#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void ResolveV(float Angle, float Velocity, float *XVelocity, float *YVelocity);
void TimeOfFlight(float YVelocity, float *TOF);

int main(int argc, char *argv[])
{
    float Angle, Velocity, XVelocity, YVelocity, TOF, Time[11], XDistance[11], YDistance[11];
    char AngleT[100], VelocityT[100], *next, save, FileName[50];
    int i;

    if (argc == 1)
    {
        printf("Please enter the angle in degrees.\n");
        scanf ("%s", &AngleT);
        printf("Please enter the velocity in m/s.\n");
        scanf ("%s", &VelocityT);
        printf("\n");
    }
    else if (argc != 3)
    {
        printf("You have entered %d variables, please enter only an angle in degrees and a velocity.\n", argc - 1);
        return(0);
    }
    else
    {
        strncpy(AngleT, argv[1], 100);
        strncpy(VelocityT, argv[2], 100);
    }

    Angle = strtof (AngleT, &next);

    if ((next == AngleT) || (*next != '\0') || (Angle <= 0) || (Angle > 90))
    {
        printf("%s is not valid, only positive numbers up to 90 are valid for the angle.\n", AngleT);
        return 0;
    }
    else
    {
        Velocity = strtof (VelocityT, &next);

        if ((next == VelocityT) || (*next != '\0') || (Velocity <= 0))
        {
            printf("%s is not valid, only positive numbers are valid for the velocity.\n", VelocityT);
            return 0;
        }
        else
        {
            printf("Angle = %f degrees\n", Angle);
            Angle = Angle * (M_PI / 180);
            printf("Velocity = %f m/s\n", Velocity);
        }
    }

    ResolveV(Angle, Velocity, &XVelocity, &YVelocity);

    TimeOfFlight(YVelocity, &TOF);

    printf("\nTime(s)        |");
    for(i=0; i<11; i++)
    {
        Time[i] = TOF * (float)i / 10;
        XDistance[i] = XVelocity * Time[i];
        YDistance[i] = YVelocity * Time[i] + (-4.905 * Time[i] * Time[i]);
        printf("%7.2f|", Time[i]);
    }
    printf("\nX Distance(m/s)|");
    for(i=0; i<11; i++)
    {
        printf("%7.2f|", XDistance[i]);
    }
    printf("\nY Distance(m/s)|");
    for(i=0; i<11; i++)
    {
        printf("%7.2f|", YDistance[i]);
    }

    printf("\n\nWould you like to save this data to a file? \nEnter y if yes, n if no.\n");

    do
    {
        save = getch();

        if (save == 'n')
        {
            printf("\n\nData will not be saved.");
        }
        else if (save == 'y')
        {
            printf("\n\nEnter the name of the file.\n");
            scanf("%s", FileName);

            FILE *fptr;
            if((fptr = fopen(FileName, "w"))== NULL)
            {
                printf("\nError opening file");
                return(0);
            }

            fprintf(fptr, "Angle: %f degrees\nVelocity: %f m/s\n\nHorizontal velocity: %f m/s\nVertical velocity: %f m/s", Angle * 180 / M_PI, Velocity, XVelocity, YVelocity);
            fprintf(fptr, "\n\nTime(s)        |");
            for(i=0; i<11; i++)
            {
                Time[i] = TOF * (float)i / 10;
                XDistance[i] = XVelocity * Time[i];
                YDistance[i] = YVelocity * Time[i] + (-4.905 * Time[i] * Time[i]);
                fprintf(fptr, "%7.2f|", Time[i]);
            }
            fprintf(fptr, "\nX Distance(m/s)|");
            for(i=0; i<11; i++)
            {
                fprintf(fptr, "%7.2f|", XDistance[i]);
            }
            fprintf(fptr, "\nY Distance(m/s)|");
            for(i=0; i<11; i++)
            {
                fprintf(fptr, "%7.2f|", YDistance[i]);
            }
            fclose(fptr);

            printf("\nFile saved.");
        }
        else
        {
            printf("\nInvalid input, press 'y' or 'n'.");
        }
    }
    while ((save !='y')&(save !='n'));

    return(0);
}

void ResolveV(float Angle, float Velocity, float *XVelocity, float *YVelocity)
{
    *XVelocity = Velocity * (cos(Angle));
    *YVelocity = Velocity * (sin(Angle));

    printf("\nThe horizontal velocity is %.2f m/s\n", *XVelocity);
    printf("The vertical velocity is %.2f m/s\n", *YVelocity);
}

void TimeOfFlight(float YVelocity, float *TOF)
{
    *TOF = -2 * (YVelocity / -9.81);
}