// 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 "base/basictypes.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/time/time.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "ui/events/gesture_detection/mock_motion_event.h"
#include "ui/events/gesture_detection/velocity_tracker_state.h"
#include "ui/gfx/geometry/point_f.h"
#include "ui/gfx/geometry/vector2d_f.h"

using base::TimeDelta;
using base::TimeTicks;

namespace ui {
namespace {

const TimeDelta kTenMillis = TimeDelta::FromMilliseconds(10);
const TimeDelta kOneSecond = TimeDelta::FromSeconds(1);
const float kEpsilson = .01f;

const char* GetStrategyName(VelocityTracker::Strategy strategy) {
  switch (strategy) {
    case VelocityTracker::LSQ1: return "LSQ1";
    case VelocityTracker::LSQ2: return "LSQ2";
    case VelocityTracker::LSQ3: return "LSQ3";
    case VelocityTracker::WLSQ2_DELTA: return "WLSQ2_DELTA";
    case VelocityTracker::WLSQ2_CENTRAL: return "WLSQ2_CENTRAL";
    case VelocityTracker::WLSQ2_RECENT: return "WLSQ2_RECENT";
    case VelocityTracker::INT1: return "INT1";
    case VelocityTracker::INT2: return "INT2";
  };
  NOTREACHED() << "Invalid strategy";
  return "";
}

}  // namespace

class VelocityTrackerTest : public testing::Test {
 public:
  VelocityTrackerTest() {}
  virtual ~VelocityTrackerTest() {}

 protected:
  static MockMotionEvent Sample(MotionEvent::Action action,
                                gfx::PointF p0,
                                TimeTicks t0,
                                gfx::Vector2dF v,
                                TimeDelta dt) {
    const gfx::PointF p = p0 + ScaleVector2d(v, dt.InSecondsF());
    return MockMotionEvent(action, t0 + dt, p.x(), p.y());
  }

  static void ApplyMovementSequence(VelocityTrackerState* state,
                                    gfx::PointF p0,
                                    gfx::Vector2dF v,
                                    TimeTicks t0,
                                    TimeDelta t,
                                    size_t samples) {
    EXPECT_TRUE(!!samples);
    if (!samples)
      return;
    const base::TimeDelta dt = t / samples;
    state->AddMovement(Sample(MotionEvent::ACTION_DOWN, p0, t0, v, dt * 0));
    ApplyMovement(state, p0, v, t0, t, samples);
    state->AddMovement(Sample(MotionEvent::ACTION_UP, p0, t0, v, t));
  }

  static void ApplyMovement(VelocityTrackerState* state,
                            gfx::PointF p0,
                            gfx::Vector2dF v,
                            TimeTicks t0,
                            TimeDelta t,
                            size_t samples) {
    EXPECT_TRUE(!!samples);
    if (!samples)
      return;
    const base::TimeDelta dt = t / samples;
    for (size_t i = 0; i < samples; ++i)
      state->AddMovement(Sample(MotionEvent::ACTION_MOVE, p0, t0, v, dt * i));
  }
};

TEST_F(VelocityTrackerTest, Basic) {
  const gfx::PointF p0(0, 0);
  const gfx::Vector2dF v(0, 500);
  const size_t samples = 60;

  for (int i = 0; i <= VelocityTracker::STRATEGY_MAX; ++i) {
    VelocityTracker::Strategy strategy =
        static_cast<VelocityTracker::Strategy>(i);

    SCOPED_TRACE(GetStrategyName(strategy));
    VelocityTrackerState state(strategy);

    // Default state should report zero velocity.
    EXPECT_EQ(0, state.GetXVelocity(0));
    EXPECT_EQ(0, state.GetYVelocity(0));

    // Sample a constant velocity sequence.
    ApplyMovementSequence(&state, p0, v, TimeTicks::Now(), kOneSecond, samples);

    // The computed velocity should match that of the input.
    state.ComputeCurrentVelocity(1000, 20000);
    EXPECT_NEAR(v.x(), state.GetXVelocity(0), kEpsilson * v.x());
    EXPECT_NEAR(v.y(), state.GetYVelocity(0), kEpsilson * v.y());

    // A pointer ID of -1 should report the velocity of the active pointer.
    EXPECT_NEAR(v.x(), state.GetXVelocity(-1), kEpsilson * v.x());
    EXPECT_NEAR(v.y(), state.GetYVelocity(-1), kEpsilson * v.y());

    // Invalid pointer ID's should report zero velocity.
    EXPECT_EQ(0, state.GetXVelocity(1));
    EXPECT_EQ(0, state.GetYVelocity(1));
    EXPECT_EQ(0, state.GetXVelocity(7));
    EXPECT_EQ(0, state.GetYVelocity(7));
  }
}

TEST_F(VelocityTrackerTest, MaxVelocity) {
  const gfx::PointF p0(0, 0);
  const gfx::Vector2dF v(-50000, 50000);
  const size_t samples = 3;
  const base::TimeDelta dt = kTenMillis * 2;

  VelocityTrackerState state;
  ApplyMovementSequence(&state, p0, v, TimeTicks::Now(), dt, samples);

  // The computed velocity should be restricted to the provided maximum.
  state.ComputeCurrentVelocity(1000, 100);
  EXPECT_NEAR(-100, state.GetXVelocity(0), kEpsilson);
  EXPECT_NEAR(100, state.GetYVelocity(0), kEpsilson);

  state.ComputeCurrentVelocity(1000, 1000);
  EXPECT_NEAR(-1000, state.GetXVelocity(0), kEpsilson);
  EXPECT_NEAR(1000, state.GetYVelocity(0), kEpsilson);
}

TEST_F(VelocityTrackerTest, VaryingVelocity) {
  const gfx::PointF p0(0, 0);
  const gfx::Vector2dF vFast(0, 500);
  const gfx::Vector2dF vSlow = ScaleVector2d(vFast, 0.5f);
  const size_t samples = 12;

  for (int i = 0; i <= VelocityTracker::STRATEGY_MAX; ++i) {
    VelocityTracker::Strategy strategy =
        static_cast<VelocityTracker::Strategy>(i);

    SCOPED_TRACE(GetStrategyName(strategy));
    VelocityTrackerState state(strategy);

    base::TimeTicks t0 = base::TimeTicks::Now();
    base::TimeDelta dt = kTenMillis * 10;
    state.AddMovement(
        Sample(MotionEvent::ACTION_DOWN, p0, t0, vFast, base::TimeDelta()));

    // Apply some fast movement and compute the velocity.
    gfx::PointF pCurr = p0;
    base::TimeTicks tCurr = t0;
    ApplyMovement(&state, pCurr, vFast, tCurr, dt, samples);
    state.ComputeCurrentVelocity(1000, 20000);
    float vOldY = state.GetYVelocity(0);

    // Apply some slow movement.
    pCurr += ScaleVector2d(vFast, dt.InSecondsF());
    tCurr += dt;
    ApplyMovement(&state, pCurr, vSlow, tCurr, dt, samples);

    // The computed velocity should have decreased.
    state.ComputeCurrentVelocity(1000, 20000);
    float vCurrentY = state.GetYVelocity(0);
    EXPECT_GT(vFast.y(), vCurrentY);
    EXPECT_GT(vOldY, vCurrentY);
    vOldY = vCurrentY;

    // Apply some additional fast movement.
    pCurr += ScaleVector2d(vSlow, dt.InSecondsF());
    tCurr += dt;
    ApplyMovement(&state, pCurr, vFast, tCurr, dt, samples);

    // The computed velocity should have increased.
    state.ComputeCurrentVelocity(1000, 20000);
    vCurrentY = state.GetYVelocity(0);
    EXPECT_LT(vSlow.y(), vCurrentY);
    EXPECT_LT(vOldY, vCurrentY);
  }
}


}  // namespace ui