// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_LOADER_NAVIGATION_LOADER_INTERCEPTOR_H_
#define CONTENT_BROWSER_LOADER_NAVIGATION_LOADER_INTERCEPTOR_H_

#include "base/functional/callback_forward.h"
#include "content/common/content_export.h"
#include "mojo/public/cpp/bindings/pending_receiver.h"
#include "mojo/public/cpp/bindings/pending_remote.h"
#include "mojo/public/cpp/system/data_pipe.h"
#include "net/url_request/redirect_info.h"
#include "services/network/public/cpp/shared_url_loader_factory.h"
#include "services/network/public/mojom/url_loader.mojom.h"
#include "services/network/public/mojom/url_response_head.mojom.h"
#include "third_party/abseil-cpp/absl/types/optional.h"

namespace blink {
class ThrottlingURLLoader;
}  // namespace blink

namespace content {

class BrowserContext;
struct ResourceRequest;
struct SubresourceLoaderParams;

// NavigationLoaderInterceptor is given a chance to create a URLLoader and
// intercept a navigation request before the request is handed off to the
// default URLLoader, e.g. the one from the network service.
// NavigationLoaderInterceptor is a per-request object and kept around during
// the lifetime of a navigation request (including multiple redirect legs).
// All methods are called on the UI thread.
class CONTENT_EXPORT NavigationLoaderInterceptor {
 public:
  NavigationLoaderInterceptor() = default;
  virtual ~NavigationLoaderInterceptor() = default;

  using LoaderCallback =
      base::OnceCallback<void(scoped_refptr<network::SharedURLLoaderFactory>)>;
  using FallbackCallback =
      base::OnceCallback<void(bool /* reset_subresource_loader_params */)>;

  // Asks this interceptor to handle this resource load request.
  // The interceptor must invoke `callback` eventually with either a non-null
  // SharedURLLoaderfactory indicating its willingness to handle the request, or
  // a nullptr to indicate that someone else should handle the request.
  //
  // The `tentative_resource_request` passed to this function and the resource
  // request later passed to the loader factory given to `callback` may not be
  // exactly the same, because URLLoaderThrottles may rewrite the request
  // between the two calls. However the URL must remain constant between the
  // two, as any modifications on the URL done by URLLoaderThrottles must result
  // in an (internal) redirect, which must restart the request with a new
  // MaybeCreateLoader().
  //
  // This interceptor might initially elect to handle the request, but later
  // decide to fall back to the default behavior. In that case, it can invoke
  // `fallback_callback` to do so. An example of this is when a service worker
  // decides to handle the request because it is in-scope, but the service
  // worker JavaScript execution does not result in a response provided, so
  // fallback to network is required.
  //
  // If `fallback_callback` is called, it must be called prior to the
  // interceptor making any URLLoaderClient calls. The
  // `reset_subresource_loader_params` parameter to |fallback_callback|
  // indicates whether to discard the subresource loader params previously
  // returned by MaybeCreateSubresourceLoaderParams().
  //
  // `callback` and `fallback_callback` must not be invoked after the
  // destruction of this interceptor.
  virtual void MaybeCreateLoader(
      const network::ResourceRequest& tentative_resource_request,
      BrowserContext* browser_context,
      LoaderCallback callback,
      FallbackCallback fallback_callback) = 0;

  // Returns a SubresourceLoaderParams if any to be used for subsequent URL
  // requests going forward. Subclasses who want to set-up custom loader for
  // subresource requests may want to override this.
  //
  // This is always called after MaybeCreateLoader().
  //
  // Note that the interceptor can return a null callback to
  // MaybeCreateLoader(), and at the same time can return non-null
  // SubresourceLoaderParams here if it does NOT want to handle the specific
  // request given to MaybeCreateLoader() but wants to handle the subsequent
  // resource requests or ensure otherinterceptors are skipped.
  virtual absl::optional<SubresourceLoaderParams>
  MaybeCreateSubresourceLoaderParams();

  // Returns true if the interceptor creates a loader for the `response_head`
  // and `response_body` passed.  `request` is the latest request whose request
  // URL may include URL fragment.  An example of where this is used is
  // WebBundles where the URL is used to check if the content must be
  // downloaded.  The URLLoader remote is returned in the `loader` parameter.
  // The mojo::PendingReceiver for the URLLoaderClient is returned in the
  // `client_receiver` parameter.
  // `status` is the loader completion status, allowing the interceptor to
  // handle failed loads differently from successful loads. For requests that
  // successfully received a response, this will be a URLLoaderCompletionStatus
  // with an error code of `net::OK`. For requests that failed, this will be a
  // URLLoaderCompletionStatus with the underlying net error.
  // The `url_loader` points to the ThrottlingURLLoader that currently controls
  // the request. It can be optionally consumed to get the current
  // URLLoaderClient and URLLoader so that the implementation can rebind them to
  // intercept the inflight loading if necessary.  Note that the `url_loader`
  // will be reset after this method is called, which will also drop the
  // URLLoader held by `url_loader_` if it is not unbound yet.
  // `skip_other_interceptors` is set to true when this interceptor will
  // exclusively handle the navigation even after redirections. TODO(horo): This
  // flag was introduced to skip service worker after signed exchange redirect.
  // Remove this flag when we support service worker and signed exchange
  // integration. See crbug.com/894755#c1. Nullptr is not allowed.
  // `will_return_unsafe_redirect` is set to true when this interceptor will
  // return an unsafe redirect response and will handle the redirected request,
  // therefore regular safety check should be exempted for the redirect.
  // Nullptr is not allowed.
  virtual bool MaybeCreateLoaderForResponse(
      const network::URLLoaderCompletionStatus& status,
      const network::ResourceRequest& request,
      network::mojom::URLResponseHeadPtr* response_head,
      mojo::ScopedDataPipeConsumerHandle* response_body,
      mojo::PendingRemote<network::mojom::URLLoader>* loader,
      mojo::PendingReceiver<network::mojom::URLLoaderClient>* client_receiver,
      blink::ThrottlingURLLoader* url_loader,
      bool* skip_other_interceptors,
      bool* will_return_unsafe_redirect);

  // Called when MaybeCreateLoader() has called the LoaderCallback with a valid
  // loader factory. Returns true when this interceptor will return an unsafe
  // redirect response and will handle the redirected request.
  virtual bool ShouldBypassRedirectChecks();
};

}  // namespace content

#endif  // CONTENT_BROWSER_LOADER_NAVIGATION_LOADER_INTERCEPTOR_H_