#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

typedef struct {
    int year;
    int month;
    int day;
} Date;

Date* date_create(int year, int month, int day) {
    Date* d = (Date*)malloc(sizeof(Date));
    d->year = year;
    d->month = month;
    d->day = day;
    return d;
}

void date_free(Date* d) {
    free(d);
}

char* date_to_string(Date* d) {
    char* buf = (char*)malloc(11);
    sprintf(buf, "%04d-%02d-%02d", d->year, d->month, d->day);
    return buf;
}

Date* date_from_string(const char* str) {
    Date* d = (Date*)malloc(sizeof(Date));
    sscanf(str, "%d-%d-%d", &d->year, &d->month, &d->day);
    return d;
}

int date_diff_days(Date* a, Date* b) {
    struct tm ta = {0}, tb = {0};
    ta.tm_year = a->year - 1900; ta.tm_mon = a->month - 1; ta.tm_mday = a->day;
    tb.tm_year = b->year - 1900; tb.tm_mon = b->month - 1; tb.tm_mday = b->day;
    time_t tta = mktime(&ta);
    time_t ttb = mktime(&tb);
    return (int)((tta - ttb) / 86400);
}

int date_compare(Date* a, Date* b) {
    if (a->year != b->year) return a->year - b->year;
    if (a->month != b->month) return a->month - b->month;
    return a->day - b->day;
}

Date* date_add_days(Date* d, int days) {
    struct tm tm = {0};
    tm.tm_year = d->year - 1900;
    tm.tm_mon = d->month - 1;
    tm.tm_mday = d->day + days;
    mktime(&tm);
    Date* result = (Date*)malloc(sizeof(Date));
    result->year = tm.tm_year + 1900;
    result->month = tm.tm_mon + 1;
    result->day = tm.tm_mday;
    return result;
}

int date_get_year(Date* d) { return d->year; }
int date_get_month(Date* d) { return d->month; }
int date_get_day(Date* d) { return d->day; }