#include "Resampler.h"
#include "ffcpp.h"
#include <stdexcept>
#include <memory>
#include <iostream>

extern "C" {
	#include <libavutil/opt.h>
}

namespace ffcpp {

	Resampler::Resampler(int inChannelLayout, int inSampleRate, AVSampleFormat inSampleFormat, int outChannelLayout,
	                     int outSampleRate, AVSampleFormat outSampleFormat) {
		_dstChannelLayout = outChannelLayout;
		_dstSampleFormat = outSampleFormat;
		_dstSampleRate = outSampleRate;

		_swrContext = swr_alloc();
		if(!_swrContext) {
			throw new std::runtime_error("cannot create resampler");
		}

		av_opt_set_int(_swrContext, "in_channel_layout",    inChannelLayout, 0);
		av_opt_set_int(_swrContext, "in_sample_rate",       inSampleRate, 0);
		av_opt_set_sample_fmt(_swrContext, "in_sample_fmt", inSampleFormat, 0);

		av_opt_set_int(_swrContext, "out_channel_layout",    outChannelLayout, 0);
		av_opt_set_int(_swrContext, "out_sample_rate",       outSampleRate, 0);
		av_opt_set_sample_fmt(_swrContext, "out_sample_fmt", outSampleFormat, 0);

		int res = swr_init(_swrContext);
		throwIfError(res, "cannot init resampler");
	}

	Resampler::Resampler(AVCodecContext *decoderCtx, AVCodecContext *encoderCtx)
			: Resampler((int)decoderCtx->channel_layout, decoderCtx->sample_rate, decoderCtx->sample_fmt,
			            (int)encoderCtx->channel_layout, encoderCtx->sample_rate, encoderCtx->sample_fmt) {
	}

	Resampler::~Resampler() {
		if(_swrContext) {
			swr_free(&_swrContext);
		}
	}

	Frame Resampler::resample(Frame& inFrame) {
		int channelsCount = av_get_channel_layout_nb_channels(_dstChannelLayout);
		AVFrame* fin = inFrame;
		int outSamples = swr_get_out_samples(_swrContext, fin->nb_samples);

		Frame outFrame(outSamples, channelsCount, _dstSampleFormat, _dstSampleRate);
		int res = swr_convert_frame(_swrContext, outFrame, inFrame);
		throwIfError(res, "cannot convert audio frame");

		return outFrame;
	}

	bool Resampler::needResampling(AVCodecContext *decoderCtx, AVCodecContext *encoderCtx) {
		return (decoderCtx->channels != encoderCtx->channels ||
				decoderCtx->channel_layout != encoderCtx->channel_layout ||
				decoderCtx->sample_fmt != encoderCtx->sample_fmt ||
				decoderCtx->sample_rate != encoderCtx->sample_rate);
	}

}