# Cargo.toml
[dependencies]
chrono = "0.4"

use chrono::{
    DateTime, Duration, Local, NaiveDate, NaiveDateTime, NaiveTime, TimeZone, Utc,
    format::strftime::StrftimeItems,
};
 
fn main() {
    // ===== Current Date and Time =====
    let now = Local::now();
    println!("Local now: {}", now);
    
    let utc_now = Utc::now();
    println!("UTC now: {}", utc_now);
 
    // ===== Creating Specific Dates/Times =====
    // Naive types (no timezone)
    let date = NaiveDate::from_ymd_opt(2024, 3, 15).expect("Invalid date");
    let time = NaiveTime::from_hms_opt(14, 30, 45).expect("Invalid time");
    let datetime = NaiveDateTime::new(date, time);
    println!("Naive datetime: {}", datetime);
 
    // Timezone-aware datetime
    let utc_datetime = Utc.with_ymd_and_hms(2024, 3, 15, 14, 30, 45).unwrap();
    println!("UTC datetime: {}", utc_datetime);
 
    // ===== Parsing from Strings =====
    // Common format (ISO 8601)
    let parsed: DateTime<Utc> = "2024-03-15T14:30:45Z".parse().unwrap();
    println!("Parsed UTC: {}", parsed);
 
    // Custom format
    let custom = NaiveDateTime::parse_from_str("15-03-2024 14:30:45", "%d-%m-%Y %H:%M:%S")
        .unwrap();
    println!("Custom parsed: {}", custom);
 
    // Parse date only
    let just_date = NaiveDate::parse_from_str("2024-03-15", "%Y-%m-%d").unwrap();
    println!("Just date: {}", just_date);
 
    // ===== Formatting =====
    let dt = Utc::now();
    println!("Default: {}", dt);
    println!("RFC 2822: {}", dt.to_rfc2822());
    println!("RFC 3339: {}", dt.to_rfc3339());
    println!("Custom: {}", dt.format("%A, %B %d, %Y at %I:%M %p"));
 
    // ===== Date/Time Arithmetic =====
    let start = Utc::now();
    
    // Add/subtract durations
    let later = start + Duration::hours(3);
    let earlier = start - Duration::days(7);
    println!("3 hours later: {}", later);
    println!("7 days earlier: {}", earlier);
 
    // Duration between datetimes
    let diff = later.signed_duration_since(start);
    println!("Difference: {} hours", diff.num_hours());
 
    // ===== Date Components =====
    let dt = Local::now();
    println!("Year: {}", dt.year());
    println!("Month: {}", dt.month());
    println!("Day: {}", dt.day());
    println!("Hour: {}", dt.hour());
    println!("Minute: {}", dt.minute());
    println!("Weekday: {:?}", dt.weekday());
    println!("Day of year: {}", dt.ordinal());
 
    // ===== Date Range Operations =====
    let start_date = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
    let end_date = NaiveDate::from_ymd_opt(2024, 12, 31).unwrap();
    
    let days_in_year = (end_date - start_date).num_days();
    println!("Days in 2024: {}", days_in_year);
 
    // Iterate over dates
    let mut current = start_date;
    while current <= end_date {
        if current.weekday() == chrono::Weekday::Fri && current.day() == 13 {
            println!("Friday the 13th: {}", current);
        }
        current = current + Duration::days(1);
    }
}

use chrono::{DateTime, FixedOffset, Utc, TimeZone};
 
fn main() {
    // Create a fixed offset timezone (UTC+8)
    let singapore = FixedOffset::east_opt(8 * 3600).unwrap();
    
    // Convert UTC to Singapore time
    let utc_time = Utc::now();
    let singapore_time: DateTime<FixedOffset> = utc_time.with_timezone(&singapore);
    
    println!("UTC: {}", utc_time);
    println!("Singapore: {}", singapore_time);
}