/*
 * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
 *           (C) 2000 Antti Koivisto (koivisto@kde.org)
 *           (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2003-2020 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#pragma once

#include <wtf/NeverDestroyed.h>
#include <wtf/Ref.h>
#include <wtf/RefCounted.h>
#include <wtf/Vector.h>

namespace WTF {
class TextStream;
}

namespace WebCore {

class TimingFunction : public RefCounted<TimingFunction> {
public:
    virtual Ref<TimingFunction> clone() const = 0;

    virtual ~TimingFunction() = default;

    enum class Type { LinearFunction, CubicBezierFunction, StepsFunction, SpringFunction };
    virtual Type type() const = 0;

    bool isLinearTimingFunction() const { return type() == Type::LinearFunction; }
    bool isCubicBezierTimingFunction() const { return type() == Type::CubicBezierFunction; }
    bool isStepsTimingFunction() const { return type() == Type::StepsFunction; }
    bool isSpringTimingFunction() const { return type() == Type::SpringFunction; }

    virtual bool operator==(const TimingFunction&) const = 0;

    enum class Before : bool { No, Yes };
    double transformProgress(double progress, double duration, Before = Before::No) const;
    String cssText() const;
};

class LinearTimingFunction final : public TimingFunction {
public:
    struct Point {
        double value;
        double progress;

        bool operator==(const Point& other) const
        {
            return value == other.value && progress == other.progress;
        }
    };

    static Ref<LinearTimingFunction> create()
    {
        return create({ });
    }

    static Ref<LinearTimingFunction> create(const Vector<Point>& points)
    {
        return adoptRef(*new LinearTimingFunction(points));
    }
    
    bool operator==(const TimingFunction& other) const final
    {
        auto* otherLinear = dynamicDowncast<LinearTimingFunction>(other);
        return otherLinear && m_points == otherLinear->m_points;
    }

    const Vector<Point>& points() const { return m_points; }

    static const LinearTimingFunction& identity()
    {
        static NeverDestroyed<Ref<LinearTimingFunction>> function { create() };
        return function.get();
    }

private:
    LinearTimingFunction(const Vector<Point>& points)
        : m_points(points)
    {
        ASSERT(m_points.isEmpty() || m_points.size() >= 2);
    }

    Type type() const final { return Type::LinearFunction; }
    Ref<TimingFunction> clone() const final
    {
        return adoptRef(*new LinearTimingFunction(m_points));
    }

    const Vector<Point> m_points;
};

class CubicBezierTimingFunction final : public TimingFunction {
public:
    enum class TimingFunctionPreset : uint8_t { Ease, EaseIn, EaseOut, EaseInOut, Custom };

    static Ref<CubicBezierTimingFunction> create()
    {
        return create(TimingFunctionPreset::Ease, 0.25, 0.1, 0.25, 1.0);
    }

    static Ref<CubicBezierTimingFunction> create(double x1, double y1, double x2, double y2)
    {
        return adoptRef(*new CubicBezierTimingFunction(TimingFunctionPreset::Custom, x1, y1, x2, y2));
    }

    static Ref<CubicBezierTimingFunction> create(TimingFunctionPreset preset, double x1, double y1, double x2, double y2)
    {
        return adoptRef(*new CubicBezierTimingFunction(preset, x1, y1, x2, y2));
    }

    WEBCORE_EXPORT static Ref<CubicBezierTimingFunction> create(TimingFunctionPreset);

    bool operator==(const TimingFunction& other) const final
    {
        auto* otherCubic = dynamicDowncast<CubicBezierTimingFunction>(other);
        if (!otherCubic || m_timingFunctionPreset != otherCubic->m_timingFunctionPreset)
            return false;
        if (m_timingFunctionPreset != TimingFunctionPreset::Custom)
            return true;
        return m_x1 == otherCubic->m_x1 && m_y1 == otherCubic->m_y1 && m_x2 == otherCubic->m_x2 && m_y2 == otherCubic->m_y2;
    }

    double x1() const { return m_x1; }
    double y1() const { return m_y1; }
    double x2() const { return m_x2; }
    double y2() const { return m_y2; }

    TimingFunctionPreset timingFunctionPreset() const { return m_timingFunctionPreset; }
    void setTimingFunctionPreset(TimingFunctionPreset preset) { m_timingFunctionPreset = preset; }

    static const CubicBezierTimingFunction& defaultTimingFunction()
    {
        static NeverDestroyed<Ref<CubicBezierTimingFunction>> function { create() };
        return function.get();
    }

    Ref<CubicBezierTimingFunction> createReversed() const
    {
        return create(TimingFunctionPreset::Custom, 1.0 - m_x2, 1.0 - m_y2, 1.0 - m_x1, 1.0 - m_y1);
    }

    bool isLinear() const
    {
        return (!m_x1 && !m_y1 && !m_x2 && !m_y2) || (m_x1 == 1.0 && m_y1 == 1.0 && m_x2 == 1.0 && m_y2 == 1.0) || (m_x1 == 0.0 && m_y1 == 0.0 && m_x2 == 1.0 && m_y2 == 1.0);
    }

private:
    explicit CubicBezierTimingFunction(TimingFunctionPreset preset, double x1, double y1, double x2, double y2)
        : m_x1(x1)
        , m_y1(y1)
        , m_x2(x2)
        , m_y2(y2)
        , m_timingFunctionPreset(preset)
    {
    }

    Type type() const final { return Type::CubicBezierFunction; }
    Ref<TimingFunction> clone() const final
    {
        return adoptRef(*new CubicBezierTimingFunction(m_timingFunctionPreset, m_x1, m_y1, m_x2, m_y2));
    }

    const double m_x1;
    const double m_y1;
    const double m_x2;
    const double m_y2;
    TimingFunctionPreset m_timingFunctionPreset;
};

class StepsTimingFunction final : public TimingFunction {
public:
    enum class StepPosition : uint8_t {
        JumpStart,
        JumpEnd,
        JumpNone,
        JumpBoth,
        Start,
        End,
    };

    static Ref<StepsTimingFunction> create(int steps, std::optional<StepPosition> stepPosition)
    {
        return adoptRef(*new StepsTimingFunction(steps, stepPosition));
    }
    static Ref<StepsTimingFunction> create()
    {
        return adoptRef(*new StepsTimingFunction(1, StepPosition::End));
    }
    
    bool operator==(const TimingFunction& other) const final
    {
        auto* otherSteps = dynamicDowncast<StepsTimingFunction>(other);
        if (!otherSteps || m_steps != otherSteps->m_steps)
            return false;

        if (m_stepPosition == otherSteps->m_stepPosition)
            return true;

        if (!m_stepPosition && *otherSteps->m_stepPosition == StepPosition::End)
            return true;

        if (!otherSteps->m_stepPosition && *m_stepPosition == StepPosition::End)
            return true;

        return false;
    }
    
    int numberOfSteps() const { return m_steps; }

    std::optional<StepPosition> stepPosition() const { return m_stepPosition; }

private:
    StepsTimingFunction(int steps, std::optional<StepPosition> stepPosition)
        : m_steps(steps)
        , m_stepPosition(stepPosition)
    {
    }

    Type type() const final { return Type::StepsFunction; }
    Ref<TimingFunction> clone() const final
    {
        return adoptRef(*new StepsTimingFunction(m_steps, m_stepPosition));
    }
    
    const int m_steps;
    const std::optional<StepPosition> m_stepPosition;
};

class SpringTimingFunction final : public TimingFunction {
public:
    static Ref<SpringTimingFunction> create(double mass, double stiffness, double damping, double initialVelocity)
    {
        return adoptRef(*new SpringTimingFunction(mass, stiffness, damping, initialVelocity));
    }

    static Ref<SpringTimingFunction> create()
    {
        // This create() function should only be used by the argument decoders, and it is expected that
        // real values will be filled in using setValues().
        return create(0, 0, 0, 0);
    }
    
    bool operator==(const TimingFunction& other) const final
    {
        auto* otherSpring = dynamicDowncast<SpringTimingFunction>(other);
        return otherSpring && m_mass == otherSpring->m_mass && m_stiffness == otherSpring->m_stiffness && m_damping == otherSpring->m_damping && m_initialVelocity == otherSpring->m_initialVelocity;
    }

    double mass() const { return m_mass; }
    double stiffness() const { return m_stiffness; }
    double damping() const { return m_damping; }
    double initialVelocity() const { return m_initialVelocity; }

private:
    explicit SpringTimingFunction(double mass, double stiffness, double damping, double initialVelocity)
        : m_mass(mass)
        , m_stiffness(stiffness)
        , m_damping(damping)
        , m_initialVelocity(initialVelocity)
    {
    }

    Type type() const final { return Type::SpringFunction; }
    Ref<TimingFunction> clone() const final
    {
        return adoptRef(*new SpringTimingFunction(m_mass, m_stiffness, m_damping, m_initialVelocity));
    }

    const double m_mass;
    const double m_stiffness;
    const double m_damping;
    const double m_initialVelocity;
};

WEBCORE_EXPORT WTF::TextStream& operator<<(WTF::TextStream&, const TimingFunction&);

} // namespace WebCore

#define SPECIALIZE_TYPE_TRAITS_TIMINGFUNCTION(ToValueTypeName, predicate) \
SPECIALIZE_TYPE_TRAITS_BEGIN(ToValueTypeName) \
static bool isType(const WebCore::TimingFunction& function) { return function.predicate; } \
SPECIALIZE_TYPE_TRAITS_END()

SPECIALIZE_TYPE_TRAITS_TIMINGFUNCTION(WebCore::LinearTimingFunction, isLinearTimingFunction())
SPECIALIZE_TYPE_TRAITS_TIMINGFUNCTION(WebCore::CubicBezierTimingFunction, isCubicBezierTimingFunction())
SPECIALIZE_TYPE_TRAITS_TIMINGFUNCTION(WebCore::StepsTimingFunction, isStepsTimingFunction())
SPECIALIZE_TYPE_TRAITS_TIMINGFUNCTION(WebCore::SpringTimingFunction, isSpringTimingFunction())