// 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.

#include "chrome/browser/policy/user_cloud_policy_store.h"

#include "base/bind.h"
#include "base/file_util.h"
#include "chrome/browser/policy/proto/cloud_policy.pb.h"
#include "chrome/browser/policy/proto/device_management_backend.pb.h"
#include "chrome/browser/policy/proto/device_management_local.pb.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/signin/signin_manager.h"
#include "chrome/browser/signin/signin_manager_factory.h"
#include "content/public/browser/browser_thread.h"

namespace em = enterprise_management;

namespace policy {

enum PolicyLoadStatus {
  // Policy blob was successfully loaded and parsed.
  LOAD_RESULT_SUCCESS,

  // No previously stored policy was found.
  LOAD_RESULT_NO_POLICY_FILE,

  // Could not load the previously stored policy due to either a parse or
  // file read error.
  LOAD_RESULT_LOAD_ERROR,
};

// Struct containing the result of a policy load - if |status| ==
// LOAD_RESULT_SUCCESS, |policy| is initialized from the policy file on disk.
struct PolicyLoadResult {
  PolicyLoadStatus status;
  em::PolicyFetchResponse policy;
};

namespace {

// Subdirectory in the user's profile for storing user policies.
const FilePath::CharType kPolicyDir[] = FILE_PATH_LITERAL("Policy");
// File in the above directory for storing user policy data.
const FilePath::CharType kPolicyCacheFile[] = FILE_PATH_LITERAL("User Policy");

// Loads policy from the backing file (must be called via a task on
// the FILE thread). Returns a PolicyLoadStruct with the results of the fetch.
policy::PolicyLoadResult LoadPolicyFromDiskOnFileThread(const FilePath& path) {
  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
  policy::PolicyLoadResult result;
  // If the backing file does not exist, just return.
  if (!file_util::PathExists(path)) {
    result.status = policy::LOAD_RESULT_NO_POLICY_FILE;
    return result;
  }
  std::string data;
  if (!file_util::ReadFileToString(path, &data) ||
      !result.policy.ParseFromArray(data.c_str(), data.size())) {
    LOG(WARNING) << "Failed to read or parse policy data from " << path.value();
    result.status = policy::LOAD_RESULT_LOAD_ERROR;
    return result;
  }

  result.status = policy::LOAD_RESULT_SUCCESS;
  return result;
}

// Stores policy to the backing file (must be called via a task on
// the FILE thread).
void StorePolicyToDiskOnFileThread(const FilePath& path,
                                   const em::PolicyFetchResponse& policy) {
  DVLOG(1) << "Storing policy to " << path.value();
  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
  std::string data;
  if (!policy.SerializeToString(&data)) {
    DLOG(WARNING) << "Failed to serialize policy data";
    return;
  }

  if (!file_util::CreateDirectory(path.DirName())) {
    DLOG(WARNING) << "Failed to create directory " << path.DirName().value();
    return;
  }

  int size = data.size();
  if (file_util::WriteFile(path, data.c_str(), size) != size) {
    DLOG(WARNING) << "Failed to write " << path.value();
  }
}

}  // namespace

UserCloudPolicyStore::UserCloudPolicyStore(Profile* profile,
                                           const FilePath& path)
    : ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
      profile_(profile),
      backing_file_path_(path) {
}

UserCloudPolicyStore::~UserCloudPolicyStore() {
}

void UserCloudPolicyStore::Load() {
  DVLOG(1) << "Initiating policy load from disk";
  // Cancel any pending Load/Store/Validate operations.
  weak_factory_.InvalidateWeakPtrs();

  // Start a new Load operation and have us get called back when it is
  // complete.
  content::BrowserThread::PostTaskAndReplyWithResult(
      content::BrowserThread::FILE, FROM_HERE,
      base::Bind(&LoadPolicyFromDiskOnFileThread, backing_file_path_),
      base::Bind(&UserCloudPolicyStore::PolicyLoaded,
                 weak_factory_.GetWeakPtr()));
}

void UserCloudPolicyStore::PolicyLoaded(PolicyLoadResult result) {
  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
  switch (result.status) {
    case LOAD_RESULT_LOAD_ERROR:
      status_ = STATUS_LOAD_ERROR;
      NotifyStoreError();
      break;

    case LOAD_RESULT_NO_POLICY_FILE:
      DVLOG(1) << "No policy found on disk";
      NotifyStoreLoaded();
      break;

    case LOAD_RESULT_SUCCESS: {
      // Found policy on disk - need to validate it before it can be used.
      scoped_ptr<em::PolicyFetchResponse> cloud_policy(
          new em::PolicyFetchResponse(result.policy));
      Validate(cloud_policy.Pass(),
               base::Bind(
                   &UserCloudPolicyStore::InstallLoadedPolicyAfterValidation,
                   weak_factory_.GetWeakPtr()));
      break;
    }
    default:
      NOTREACHED();
  }
}

void UserCloudPolicyStore::InstallLoadedPolicyAfterValidation(
    UserCloudPolicyValidator* validator) {
  validation_status_ = validator->status();
  if (!validator->success()) {
    DVLOG(1) << "Validation failed: status=" << validation_status_;
    status_ = STATUS_VALIDATION_ERROR;
    NotifyStoreError();
    return;
  }

  DVLOG(1) << "Validation succeeded - installing policy with dm_token: " <<
      validator->policy_data()->request_token();
  DVLOG(1) << "Device ID: " << validator->policy_data()->device_id();

  InstallPolicy(validator->policy_data().Pass(), validator->payload().Pass());
  status_ = STATUS_OK;
  NotifyStoreLoaded();
}

void UserCloudPolicyStore::RemoveStoredPolicy() {
  content::BrowserThread::PostTask(
      content::BrowserThread::FILE, FROM_HERE,
      base::Bind(base::IgnoreResult(&file_util::Delete),
                 backing_file_path_,
                 false));
}

void UserCloudPolicyStore::Store(const em::PolicyFetchResponse& policy) {
  // Stop any pending requests to store policy, then validate the new policy
  // before storing it.
  weak_factory_.InvalidateWeakPtrs();
  scoped_ptr<em::PolicyFetchResponse> policy_copy(
      new em::PolicyFetchResponse(policy));
  Validate(policy_copy.Pass(),
           base::Bind(&UserCloudPolicyStore::StorePolicyAfterValidation,
                      weak_factory_.GetWeakPtr()));
}

void UserCloudPolicyStore::Validate(
    scoped_ptr<em::PolicyFetchResponse> policy,
    const UserCloudPolicyValidator::CompletionCallback& callback) {
  // Configure the validator.
  scoped_ptr<UserCloudPolicyValidator> validator =
      CreateValidator(policy.Pass(), callback);
  SigninManager* signin = SigninManagerFactory::GetForProfile(profile_);
  std::string username = signin->GetAuthenticatedUsername();
  DCHECK(!username.empty());
  validator->ValidateUsername(username);

  // Start validation. The Validator will free itself once validation is
  // complete.
  validator.release()->StartValidation();
}

void UserCloudPolicyStore::StorePolicyAfterValidation(
    UserCloudPolicyValidator* validator) {
  validation_status_ = validator->status();
  DVLOG(1) << "Policy validation complete: status = " << validation_status_;
  if (!validator->success()) {
    status_ = STATUS_VALIDATION_ERROR;
    NotifyStoreError();
    return;
  }

  // Persist the validated policy (just fire a task - don't bother getting a
  // reply because we can't do anything if it fails).
  content::BrowserThread::PostTask(
      content::BrowserThread::FILE, FROM_HERE,
      base::Bind(&StorePolicyToDiskOnFileThread,
                 backing_file_path_, *validator->policy()));
  InstallPolicy(validator->policy_data().Pass(), validator->payload().Pass());
  status_ = STATUS_OK;
  NotifyStoreLoaded();
}

// static
scoped_ptr<CloudPolicyStore> CloudPolicyStore::CreateUserPolicyStore(
    Profile* profile) {
  FilePath path =
      profile->GetPath().Append(kPolicyDir).Append(kPolicyCacheFile);
  return scoped_ptr<CloudPolicyStore>(new UserCloudPolicyStore(profile, path));
}

}  // namespace policy