e 's/,/\'$'\n''/g')
 do
-    ./bin/utils/export_generator.sh $GENERATOR
+    ./bin/utils/export_generator.sh ${GENERATOR}
 done

bin/utils/export_generator.sh

@@ -1,17 +1,19 @@
 #!/bin/bash
 
 SCRIPT="$0"
-echo "# START SCRIPT: $SCRIPT"
 
 if [[ "$1" != "" ]]; then
     NAME="$1"
+    echo "# START SCRIPT: ${SCRIPT} ${NAME}"
 else
-    echo "Missing argument. Usage e.g.: ./bin/utils/export-generator.sh jaxrs-jersey"
+    echo "Missing argument to ${SCRIPT}."
+    echo "    Usage: ${SCRIPT} generator-name"
+    echo "    Example: ${SCRIPT} groovy"
     exit 1;
 fi
 
 executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
 
-java -jar $executable config-help -g $NAME | sed -e 's/CONFIG OPTIONS/CONFIG OPTIONS for '$NAME'\'$'\n''/g' > docs/generators/$NAME.md
+java -jar ${executable} config-help -g ${NAME} --named-header -o docs/generators/${NAME}.md
 
-echo "Back to the [generators list](README.md)" >> docs/generators/$NAME.md
+echo "Back to the [generators list](README.md)" >> docs/generators/${NAME}.md

modules/openapi-generator-cli/src/main/java/org/openapitools/codegen/cmd/ConfigHelp.java

@@ -26,6 +26,9 @@ import org.openapitools.codegen.GeneratorNotFoundException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+
 import static org.apache.commons.lang3.StringUtils.isEmpty;
 import static org.apache.commons.lang3.StringUtils.isNotEmpty;
 
@@ -42,6 +45,16 @@ public class ConfigHelp implements Runnable {
             description = "generator to get config help for")
     private String generatorName;
 
+    @Option(name = {"--named-header"}, title = "named header",
+            description = "Header includes the generator name, for clarity in output")
+    private Boolean namedHeader;
+
+    @Option(name = {"-o", "--output"}, title = "output location",
+            description = "Optionally write help to this location, otherwise default is standard output")
+    private String outputFile;
+
+    private String newline = System.lineSeparator();
+
     @Override
     public void run() {
 
@@ -57,19 +70,47 @@ public class ConfigHelp implements Runnable {
         }
 
         try {
+            StringBuilder sb = new StringBuilder();
             CodegenConfig config = CodegenConfigLoader.forName(generatorName);
-            System.out.println();
-            System.out.println("CONFIG OPTIONS");
-            for (CliOption langCliOption : config.cliOptions()) {
-                System.out.println("\t" + langCliOption.getOpt());
-                System.out.println("\t    "
-                        + langCliOption.getOptionHelp().replaceAll("\n", System.lineSeparator() + "\t    "));
-                System.out.println();
+
+            generatePlainTextHelp(sb, config);
+
+            if (!isEmpty(outputFile)) {
+                File out = new File(outputFile);
+                //noinspection ResultOfMethodCallIgnored
+                out.mkdirs();
+
+                Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(out), StandardCharsets.UTF_8));
+
+                writer.write(sb.toString());
+                writer.close();
+            } else {
+                System.out.print(sb.toString());
             }
         } catch (GeneratorNotFoundException e) {
             System.err.println(e.getMessage());
             System.err.println("[error] Check the spelling of the generator's name and try again.");
             System.exit(1);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private void generatePlainTextHelp(StringBuilder sb, CodegenConfig config) {
+        sb.append(newline);
+        sb.append("CONFIG OPTIONS");
+        if (Boolean.TRUE.equals(namedHeader)) {
+            sb.append(" for ").append(generatorName).append(newline);
+        }
+
+        sb.append(newline);
+
+        for (CliOption langCliOption : config.cliOptions()) {
+            sb.append("\t").append(langCliOption.getOpt());
+            sb.append(newline);
+            sb.append("\t    ").append(langCliOption.getOptionHelp().replaceAll("\n", System.lineSeparator() + "\t    "));
+            sb.append(newline);
+            sb.append(newline);
         }
     }
 }