// Copyright (c) 2010 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/policy/device_token_fetcher.h"

#include "base/file_util.h"
#include "base/path_service.h"
#include "base/singleton.h"
#include "chrome/browser/guid.h"
#include "chrome/browser/net/gaia/token_service.h"
#include "chrome/browser/policy/proto/device_management_local.pb.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/net/gaia/gaia_constants.h"
#include "chrome/common/notification_details.h"
#include "chrome/common/notification_service.h"
#include "chrome/common/notification_source.h"
#include "chrome/common/notification_type.h"

namespace policy {

namespace em = enterprise_management;

DeviceTokenFetcher::DeviceTokenFetcher(
    DeviceManagementBackend* backend,
    const FilePath& token_path)
    : token_path_(token_path),
      backend_(backend),
      state_(kStateNotStarted),
      device_token_load_complete_event_(true, false) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  // The token fetcher gets initialized AuthTokens for the device management
  // server are available. Install a notification observer to ensure that the
  // device management token gets fetched after the AuthTokens are available.
  registrar_.Add(this,
                 NotificationType::TOKEN_AVAILABLE,
                 NotificationService::AllSources());
}

void DeviceTokenFetcher::Observe(NotificationType type,
                                 const NotificationSource& source,
                                 const NotificationDetails& details) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (type == NotificationType::TOKEN_AVAILABLE) {
    const Source<TokenService> token_service(source);
    const TokenService::TokenAvailableDetails* token_details =
        Details<const TokenService::TokenAvailableDetails>(details).ptr();
    if (token_details->service() == GaiaConstants::kDeviceManagementService) {
      if (!HasAuthToken()) {
        auth_token_ = token_details->token();
        SendServerRequestIfPossible();
      }
    }
  } else {
    NOTREACHED();
  }
}

void DeviceTokenFetcher::HandleRegisterResponse(
    const em::DeviceRegisterResponse& response) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK_EQ(kStateRequestingDeviceTokenFromServer, state_);
  if (response.has_device_management_token()) {
    device_token_ = response.device_management_token();
    BrowserThread::PostTask(
        BrowserThread::FILE,
        FROM_HERE,
        NewRunnableFunction(&WriteDeviceTokenToDisk,
                            token_path_,
                            device_token_,
                            device_id_));
    SetState(kStateHasDeviceToken);
  } else {
    NOTREACHED();
    SetState(kStateFailure);
  }
}

void DeviceTokenFetcher::OnError(DeviceManagementBackend::ErrorCode code) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  // For privacy reasons, delete all identifying data when this device is not
  // managed.
  if (code == DeviceManagementBackend::kErrorServiceManagementNotSupported) {
    device_token_ = std::string();
    device_id_ = std::string();
    file_util::Delete(token_path_, false);
  }
  SetState(kStateFailure);
}

void DeviceTokenFetcher::StartFetching() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (state_ == kStateNotStarted) {
    SetState(kStateLoadDeviceTokenFromDisk);
    // The file calls for loading the persisted token must be deferred to the
    // FILE thread.
    BrowserThread::PostTask(
        BrowserThread::FILE,
        FROM_HERE,
        NewRunnableMethod(this,
                          &DeviceTokenFetcher::AttemptTokenLoadFromDisk));
  }
}

void DeviceTokenFetcher::AttemptTokenLoadFromDisk() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
  if (file_util::PathExists(token_path_)) {
    std::string data;
    em::DeviceCredentials device_credentials;
    if (file_util::ReadFileToString(token_path_, &data) &&
        device_credentials.ParseFromArray(data.c_str(), data.size())) {
      device_token_ = device_credentials.device_token();
      device_id_ = device_credentials.device_id();
      if (!device_token_.empty() && !device_id_.empty()) {
        BrowserThread::PostTask(
            BrowserThread::UI,
            FROM_HERE,
            NewRunnableMethod(this,
                              &DeviceTokenFetcher::SetState,
                              kStateHasDeviceToken));
        return;
      }
    }
  }

  BrowserThread::PostTask(
      BrowserThread::UI,
      FROM_HERE,
      NewRunnableMethod(this,
                        &DeviceTokenFetcher::MakeReadyToRequestDeviceToken));
}

void DeviceTokenFetcher::MakeReadyToRequestDeviceToken() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  SetState(kStateReadyToRequestDeviceTokenFromServer);
  SendServerRequestIfPossible();
}

void DeviceTokenFetcher::SendServerRequestIfPossible() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (state_ == kStateReadyToRequestDeviceTokenFromServer
      && HasAuthToken()) {
    em::DeviceRegisterRequest register_request;
    SetState(kStateRequestingDeviceTokenFromServer);
    backend_->ProcessRegisterRequest(auth_token_,
                                     GetDeviceID(),
                                     register_request,
                                     this);
  }
}

bool DeviceTokenFetcher::IsTokenPending() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  return !device_token_load_complete_event_.IsSignaled();
}

std::string DeviceTokenFetcher::GetDeviceToken() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  device_token_load_complete_event_.Wait();
  return device_token_;
}

std::string DeviceTokenFetcher::GetDeviceID() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  // As long as access to this is only allowed from the UI thread, no explicit
  // locking is necessary to prevent the ID from being generated twice.
  if (device_id_.empty())
    device_id_ = GenerateNewDeviceID();
  return device_id_;
}

void DeviceTokenFetcher::SetState(FetcherState state) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (state_ == state)
    return;
  state_ = state;
  if (state == kStateFailure) {
    device_token_load_complete_event_.Signal();
  } else if (state == kStateHasDeviceToken) {
    device_token_load_complete_event_.Signal();
    NotificationService::current()->Notify(
        NotificationType::DEVICE_TOKEN_AVAILABLE,
        Source<DeviceTokenFetcher>(this),
        NotificationService::NoDetails());
  }
}

void DeviceTokenFetcher::GetDeviceTokenPath(FilePath* token_path) const {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  *token_path = token_path_;
}

bool DeviceTokenFetcher::IsTokenValid() const {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  return state_ == kStateHasDeviceToken;
}

// static
void DeviceTokenFetcher::WriteDeviceTokenToDisk(
    const FilePath& path,
    const std::string& device_token,
    const std::string& device_id) {
  em::DeviceCredentials device_credentials;
  device_credentials.set_device_token(device_token);
  device_credentials.set_device_id(device_id);
  std::string data;
  bool no_error = device_credentials.SerializeToString(&data);
  DCHECK(no_error);
  file_util::WriteFile(path, data.c_str(), data.length());
}

// static
std::string DeviceTokenFetcher::GenerateNewDeviceID() {
  return guid::GenerateGUID();
}

}  // namespace policy