/*******************************************************************************
* Copyright 2015-2016 Juan Francisco Crespo Galán
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/

#pragma once

/**
* @file ImpulseResponse.h
* @ingroup fx
* The ImpulseResponse class.
*/

#include "util/StreamBuffer.h"
#include "util/FFTPlan.h"
#include "IReader.h"

#include <memory>
#include <vector>

AUD_NAMESPACE_BEGIN

/**
* This class represents an impulse response that can be used in convolution.
* When this class is instanced, the impulse response is divided in channels and those channels are divided in parts of N/2 samples (N being the size of the FFT plan used).
* The main objetive of this class is to allow the reutilization of an impulse response in various sounds without having to process it more than one time.
* \warning The size of the FFTPlan used to process the impulse response must be the same as the one used in the convolver classes.
*/
class AUD_API ImpulseResponse
{
private:
	/**
	* A tri-dimensional array (channels, parts, values) The impulse response is divided in channels and those channels are divided
	* in parts of N/2 samples. Those parts are transformed to the frequency domain transform which generates uni-dimensional 
	* arrays of fftwtf_complex data (complex numbers).
	*/
	std::vector<std::shared_ptr<std::vector<std::shared_ptr<std::vector<std::complex<sample_t>>>>>> m_processedIR;

	/**
	* The specification of the samples.
	*/
	Specs m_specs;

	/**
	* The length of the impulse response.
	*/
	int m_length;

	// delete copy constructor and operator=
	ImpulseResponse(const ImpulseResponse&) = delete;
	ImpulseResponse& operator=(const ImpulseResponse&) = delete;

public:
	/**
	* Creates a new ImpulseResponse object.
	* The impulse response will be split and transformed to the frequency domain.
	* \param impulseResponse The impulse response sound.
	* \param plan A shared pointer to a FFT plan used to transform the impulse response.
	*/
	ImpulseResponse(std::shared_ptr<StreamBuffer> impulseResponse, std::shared_ptr<FFTPlan> plan);

	/**
	* Creates a new ImpulseResponse object. This overload instances its own FFTPlan with default size.
	* The impulse response will be split and transformed to the frequency domain.
	* \param impulseResponse The impulse response sound.
	*/
	ImpulseResponse(std::shared_ptr<StreamBuffer> impulseResponse);

	/**
	* Returns the specification of the impulse response.
	* \return The specification of the impulse response.
	*/
	Specs getSpecs();

	/**
	* Retrieves the length of the impulse response.
	* \return The length of the impulse response.
	*/
	int getLength();

	/**
	* Retrieves one channel of the impulse response.
	* \param n The desired channel number (from 0 to channels-1).
	* \return The desired channel of the impulse response.
	*/
	std::shared_ptr<std::vector<std::shared_ptr<std::vector<std::complex<sample_t>>>>> getChannel(int n);

private:
	/**
	* Processes the impulse response sound for its use in the convovler classes.
	* \param A shared pointer to a reader of the desired sound.
	* \param plan A shared pointer to a FFT plan used to transform the impulse response.
	*/
	void processImpulseResponse(std::shared_ptr<IReader> reader, std::shared_ptr<FFTPlan> plan);
};

AUD_NAMESPACE_END