// Copyright (c) 2011 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.

#include "chrome/browser/chromeos/system/udev_info_provider.h"

#include "base/command_line.h"
#include "base/bind.h"
#include "base/lazy_instance.h"
#include "base/process_util.h"
#include "base/string_util.h"
#include "chrome/browser/chromeos/system/name_value_pairs_parser.h"
#include "content/browser/browser_thread.h"

namespace chromeos {
namespace system {

namespace {

// Absolute path of the udevadm tool.
const char kUdevadmToolPath[] = "/sbin/udevadm";
// Args to pass to udevadm (followed by the device path).
const char* kUdevadmToolArgs[] = { "info", "--query=property", "--path" };
// Key-value separator and string delimiter in output of "udevadm info".
const char kUdevadmEq[] = "=";
const char kUdevadmDelim[] = "\n";

}  // namespace

class UdevInfoProviderImpl : public UdevInfoProvider {
 public:
  UdevInfoProviderImpl() {}

  // UdevInfoProvider implementation.
  virtual bool QueryDeviceProperty(const std::string& sys_path,
                                   const std::string& property_name,
                                   std::string* result) const OVERRIDE;

  static UdevInfoProvider* GetInstance();

 private:
  DISALLOW_COPY_AND_ASSIGN(UdevInfoProviderImpl);
};

base::LazyInstance<UdevInfoProviderImpl> g_udev_info_provider(
    base::LINKER_INITIALIZED);

bool UdevInfoProviderImpl::QueryDeviceProperty(const std::string& sys_path,
                                               const std::string& property_name,
                                               std::string* result) const {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));

  FilePath udevadm_path(kUdevadmToolPath);
  CommandLine cmd_line(udevadm_path);

  // TODO(ivankr): manually appending switches with AppendArg is a workaround
  // to pass "info" argument before switches like "--path" (CommandLine forces
  // arguments after switches).
  for (size_t i = 0; i < arraysize(kUdevadmToolArgs); ++i)
    cmd_line.AppendArg(kUdevadmToolArgs[i]);
  cmd_line.AppendArg(sys_path);

  std::string output_string;
  if (!base::GetAppOutput(cmd_line, &output_string)) {
    LOG(ERROR) << "Error executing: " << cmd_line.GetCommandLineString();
    return false;
  }
  TrimWhitespaceASCII(output_string, TRIM_ALL, &output_string);

  NameValuePairsParser::NameValueMap device_info;
  NameValuePairsParser parser(&device_info);

  if (!parser.ParseNameValuePairs(output_string, kUdevadmEq, kUdevadmDelim))
    return false;

  NameValuePairsParser::NameValueMap::const_iterator it =
      device_info.find(property_name);
  if (it == device_info.end())
    return false;

  *result = it->second;
  return true;
}

UdevInfoProvider* UdevInfoProviderImpl::GetInstance() {
  return &g_udev_info_provider.Get();
}

UdevInfoProvider* UdevInfoProvider::GetInstance() {
  return UdevInfoProviderImpl::GetInstance();
}

}  // namespace system
}  // namespace chromeos