CS Hw1 v2 (Final?)

/*
 * production.c
 *
 *  Created on: Jan 15, 2018
 *      Author: Tyler Bouwens / trbouwens
 *      @author Tyler Bouwens / trbouwens
 */

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "production.h"
#include <math.h>

/** Your production code goes in this function.
 *
 * @param argc Number of words on the command line
 * @param argv Array of pointers to character strings representing the words on the command line.
 * @return true if Program was able to print a calendar.
 *         false if User entered bad input.
 */

bool production(int argc, char* argv[])
{
    bool results = false;
    bool done = false;
    //get the year, Usage as needed.
    int year = -1;
    puts("\nCALENDAR");
    if(argc<2)
    {
        puts("Enter a year");
        scanf("%d",&year);
        if(year<1752)
        {
            printf("Usage: Year should be greater than 1751, received %d.\n",year);
            done = true;
        }
    }
    else
    {
        char* ptr=0;
        long year_l = strtol(argv[1],&ptr,10);
        year = (int)year_l;
        if(year<1752)
        {
            printf("Usage: Year should be greater than 1751, received %d.\n",year);
            done = true;
        }
    }
    if(!done)
    {
        puts("January");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(0, year);
        puts("February");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(1, year);
        puts("March");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(2, year);
        puts("April");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(3, year);
        puts("May");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(4, year);
        puts("June");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(5, year);
        puts("July");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(6, year);
        puts("August");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(7, year);
        puts("September");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(8, year);
        puts("October");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(9, year);
        puts("November");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(10, year);
        puts("December");
        puts("Sun  Mon  Tue  Wed  Thu  Fri  Sat");
        printCalendarDates(11, year);


    }
    if(!done)
    {
        results=true;
    }
    return results;
}

/**
 *
 */
void printCalendarDates(int month, int year) {
    int i = 0;
    int x = calculate_day_of_week(1, month, year);

    // Adds 5 lines of whitespace on every day prior to
    // the correct starting date of the 1st
    while(i < calculate_day_of_week(1, month, year)) {
        printf("     ");
        i++;
    }

    int j = 1;
    // This loops prints the calendar
    while (j <= calculate_days_in_month(year, month)) {
        // x is the counter responsible for keeping track
        // of what day of the week it is
        x++;
        // Checks if its the last day of the year, to add a space
        // for the next month name (formatting)
        if (j == calculate_days_in_month(year, month)){
            // Last date will always be two digits
            printf(" %d\n",j);
        }
        // If the date is not saturday, allow for the next date to
        // be printed right next to it
        else if (!(x % 7 == 0)) {
            // Gives two spaces before a number for single digit
            if (j < 10) {
                printf("  %d  ",j);
            }
            // Gives one space before a number for double digit
            else {
                printf(" %d  ",j);
            }
        }
        // If the date is on a satuday, this prints a newline character so that
        // the next dates are on the next line
        else {
            // Gives two spaces before a number for single digit w/ newline
            if (j < 10) {
                printf("  %d\n",j);
            }
            // Gives one space before a number for double digit w/ newline
            else {
                printf(" %d\n",j);
            }
        }
        j++;
    }
    printf("\n");


}
/** Calculates how many days are in a given month for a given year.
 * @param year The year we are checking.
 * @param month The month we are checking. Range 0 through 11, where January = 0.
 * @return Day of the week. Range 0 through 6, where Sunday = 0.
 *         -1 if invalid input (e.g., year < 1752, month out of range).
 */
int calculate_days_in_month(int year, int month)
{
    int answer = -1;
    bool done = false;
    if (year < 1752) {
        answer = -1;
    }
    else if (month == 0 || month == 2 ||
             month == 4 || month == 6 ||
             month == 7 || month == 9 ||
             month ==11) {
        answer = 31;
    }
    else if (month == 3 || month == 5 ||
             month == 8 || month == 10) {
        answer = 30;
    }
    else if (month == 1 && is_leap_year(year) == 0) {
        answer = 28;
    }
    else if (month == 1 && is_leap_year(year) == 1) {
        answer = 29;
    }
    else {
        answer = -1;
    }


    return(answer);
}
/** Test if a given year is a leap year or not.
 * @param year The year we are testing
 * @return 1 if it is a valid leap year.
 *         0 if a valid year, but not a leap year.
 *        -1 if not a valid year (i.e. before the calendar rule changed in 1752).
 */

int is_leap_year(int year)
{
    bool done = false;
    int ans = -2; //Start with an invalid answer

    if(year < 1752) {
        ans = -1;
        done = true;
    }
    else if(year % 100 == 0 && year % 400 == 0) {
        ans = 1;
        done = true;
    }
    else if(year % 100 == 0 && !(year % 400 == 0)) {
        ans = 0;
        done = true;
    }
    else if(year % 4 == 0) {
        ans = 1;
        done = true;
    }
    else {
        ans = 0;
        done = true;
    }

    return ans;

}
/** Determines what day of the week a particular date falls on.
 * @param day Day of the month, counting from 1.
 * @param month Range 0 through 11, where January = 0.
 * @param year The year.
 * @return -1 for invalid input (e.g., year < 1752, month out of range,
 *            day < 1 or > appropriate for that month & year
 *         0 through 6, where Sunday = 0.
 *
 */
int calculate_day_of_week(int day, //first day of month is 1
        int month, //uses 0 for January
        int year)
{//invalid input gets a -1 answer
    int Y = -1;
    int y = -1;
    int c = -1;
    int d = day;
    int m = 0;
    int ans = -1;
    int cor = 0;
    bool done = false;

    // Assigning value to Y
    if (month == 0 || month == 1) {
        Y = year - 1;
    }
    else {
        Y = year;
    }

    y = Y % 100;
    // printf("y = %d\n", y);

    // Assign Value to c
    c = Y;
    while (c >= 100) {
        c /= 10;
    }
    //printf("c = %d\n", c);

    // Assigns value to m
    if (month == 0) {
        m = 11;
    }
    else if (month == 1) {
        m = 12;
    }
    else {
        m = month - 1;
    }

    // runs the final equation
    int a1 = floor((2.6 * m) - 0.2);
    int b1 = floor(y/4);
    int c1 = floor(c/4);
    //printf("%d\n",y);
    int z = (d + (a1) + y + (b1) + (c1) - (2 * c));
    ans = (z % 7);


    if (ans < 0) {
        ans += 7;
    }

    return ans;
}