//
// Copyright (C) 2012 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#ifndef SHILL_HTTP_REQUEST_H_
#define SHILL_HTTP_REQUEST_H_

#include <memory>
#include <string>
#include <vector>

#include <base/callback.h>
#include <base/cancelable_callback.h>
#include <base/memory/ref_counted.h>
#include <base/memory/weak_ptr.h>

#include "shill/net/byte_string.h"
#include "shill/net/shill_time.h"
#include "shill/refptr_types.h"

namespace shill {

class AsyncConnection;
class DNSClient;
class Error;
class EventDispatcher;
class HTTPURL;
struct InputData;
class IOHandler;
class IPAddress;
class Sockets;

// The HTTPRequest class implements facilities for performing
// a simple "GET" request and returning the contents via a
// callback.
class HTTPRequest {
 public:
  enum Result {
    kResultUnknown,
    kResultInProgress,
    kResultDNSFailure,
    kResultDNSTimeout,
    kResultConnectionFailure,
    kResultConnectionTimeout,
    kResultRequestFailure,
    kResultRequestTimeout,
    kResultResponseFailure,
    kResultResponseTimeout,
    kResultSuccess
  };

  HTTPRequest(ConnectionRefPtr connection,
              EventDispatcher* dispatcher,
              Sockets* sockets);
  virtual ~HTTPRequest();

  // Start an http GET request to the URL |url|.  Whenever any data is
  // read from the server, |read_event_callback| is called with the
  // current contents of the response data coming from the server.
  // This callback could be called more than once as data arrives.
  //
  // When the transaction completes, |result_callback| will be called with
  // the final status from the transaction.  It is valid for the callback
  // function to destroy this HTTPRequest object, because at this time all
  // object state has already been cleaned up.  |result_callback| will not be
  // called if either the Start() call fails or if Stop() is called before
  // the transaction completes.
  //
  // This (Start) function returns a failure result if the request
  // failed during initialization, or kResultInProgress if the request
  // has started successfully and is now in progress.
  virtual Result Start(
      const HTTPURL& url,
      const base::Callback<void(const ByteString&)>& read_event_callback,
      const base::Callback<void(Result, const ByteString&)>& result_callback);

  // Stop the current HTTPRequest.  No callback is called as a side
  // effect of this function.
  virtual void Stop();

  // Returns the data received so far from the server in the current
  // request.  This data is available only while the request is active,
  // and before the result callback is called.
  virtual const ByteString& response_data() const { return response_data_; }

 private:
  friend class HTTPRequestTest;

  // Time to wait for connection to remote server.
  static const int kConnectTimeoutSeconds;
  // Time to wait for DNS server.
  static const int kDNSTimeoutSeconds;
  // Time to wait for any input from server.
  static const int kInputTimeoutSeconds;

  static const char kHTTPRequestTemplate[];

  bool ConnectServer(const IPAddress& address, int port);
  void GetDNSResult(const Error& error, const IPAddress& address);
  void OnConnectCompletion(bool success, int fd);
  void OnServerReadError(const std::string& error_msg);
  void ReadFromServer(InputData* data);
  void SendStatus(Result result);
  void StartIdleTimeout(int timeout_seconds, Result timeout_result);
  void TimeoutTask();
  void WriteToServer(int fd);

  ConnectionRefPtr connection_;
  EventDispatcher* dispatcher_;
  Sockets* sockets_;

  base::WeakPtrFactory<HTTPRequest> weak_ptr_factory_;
  base::Callback<void(bool, int)> connect_completion_callback_;
  base::Callback<void(const Error&, const IPAddress&)> dns_client_callback_;
  base::Callback<void(InputData*)> read_server_callback_;
  base::Callback<void(int)> write_server_callback_;
  base::Callback<void(Result, const ByteString&)> result_callback_;
  base::Callback<void(const ByteString&)> read_event_callback_;
  std::unique_ptr<IOHandler> read_server_handler_;
  std::unique_ptr<IOHandler> write_server_handler_;
  std::unique_ptr<DNSClient> dns_client_;
  std::unique_ptr<AsyncConnection> server_async_connection_;
  std::string server_hostname_;
  int server_port_;
  int server_socket_;
  base::CancelableClosure timeout_closure_;
  Result timeout_result_;
  ByteString request_data_;
  ByteString response_data_;
  bool is_running_;

  DISALLOW_COPY_AND_ASSIGN(HTTPRequest);
};

}  // namespace shill

#endif  // SHILL_HTTP_REQUEST_H_