#include <assert.h>
#include <cmath>
#include <string>
#include <iostream>
#include <cstdlib>

#include "../libsamplerate/samplerate.h"
#include "Resampler.h"

using namespace std;

Resampler::Resampler(int input_len, double resampling_factor)
    : input_len_(input_len),
    resample_factor_(resampling_factor) {
    assert(resample_factor_ > 0);

    int error;
    static const int channels = 1;
    libsamplerate_handle_ = src_new(SRC_SINC_BEST_QUALITY, channels, &error);
    if (!libsamplerate_handle_) {
        cerr << "Error during libsamplerate initialization: "
            << string(src_strerror(error));
        exit(1);
    }

    // Next power of 2 of (input_len_ * resample_factor_)
    //int output_len_bits = static_cast<int>(floor(
    //    log(input_len_ * resample_factor_) / log(2)));
    //output_len_ = 1 << (output_len_bits + 1);
    output_len_ = input_len_ * resample_factor_ + 1;

    assert(libsamplerate_handle_ && "Creating libsamplerate handler failed");
}

Resampler::~Resampler() {
    assert(libsamplerate_handle_);
    libsamplerate_handle_ = src_delete(libsamplerate_handle_);
}

void Resampler::Resample(const vector<float>& input, vector<float>* output) {
    assert(output);
    if (resample_factor_ != 1.0) {
        output->clear();
        output->resize(output_len_, 0.0f);

        SRC_DATA libsamplerate_data;
        libsamplerate_data.data_in = const_cast<float*>(&input[0]);
        libsamplerate_data.input_frames = input.size();
        libsamplerate_data.data_out = &((*output)[0]);
        libsamplerate_data.output_frames = output->size();
        libsamplerate_data.src_ratio = resample_factor_;
        libsamplerate_data.end_of_input = 1;

        int error = src_reset(libsamplerate_handle_);
        if (error != 0) {
            cerr << "Error during libsamplerate reset: "
                << string(src_strerror(error));
            exit(1);
        }
        error = src_set_ratio(libsamplerate_handle_, resample_factor_);
        if (error != 0) {
            cerr << "Error setting resampling ratio: " << string(src_strerror(error));
            exit(1);
        }
        error = src_process(libsamplerate_handle_, &libsamplerate_data);
        if (error != 0) {
            cerr << "Error during resampling: " << string(src_strerror(error));
            exit(1);
        }
    }
    else {
        // Copy signal if resample factor is 1.0
        output->assign(input.begin(), input.end());
    }
}

int Resampler::GetOutputLength() {
    return output_len_;
}