#include <sycl/ext/intel/fpga_extensions.hpp>
#include <chrono>
#include "kernel.hpp"


template<typename T>
SYCL_EXTERNAL bool checkOptimality(device_ptr<T> C, int size) {
    bool isOptimal = false;
	int positveValueCount = 0;
    //check if the coefficients of the objective function are negative
	for(int i=0; i<size;i++){
	    float value = C[i];
	    if(value >= 0){
	        positveValueCount++;
	    }
	}
	//if all the constraints are positive now,the table is optimal
	if(positveValueCount == size){
	    isOptimal = true;
	}
    return isOptimal;
}


template<typename T>
SYCL_EXTERNAL int findPivotColumn(device_ptr<T> C, int size) {
	int location = 0;
	float minimum = C[0];
	for(int i=1; i<size; ++i) {
		if(C[i]<minimum) {
			minimum = C[i];
			location = i;
		}
	}
	return location;
}


//find the row with the pivot value.The least value item's row in the B array
template<typename T>
SYCL_EXTERNAL int findPivotRow(device_ptr<T> A, device_ptr<T> B, device_ptr<T> C, int pivotColumn, int rows, int cols, bool *isUnbounded) {
	int negativeValueCount = 0;
	for (int i = 0; i < rows; i++) {
		// 2d to 1d array index mapping
		int pivotColumnIndex = (i*cols)+pivotColumn;
		if (A[pivotColumnIndex] <= 0) {
			negativeValueCount += 1;
		}
	}
	int location = 0;
	//checking the unbound condition if all the values are negative ones
	if (negativeValueCount == rows) {
		*isUnbounded = true;
	} else {
		float minimum = 99999999.0;

		for (int i = 0; i < rows; ++i) {
			// 2d to 1d array index mapping
			int pivotColumnIndex = (i*cols)+pivotColumn;
			float tmpACols = A[pivotColumnIndex];
			if (tmpACols > 0) {
				float result = B[i] / tmpACols;
				if (result > 0 && result < minimum) {
					minimum = result;
					location = i;
				}
			}
		}
	}
	return location;
}

template<typename T>
SYCL_EXTERNAL void doPivotting(device_ptr<T> A, device_ptr<T> B, device_ptr<T> C, int pivotRow, int pivotColumn, int rows, int cols) {
	int columnIndex = (pivotRow*cols)+pivotColumn;
	float pivetValue = A[columnIndex];

	float pivotRowVals[6]; //the column with the pivot
	float pivotColVals[3]; //the row with the pivot
	float rowNew[6]; //the row after processing the pivot value

	float maximum = 0;
	maximum = maximum-(C[pivotColumn]*(B[pivotRow]/pivetValue)); //set the maximum step by step


	//get the row that has the pivot value
	for (int i = 0; i < cols; ++i) {
		int pivotRowIndex = (pivotRow*cols)+i;
		pivotRowVals[i] = A[pivotRowIndex];
	}
	//get the column that has the pivot value
	for (int j = 0; j < rows; ++j) {
		int pivotColIndex = (j*cols)+pivotColumn;
		pivotColVals[j] = A[pivotColIndex];
	}

	//set the row values that has the pivot value divided by the pivot value and put into new row
	for (int k = 0; k < cols; ++k) {
		rowNew[k] = pivotRowVals[k]/pivetValue;
	}

	B[pivotRow] = B[pivotRow]/pivetValue;

	//process the other coefficients in the A array by subtracting
	for (int m=0; m < rows; ++m) {
		//ignore the pivot row as we already calculated that
		if (m != pivotRow) {
			for (int p = 0; p<cols; ++p) {
				float multiplyValue = pivotColVals[m];
				int indexA_M_P = (m*cols)+p;
				A[indexA_M_P] = A[indexA_M_P] - (multiplyValue * rowNew[p]);
				//C[p] = C[p] - (multiplyValue*C[pivotRow]);
				//B[i] = B[i] - (multiplyValue*B[pivotRow]);
			}

		}
	}

	//process the values of the B array
	for (int i = 0; i<rows; ++i) {  // rows = B.size()
		if (i != pivotRow) {
			float multiplyValue = pivotColVals[i];
			B[i] = B[i]-(multiplyValue*B[pivotRow]);

		}
	}
	//the least coefficient of the constraints of the objective function
	float multiplyValue = C[pivotColumn];
	//process the C array
	for (int i = 0; i < C.size(); i++) {
		C[i] = C[i]-(multiplyValue * rowNew[i]);

	}

	//replacing the pivot row in the new calculated A array
	for (int i = 0; i<cols; ++i) {
		int indexA_pivotRow_i = (pivotRow*cols)+i;
		A[indexA_pivotRow_i] = rowNew[i];
	}
}

// Forward declare the kernel names in the global scope. This FPGA best practice
// reduces compiler name mangling in the optimization reports.
class SimplexCalc;

double RunKernel(queue &q, std::vector<T> &inAHost, std::vector<T> &inBHost,
		std::vector<T> &inCHost, std::vector<int>& resultFlags) {

	int rowSizeA = inBHost.size();
	int colSizeA = inCHost.size();

	T *inADevice = malloc_device<T> (inAHost.size(), q);
	T *inBDevice = malloc_device<T> (inBHost.size(), q);
	T *inCDevice = malloc_device<T> (inCHost.size(), q);
	int *inResultFlagsDevice = malloc_device<int> (resultFlags.size(), q);

	if (inADevice == nullptr) {
		std::cerr << "ERROR: failed to allocate space for 'inADevice'\n";
		std::terminate();
	}
	if (inBDevice == nullptr) {
		std::cerr << "ERROR: failed to allocate space for 'inBDevice'\n";
		std::terminate();
	}
	if (inCDevice == nullptr) {
		std::cerr << "ERROR: failed to allocate space for 'inCDevice'\n";
		std::terminate();
	}

	auto start = std::chrono::high_resolution_clock::now();

	q.memcpy(inADevice, inAHost.data(), inAHost.size()*sizeof(T)).wait();
	q.memcpy(inBDevice, inBHost.data(), inBHost.size() * sizeof(T)).wait();
	q.memcpy(inCDevice, inCHost.data(), inCHost.size() * sizeof(T)).wait();
	q.memcpy(inResultFlagsDevice, resultFlags.data(), resultFlags.size()*sizeof(int)).wait();

	q.submit([&](handler &h) {
		h.single_task < SimplexCalc > ([=]()[[intel::kernel_args_restrict]] {
			device_ptr<T> inA(inADevice);
			device_ptr<T> inB(inBDevice);
			device_ptr<T> inC(inCDevice);
			device_ptr<int> inResultFlags(inResultFlagsDevice);

			bool tempIsOptimizal = checkOptimality(inC, colSizeA);
			if (tempIsOptimizal) {
				inResultFlags[0] = 1;
				return;
			} else {
				inResultFlags[0] = 0;
			}

			int pivotColumn = findPivotColumn(inC, colSizeA);
			inResultFlags[1] = pivotColumn;

			inA[0] = 43.0; //test only
			bool isUnbounded = true;
			int pivotRow = findPivotRow(inA, inB, inC, pivotColumn, rowSizeA, colSizeA, &isUnbounded);
			inResultFlags[2] = pivotRow;
		});
	}).wait();

	q.memcpy(inAHost.data(), inADevice, inAHost.size()*sizeof(T));
	q.memcpy(inBHost.data(), inBDevice, inBHost.size()*sizeof(T));
	q.memcpy(inCHost.data(), inCDevice, inCHost.size()*sizeof(T));
	q.memcpy(resultFlags.data(), inResultFlagsDevice, resultFlags.size()*sizeof(int));

	auto end = std::chrono::high_resolution_clock::now();
	std::chrono::duration<double, std::milli> diff = end - start;

	sycl::free(inADevice, q);
	sycl::free(inBDevice, q);
	sycl::free(inCDevice, q);
	sycl::free(inResultFlagsDevice, q);

	return diff.count();
}