A date Validator in C

validate.c

//Header files:

#ifndef ALARM_H
#define ALARM_H

/* 0 is AM, 1 is PM */
typedef struct {
        int year;
        int month;
        int day;
        int hour;
        int minute;
        int second;
        int am_or_pm;
        struct tm time_s;
	time_t unix_tm;
	int set;
	int finished;
} alarm_t;

#endif


#ifndef Calarm_t_H
#define Calarm_t_H

#include <time.h>
#include "alarm.h"

int validate(char c, alarm_t* alarm_ptr, int val); 
int validate_year(alarm_t* alarm_ptr, int val);
int validate_month(alarm_t* alarm_ptr, int val);
int validate_day(alarm_t* alarm_ptr, int val);
int validate_hour(alarm_t* alarm_ptr, int val);
int validate_minute(alarm_t* alarm_ptr, int val);
int validate_second(alarm_t* alarm_ptr, int val);

#endif

//C Code:

#include <stdio.h>
#include "curtime.h"
#include "validate.h"
#include "calarm.h"

int validate(char c, alarm_t* alarm_ptr, int val) {
	struct tm time_s;
	/* optimize */
	switch(c) {
		case 'Y':
			return (validate_year(alarm_ptr, val) == 0 || validate_year(alarm_ptr, val) == 1);
			break;
		case 'M':
			if (validate_year(alarm_ptr, alarm_ptr->year) == 1) {
				return (validate_month(alarm_ptr, val) != -1);
			} else if (validate_year(alarm_ptr, alarm_ptr->year) == 0) {
				return (val <= 11 && val >= 0);
			}
			break;
		case 'D':
			if (validate_year(alarm_ptr, alarm_ptr->year) == 1) {
				if (validate_month(alarm_ptr, alarm_ptr->month) == 1) {
					return (validate_day(alarm_ptr, val) != -1);	
				} else if (validate_month(alarm_ptr, alarm_ptr->month) == 0) {
					/* Possible bug */
					return (val <= 31 && val >= 1);
	                        }
                        } else if (validate_year(alarm_ptr, alarm_ptr->year) == 0) {
				return (val <= 31 && val >= 1);
                        }
			break;
		case 'h':
			if (validate_year(alarm_ptr, alarm_ptr->year) == 1) {
				 if (validate_month(alarm_ptr, alarm_ptr->month) == 1) {
					if (validate_day(alarm_ptr, alarm_ptr->day) == 1) {
						return (validate_hour(alarm_ptr, val) != -1);
					} else if (validate_day(alarm_ptr, alarm_ptr->day) == 0) {
						return (val <= 23 && val >= 0);
                                        }
                                } else if (validate_month(alarm_ptr, alarm_ptr->month) == 0) {
                                        return (val <= 23 && val >= 0);
                                }
                        } else if (validate_year(alarm_ptr, alarm_ptr->year) == 0) {
                                return (val <= 23 && val >= 0);
                        }
			break;
		case 'm':
			if (validate_year(alarm_ptr, alarm_ptr->year) == 1) {
                                if (validate_month(alarm_ptr, alarm_ptr->month) == 1) {
                                        if (validate_day(alarm_ptr, alarm_ptr->day) == 1) {
                                        	if (validate_hour(alarm_ptr, alarm_ptr->hour) == 1) {
							return (validate_minute(alarm_ptr, val) != -1);
						} else if (validate_hour(alarm_ptr, alarm_ptr->hour) == 0) {
							return (val <= 59 && val >= 0);
                                                }
                                        } else if (validate_day(alarm_ptr, alarm_ptr->day) == 0) {
                                                return (val <= 59 && val >= 0);
                                        }
                                } else if (validate_month(alarm_ptr, alarm_ptr->month) == 0) {
                                        return (val <= 59 && val >= 0);
                                }
                        } else if (validate_year(alarm_ptr, alarm_ptr->year) == 0) {
                                return (val <= 59 && val >= 0);
                        }
			break;
		case 's':
			if (validate_year(alarm_ptr, alarm_ptr->year) == 1) {
                                if (validate_month(alarm_ptr, alarm_ptr->month) == 1) {
					if (validate_day(alarm_ptr, alarm_ptr->day) == 1) {
						if (validate_hour(alarm_ptr, alarm_ptr->hour) == 1) {
							if (validate_minute(alarm_ptr, alarm_ptr->minute) == 1) {
								return (validate_second(alarm_ptr, val) != -1);
							} else if (validate_minute(alarm_ptr, val) == 0) {
                                                                return (val <= 61 && val >= 0);
                                                        }
                                                } else if (validate_hour(alarm_ptr, alarm_ptr->hour) == 0) {
                                                        return (val <= 61 && val >= 0);
                                                }
                                        } else if (validate_day(alarm_ptr, alarm_ptr->day) == 0) {
                                                return (val <= 61 && val >= 0);
                                        }
                                } else if (validate_month(alarm_ptr, alarm_ptr->month) == 0) {
                                        return (val <= 61 && val >= 0);
                                }       
                        } else if (validate_year(alarm_ptr, alarm_ptr->year) == 0) {
                        	return (val <= 61 && val >= 0);
			}   
			break;
	}

	return 0;
}

int validate_year(alarm_t* alarm_ptr, int val) {
	if (val == -1) {
		return 0;
	} else {
		struct tm time_s;
		time_s = build_cur_tm();
		if (val - (time_s.tm_year + 1900)  == 0) {
                        return 1;
                } else if (val - (time_s.tm_mon + 1900) > 0) {
                        return 0;
                }

	}
	return -1;
}

int validate_month(alarm_t* alarm_ptr, int val) {
	if (val >= 12 || val < 0) {
		return -1;
	}
	if (val == -1) {
		return 0;
	} else {
		struct tm time_s;
                time_s = build_cur_tm();
		if (val - time_s.tm_mon == 0) {
			return 1;
		} else if (val - time_s.tm_mon > 0) {
			return 0;
		}
	}
        return -1;
}

int validate_day(alarm_t* alarm_ptr, int val) {
        if (val >= 31 || val < 0) {
		return -1;
	}
	if (val == -1) {
	        return 0;
        } else {
	        struct tm time_s;
                time_s = build_cur_tm();
                if (val >= time_s.tm_mday) {
			/* 30 days hath september */
			if (alarm_ptr->month == -1) {
				return 1;	/* 1 or 0? */
			} else {
				if (alarm_ptr->month == 1) {
					return (val <= 28 && val >= 0);
				}
				if (alarm_ptr->month == 3 || alarm_ptr->month == 5 || alarm_ptr->month == 8 || alarm_ptr->month == 10) {
					return (val <= 30 && val >= 0);
				} else {
					return (val <= 31 && val >= 0);
				}
			}
		}
        }
        return -1;
}

int validate_hour(alarm_t* alarm_ptr, int val) {
	if (val >= 24 || val < 0) {
		return -1;
	}
	if (val == -1) {
                return 0;
        } else {
                struct tm time_s;
                time_s = build_cur_tm();
                return (val >= time_s.tm_hour);
        }
        return -1;
}

int validate_minute(alarm_t* alarm_ptr, int val) {
	if (val >= 60 || val < 0) {
		return -1;
	}
        if (val == -1) {
                return 0;
        } else {
                struct tm time_s;
                time_s = build_cur_tm();
                return (val >= time_s.tm_min);
        }
        return -1;
}

int validate_second(alarm_t* alarm_ptr, int val) {
	if (val >= 62 || val < 0) {
		return -1;
	}
        if (val == -1) {
                return 0;
        } else {
                struct tm time_s;
                time_s = build_cur_tm();
                return (val >= time_s.tm_sec);
        }
        return -1;
}