// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_DOWNLOAD_BASE_FILE_H_
#define CONTENT_BROWSER_DOWNLOAD_BASE_FILE_H_
#pragma once

#include <string>

#include "base/file_path.h"
#include "base/gtest_prod_util.h"
#include "base/memory/linked_ptr.h"
#include "base/memory/scoped_ptr.h"
#include "base/time.h"
#include "content/common/content_export.h"
#include "googleurl/src/gurl.h"
#include "net/base/file_stream.h"
#include "net/base/net_errors.h"
#include "net/base/net_log.h"

namespace crypto {
class SecureHash;
}
namespace net {
class FileStream;
}

// File being downloaded and saved to disk. This is a base class
// for DownloadFile and SaveFile, which keep more state information.
class CONTENT_EXPORT BaseFile {
 public:
  BaseFile(const FilePath& full_path,
           const GURL& source_url,
           const GURL& referrer_url,
           int64 received_bytes,
           bool calculate_hash,
           const std::string& hash_state,
           const linked_ptr<net::FileStream>& file_stream,
           const net::BoundNetLog& bound_net_log);
  virtual ~BaseFile();

  // Returns net::OK on success, or a network error code on failure.
  net::Error Initialize();

  // Write a new chunk of data to the file.
  // Returns net::OK on success (all bytes written to the file),
  // or a network error code on failure.
  net::Error AppendDataToFile(const char* data, size_t data_len);

  // Rename the download file.
  // Returns net::OK on success, or a network error code on failure.
  virtual net::Error Rename(const FilePath& full_path);

  // Detach the file so it is not deleted on destruction.
  virtual void Detach();

  // Abort the download and automatically close the file.
  void Cancel();

  // Indicate that the download has finished. No new data will be received.
  void Finish();

  // Informs the OS that this file came from the internet.
  void AnnotateWithSourceInformation();

  // Calculate and return the current speed in bytes per second.
  int64 CurrentSpeed() const;

  FilePath full_path() const { return full_path_; }
  bool in_progress() const { return file_stream_ != NULL; }
  int64 bytes_so_far() const { return bytes_so_far_; }

  // Fills |hash| with the hash digest for the file.
  // Returns true if digest is successfully calculated.
  virtual bool GetHash(std::string* hash);

  // Returns the current (intermediate) state of the hash as a byte string.
  virtual std::string GetHashState();

  // Returns true if the given hash is considered empty.  An empty hash is
  // a string of size kSha256HashLen that contains only zeros (initial value
  // for the hash).
  static bool IsEmptyHash(const std::string& hash);

  virtual std::string DebugString() const;

 protected:
  virtual void CreateFileStream();  // For testing.
  // Returns net::OK on success, or a network error code on failure.
  net::Error Open();
  void Close();

  // Full path to the file including the file name.
  FilePath full_path_;

 private:
  friend class BaseFileTest;
  FRIEND_TEST_ALL_PREFIXES(BaseFileTest, IsEmptyHash);

  // Split out from CurrentSpeed to enable testing.
  int64 CurrentSpeedAtTime(base::TimeTicks current_time) const;

  // Resets the current state of the hash to the contents of |hash_state_bytes|.
  virtual bool SetHashState(const std::string& hash_state_bytes);

  net::Error ClearStream(net::Error error);

  static const size_t kSha256HashLen = 32;
  static const unsigned char kEmptySha256Hash[kSha256HashLen];

  // Source URL for the file being downloaded.
  GURL source_url_;

  // The URL where the download was initiated.
  GURL referrer_url_;

  // OS file stream for writing
  linked_ptr<net::FileStream> file_stream_;

  // Amount of data received up so far, in bytes.
  int64 bytes_so_far_;

  // Start time for calculating speed.
  base::TimeTicks start_tick_;

  // Indicates if hash should be calculated for the file.
  bool calculate_hash_;

  // Used to calculate hash for the file when calculate_hash_
  // is set.
  scoped_ptr<crypto::SecureHash> secure_hash_;

  unsigned char sha256_hash_[kSha256HashLen];

  // Indicates that this class no longer owns the associated file, and so
  // won't delete it on destruction.
  bool detached_;

  net::BoundNetLog bound_net_log_;

  DISALLOW_COPY_AND_ASSIGN(BaseFile);
};

#endif  // CONTENT_BROWSER_DOWNLOAD_BASE_FILE_H_