/*
 * Copyright 2014 Red Hat, Inc.
 *
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  and Apache License v2.0 which accompanies this distribution.
 *
 *  The Eclipse Public License is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 *
 *  The Apache License v2.0 is available at
 *  http://www.opensource.org/licenses/apache2.0.php
 *
 *  You may elect to redistribute this code under either of these licenses.
 */

package io.vertx.ext.web;

import io.vertx.codegen.annotations.Fluent;
import io.vertx.codegen.annotations.Nullable;
import io.vertx.codegen.annotations.VertxGen;
import io.vertx.core.Future;
import io.vertx.core.Handler;
import io.vertx.core.buffer.Buffer;
import io.vertx.core.http.HttpHeaders;
import io.vertx.core.http.HttpMethod;
import io.vertx.ext.web.handler.impl.HttpStatusException;

import java.util.List;
import java.util.Set;
import java.util.function.Function;

A route is a holder for a set of criteria which determine whether an HTTP request or failure should be routed
to a handler.
Author:
Tim Fox/**
 * A route is a holder for a set of criteria which determine whether an HTTP request or failure should be routed
 * to a handler.
 *
 * @author <a href="http://tfox.org">Tim Fox</a>
 */
@VertxGen
public interface Route {

  
Add an HTTP method for this route. By default a route will match all HTTP methods. If any are specified then the route
will only match any of the specified methods
Params:
method – the HTTP method to add
Returns:
a reference to this, so the API can be used fluently/**
   * Add an HTTP method for this route. By default a route will match all HTTP methods. If any are specified then the route
   * will only match any of the specified methods
   *
   * @param method the HTTP method to add
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route method(HttpMethod method);

  
Set the path prefix for this route. If set then this route will only match request URI paths which start with this
path prefix. Only a single path or path regex can be set for a route.
Params:
path – the path prefix
Returns:
a reference to this, so the API can be used fluently/**
   * Set the path prefix for this route. If set then this route will only match request URI paths which start with this
   * path prefix. Only a single path or path regex can be set for a route.
   *
   * @param path the path prefix
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route path(String path);

  
Set the path prefix as a regular expression. If set then this route will only match request URI paths, the beginning
of which match the regex. Only a single path or path regex can be set for a route.
Params:
path – the path regex
Returns:
a reference to this, so the API can be used fluently/**
   * Set the path prefix as a regular expression. If set then this route will only match request URI paths, the beginning
   * of which match the regex. Only a single path or path regex can be set for a route.
   *
   * @param path the path regex
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route pathRegex(String path);

  
Add a content type produced by this route. Used for content based routing.
Params:
contentType – the content type
Returns:
a reference to this, so the API can be used fluently/**
   * Add a content type produced by this route. Used for content based routing.
   *
   * @param contentType the content type
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route produces(String contentType);

  
Add a content type consumed by this route. Used for content based routing.
Params:
contentType – the content type
Returns:
a reference to this, so the API can be used fluently/**
   * Add a content type consumed by this route. Used for content based routing.
   *
   * @param contentType the content type
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route consumes(String contentType);

  
Add a virtual host filter for this route.
Params:
hostnamePattern – the hostname pattern that should match Host header of the requests
Returns:
a reference to this, so the API can be used fluently/**
   * Add a virtual host filter for this route.
   *
   * @param hostnamePattern the hostname pattern that should match {@code Host} header of the requests
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route virtualHost(String hostnamePattern);

  
Specify the order for this route. The router tests routes in that order.
Params:
order – the order
Returns:
a reference to this, so the API can be used fluently/**
   * Specify the order for this route. The router tests routes in that order.
   *
   * @param order the order
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route order(int order);

  
Specify this is the last route for the router.
Returns:
a reference to this, so the API can be used fluently/**
   * Specify this is the last route for the router.
   *
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route last();

  
Append a request handler to the route handlers list. The router routes requests to handlers depending on whether the various
criteria such as method, path, etc match. When method, path, etc are the same for different routes, You should add multiple
handlers to the same route object rather than creating two different routes objects with one handler for route
Params:
requestHandler – the request handler
Returns:
a reference to this, so the API can be used fluently/**
   * Append a request handler to the route handlers list. The router routes requests to handlers depending on whether the various
   * criteria such as method, path, etc match. When method, path, etc are the same for different routes, You should add multiple
   * handlers to the same route object rather than creating two different routes objects with one handler for route
   *
   * @param requestHandler the request handler
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route handler(Handler<RoutingContext> requestHandler);


  
Like blockingHandler(Handler<RoutingContext>, boolean) called with ordered = true /**
   * Like {@link io.vertx.ext.web.Route#blockingHandler(Handler, boolean)} called with ordered = true
   */
  @Fluent
  Route blockingHandler(Handler<RoutingContext> requestHandler);

  
Use a (sub) Router as a handler. There are several requirements to be fulfilled for this to be accepted. 

    
The route path must end with a wild card
    
Parameters are allowed but full regex patterns not
    
No other handler can be registered before or after this call (but they can on a new route object for the same path)
    
Only 1 router per path object

Params:
subRouter – the router to add
Returns:
a reference to this, so the API can be used fluently/**
   * Use a (sub) {@link Router} as a handler. There are several requirements to be fulfilled for this
   * to be accepted.
   *
   * <ul>
   *     <li>The route path must end with a wild card</li>
   *     <li>Parameters are allowed but full regex patterns not</li>
   *     <li>No other handler can be registered before or after this call (but they can on a new route object for the same path)</li>
   *     <li>Only 1 router per path object</li>
   * </ul>
   *
   * @param subRouter the router to add
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route subRouter(Router subRouter);

  
Specify a blocking request handler for the route. This method works just like handler(Handler<RoutingContext>) excepted that it will run the blocking handler on a worker thread so that it won't block the event loop. Note that it's safe to call context.next() from the blocking handler as it will be executed on the event loop context (and not on the worker thread. 

If the blocking handler is ordered it means that any blocking handlers for the same context are never executed
concurrently but always in the order they were called. The default value of ordered is true. If you do not want this
behaviour and don't mind if your blocking handlers are executed in parallel you can set ordered to false.
Params:
requestHandler – the blocking request handler
ordered –        if true handlers are executed in sequence, otherwise are run in parallel
Returns:
a reference to this, so the API can be used fluently/**
   * Specify a blocking request handler for the route.
   * This method works just like {@link #handler(Handler)} excepted that it will run the blocking handler on a worker thread
   * so that it won't block the event loop. Note that it's safe to call context.next() from the
   * blocking handler as it will be executed on the event loop context (and not on the worker thread.
   * <p>
   * If the blocking handler is ordered it means that any blocking handlers for the same context are never executed
   * concurrently but always in the order they were called. The default value of ordered is true. If you do not want this
   * behaviour and don't mind if your blocking handlers are executed in parallel you can set ordered to false.
   *
   * @param requestHandler the blocking request handler
   * @param ordered        if true handlers are executed in sequence, otherwise are run in parallel
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route blockingHandler(Handler<RoutingContext> requestHandler, boolean ordered);

  
Append a failure handler to the route failure handlers list. The router routes failures to failurehandlers depending on whether the various
criteria such as method, path, etc match. When method, path, etc are the same for different routes, You should add multiple
failure handlers to the same route object rather than creating two different routes objects with one failure handler for route
Params:
failureHandler – the request handler
Returns:
a reference to this, so the API can be used fluently/**
   * Append a failure handler to the route failure handlers list. The router routes failures to failurehandlers depending on whether the various
   * criteria such as method, path, etc match. When method, path, etc are the same for different routes, You should add multiple
   * failure handlers to the same route object rather than creating two different routes objects with one failure handler for route
   *
   * @param failureHandler the request handler
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route failureHandler(Handler<RoutingContext> failureHandler);

  
Remove this route from the router
Returns:
a reference to this, so the API can be used fluently/**
   * Remove this route from the router
   *
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route remove();

  
Disable this route. While disabled the router will not route any requests or failures to it.
Returns:
a reference to this, so the API can be used fluently/**
   * Disable this route. While disabled the router will not route any requests or failures to it.
   *
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route disable();

  
Enable this route.
Returns:
a reference to this, so the API can be used fluently/**
   * Enable this route.
   *
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route enable();

  
Use useNormalizedPath(boolean) instead /**
   * Use {@link #useNormalizedPath(boolean)} instead
   */
  @Fluent
  @Deprecated
  default Route useNormalisedPath(boolean useNormalizedPath) {
    return this.useNormalizedPath(useNormalizedPath);
  }

  
If true then the normalized request path will be used when routing (e.g. removing duplicate /)
Default is true
Params:
useNormalizedPath – use normalized path for routing?
Returns:
a reference to this, so the API can be used fluently/**
   * If true then the normalized request path will be used when routing (e.g. removing duplicate /)
   * Default is true
   *
   * @param useNormalizedPath use normalized path for routing?
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route useNormalizedPath(boolean useNormalizedPath);

  
Returns:
the path prefix (if any) for this route/**
   * @return the path prefix (if any) for this route
   */
  @Nullable
  String getPath();

  
Returns true of the path is a regular expression, this includes expression paths.
Returns:
true if backed by a pattern./**
   * Returns true of the path is a regular expression, this includes expression paths.
   *
   * @return true if backed by a pattern.
   */
  boolean isRegexPath();

  
Returns:
the http methods accepted by this route/**
   * @return the http methods accepted by this route
   */
  Set<HttpMethod> methods();

  
When you add a new route with a regular expression, you can add named capture groups for parameters. 

However, if you need more complex parameters names (like "param_name"), you can add parameters names with
this function. You have to name capture groups in regex with names: "p0", "p1", "p2", ... 



For example: If you declare route with regex \/(?[a-z]*)\/(?[a-z]*) and group names ["param_a", "param-b"]
for uri /hello/world you receive inside pathParams() the parameter param_a = "hello"
Params:
groups – group names
Returns:
a reference to this, so the API can be used fluently/**
   * When you add a new route with a regular expression, you can add named capture groups for parameters. <br/>
   * However, if you need more complex parameters names (like "param_name"), you can add parameters names with
   * this function. You have to name capture groups in regex with names: "p0", "p1", "p2", ... <br/>
   * <br/>
   * For example: If you declare route with regex \/(?<p0>[a-z]*)\/(?<p1>[a-z]*) and group names ["param_a", "param-b"]
   * for uri /hello/world you receive inside pathParams() the parameter param_a = "hello"
   *
   * @param groups group names
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route setRegexGroupsNames(List<String> groups);

  
Giving a name to a route will provide this name as metadata to requests matching this route.
This metadata is used by metrics and is meant to group requests with different URI paths (due
to parameters) by a common identifier, for example "/resource/:resourceID"
common name
Params:
name – The name of the route.
Returns:
a reference to this, so the API can be used fluently/**
   * Giving a name to a route will provide this name as metadata to requests matching this route.
   * This metadata is used by metrics and is meant to group requests with different URI paths (due
   * to parameters) by a common identifier, for example "/resource/:resourceID"
   * common name
   *
   * @param name The name of the route.
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  Route setName(String name);

  
Returns:
the name of the route. If not given explicitly, the path or the pattern or
null is returned (in that order)/**
   * @return the name of the route. If not given explicitly, the path or the pattern or
   * null is returned (in that order)
   */
  String getName();

  
Append a function request handler to the route handlers list. The function expects to receive the routing context and users are expected to return a Future. The use of this functional interface allows users to quickly link the responses from other vert.x APIs or clients directly to a handler. If the context response has been ended, for example, RoutingContext.end() has been called, then nothing shall happen. For the remaining cases, the following rules apply: 

  
When body is null then the status code of the response shall be 204 (NO CONTENT)
  
When body is of type Buffer and the Content-Type isn't set then the Content-Type shall be application/octet-stream
  
When body is of type String and the Content-Type isn't set then the Content-Type shall be text/html
  
Otherwise the response of the future is then passed to the method RoutingContext.json(Object) to perform a JSON serialization of the result

Internally the function is wrapped as a handler that handles error cases for the user too. For example, if the
function throws an exception the error will be catched and a proper error will be propagated throw the router.
Also if the same happens while encoding the response, errors are catched and propagated to the router.
Params:
function – the request handler function
Type parameters:
<T> –      a generic type to allow type safe API
Returns:
a reference to this, so the API can be used fluently/**
   * Append a function request handler to the route handlers list. The function expects to receive the routing context
   * and users are expected to return a {@link Future}. The use of this functional interface allows users to quickly
   * link the responses from other vert.x APIs or clients directly to a handler. If the context response has been ended,
   * for example, {@link RoutingContext#end()} has been called, then nothing shall happen. For the remaining cases, the
   * following rules apply:
   *
   * <ol>
   *   <li>When {@code body} is {@code null} then the status code of the response shall be 204 (NO CONTENT)</li>
   *   <li>When {@code body} is of type {@link Buffer} and the {@code Content-Type} isn't set then the {@code Content-Type} shall be {@code application/octet-stream}</li>
   *   <li>When {@code body} is of type {@link String} and the {@code Content-Type} isn't set then the {@code Content-Type} shall be {@code text/html}</li>
   *   <li>Otherwise the response of the future is then passed to the method {@link RoutingContext#json(Object)} to perform a JSON serialization of the result</li>
   * </ol>
   *
   * Internally the function is wrapped as a handler that handles error cases for the user too. For example, if the
   * function throws an exception the error will be catched and a proper error will be propagated throw the router.
   *
   * Also if the same happens while encoding the response, errors are catched and propagated to the router.
   *
   * @param <T>      a generic type to allow type safe API
   * @param function the request handler function
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  default <T> Route respond(Function<RoutingContext, Future<@Nullable T>> function) {
    return handler(ctx -> {
      try {
        function.apply(ctx)
          .onFailure(ctx::fail)
          .onSuccess(body -> {
            if (!ctx.response().headWritten()) {
              if (body == null) {
                ctx
                  .response()
                  .setStatusCode(204)
                  .end();
              } else {
                final boolean hasContentType = ctx.response().headers().contains(HttpHeaders.CONTENT_TYPE);
                if (body instanceof Buffer) {
                  if (!hasContentType) {
                    ctx.response().putHeader(HttpHeaders.CONTENT_TYPE, "application/octet-stream");
                  }
                  ctx.end((Buffer) body);
                } else if (body instanceof String) {
                  if (!hasContentType) {
                    ctx.response().putHeader(HttpHeaders.CONTENT_TYPE, "text/html");
                  }
                  ctx.end((String) body);
                } else {
                  ctx.json(body);
                }
              }
            } else {
              if (body == null) {
                if (!ctx.response().ended()) {
                  ctx.end();
                }
              } else {
                ctx.fail(new HttpStatusException(500, "Response already written"));
              }
            }
          });
      } catch (RuntimeException e) {
        ctx.fail(e);
      }
    });
  }
}