improved faker help

riot-gen/src/main/java/com/redislabs/riot/gen/FakerHelpCommand.java

@@ -1,48 +1,78 @@
 package com.redislabs.riot.gen;
 
-import java.io.PrintWriter;
-import java.lang.reflect.Method;
-import java.util.Arrays;
-import java.util.List;
-import java.util.stream.Collectors;
-
 import com.github.javafaker.Faker;
-
+import org.springframework.util.ClassUtils;
 import picocli.CommandLine;
 import picocli.CommandLine.Command;
 import picocli.CommandLine.Help;
 import picocli.CommandLine.IHelpCommandInitializable2;
 
+import java.io.PrintWriter;
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+import java.util.*;
+import java.util.stream.Stream;
+
 @Command(name = "faker-help", header = "Displays help information about Faker", synopsisHeading = "%nUsage: ", helpCommand = true)
 public class FakerHelpCommand implements IHelpCommandInitializable2, Runnable {
 
-	private final static List<String> EXCLUDES = Arrays.asList("instance", "options");
-
-	private PrintWriter outWriter;
-
-	public void run() {
-		for (Method method : Faker.class.getDeclaredMethods()) {
-			if (EXCLUDES.contains(method.getName())) {
-				continue;
-			}
-			if (!method.getReturnType().getPackage().equals(Faker.class.getPackage())) {
-				continue;
-			}
-			List<String> names = Arrays.stream(method.getReturnType().getDeclaredMethods())
-					.filter(m -> m.getParameters().length == 0).map(Method::getName).collect(Collectors.toList());
-			outWriter.println(String.format("%-30.30s: %s", method.getName(), String.join(" ", names)));
-		}
-	}
-
-	public void init(CommandLine helpCommandLine, Help.ColorScheme colorScheme, PrintWriter out, PrintWriter err) {
-		this.outWriter = notNull(out, "outWriter");
-	}
-
-	static <T> T notNull(T object, String description) {
-		if (object == null) {
-			throw new NullPointerException(description);
-		}
-		return object;
-	}
+    @CommandLine.Parameters(description = "Name of the Faker provider to show help for", paramLabel = "<name>")
+    private String provider;
+
+    private final static List<String> EXCLUDES = Arrays.asList("instance", "options");
+
+    private PrintWriter outWriter;
+
+    @Override
+    public void run() {
+        Stream<Method> methods = Arrays.stream(Faker.class.getDeclaredMethods()).filter(m -> !EXCLUDES.contains(m.getName())).filter(m -> m.getReturnType().getPackage().equals(Faker.class.getPackage()));
+        if (provider == null) {
+            outWriter.println("Run 'riot-gen faker-help <provider>' for documentation on a specific Faker provider:");
+            methods.sorted(Comparator.comparing(Method::getName)).forEach(p -> outWriter.println("  " + p.getName() + " " + url(ClassUtils.getShortName(p.getReturnType()))));
+        } else {
+            Optional<Method> method = methods.filter(m -> m.getName().equals(provider)).findFirst();
+            if (method.isPresent()) {
+                Class<?> type = method.get().getReturnType();
+                String shortName = ClassUtils.getShortName(type);
+                outWriter.println("Available fakes: " + url(shortName));
+                for (Method subMethod : type.getDeclaredMethods()) {
+                    outWriter.println("  " + provider + "." + methodToString(subMethod));
+                }
+            } else {
+                outWriter.println("No such field: " + provider);
+            }
+        }
+    }
+
+    private String url(String name) {
+        return "http://dius.github.io/java-faker/apidocs/com/github/javafaker/" + name + ".html";
+    }
+
+    private String methodToString(Method method) {
+        String result = method.getName();
+        Parameter[] parameters = method.getParameters();
+        if (parameters.length == 0) {
+            return result;
+        }
+        result += "(";
+        List<String> paramNames = new ArrayList<>();
+        for (Parameter parameter : parameters) {
+            paramNames.add(ClassUtils.getShortName(parameter.getType()));
+        }
+        result += String.join(",", paramNames);
+        result += ")";
+        return result;
+    }
+
+    public void init(CommandLine helpCommandLine, Help.ColorScheme colorScheme, PrintWriter out, PrintWriter err) {
+        this.outWriter = notNull(out, "outWriter");
+    }
+
+    static <T> T notNull(T object, String description) {
+        if (object == null) {
+            throw new NullPointerException(description);
+        }
+        return object;
+    }
 
 }