// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/site_engagement/content/site_engagement_helper.h"

#include <utility>
#include <vector>

#include "base/functional/bind.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_contents.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_manager.h"
#include "components/site_engagement/content/engagement_type.h"
#include "content/public/browser/navigation_handle.h"
#include "content/public/browser/web_contents.h"

namespace site_engagement {

namespace {

int g_seconds_to_pause_engagement_detection = 10;
int g_seconds_delay_after_navigation = 10;
int g_seconds_delay_after_media_starts = 10;
int g_seconds_delay_after_show = 5;

}  // anonymous namespace

// static
void SiteEngagementService::Helper::SetSecondsBetweenUserInputCheck(
    int seconds) {
  g_seconds_to_pause_engagement_detection = seconds;
}

// static
void SiteEngagementService::Helper::SetSecondsTrackingDelayAfterNavigation(
    int seconds) {
  g_seconds_delay_after_navigation = seconds;
}

// static
void SiteEngagementService::Helper::SetSecondsTrackingDelayAfterShow(
    int seconds) {
  g_seconds_delay_after_show = seconds;
}

SiteEngagementService::Helper::~Helper() {
  if (web_contents()) {
    input_tracker_.Stop();
    media_tracker_.Stop();
  }
}

SiteEngagementService::Helper::PeriodicTracker::PeriodicTracker(
    SiteEngagementService::Helper* helper)
    : helper_(helper), pause_timer_(std::make_unique<base::OneShotTimer>()) {}

SiteEngagementService::Helper::PeriodicTracker::~PeriodicTracker() = default;

void SiteEngagementService::Helper::PeriodicTracker::Start(
    base::TimeDelta initial_delay) {
  StartTimer(initial_delay);
}

void SiteEngagementService::Helper::PeriodicTracker::Pause() {
  TrackingStopped();
  StartTimer(base::Seconds(g_seconds_to_pause_engagement_detection));
}

void SiteEngagementService::Helper::PeriodicTracker::Stop() {
  TrackingStopped();
  pause_timer_->Stop();
}

bool SiteEngagementService::Helper::PeriodicTracker::IsTimerRunning() {
  return pause_timer_->IsRunning();
}

void SiteEngagementService::Helper::PeriodicTracker::SetPauseTimerForTesting(
    std::unique_ptr<base::OneShotTimer> timer) {
  pause_timer_ = std::move(timer);
}

void SiteEngagementService::Helper::PeriodicTracker::StartTimer(
    base::TimeDelta delay) {
  pause_timer_->Start(
      FROM_HERE, delay,
      base::BindOnce(
          &SiteEngagementService::Helper::PeriodicTracker::TrackingStarted,
          base::Unretained(this)));
}

SiteEngagementService::Helper::InputTracker::InputTracker(
    SiteEngagementService::Helper* helper,
    content::WebContents* web_contents)
    : PeriodicTracker(helper),
      content::WebContentsObserver(web_contents),
      is_tracking_(false) {}

void SiteEngagementService::Helper::InputTracker::TrackingStarted() {
  is_tracking_ = true;
}

void SiteEngagementService::Helper::InputTracker::TrackingStopped() {
  is_tracking_ = false;
}

// Record that there was some user input, and defer handling of the input event.
// Once the timer finishes running, the callbacks detecting user input will be
// registered again.
void SiteEngagementService::Helper::InputTracker::DidGetUserInteraction(
    const blink::WebInputEvent& event) {
  if (!is_tracking_)
    return;

  const blink::WebInputEvent::Type type = event.GetType();

  // This switch has a default NOTREACHED case because it will not test all
  // of the values of the WebInputEvent::Type enum (hence it won't require the
  // compiler verifying that all cases are covered).
  switch (type) {
    // Only respond to key down events to avoid multiple triggering on a single
    // input (e.g. keypress is a key down then key up).
    case blink::WebInputEvent::Type::kRawKeyDown:
    case blink::WebInputEvent::Type::kKeyDown:
      helper()->RecordUserInput(EngagementType::kKeypress);
      break;
    case blink::WebInputEvent::Type::kMouseDown:
      helper()->RecordUserInput(EngagementType::kMouse);
      break;
    case blink::WebInputEvent::Type::kTouchStart:
      helper()->RecordUserInput(EngagementType::kTouchGesture);
      break;
    case blink::WebInputEvent::Type::kGestureScrollBegin:
      helper()->RecordUserInput(EngagementType::kScroll);
      break;
    default:
      NOTREACHED();
  }
  Pause();
}

SiteEngagementService::Helper::MediaTracker::MediaTracker(
    SiteEngagementService::Helper* helper,
    content::WebContents* web_contents)
    : PeriodicTracker(helper), content::WebContentsObserver(web_contents) {}

SiteEngagementService::Helper::MediaTracker::~MediaTracker() = default;

void SiteEngagementService::Helper::MediaTracker::TrackingStarted() {
  if (!active_media_players_.empty()) {
    // TODO(dominickn): Consider treating OCCLUDED tabs like HIDDEN tabs when
    // computing engagement score. They are currently treated as VISIBLE tabs to
    // preserve old behavior.
    helper()->RecordMediaPlaying(web_contents()->GetVisibility() ==
                                 content::Visibility::HIDDEN);
  }

  Pause();
}

void SiteEngagementService::Helper::MediaTracker::PrimaryPageChanged(
    content::Page& page) {
  // Media stops playing on navigation, so clear our state.
  active_media_players_.clear();
}

void SiteEngagementService::Helper::MediaTracker::MediaStartedPlaying(
    const MediaPlayerInfo& media_info,
    const content::MediaPlayerId& id) {
  // Only begin engagement detection when media actually starts playing.
  active_media_players_.push_back(id);
  if (!IsTimerRunning())
    Start(base::Seconds(g_seconds_delay_after_media_starts));
}

void SiteEngagementService::Helper::MediaTracker::MediaStoppedPlaying(
    const MediaPlayerInfo& media_info,
    const content::MediaPlayerId& id,
    WebContentsObserver::MediaStoppedReason reason) {
  std::erase(active_media_players_, id);
}

SiteEngagementService::Helper::Helper(
    content::WebContents* web_contents,
    prerender::NoStatePrefetchManager* prefetch_manager)
    : content::WebContentsObserver(web_contents),
      content::WebContentsUserData<SiteEngagementService::Helper>(
          *web_contents),
      input_tracker_(this, web_contents),
      media_tracker_(this, web_contents),
      service_(SiteEngagementService::Get(web_contents->GetBrowserContext())),
      prefetch_manager_(prefetch_manager) {}

void SiteEngagementService::Helper::RecordUserInput(EngagementType type) {
  TRACE_EVENT0("SiteEngagement", "RecordUserInput");
  content::WebContents* contents = web_contents();
  if (contents)
    service_->HandleUserInput(contents, type);
}

void SiteEngagementService::Helper::RecordMediaPlaying(bool is_hidden) {
  content::WebContents* contents = web_contents();
  if (contents)
    service_->HandleMediaPlaying(contents, is_hidden);
}

void SiteEngagementService::Helper::DidFinishNavigation(
    content::NavigationHandle* handle) {
  // Ignore uncommitted, non main-frame, same page, or error page navigations.
  if (!handle->HasCommitted() || !handle->IsInPrimaryMainFrame() ||
      handle->IsSameDocument() || handle->IsErrorPage()) {
    return;
  }

  input_tracker_.Stop();
  media_tracker_.Stop();

  // Ignore no-state prefetcher loads. This means that no-state prefetchers will
  // not receive navigation engagement. The implications are as follows:
  //
  // - Instant search prefetchers from the omnibox trigger DidFinishNavigation
  //   twice: once for the prefetcher, and again when the page swaps in. The
  //   second trigger has transition GENERATED and receives navigation
  //   engagement.
  // - Prefetchers initiated by <link rel="prerender"> (e.g. search results) are
  //   always assigned the LINK transition, which is ignored for navigation
  //   engagement.
  //
  // Prefetchers trigger WasShown() when they are swapped in, so input
  // engagement will activate even if navigation engagement is not scored.
  if (prefetch_manager_ &&
      prefetch_manager_->GetNoStatePrefetchContents(web_contents()))
    return;

  service_->HandleNavigation(web_contents(), handle->GetPageTransition());

  input_tracker_.Start(base::Seconds(g_seconds_delay_after_navigation));
}

void SiteEngagementService::Helper::OnVisibilityChanged(
    content::Visibility visibility) {
  // TODO(fdoray): Once the page visibility API [1] treats hidden and occluded
  // documents the same way, consider stopping |input_tracker_| when
  // |visibility| is OCCLUDED. https://crbug.com/668690
  // [1] https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API
  if (visibility == content::Visibility::HIDDEN) {
    input_tracker_.Stop();
  } else {
    // Start a timer to track input if it isn't already running and input isn't
    // already being tracked.
    if (!input_tracker_.IsTimerRunning() && !input_tracker_.is_tracking()) {
      input_tracker_.Start(base::Seconds(g_seconds_delay_after_show));
    }
  }
}

WEB_CONTENTS_USER_DATA_KEY_IMPL(SiteEngagementService::Helper);

}  // namespace site_engagement