// Copyright 2014 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 "components/component_updater/component_updater_service.h"

#include <algorithm>
#include <map>
#include <string>
#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/sequenced_task_runner.h"
#include "base/single_thread_task_runner.h"
#include "base/thread_task_runner_handle.h"
#include "base/threading/sequenced_worker_pool.h"
#include "base/threading/thread_checker.h"
#include "base/timer/timer.h"
#include "components/component_updater/component_updater_service_internal.h"
#include "components/component_updater/timer.h"
#include "components/update_client/configurator.h"
#include "components/update_client/crx_update_item.h"
#include "components/update_client/update_client.h"
#include "components/update_client/utils.h"
#include "url/gurl.h"

using CrxInstaller = update_client::CrxInstaller;
using UpdateClient = update_client::UpdateClient;

namespace component_updater {

CrxUpdateService::CrxUpdateService(
    const scoped_refptr<Configurator>& config,
    const scoped_refptr<UpdateClient>& update_client)
    : config_(config),
      update_client_(update_client),
      blocking_task_runner_(config->GetSequencedTaskRunner()) {
  AddObserver(this);
}

CrxUpdateService::~CrxUpdateService() {
  DCHECK(thread_checker_.CalledOnValidThread());

  for (const auto item : ready_callbacks_) {
    item.second.Run();
  }

  RemoveObserver(this);

  Stop();
}

void CrxUpdateService::AddObserver(Observer* observer) {
  DCHECK(thread_checker_.CalledOnValidThread());
  update_client_->AddObserver(observer);
}

void CrxUpdateService::RemoveObserver(Observer* observer) {
  DCHECK(thread_checker_.CalledOnValidThread());
  update_client_->RemoveObserver(observer);
}

void CrxUpdateService::Start() {
  DCHECK(thread_checker_.CalledOnValidThread());
  VLOG(1) << "CrxUpdateService starting up. "
          << "First update attempt will take place in "
          << config_->InitialDelay() << " seconds. "
          << "Next update attempt will take place in "
          << config_->NextCheckDelay() << " seconds. ";

  timer_.Start(
      base::TimeDelta::FromSeconds(config_->InitialDelay()),
      base::TimeDelta::FromSeconds(config_->NextCheckDelay()),
      base::Bind(base::IgnoreResult(&CrxUpdateService::CheckForUpdates),
                 base::Unretained(this)));
}

// Stops the update loop. In flight operations will be completed.
void CrxUpdateService::Stop() {
  DCHECK(thread_checker_.CalledOnValidThread());
  VLOG(1) << "CrxUpdateService stopping";
  timer_.Stop();
}

// Adds a component to be checked for upgrades. If the component exists it
// it will be replaced.
bool CrxUpdateService::RegisterComponent(const CrxComponent& component) {
  DCHECK(thread_checker_.CalledOnValidThread());
  if (component.pk_hash.empty() || !component.version.IsValid() ||
      !component.installer) {
    return false;
  }

  // Update the registration data if the component has been registered before.
  const std::string id(GetCrxComponentID(component));
  auto it = components_.find(id);
  if (it != components_.end()) {
    it->second = component;
    return true;
  }

  components_.insert(std::make_pair(id, component));
  components_order_.push_back(id);

  // Create an initial state for this component. The state is mutated in
  // response to events from the UpdateClient instance.
  CrxUpdateItem item;
  item.id = id;
  item.component = component;
  const auto inserted = component_states_.insert(std::make_pair(id, item));
  DCHECK(inserted.second);

  // Start the timer if this is the first component registered. The first timer
  // event occurs after an interval defined by the component update
  // configurator. The subsequent timer events are repeated with a period
  // defined by the same configurator.
  if (components_.size() == 1)
    Start();

  return true;
}

bool CrxUpdateService::UnregisterComponent(const std::string& id) {
  DCHECK(thread_checker_.CalledOnValidThread());
  auto it = components_.find(id);
  if (it == components_.end())
    return false;

  DCHECK_EQ(id, it->first);

  // Delay the uninstall of the component if the component is being updated.
  if (update_client_->IsUpdating(id)) {
    components_pending_unregistration_.push_back(id);
    return true;
  }

  return DoUnregisterComponent(it->second);
}

bool CrxUpdateService::DoUnregisterComponent(const CrxComponent& component) {
  DCHECK(thread_checker_.CalledOnValidThread());

  const auto id = GetCrxComponentID(component);
  DCHECK(ready_callbacks_.find(id) == ready_callbacks_.end());

  const bool result = component.installer->Uninstall();

  const auto pos =
      std::find(components_order_.begin(), components_order_.end(), id);
  if (pos != components_order_.end())
    components_order_.erase(pos);

  components_.erase(id);
  component_states_.erase(id);

  return result;
}

std::vector<std::string> CrxUpdateService::GetComponentIDs() const {
  DCHECK(thread_checker_.CalledOnValidThread());
  std::vector<std::string> ids;
  for (const auto& it : components_)
    ids.push_back(it.first);
  return ids;
}

OnDemandUpdater& CrxUpdateService::GetOnDemandUpdater() {
  DCHECK(thread_checker_.CalledOnValidThread());
  return *this;
}

const CrxComponent* CrxUpdateService::GetComponent(
    const std::string& id) const {
  DCHECK(thread_checker_.CalledOnValidThread());
  const auto it(components_.find(id));
  return it != components_.end() ? &(it->second) : NULL;
}

const CrxUpdateItem* CrxUpdateService::GetComponentState(
    const std::string& id) const {
  DCHECK(thread_checker_.CalledOnValidThread());
  const auto it(component_states_.find(id));
  return it != component_states_.end() ? &it->second : NULL;
}

void CrxUpdateService::MaybeThrottle(const std::string& id,
                                     const base::Closure& callback) {
  DCHECK(thread_checker_.CalledOnValidThread());
  auto it = components_.find(id);
  if (it != components_.end()) {
    DCHECK_EQ(it->first, id);
    if (OnDemandUpdateWithCooldown(id)) {
      ready_callbacks_.insert(std::make_pair(id, callback));
      return;
    }
  }

  callback.Run();  // Unblock the request if the request can't be throttled.
}

bool CrxUpdateService::OnDemandUpdate(const std::string& id) {
  DCHECK(thread_checker_.CalledOnValidThread());

  if (!GetComponent(id))
    return false;

  return OnDemandUpdateInternal(id);
}

bool CrxUpdateService::OnDemandUpdateWithCooldown(const std::string& id) {
  DCHECK(thread_checker_.CalledOnValidThread());

  DCHECK(GetComponent(id));

  // Check if the request is too soon.
  const auto component_state(GetComponentState(id));
  if (component_state) {
    base::TimeDelta delta = base::Time::Now() - component_state->last_check;
    if (delta < base::TimeDelta::FromSeconds(config_->OnDemandDelay()))
      return false;
  }

  return OnDemandUpdateInternal(id);
}

bool CrxUpdateService::OnDemandUpdateInternal(const std::string& id) {
  DCHECK(thread_checker_.CalledOnValidThread());

  update_client_->Install(
      id, base::Bind(&CrxUpdateService::OnUpdate, base::Unretained(this)),
      base::Bind(&CrxUpdateService::OnUpdateComplete, base::Unretained(this)));

  return true;
}

bool CrxUpdateService::CheckForUpdates() {
  DCHECK(thread_checker_.CalledOnValidThread());
  std::vector<std::string> ids;
  for (const auto id : components_order_) {
    DCHECK(components_.find(id) != components_.end());
    ids.push_back(id);
  }

  update_client_->Update(
      ids, base::Bind(&CrxUpdateService::OnUpdate, base::Unretained(this)),
      base::Bind(&CrxUpdateService::OnUpdateComplete, base::Unretained(this)));

  return true;
}

scoped_refptr<base::SequencedTaskRunner>
CrxUpdateService::GetSequencedTaskRunner() {
  DCHECK(thread_checker_.CalledOnValidThread());
  return blocking_task_runner_;
}

bool CrxUpdateService::GetComponentDetails(const std::string& id,
                                           CrxUpdateItem* item) const {
  DCHECK(thread_checker_.CalledOnValidThread());

  // First, if this component is currently being updated, return its state from
  // the update client.
  if (update_client_->GetCrxUpdateState(id, item))
    return true;

  // Otherwise, return the last seen state of the component, if such a
  // state exists.
  const auto component_states_it = component_states_.find(id);
  if (component_states_it != component_states_.end()) {
    *item = component_states_it->second;
    return true;
  }

  return false;
}

void CrxUpdateService::OnUpdate(const std::vector<std::string>& ids,
                                std::vector<CrxComponent>* components) {
  DCHECK(thread_checker_.CalledOnValidThread());
  DCHECK(components->empty());

  for (const auto& id : ids) {
    const auto registered_component(GetComponent(id));
    if (registered_component) {
      components->push_back(*registered_component);
    }
  }
}

void CrxUpdateService::OnUpdateComplete(int error) {
  DCHECK(thread_checker_.CalledOnValidThread());
  VLOG(1) << "Update completed with error " << error;

  for (const auto id : components_pending_unregistration_) {
    if (!update_client_->IsUpdating(id)) {
      const auto component = GetComponent(id);
      if (component)
        DoUnregisterComponent(*component);
    }
  }
}

void CrxUpdateService::OnEvent(Events event, const std::string& id) {
  DCHECK(thread_checker_.CalledOnValidThread());

  // Unblock all throttles for the component.
  if (event == Observer::Events::COMPONENT_UPDATED ||
      event == Observer::Events::COMPONENT_NOT_UPDATED) {
    auto callbacks = ready_callbacks_.equal_range(id);
    for (auto it = callbacks.first; it != callbacks.second; ++it) {
      it->second.Run();
    }
    ready_callbacks_.erase(id);
  }

  CrxUpdateItem update_item;
  if (!update_client_->GetCrxUpdateState(id, &update_item))
    return;

  // Update the state of the item.
  auto it = component_states_.find(id);
  DCHECK(it != component_states_.end());
  it->second = update_item;

  // Update the component registration with the new version.
  if (event == Observer::Events::COMPONENT_UPDATED) {
    auto component(const_cast<CrxComponent*>(GetComponent(id)));
    if (component) {
      component->version = update_item.next_version;
      component->fingerprint = update_item.next_fp;
    }
  }
}

///////////////////////////////////////////////////////////////////////////////

// The component update factory. Using the component updater as a singleton
// is the job of the browser process.
// TODO(sorin): consider making this a singleton.
scoped_ptr<ComponentUpdateService> ComponentUpdateServiceFactory(
    const scoped_refptr<Configurator>& config) {
  DCHECK(config);
  auto update_client = update_client::UpdateClientFactory(config);
  return scoped_ptr<ComponentUpdateService>(
      new CrxUpdateService(config, update_client.Pass()));
}

}  // namespace component_updater