// ================================================================================
// ==      This file is a part of Turbo Badger. (C) 2011-2014, Emil Segerås      ==
// ==                     See tb_core.h for more information.                    ==
// ================================================================================

#include "animation/tb_animation.h"
#include "tb_system.h"

namespace tb {

// == Helpers =======================================================

#define SMOOTHSTEP(x) ((x) * (x) * (3.0f - 2.0f * (x)))

static float sc(float x)
{
    float s = x < 0 ? -1.f : 1.f;
    x = ABS(x);
    if (x >= 1)
        return s;
    return s * (x < 0 ? x / 0.5f : (x / (1 + x * x)) / 0.5f);
}

static float SmoothCurve(float x, float a)
{
    float r = a * x / (2 * a * x - a - x + 1);
    r = (r - 0.5f) * 2;
    return sc(r) * 0.5f + 0.5f;
}

// == TBAnimationObject ===============================================

void TBAnimationObject::InvokeOnAnimationStart()
{
    TBLinkListOf<TBAnimationListener>::Iterator li = m_listeners.IterateForward();
    OnAnimationStart();
    while (TBAnimationListener *listener = li.GetAndStep())
        listener->OnAnimationStart(this);
}

void TBAnimationObject::InvokeOnAnimationUpdate(float progress)
{
    TBLinkListOf<TBAnimationListener>::Iterator li = m_listeners.IterateForward();
    OnAnimationUpdate(progress);
    while (TBAnimationListener *listener = li.GetAndStep())
        listener->OnAnimationUpdate(this, progress);
}

void TBAnimationObject::InvokeOnAnimationStop(bool aborted)
{
    TBLinkListOf<TBAnimationListener>::Iterator li = m_listeners.IterateForward();
    OnAnimationStop(aborted);
    while (TBAnimationListener *listener = li.GetAndStep())
        listener->OnAnimationStop(this, aborted);
}

// == TBAnimationManager ==============================================

TBLinkListOf<TBAnimationObject> TBAnimationManager::animating_objects;
static int block_animations_counter = 0;

//static
void TBAnimationManager::AbortAllAnimations()
{
    while (TBAnimationObject *obj = animating_objects.GetFirst())
        AbortAnimation(obj, true);
}

//static
void TBAnimationManager::Update()
{
    double time_now = TBSystem::GetTimeMS();

    TBLinkListOf<TBAnimationObject>::Iterator iter = animating_objects.IterateForward();
    while (TBAnimationObject *obj = iter.GetAndStep())
    {
        // Adjust the start time if it's the first update time for this object.
        if (obj->adjust_start_time)
        {
            obj->animation_start_time = time_now;
            obj->adjust_start_time = false;
        }

        // Calculate current progress
        // If animation_duration is 0, it should just complete immediately.
        float progress = 1.0f;
        if (obj->animation_duration != 0)
        {
            progress = (float)(time_now - obj->animation_start_time) / (float)obj->animation_duration;
            progress = MIN(progress, 1.0f);
        }

        // Apply animation curve
        float tmp;
        switch (obj->animation_curve)
        {
        case ANIMATION_CURVE_SLOW_DOWN:
            tmp = 1 - progress;
            progress = 1 - tmp * tmp * tmp;
            break;
        case ANIMATION_CURVE_SPEED_UP:
            progress = progress * progress * progress;
            break;
        case ANIMATION_CURVE_BEZIER:
            progress = SMOOTHSTEP(progress);
            break;
        case ANIMATION_CURVE_SMOOTH:
            progress = SmoothCurve(progress, 0.6f);
            break;
        default: // linear (progress is already linear)
            break;
        };

        // Update animation
        obj->InvokeOnAnimationUpdate(progress);

        // Remove completed animations
        if (progress == 1.0f)
        {
            animating_objects.Remove(obj);
            obj->InvokeOnAnimationStop(false);
            delete obj;
        }
    }
}

//static
bool TBAnimationManager::HasAnimationsRunning()
{
    return animating_objects.HasLinks();
}

//static
void TBAnimationManager::StartAnimation(TBAnimationObject *obj, ANIMATION_CURVE animation_curve, double animation_duration, ANIMATION_TIME animation_time)
{
    if (obj->IsAnimating())
        AbortAnimation(obj, false);
    if (IsAnimationsBlocked())
        animation_duration = 0;
    obj->adjust_start_time = (animation_time == ANIMATION_TIME_FIRST_UPDATE ? true : false);
    obj->animation_start_time = TBSystem::GetTimeMS();
    obj->animation_duration = MAX(animation_duration, 0.0);
    obj->animation_curve = animation_curve;
    animating_objects.AddLast(obj);
    obj->InvokeOnAnimationStart();
}

//static
void TBAnimationManager::AbortAnimation(TBAnimationObject *obj, bool delete_animation)
{
    if (obj->IsAnimating())
    {
        animating_objects.Remove(obj);
        obj->InvokeOnAnimationStop(true);
        if (delete_animation)
            delete obj;
    }
}

//static
bool TBAnimationManager::IsAnimationsBlocked()
{
    return block_animations_counter > 0;
}

//static
void TBAnimationManager::BeginBlockAnimations()
{
    block_animations_counter++;
}

//static
void TBAnimationManager::EndBlockAnimations()
{
    assert(block_animations_counter > 0);
    block_animations_counter--;
}

}; // namespace tb