FluentScratch.java

FluentScratch.java

import java.util.ArrayList;
import java.util.List;

class Scratch {

  public static void main(String[] args) {
    Javalin.create("port or something", Routings
      .path("/api")
        .get("/users", UserController::getAll)
        .post("/users", UserController::create)
        .subPath("/users")
          .get("/:user-id", UserController::getOne)
          .patch("/:user-id", UserController::update)
          .delete("/:user-id", UserController::delete)
      .path("/back-to-root")
        .get("/:user-id", UserController::getOne)
    );
  }

}

class Javalin {

  public static ServerInstance create(String params, RoutingsCollector collected) { // potentially vararg
    ServerInstance server = new ServerInstance();
    server.resolve(collected.routings());
    return server;
  }
  
}

class Routings {

  public static RoutingsCollector path(String path) {
    return new RoutingsCollector(path, new ArrayList<>());
  }
  
}

class RoutingsCollector {

  private final String rootPath;
  private final List<Routing> routings;

  public RoutingsCollector(String path, List<Routing> routings) {
    this.rootPath = path;
    this.routings = routings;
  }

  public RoutingsCollector get(String path, Runnable mapping) {
    this.routings.add(new Routing(rootPath + path, mapping));
    return this;
  }

  public RoutingsCollector post(String path, Runnable mapping) {
    this.routings.add(new Routing(rootPath + path, mapping));
    return this;
  }

  public RoutingsCollector patch(String path, Runnable mapping) {
    this.routings.add(new Routing(rootPath + path, mapping));
    return this;
  }

  public RoutingsCollector delete(String path, Runnable mapping) {
    this.routings.add(new Routing(rootPath + path, mapping));
    return this;
  }

  public RoutingsCollector subPath(String path) {
    return new RoutingsCollector(rootPath + path, routings);
  }

  public RoutingsCollector path(String path) {
    return new RoutingsCollector(path, routings);
  }

  public List<Routing> routings() {
    return routings;
  }

}

class Routing {

  private final String path;
  private final Runnable mapping;

  public Routing(String path, Runnable mapping) {
    this.path = path;
    this.mapping = mapping;
  }

  @Override
  public String toString() {
    return "Routing{" +
      "path='" + path + '\'' +
      ", mapping=" + mapping +
      '}';
  }

}

class ServerInstance {
  
  public void resolve(List<Routing> routings) {
    // as a form of a test
    System.out.println("routings = " + routings);
    throw new RuntimeException("TODO");
  }

}

class UserController {

  public static void getAll() {}
  public static void create() {}
  public static void getOne() {}
  public static void update() {}
  public static void delete() {}

}