//Allocate and free dynamic memory, group data structures and using arrays
#define _CRT_SECURE_NO_DEPRECATE
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
#define PI 3.14159265359

typedef struct {
	double latitudes;
	double longitudes;
} geoCoord;

double radians(double);
double distanceKm(geoCoord *, double *, int);

int main(void)
{
	int arraySize = 0;
	double totalDistance = 0;
	double distance = 0;
	geoCoord *coord;

	printf("Please enter the number of waypoints you  like to enter: ");

	while (1)
	{
		if (scanf("%d", &arraySize) == 1)

			break;
		else
			while (getchar() != '\n')
				continue;

		printf("Try again (expected number >= 0): ");
	}
	getchar();

	//using malloc(memory allocation) to specify the number of bytes in memory
	coord = (geoCoord *)malloc(arraySize * sizeof(geoCoord));

	//users shall enter the place of depature and the destinations
	printf("Enter number of waypoints as \"<latitude> <longitude>\": ");
	for (int i = 0; i < arraySize; i++)
	{
		while (1)
		{
			printf("\n Waypoint %d: ", i + 1);

			//sscanf is used to read formatted input from a string/buffer

			if (scanf("%lf %lf", &coord[i].latitudes, &coord[i].longitudes) != 2)
			{
				printf("Invalid input (expected \"<latitude> <longitude>\"):  ");
			}
			else
			{
				break;
			}
			while (getchar() != '\n')
				continue;
		}

	}
	getchar();

	distance = distanceKm(coord, &totalDistance, arraySize);
	printf("\nBy taking this route you will travel %.1lf Km.", distance);

	//function loop to go through and add up all the way points (can use previous lab module)

	//Clear memory
	free(coord);
	getchar();
	return 0;
}

double distanceKm(geoCoord *coord, double *totalDistance, int arraySize)
{
	double deltaX, deltaY, lDistKm;
	double latA, lonA, latB, lonB;

	//for loop to compare previous coordinate to next coordinate
	//count initially set to 1 so that element 0 is compared to element 1 etc etc.
	//with each loop j increases until it is 7 but comp is always 1 ahead.
	for (int j = 0; j < arraySize - 1; j++)
	{
		latA = coord[j].latitudes;
		lonA = coord[j].longitudes;
		lonB = coord[j + 1].longitudes;
		latB = coord[j + 1].latitudes;

		//used local distance KM formula
		deltaY = 111.3 * fabs((radians(latA - latB)));
		deltaX = 111.3 * cos((radians(latA + latB)) / 2) * fabs(radians(lonA - lonB));
		lDistKm = sqrt(deltaX * deltaX + deltaY * deltaY) * (180 / PI);

		//Sets value in pointer
		*totalDistance += lDistKm;

		/*Sum check - uncomment to use*/
//		printf("|latA %lf lonA %lf| + |latB %lf lonB %lf| = %.2lf\n", latA, lonA, latB, lonB, *totalDistance);
	}
	return *totalDistance;
}
double radians(double rad)
{
	return(rad * PI / 180);
}