/*
   Copyright (C) 2004 by Philippe Plantier <ayin@anathas.org>
   Copyright (C) 2005 - 2015 by Guillaume Melquiond <guillaume.melquiond@gmail.com>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org/

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License version 2
   or at your option any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

/**
 * @file animated.tpp
 * Templates related to animations.
 */

#include "global.hpp"

#include <climits>

#include "SDL.h"
#include "animated.hpp"

namespace {
	int current_ticks = 0;
}

void new_animation_frame()
{
	current_ticks = SDL_GetTicks();
}

int get_current_animation_tick()
{
	return current_ticks;
}

template<typename T, typename T_void_value>
const T animated<T,T_void_value>::void_value_ = T_void_value()();

template<typename T, typename T_void_value>
animated<T,T_void_value>::animated(int start_time) :
	starting_frame_time_(start_time),
	does_not_change_(true),
	started_(false),
	force_next_update_(false),
    frames_(),
	start_tick_(0),
	cycles_(false),
	acceleration_(1),
	last_update_tick_(0),
	current_frame_key_(0)
{
}

template<typename T,  typename T_void_value>
animated<T,T_void_value>::animated(const std::vector<std::pair<int,T> > &cfg, int start_time, bool force_change ):
	starting_frame_time_(start_time),
	does_not_change_(true),
	started_(false),
	force_next_update_(false),
    frames_(),
	start_tick_(0),
	cycles_(false),
	acceleration_(1),
	last_update_tick_(0),
	current_frame_key_(0)
{

	typename std::vector< std::pair<int,T> >::const_iterator itor = cfg.begin();
	for(; itor != cfg.end(); ++itor) {

		add_frame(itor->first,itor->second,force_change);
	}
}



template<typename T,  typename T_void_value>
void animated<T,T_void_value>::add_frame(int duration, const T& value,bool force_change)
{
	if(frames_.empty() ) {
		does_not_change_=!force_change;
		frames_.push_back( frame(duration,value,starting_frame_time_));
	} else {
		does_not_change_=false;
		frames_.push_back( frame(duration,value,frames_.back().start_time_+frames_.back().duration_));
	}
}

template<typename T,  typename T_void_value>
void animated<T,T_void_value>::start_animation(int start_time, bool cycles)
{
	started_ = true;
	last_update_tick_ = current_ticks;
	acceleration_ = 1.0; //assume acceleration is 1, this will be fixed at first update_last_draw_time
	start_tick_ =  last_update_tick_ +
        static_cast<int>(( starting_frame_time_ - start_time)/acceleration_);

	cycles_ = cycles;
	if(acceleration_ <=0) acceleration_ = 1;
	current_frame_key_= 0;
	force_next_update_ = !frames_.empty();
}


template<typename T,  typename T_void_value>
void animated<T,T_void_value>::update_last_draw_time(double acceleration)
{
        if (acceleration > 0 && acceleration_ != acceleration) {
                int tmp = tick_to_time(last_update_tick_);
                acceleration_ = acceleration;
                start_tick_ =  last_update_tick_ +
                        static_cast<int>(( starting_frame_time_ - tmp)/acceleration_);
        }
        if(!started_ && start_tick_ != 0) {
                // animation is paused
                start_tick_ +=current_ticks -last_update_tick_;
        }
	last_update_tick_ = current_ticks;
	if (force_next_update_) {
		force_next_update_ = false;
		return;
	}
	if(does_not_change_)
		return;

	// Always update last_update_tick_, for the animation_time functions to work.
	if(!started_) {
		return;
	}

	if(frames_.empty()) {
		does_not_change_ = true;
		return;
	}
	if(cycles_) {
		while(get_animation_time() > get_end_time()){  // cut extra time
			start_tick_ += std::max<int>(static_cast<int>(get_animation_duration()/acceleration_),1);
			current_frame_key_ = 0;
		}
	}
	if(get_current_frame_end_time() < get_animation_time() &&  // catch up
			get_current_frame_end_time() < get_end_time()) {// don't go after the end
		current_frame_key_++;
	}
}

template<typename T,  typename T_void_value>
bool animated<T,T_void_value>::need_update() const
{
	if(force_next_update_) {
		return true;
	}
	if(does_not_change_) {
		return false;
	}
	if(frames_.empty()) {
		return false;
	}
	if(!started_ && start_tick_ == 0) {
		return false;
	}
	if(current_ticks >
            static_cast<int>(get_current_frame_end_time() /
            acceleration_+start_tick_)){

		return true;
	}
	return false;
}

template<typename T,  typename T_void_value>
bool animated<T,T_void_value>::animation_finished_potential() const
{
	if(frames_.empty())
		return true;
	if(!started_ && start_tick_ == 0)
		return true;
	if(cycles_ )
                return true;
        if(tick_to_time(current_ticks) > get_end_time())
		return true;

	return false;
}
template<typename T,  typename T_void_value>
bool animated<T,T_void_value>::animation_finished() const
{
	if(frames_.empty())
		return true;
	if(!started_ && start_tick_ == 0)
		return true;
        if(cycles_)
                return true;
	if(get_animation_time() >  get_end_time())
		return true;

	return false;
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_animation_time_potential() const
{
	if(!started_  && start_tick_ == 0 ) return starting_frame_time_;

	return  tick_to_time(current_ticks);
}
template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_animation_time() const
{
	if(!started_  && start_tick_ == 0 ) return starting_frame_time_;

	return  tick_to_time(last_update_tick_);
}

template<typename T,  typename T_void_value>
void animated<T,T_void_value>::set_animation_time(int time)
{
	start_tick_ =  last_update_tick_ +
        static_cast<int>(( starting_frame_time_ - time)/acceleration_);

	current_frame_key_= 0;
	force_next_update_ = true;
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_animation_duration() const
{
	return get_end_time() - get_begin_time();
}

template<typename T,  typename T_void_value>
const T& animated<T,T_void_value>::get_current_frame() const
{
	if(frames_.empty() )
		return void_value_;
	return frames_[current_frame_key_].value_;
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_current_frame_begin_time() const
{
	if(frames_.empty() )
		return starting_frame_time_;
	return frames_[current_frame_key_].start_time_;
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_current_frame_end_time() const
{
	if(frames_.empty() )
		return starting_frame_time_;
	return get_current_frame_begin_time() +get_current_frame_duration();
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_current_frame_duration() const
{
	if(frames_.empty() )
		return 0;
	return frames_[current_frame_key_].duration_;
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_current_frame_time() const
{
	if(frames_.empty() )
		return 0;
	//FIXME: get_animation_time() use acceleration but get_current_frame_begin_time() doesn't ?
	return std::max<int>(0,get_animation_time() - get_current_frame_begin_time());
}

template<typename T,  typename T_void_value>
const T& animated<T,T_void_value>::get_first_frame() const
{
	if(frames_.empty() )
		return void_value_;
	return frames_[0].value_;
}

template<typename T,  typename T_void_value>
const T& animated<T,T_void_value>::get_frame(size_t n) const
{
	if(n >= frames_.size())
		return void_value_;
	return frames_[n].value_;
}

template<typename T,  typename T_void_value>
const T& animated<T,T_void_value>::get_last_frame() const
{
	if(frames_.empty() )
		return void_value_;
	return frames_.back().value_;
}

template<typename T, typename T_void_value>
size_t animated<T,T_void_value>::get_frames_count() const
{
	return frames_.size();
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_begin_time() const
{
	return starting_frame_time_;
}

template<typename T,  typename T_void_value>
int animated<T,T_void_value>::time_to_tick(int animation_time) const
{
        if(!started_ && start_tick_ == 0) return 0;
        return start_tick_ + static_cast<int>((animation_time-starting_frame_time_)/acceleration_);
}
template<typename T,  typename T_void_value>
int animated<T,T_void_value>::tick_to_time(int animation_tick) const
{
        if(!started_ && start_tick_ == 0) return 0;
	return static_cast<int>(
        (static_cast<double>(animation_tick - start_tick_) *
        acceleration_) + starting_frame_time_);
}
template<typename T,  typename T_void_value>
int animated<T,T_void_value>::get_end_time() const
{
	if(frames_.empty())
		return starting_frame_time_;
	return frames_.back().start_time_ + frames_.back().duration_;
}
template<typename T,  typename T_void_value>
void animated<T,T_void_value>::remove_frames_until(int new_starting_time)
{
        while (starting_frame_time_  < new_starting_time && !frames_.empty() )  {
                starting_frame_time_ += frames_[0].duration_;
                frames_.erase(frames_.begin());
        }

}
template<typename T,  typename T_void_value>
void animated<T,T_void_value>::set_end_time(int new_ending_time)
{
int last_start_time = starting_frame_time_;
typename std::vector<frame>::iterator current_frame = frames_.begin();
        while (last_start_time  < new_ending_time && current_frame != frames_.end()) {
                last_start_time += current_frame->duration_;
                ++current_frame;
        }
        // at this point last_start_time is set to the beginning of the first frame past the end
        // or set to frames_.end()
        frames_.erase(current_frame,frames_.end());
        frames_.back().duration_ += new_ending_time - last_start_time;

}


template<typename T,  typename T_void_value>
void animated<T,T_void_value>::set_begin_time(int new_begin_time)
{
        const int variation = new_begin_time - starting_frame_time_;
        starting_frame_time_ += variation;
        for(typename std::vector<frame>::iterator itor = frames_.begin(); itor != frames_.end() ; ++itor) {
                itor->start_time_ += variation;
        }
}