// 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_SERVICE_WORKER_SERVICE_WORKER_NEW_SCRIPT_LOADER_H_
#define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_NEW_SCRIPT_LOADER_H_

#include "content/browser/service_worker/service_worker_cache_writer.h"
#include "content/browser/service_worker/url_loader_client_checker.h"
#include "content/common/content_export.h"
#include "content/public/browser/global_routing_id.h"
#include "mojo/public/cpp/bindings/pending_remote.h"
#include "mojo/public/cpp/bindings/receiver.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "services/network/public/cpp/net_adapters.h"
#include "services/network/public/cpp/resource_request.h"
#include "services/network/public/cpp/shared_url_loader_factory.h"
#include "services/network/public/mojom/url_loader.mojom.h"
#include "third_party/blink/public/mojom/loader/resource_load_info.mojom-shared.h"
#include "url/gurl.h"

namespace blink {

class ThrottlingURLLoader;

}  // namespace blink

namespace content {

class ServiceWorkerVersion;

// This is the URLLoader used for loading scripts for a new (installing) service
// worker. It fetches the script (the main script or imported script) and
// returns the response to |client|, while also writing the response into the
// service worker script storage.
//
// This loader works as follows:
//   1. Makes a network request.
//   2. OnReceiveResponse() is called, writes the response headers to the
//      service worker script storage and responds with them to the |client|
//      (which is the service worker in the renderer). Reads the network
//      response from the data pipe. While reading the response, writes it to
//      the service worker script storage and responds with it to the |client|.
//   3. OnComplete() for the network load and OnWriteDataComplete() are called,
//      calls CommitCompleted() and closes the connections with the network
//      service and the renderer process.
//
// A set of |network_loader_state_|, |header_writer_state_|, and
// |body_writer_state_| is the state of this loader. Each of them is changed
// independently, while some state changes have dependency to other state
// changes. See the comment for each field below to see exactly when their state
// changes happen.
//
// NOTE: To perform the network request, this class uses |loader_factory_| which
// may internally use a non-NetworkService factory if URL has a non-http(s)
// scheme, e.g., a chrome-extension:// URL. Regardless, that is still called a
// "network" request in comments and naming. "network" is meant to distinguish
// from the load this URLLoader does for its client:
//     "network" <------> SWNewScriptLoader <------> client
class CONTENT_EXPORT ServiceWorkerNewScriptLoader final
    : public network::mojom::URLLoader,
      public network::mojom::URLLoaderClient {
 public:
  enum class LoaderState {
    kNotStarted,
    kLoadingHeader,
    kWaitingForBody,
    kLoadingBody,
    kCompleted,
  };

  enum class WriterState { kNotStarted, kWriting, kCompleted };

  // If |is_throttle_needed| is true, the load will go through
  // URLLoaderThrottles. Generally, all network requests need to go through
  // throttles. It should be set to false only if this loader is being created
  // after a request already went through throttles. Currently, this function
  // has two callsites:
  //
  // - ServiceWorkerScriptLoaderFactory: in response to a request from the
  // renderer. |is_throttle_needed| is false because the renderer is assumed to
  // have already throttled the request. More precisely throttles should be set
  // by ServiceWorkerFetchContextImpl::WillSendRequest.
  // - ServiceWorkerNewScriptFetcher: directly in the browser process.
  // |is_throttle_needed| is true because the request has not gone through
  // throttles.
  static std::unique_ptr<ServiceWorkerNewScriptLoader> CreateAndStart(
      int32_t request_id,
      uint32_t options,
      const network::ResourceRequest& original_request,
      mojo::PendingRemote<network::mojom::URLLoaderClient> client,
      scoped_refptr<ServiceWorkerVersion> version,
      scoped_refptr<network::SharedURLLoaderFactory> loader_factory,
      const net::MutableNetworkTrafficAnnotationTag& traffic_annotation,
      int64_t cache_resource_id,
      bool is_throttle_needed,
      const GlobalRenderFrameHostId& requesting_frame_id);

  ServiceWorkerNewScriptLoader(const ServiceWorkerNewScriptLoader&) = delete;
  ServiceWorkerNewScriptLoader& operator=(const ServiceWorkerNewScriptLoader&) =
      delete;

  ~ServiceWorkerNewScriptLoader() override;

  // network::mojom::URLLoader:
  void FollowRedirect(
      const std::vector<std::string>& removed_headers,
      const net::HttpRequestHeaders& modified_headers,
      const net::HttpRequestHeaders& modified_cors_exempt_headers,
      const std::optional<GURL>& new_url) override;
  void SetPriority(net::RequestPriority priority,
                   int32_t intra_priority_value) override;

  // network::mojom::URLLoaderClient for the network load:
  void OnReceiveEarlyHints(network::mojom::EarlyHintsPtr early_hints) override;
  void OnReceiveResponse(
      network::mojom::URLResponseHeadPtr response_head,
      mojo::ScopedDataPipeConsumerHandle body,
      std::optional<mojo_base::BigBuffer> cached_metadata) override;
  void OnReceiveRedirect(
      const net::RedirectInfo& redirect_info,
      network::mojom::URLResponseHeadPtr response_head) override;
  void OnUploadProgress(int64_t current_position,
                        int64_t total_size,
                        OnUploadProgressCallback ack_callback) override;
  void OnTransferSizeUpdated(int32_t transfer_size_diff) override;
  void OnComplete(const network::URLLoaderCompletionStatus& status) override;

  // Buffer size for reading script data from network.
  const static uint32_t kReadBufferSize;

 private:
  class WrappedIOBuffer;

  ServiceWorkerNewScriptLoader(
      int32_t request_id,
      uint32_t options,
      const network::ResourceRequest& original_request,
      mojo::PendingRemote<network::mojom::URLLoaderClient> client,
      scoped_refptr<ServiceWorkerVersion> version,
      scoped_refptr<network::SharedURLLoaderFactory> loader_factory,
      const net::MutableNetworkTrafficAnnotationTag& traffic_annotation,
      int64_t cache_resource_id,
      bool is_throttle_needed,
      const GlobalRenderFrameHostId& requesting_frame_id);

  // Writes the given headers into the service worker script storage.
  void WriteHeaders(network::mojom::URLResponseHeadPtr response_head);
  void OnWriteHeadersComplete(net::Error error);

  // Starts watching the data pipe for the network load (i.e.,
  // |network_consumer_|) if it's ready.
  void MaybeStartNetworkConsumerHandleWatcher();

  // Called when |network_consumer_| is ready to be read. Can be called multiple
  // times.
  void OnNetworkDataAvailable(MojoResult);

  // Writes the given data into the service worker script storage.
  void WriteData(scoped_refptr<network::MojoToNetPendingBuffer> pending_buffer,
                 uint32_t bytes_available);
  void OnWriteDataComplete(
      scoped_refptr<network::MojoToNetPendingBuffer> pending_buffer,
      size_t bytes_written,
      net::Error error);

  // This is the last method that is called on this class. Notifies the final
  // result to |client_| and clears all mojo connections etc.
  void CommitCompleted(const network::URLLoaderCompletionStatus& status,
                       const std::string& status_message,
                       network::mojom::URLResponseHeadPtr response_head);

  // Called when `client_producer_` is writable. Must be called only when
  // `pending_write_buffer_` is available. It writes
  // `pending_write_buffer_` to `client_producer_` via WriteData().
  void OnClientWritable(MojoResult);

  // Called when ServiceWorkerCacheWriter::Resume() completes its work.
  // If not all data are received, it continues to download from network.
  void OnCacheWriterResumed(net::Error error);

  const int request_id_;

  const GURL request_url_;

  const bool is_main_script_;

  // Load options originally passed to this loader. The options passed to the
  // network loader might be different from this.
  const uint32_t original_options_;

  scoped_refptr<ServiceWorkerVersion> version_;

  std::unique_ptr<ServiceWorkerCacheWriter> cache_writer_;

  // Used for fetching the script from the network (or other sources like
  // extensions for example). Depending on where the
  // ServiceWorkerNewScriptLoader is started from, and depending on the
  // constructor's |is_throttle_needed| parameter, this might or might not
  // have throttles. See CreateAndStart() for details.
  std::unique_ptr<blink::ThrottlingURLLoader> network_loader_;

  mojo::ScopedDataPipeConsumerHandle network_consumer_;
  mojo::SimpleWatcher network_watcher_;
  scoped_refptr<network::SharedURLLoaderFactory> loader_factory_;

  // Used for responding with the fetched script to this loader's client.
  URLLoaderClientCheckedRemote client_;
  mojo::ScopedDataPipeProducerHandle client_producer_;
  mojo::SimpleWatcher client_producer_watcher_;

  // Holds a part of body data from network that wasn't able to write to
  // `client_producer_` since the data pipe was full. Only available when
  // `client_producer_` gets blocked.
  scoped_refptr<network::MojoToNetPendingBuffer> pending_network_buffer_;
  uint32_t pending_network_bytes_available_ = 0;

  // Represents the state of |network_loader_|.
  // Corresponds to the steps described in the class comments.
  //
  // When response body exists:
  // CreateLoaderAndStart(): kNotStarted -> kLoadingHeader
  // OnReceiveResponse(): kLoadingHeader -> kLoadingBody
  // OnComplete(): kLoadingBody -> kCompleted
  //
  // When response body is empty:
  // CreateLoaderAndStart(): kNotStarted -> kLoadingHeader
  // OnReceiveResponse(): kLoadingHeader -> kWaitingForBody
  // OnComplete(): kWaitingForBody -> kCompleted
  LoaderState network_loader_state_ = LoaderState::kNotStarted;

  // Represents the state of |cache_writer_|.
  // Set to kWriting when it starts to write the header, and set to kCompleted
  // when the header has been written.
  //
  // OnReceiveResponse(): kNotStarted -> kWriting (in WriteHeaders())
  // OnWriteHeadersComplete(): kWriting -> kCompleted
  WriterState header_writer_state_ = WriterState::kNotStarted;

  // Represents the state of |cache_writer_| and |network_consumer_|.
  // Set to kWriting when |this| starts watching |network_consumer_|, and set to
  // kCompleted when all data has been written to |cache_writer_|.
  //
  // OnWriteHeadersComplete():
  //     kNotStarted -> kWriting
  // OnNetworkDataAvailable() && MOJO_RESULT_FAILED_PRECONDITION:
  //     kWriting -> kCompleted
  WriterState body_writer_state_ = WriterState::kNotStarted;

  // When fetching the main script of a newly installed ServiceWorker with
  // PlzServiceWorker, we don't have a renderer assigned yet. We could also fail
  // the fetch and never get one. If that happens, we need to have a frame id
  // to log the failure into devtools.
  const GlobalRenderFrameHostId requesting_frame_id_;

  base::WeakPtrFactory<ServiceWorkerNewScriptLoader> weak_factory_{this};
};

}  // namespace content

#endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_NEW_SCRIPT_LOADER_H_