#include <psemek/audio/effect/volume_base.hpp>
#include <psemek/audio/constants.hpp>
#include <psemek/audio/smooth.hpp>

#include <cmath>

namespace psemek::audio
{

	volume_base::volume_base(float gain_left, float gain_right, float smoothness)
		: gain_{gain_left, gain_right}
		, smoothness_multiplier_{smoothness_to_multiplier(smoothness)}
		, real_gain_{gain_left, gain_right}
		, last_sample_src_{0.f, 0.f}
		, last_sample_tgt_{0.f, 0.f}
	{}

	float volume_base::smoothness() const
	{
		return multiplier_to_smoothness(smoothness_multiplier_.load());
	}

	float volume_base::smoothness(float value)
	{
		auto old = smoothness_multiplier_.exchange(smoothness_to_multiplier(value));
		return multiplier_to_smoothness(old);
	}

	void volume_base::apply(float * data, std::size_t sample_count)
	{
		float gain[2] = {gain_[0].load(), gain_[1].load()};
		float smoothness_multiplier = smoothness_multiplier_.load();

		auto apply_impl = [this](float & target, int i)
		{
			auto old = target;
			target = last_sample_tgt_[i] + (old - last_sample_src_[i]) * real_gain_[i];
			last_sample_src_[i] = old;
			last_sample_tgt_[i] = target;
		};

		auto end = data + sample_count;
		for (auto p = data; p < end;)
		{
			apply_impl(*p++, 0);
			apply_impl(*p++, 1);

			smooth_update(real_gain_[0], gain[0], smoothness_multiplier);
			smooth_update(real_gain_[1], gain[1], smoothness_multiplier);
		}
	}

}