#ifndef FIRREAL_H
#define FIRREAL_H

#include <vector>
#include <cmath>
#include <string>
#include "../../../Assertions.h"

namespace FIR {

	namespace Real {

		using Kernel = std::vector<float>;
		using DataVec = std::vector<float>;

		class Filter {

			Kernel kernel;
			DataVec data;

		public:

			/** ctor */
			Filter(const Kernel& kernel) : kernel(kernel) {
				;
			}

			/** empty ctor */
			Filter() : kernel() {
				;
			}

			/** set the filter-kernel */
			void setKernel(const Kernel& kernel) {
				this->kernel = kernel;
			}

			/** filter the given incoming real data */
			DataVec append(const DataVec& newData) {
				// append to local buffer (as we need some history)
				data.insert(data.end(), newData.begin(), newData.end());
				return processLocalBuffer();
			}

			/** filter the given incoming real value */
			float append(const float val) {
				data.push_back(val);
				auto tmp = processLocalBuffer();
				if (tmp.size() == 0) {return NAN;}
				if (tmp.size() == 1) {return tmp[0];}
				throw Exception("FIR::Real::Filter detected invalid result");
			}

		private:

			DataVec processLocalBuffer() {

				// sanity check
				Assert::isNot0(kernel.size(), "FIRComplex:: kernel not yet configured!");

				// number of processable elements (due to filter size)
				const int processable = data.size() - kernel.size() + 1 - kernel.size()/2;

				// nothing to-do?
				if (processable <= 0) {return DataVec();}

				// result-vector
				DataVec res;
				res.resize(processable);

				// fire
				convolve(data.data(), res.data(), processable);

				// drop processed elements from the local buffer
				data.erase(data.begin(), data.begin() + processable);

				// done
				return res;

			}

			template <typename T> void convolve(const float* src, T* dst, const size_t cnt) {

				const size_t ks = kernel.size();

				for (size_t i = 0; i < cnt; ++i) {
					T t = T();
					for (size_t j = 0; j < ks; ++j) {
						t += src[j+i] * kernel[j];
					}
					if (t != t) {throw std::runtime_error("detected NaN");}
					dst[i] = t;
				}

			}


		};

	}

}

#endif // FIRREAL_H