// 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 "ui/chromeos/touch_exploration_controller.h"

#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "ui/aura/client/cursor_client.h"
#include "ui/aura/window.h"
#include "ui/aura/window_event_dispatcher.h"
#include "ui/aura/window_tree_host.h"
#include "ui/events/event.h"
#include "ui/events/event_processor.h"

#define VLOG_STATE() if (VLOG_IS_ON(0)) VlogState(__func__)
#define VLOG_EVENT(event) if (VLOG_IS_ON(0)) VlogEvent(event, __func__)

namespace ui {

namespace {
// The default value for initial_touch_id_passthrough_mapping_ used
// when the user has not yet released any fingers yet, so there's no
// touch id remapping yet.
const int kTouchIdUnassigned = 0;

// The value for initial_touch_id_passthrough_mapping_ if the user has
// released the first finger but some other fingers are held down. In this
// state we don't do any touch id remapping, but we distinguish it from the
// kTouchIdUnassigned state because we don't want to assign
// initial_touch_id_passthrough_mapping_ a touch id anymore,
// until all fingers are released.
const int kTouchIdNone = -1;
}  // namespace

TouchExplorationController::TouchExplorationController(
    aura::Window* root_window)
    : root_window_(root_window),
      initial_touch_id_passthrough_mapping_(kTouchIdUnassigned),
      state_(NO_FINGERS_DOWN),
      event_handler_for_testing_(NULL),
      prev_state_(NO_FINGERS_DOWN) {
  CHECK(root_window);
  root_window->GetHost()->GetEventSource()->AddEventRewriter(this);
}

TouchExplorationController::~TouchExplorationController() {
  root_window_->GetHost()->GetEventSource()->RemoveEventRewriter(this);
}

void TouchExplorationController::CallTapTimerNowForTesting() {
  DCHECK(tap_timer_.IsRunning());
  tap_timer_.Stop();
  OnTapTimerFired();
}

void TouchExplorationController::SetEventHandlerForTesting(
    ui::EventHandler* event_handler_for_testing) {
  event_handler_for_testing_ = event_handler_for_testing;
}

bool TouchExplorationController::IsInNoFingersDownStateForTesting() const {
  return state_ == NO_FINGERS_DOWN;
}

ui::EventRewriteStatus TouchExplorationController::RewriteEvent(
    const ui::Event& event,
    scoped_ptr<ui::Event>* rewritten_event) {
  if (!event.IsTouchEvent())
    return ui::EVENT_REWRITE_CONTINUE;
  const ui::TouchEvent& touch_event =
      static_cast<const ui::TouchEvent&>(event);

  // If the tap timer should have fired by now but hasn't, run it now and
  // stop the timer. This is important so that behavior is consistent with
  // the timestamps of the events, and not dependent on the granularity of
  // the timer.
  if (tap_timer_.IsRunning() &&
      touch_event.time_stamp() - initial_press_->time_stamp() >
          gesture_detector_config_.double_tap_timeout) {
    tap_timer_.Stop();
    OnTapTimerFired();
    // Note: this may change the state. We should now continue and process
    // this event under this new state.
  }

  const ui::EventType type = touch_event.type();
  const gfx::PointF& location = touch_event.location_f();
  const int touch_id = touch_event.touch_id();

  // Always update touch ids and touch locations, so we can use those
  // no matter what state we're in.
  if (type == ui::ET_TOUCH_PRESSED) {
    current_touch_ids_.push_back(touch_id);
    touch_locations_.insert(std::pair<int, gfx::PointF>(touch_id, location));
  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
    std::vector<int>::iterator it = std::find(
        current_touch_ids_.begin(), current_touch_ids_.end(), touch_id);

    // Can happen if touch exploration is enabled while fingers were down.
    if (it == current_touch_ids_.end())
      return ui::EVENT_REWRITE_CONTINUE;

    current_touch_ids_.erase(it);
    touch_locations_.erase(touch_id);
  } else if (type == ui::ET_TOUCH_MOVED) {
    std::vector<int>::iterator it = std::find(
        current_touch_ids_.begin(), current_touch_ids_.end(), touch_id);

    // Can happen if touch exploration is enabled while fingers were down.
    if (it == current_touch_ids_.end())
      return ui::EVENT_REWRITE_CONTINUE;

    touch_locations_[*it] = location;
  }
  VLOG_STATE();
  VLOG_EVENT(touch_event);
  // The rest of the processing depends on what state we're in.
  switch(state_) {
    case NO_FINGERS_DOWN:
      return InNoFingersDown(touch_event, rewritten_event);
    case SINGLE_TAP_PRESSED:
      return InSingleTapPressed(touch_event, rewritten_event);
    case SINGLE_TAP_RELEASED:
      return InSingleTapReleased(touch_event, rewritten_event);
    case DOUBLE_TAP_PRESSED:
      return InDoubleTapPressed(touch_event, rewritten_event);
    case TOUCH_EXPLORATION:
      return InTouchExploration(touch_event, rewritten_event);
    case PASSTHROUGH_MINUS_ONE:
      return InPassthroughMinusOne(touch_event, rewritten_event);
    case TOUCH_EXPLORE_SECOND_PRESS:
      return InTouchExploreSecondPress(touch_event, rewritten_event);
  }

  NOTREACHED();
  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::NextDispatchEvent(
    const ui::Event& last_event, scoped_ptr<ui::Event>* new_event) {
  NOTREACHED();
  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::InNoFingersDown(
    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
  const ui::EventType type = event.type();
  if (type == ui::ET_TOUCH_PRESSED) {
    initial_press_.reset(new TouchEvent(event));
    tap_timer_.Start(FROM_HERE,
                     gesture_detector_config_.double_tap_timeout,
                     this,
                     &TouchExplorationController::OnTapTimerFired);
    state_ = SINGLE_TAP_PRESSED;
    VLOG_STATE();
    return ui::EVENT_REWRITE_DISCARD;
  }

  NOTREACHED();
  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::InSingleTapPressed(
    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
  const ui::EventType type = event.type();

  if (type == ui::ET_TOUCH_PRESSED) {
    // Adding a second finger within the timeout period switches to
    // passthrough.
    state_ = PASSTHROUGH_MINUS_ONE;
    return InPassthroughMinusOne(event, rewritten_event);
  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
    DCHECK_EQ(0U, current_touch_ids_.size());
    state_ = SINGLE_TAP_RELEASED;
    VLOG_STATE();
    return EVENT_REWRITE_DISCARD;
  } else if (type == ui::ET_TOUCH_MOVED) {
    // If the user moves far enough from the initial touch location (outside
    // the "slop" region, jump to the touch exploration mode early.
    // TODO(evy, lisayin): Add gesture recognition here instead -
    // we should probably jump to gesture mode here if the velocity is
    // high enough, and touch exploration if the velocity is lower.
    float delta = (event.location() - initial_press_->location()).Length();
    if (delta > gesture_detector_config_.touch_slop) {
      EnterTouchToMouseMode();
      state_ = TOUCH_EXPLORATION;
      VLOG_STATE();
      return InTouchExploration(event, rewritten_event);
    }

    return EVENT_REWRITE_DISCARD;
  }
  NOTREACHED() << "Unexpected event type received.";
  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::InSingleTapReleased(
    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
  const ui::EventType type = event.type();
  if (type == ui::ET_TOUCH_PRESSED) {
    // This is the second tap in a double-tap (or double tap-hold).
    // Rewrite at location of last touch exploration.
    // If there is no touch exploration yet, discard instead.
    if (!last_touch_exploration_) {
      return ui::EVENT_REWRITE_DISCARD;
    }
    rewritten_event->reset(
        new ui::TouchEvent(ui::ET_TOUCH_PRESSED,
                           last_touch_exploration_->location(),
                           event.touch_id(),
                           event.time_stamp()));
    (*rewritten_event)->set_flags(event.flags());
    state_ = DOUBLE_TAP_PRESSED;
    VLOG_STATE();
    return ui::EVENT_REWRITE_REWRITTEN;
  }
  // If the previous press was discarded, we need to also handle its release.
  if (type == ui::ET_TOUCH_RELEASED && !last_touch_exploration_) {
    if (current_touch_ids_.size() == 0) {
      state_ = NO_FINGERS_DOWN;
    }
    return ui::EVENT_REWRITE_DISCARD;
  }
  NOTREACHED();
  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::InDoubleTapPressed(
    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
  const ui::EventType type = event.type();
  if (type == ui::ET_TOUCH_PRESSED) {
    return ui::EVENT_REWRITE_DISCARD;
  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
    if (current_touch_ids_.size() != 0)
      return EVENT_REWRITE_DISCARD;

    // Rewrite release at location of last touch exploration with the same
    // id as the prevoius press.
    rewritten_event->reset(
        new ui::TouchEvent(ui::ET_TOUCH_RELEASED,
                           last_touch_exploration_->location(),
                           initial_press_->touch_id(),
                           event.time_stamp()));
    (*rewritten_event)->set_flags(event.flags());
    ResetToNoFingersDown();
    return ui::EVENT_REWRITE_REWRITTEN;
  } else if (type == ui::ET_TOUCH_MOVED) {
    return ui::EVENT_REWRITE_DISCARD;
  }
  NOTREACHED() << "Unexpected event type received.";
  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::InTouchExploration(
    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
  const ui::EventType type = event.type();
  if (type == ui::ET_TOUCH_PRESSED) {
    // Handle split-tap.
    initial_press_.reset(new TouchEvent(event));
    if (tap_timer_.IsRunning())
      tap_timer_.Stop();
    rewritten_event->reset(
        new ui::TouchEvent(ui::ET_TOUCH_PRESSED,
                           last_touch_exploration_->location(),
                           event.touch_id(),
                           event.time_stamp()));
    (*rewritten_event)->set_flags(event.flags());
    state_ = TOUCH_EXPLORE_SECOND_PRESS;
    VLOG_STATE();
    return ui::EVENT_REWRITE_REWRITTEN;
  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
    if (current_touch_ids_.size() == 0)
      ResetToNoFingersDown();
  } else if (type != ui::ET_TOUCH_MOVED) {
    NOTREACHED() << "Unexpected event type received.";
    return ui::EVENT_REWRITE_CONTINUE;
  }

  // Rewrite as a mouse-move event.
  *rewritten_event = CreateMouseMoveEvent(event.location(), event.flags());
  last_touch_exploration_.reset(new TouchEvent(event));
  return ui::EVENT_REWRITE_REWRITTEN;
}

ui::EventRewriteStatus TouchExplorationController::InPassthroughMinusOne(
    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
  ui::EventType type = event.type();
  gfx::PointF location = event.location_f();

  if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
    if (current_touch_ids_.size() == 0)
      ResetToNoFingersDown();

    if (initial_touch_id_passthrough_mapping_ == kTouchIdUnassigned) {
      if (event.touch_id() == initial_press_->touch_id()) {
        initial_touch_id_passthrough_mapping_ = kTouchIdNone;
      } else {
        // If the only finger now remaining is the first finger,
        // rewrite as a move to the location of the first finger.
        initial_touch_id_passthrough_mapping_ = event.touch_id();
        rewritten_event->reset(
            new ui::TouchEvent(ui::ET_TOUCH_MOVED,
                               touch_locations_[initial_press_->touch_id()],
                               initial_touch_id_passthrough_mapping_,
                               event.time_stamp()));
        (*rewritten_event)->set_flags(event.flags());
        return ui::EVENT_REWRITE_REWRITTEN;
      }
    }
  }

  if (event.touch_id() == initial_press_->touch_id()) {
    if (initial_touch_id_passthrough_mapping_ == kTouchIdNone ||
        initial_touch_id_passthrough_mapping_ == kTouchIdUnassigned) {
      return ui::EVENT_REWRITE_DISCARD;
    }

    rewritten_event->reset(
        new ui::TouchEvent(type,
                           location,
                           initial_touch_id_passthrough_mapping_,
                           event.time_stamp()));
    (*rewritten_event)->set_flags(event.flags());
    return ui::EVENT_REWRITE_REWRITTEN;
  }

  return ui::EVENT_REWRITE_CONTINUE;
}

ui::EventRewriteStatus TouchExplorationController::InTouchExploreSecondPress(
    const ui::TouchEvent& event,
    scoped_ptr<ui::Event>* rewritten_event) {
  ui::EventType type = event.type();
  gfx::PointF location = event.location_f();
  if (type == ui::ET_TOUCH_PRESSED) {
    return ui::EVENT_REWRITE_DISCARD;
  } else if (type == ui::ET_TOUCH_MOVED) {
    // Currently this is a discard, but could be something like rotor
    // in the future.
    return ui::EVENT_REWRITE_DISCARD;
  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
    // If the touch exploration finger is lifted, there is no option to return
    // to touch explore anymore. The remaining finger acts as a pending
    // tap or long tap for the last touch explore location.
    if (event.touch_id() == last_touch_exploration_->touch_id()){
      state_ = DOUBLE_TAP_PRESSED;
      VLOG_STATE();
      return EVENT_REWRITE_DISCARD;
    }

    // Continue to release the touch only if the touch explore finger is the
    // only finger remaining.
    if (current_touch_ids_.size() != 1)
      return EVENT_REWRITE_DISCARD;

    // Continue to release the touch only if the touch explore finger is the
    // only finger remaining.
    if (current_touch_ids_.size() != 1)
      return EVENT_REWRITE_DISCARD;

    // Rewrite at location of last touch exploration.
    rewritten_event->reset(
        new ui::TouchEvent(ui::ET_TOUCH_RELEASED,
                           last_touch_exploration_->location(),
                           initial_press_->touch_id(),
                           event.time_stamp()));
    (*rewritten_event)->set_flags(event.flags());
    state_ = TOUCH_EXPLORATION;
    VLOG_STATE();
    return ui::EVENT_REWRITE_REWRITTEN;
  }
  NOTREACHED() << "Unexpected event type received.";
  return ui::EVENT_REWRITE_CONTINUE;
}

void TouchExplorationController::OnTapTimerFired() {
  if (state_ != SINGLE_TAP_RELEASED && state_ != SINGLE_TAP_PRESSED)
    return;

  if (state_ == SINGLE_TAP_RELEASED) {
    ResetToNoFingersDown();
  } else {
    EnterTouchToMouseMode();
    state_ = TOUCH_EXPLORATION;
    VLOG_STATE();
  }

  scoped_ptr<ui::Event> mouse_move = CreateMouseMoveEvent(
      initial_press_->location(), initial_press_->flags());
  DispatchEvent(mouse_move.get());
  last_touch_exploration_.reset(new TouchEvent(*initial_press_));
}

void TouchExplorationController::DispatchEvent(ui::Event* event) {
  if (event_handler_for_testing_) {
    event_handler_for_testing_->OnEvent(event);
    return;
  }

  ui::EventDispatchDetails result ALLOW_UNUSED =
      root_window_->GetHost()->dispatcher()->OnEventFromSource(event);
}

scoped_ptr<ui::Event> TouchExplorationController::CreateMouseMoveEvent(
    const gfx::PointF& location,
    int flags) {
  return scoped_ptr<ui::Event>(
      new ui::MouseEvent(
          ui::ET_MOUSE_MOVED,
          location,
          location,
          flags | ui::EF_IS_SYNTHESIZED | ui::EF_TOUCH_ACCESSIBILITY,
          0));
}

void TouchExplorationController::EnterTouchToMouseMode() {
  aura::client::CursorClient* cursor_client =
      aura::client::GetCursorClient(root_window_);
  if (cursor_client && !cursor_client->IsMouseEventsEnabled())
    cursor_client->EnableMouseEvents();
  if (cursor_client && cursor_client->IsCursorVisible())
    cursor_client->HideCursor();
}

void TouchExplorationController::ResetToNoFingersDown() {
  state_ = NO_FINGERS_DOWN;
  initial_touch_id_passthrough_mapping_ = kTouchIdUnassigned;
  VLOG_STATE();
  if (tap_timer_.IsRunning())
    tap_timer_.Stop();
}

void TouchExplorationController::VlogState(const char* function_name) {
  if (prev_state_ == state_)
    return;
  prev_state_ = state_;
  const char* state_string = EnumStateToString(state_);
  VLOG(0) << "\n Function name: " << function_name
          << "\n State: " << state_string;
}

void TouchExplorationController::VlogEvent(const ui::TouchEvent& touch_event,
                                           const char* function_name) {
  CHECK(touch_event.IsTouchEvent());
  if (prev_event_ == NULL || prev_event_->type() != touch_event.type() ||
      prev_event_->touch_id() != touch_event.touch_id()) {
    const std::string type = EnumEventTypeToString(touch_event.type());
    const gfx::PointF& location = touch_event.location_f();
    const int touch_id = touch_event.touch_id();

    VLOG(0) << "\n Function name: " << function_name
            << "\n Event Type: " << type
            << "\n Location: " << location.ToString()
            << "\n Touch ID: " << touch_id
            << "\n Number of fingers down: " << current_touch_ids_.size();
    prev_event_.reset(new TouchEvent(touch_event));
  }
}

const char* TouchExplorationController::EnumStateToString(State state) {
  switch (state) {
    case NO_FINGERS_DOWN:
      return "NO_FINGERS_DOWN";
    case SINGLE_TAP_PRESSED:
      return "SINGLE_TAP_PRESSED";
    case SINGLE_TAP_RELEASED:
      return "SINGLE_TAP_RELEASED";
    case DOUBLE_TAP_PRESSED:
      return "DOUBLE_TAP_PRESSED";
    case TOUCH_EXPLORATION:
      return "TOUCH_EXPLORATION";
    case PASSTHROUGH_MINUS_ONE:
      return "PASSTHROUGH_MINUS_ONE";
    case TOUCH_EXPLORE_SECOND_PRESS:
      return "TOUCH_EXPLORE_SECOND_PRESS";
  }
  return "Not a state";
}

std::string TouchExplorationController::EnumEventTypeToString(
    ui::EventType type) {
  // Add more cases later. For now, these are the most frequently seen
  // event types.
  switch (type) {
    case ET_TOUCH_RELEASED:
      return "ET_TOUCH_RELEASED";
    case ET_TOUCH_PRESSED:
      return "ET_TOUCH_PRESSED";
    case ET_TOUCH_MOVED:
      return "ET_TOUCH_MOVED";
    case ET_TOUCH_CANCELLED:
      return "ET_TOUCH_CANCELLED";
    default:
      return base::IntToString(type);
  }
}

}  // namespace ui