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#[macro_use]
extern crate lazy_static;
use chrono::prelude::*;
use chrono::Duration;
use num_traits::cast::FromPrimitive;
use rand::Rng;
use std::collections::HashMap;
lazy_static! {
static ref YEARS: HashMap<i32, i32> = {
const T3: [i32; 7] = [0, 5, 3, 1, 6, 4, 2];
let mut years = HashMap::new();
let mut cycled = T3.iter().cycle();
for year in (1584..1600).step_by(4) {
years.insert(year, *cycled.next().unwrap());
}
let mut cycled = T3.iter().cycle();
for year in (1600..1700).step_by(4) {
years.insert(year, 6 + *cycled.next().unwrap());
}
let mut cycled = T3.iter().cycle();
for year in (1700..1800).step_by(4) {
years.insert(year, 4 + *cycled.next().unwrap());
}
let mut cycled = T3.iter().cycle();
for year in (1800..1900).step_by(4) {
years.insert(year, 2 + *cycled.next().unwrap());
}
let mut cycled = T3.iter().cycle();
for year in (1900..2000).step_by(4) {
years.insert(year, *cycled.next().unwrap());
}
let mut cycled = T3.iter().cycle();
for year in (2000..2100).step_by(4) {
years.insert(year, 6 + *cycled.next().unwrap());
}
let mut cycled = T3.iter().cycle();
for year in (2100..2200).step_by(4) {
years.insert(year, 4 + *cycled.next().unwrap());
}
years
};
}
fn is_leap_year(y: i32) -> bool {
(y % 4 == 0) && (y % 100 != 0) || (y % 400 == 0)
}
pub fn tomohiko_sakamoto(dt: NaiveDate) -> Weekday {
const DAYS: [i32; 12] = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4];
let y = if dt.month() < 3 {
dt.year() - 1
} else {
dt.year()
};
let day = (y + y / 4 - y / 100 + y / 400 + DAYS[dt.month0() as usize] + dt.day() as i32) % 7;
Weekday::from_i32(day).unwrap().pred()
}
pub fn shakuntala_devi(dt: NaiveDate) -> (Weekday, Vec<String>) {
let mut v: Vec<String> = Vec::new();
const T2: [i32; 12] = [0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5];
let day = dt.day() % 7;
let day = (day as i32 + T2[dt.month0() as usize]) % 7;
v.push(format!("Step 1 is {}", day));
let t1 = YEARS.get(&dt.year());
let day = match t1 {
Some(result) => {
v.push(format!("Step 2 is {:#?}", result));
if is_leap_year(dt.year()) {
if dt.month() > 2 {
day + result
} else {
day + result - 1
}
} else {
let mut nearest_leap_year = dt.year() - 1;
while !is_leap_year(nearest_leap_year) {
nearest_leap_year -= 1;
}
v.push(format!("Step 3 is {:#?}", nearest_leap_year));
day + YEARS.get(&nearest_leap_year).unwrap() + dt.year() - nearest_leap_year
}
}
None => {
v.push("Step 2 is not in the year table".into());
let mut nearest_leap_year = dt.year() - 1;
while !is_leap_year(nearest_leap_year) {
nearest_leap_year -= 1;
}
v.push(format!("Step 3 is {:#?}", nearest_leap_year));
day + YEARS.get(&nearest_leap_year).unwrap() + dt.year() - nearest_leap_year
}
};
(Weekday::from_i32(day.rem_euclid(7)).unwrap().pred(), v)
}
pub fn random_date() -> NaiveDate {
let start = NaiveDate::from_ymd(1583, 1, 1).num_days_from_ce();
let end = NaiveDate::from_ymd(2204, 1, 1).num_days_from_ce();
let days = rand::thread_rng().gen_range(1..end - start);
let dt = NaiveDate::from_ymd(1583, 1, 7);
dt + Duration::days(days as i64)
}
#[test]
fn tomohiko_sakamoto_check() {
let calendar = NaiveDate::from_ymd(1583, 1, 1).iter_days();
for dt in calendar {
assert_eq!(tomohiko_sakamoto(dt), dt.weekday());
if dt.year() == 10000 {
break;
};
}
}
#[test]
fn shakuntala_devi_check() {
let calendar = NaiveDate::from_ymd(1584, 1, 1).iter_days();
for dt in calendar {
assert_eq!(shakuntala_devi(dt).0, dt.weekday());
if dt.year() == 2204 {
break;
};
}
}
#[test]
fn shakuntala_devi_unit_check() {
let dt = NaiveDate::from_ymd(1928, 1, 7);
println!("response {} {} ", dt.year(), dt.weekday());
assert_eq!(shakuntala_devi(dt).0, dt.weekday());
}
#[test]
fn leap_year_unit_check() {
assert!(is_leap_year(1584));
}
#[test]
fn leap_year_check() {
for year in 1853..10000 {
assert!(is_leap_year(year) == NaiveDate::from_ymd_opt(year, 2, 29).is_some());
}
}
#[test]
fn leap_year_reverse_check() {
for year in 1853..2200 {
if is_leap_year(year) {
assert!(YEARS.get(&year) != None)
};
}
}