// 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 CHROME_BROWSER_HISTORY_DOWNLOAD_DATABASE_H_
#define CHROME_BROWSER_HISTORY_DOWNLOAD_DATABASE_H_

#include <string>
#include <vector>

#include "base/threading/platform_thread.h"
#include "sql/meta_table.h"

class FilePath;

namespace sql {
class Connection;
}

namespace history {

struct DownloadRow;

// Maintains a table of downloads.
class DownloadDatabase {
 public:
  // The value of |db_handle| indicating that the associated DownloadItem is not
  // yet persisted.
  static const int64 kUninitializedHandle;

  // Must call InitDownloadTable before using any other functions.
  DownloadDatabase();
  virtual ~DownloadDatabase();

  int next_download_id() const { return next_id_; }

  // Get all the downloads from the database.
  void QueryDownloads(
      std::vector<DownloadRow>* results);

  // Update the state of one download. Returns true if successful.
  // Does not update |url|, |start_time|; uses |db_handle| only
  // to select the row in the database table to update.
  bool UpdateDownload(const DownloadRow& data);

  // Fixes state of the download entries. Sometimes entries with IN_PROGRESS
  // state are not updated during browser shutdown (particularly when crashing).
  // On the next start such entries are considered canceled. This functions
  // fixes such entries.
  bool CleanUpInProgressEntries();

  // Create a new database entry for one download and return its primary db id.
  int64 CreateDownload(const DownloadRow& info);

  // Remove |handle| from the database.
  void RemoveDownload(int64 handle);

  int CountDownloads();

 protected:
  // Returns the database for the functions in this interface.
  virtual sql::Connection& GetDB() = 0;

  // Returns the meta-table object for the functions in this interface.
  virtual sql::MetaTable& GetMetaTable() = 0;

  // Returns true if able to successfully rewrite the invalid values for the
  // |state| field from 3 to 4. Returns false if there was an error fixing the
  // database. See http://crbug.com/140687
  bool MigrateDownloadsState();

  // Creates the downloads table if needed.
  bool InitDownloadTable();

  // Used to quickly clear the downloads. First you would drop it, then you
  // would re-initialize it.
  bool DropDownloadTable();

 private:
  bool EnsureColumnExists(const std::string& name, const std::string& type);

  bool owning_thread_set_;
  base::PlatformThreadId owning_thread_;

  int next_id_;
  int next_db_handle_;

  DISALLOW_COPY_AND_ASSIGN(DownloadDatabase);
};

}  // namespace history

#endif  // CHROME_BROWSER_HISTORY_DOWNLOAD_DATABASE_H_