Files
flexcal/src/calendar.rs
2021-12-03 15:18:43 -04:00

326 lines
10 KiB
Rust

use chrono::naive::NaiveDate;
use chrono::{Datelike, Month, Weekday};
use serde::{Deserialize, Serialize};
use std::collections::HashSet;
/*
There are a few gaping holes here, and some deficiencies:
- Holidays are only calculated within a year. If a holiday in a prior
year is bumped to the next year, it won't be considered.
- Holiday impact is searched forward. If there is a mix of AdjustmentPolicy's
then some weird stuff can happen (Holidays occur A, B, but end up getting
observed B, A)
- No support for holiday ranges (e.g. Golden Week)
*/
#[derive(Copy, Clone, Serialize, Deserialize, Debug)]
enum AdjustmentPolicy {
Prev,
Next,
Closest,
NoAdjustment,
}
#[derive(Clone, Serialize, Deserialize, Debug)]
enum DateSpec {
SpecificDate {
date: NaiveDate,
description: String,
},
MonthDay {
month: chrono::Month,
day: u32,
observed: AdjustmentPolicy,
description: String,
since: Option<NaiveDate>,
until: Option<NaiveDate>,
},
MonthNthDay {
month: Month,
dow: Weekday,
offset: i8,
observed: AdjustmentPolicy,
description: String,
since: Option<NaiveDate>,
until: Option<NaiveDate>,
},
}
impl DateSpec {
/// Get exact date of event and its policy, if it occured in that year
fn resolve(&self, year: i32) -> Option<(NaiveDate, AdjustmentPolicy)> {
use DateSpec::*;
match self {
SpecificDate { date, .. } => Some((*date, AdjustmentPolicy::NoAdjustment)),
MonthDay {
month,
day,
since,
until,
observed,
..
} => {
if since.is_some() && since.unwrap().year() > year {
None
} else if until.is_some() && until.unwrap().year() < year {
None
} else {
Some((
NaiveDate::from_ymd(year, month.number_from_month(), *day),
*observed,
))
}
}
MonthNthDay {
month,
dow,
offset,
since,
until,
observed,
..
} => {
if since.is_some() && since.unwrap().year() > year {
None
} else if until.is_some() && until.unwrap().year() < year {
None
} else {
let month_num = month.number_from_month();
if *offset < 0i8 {
let mut date = if month_num == 12 {
NaiveDate::from_ymd(year, 12, 31)
} else {
NaiveDate::from_ymd(year, month_num + 1, 1).pred()
};
while date.weekday() != *dow {
date = date.pred()
}
let mut off = offset + 1;
while off < 0 {
date = date.checked_sub_signed(chrono::Duration::days(7)).unwrap();
off += 1;
}
Some((date, *observed))
} else {
let mut date = NaiveDate::from_ymd(year, month_num, 1);
while date.weekday() != *dow {
date = date.succ()
}
let mut off = offset - 1;
while off > 0 {
date = date.checked_add_signed(chrono::Duration::days(7)).unwrap();
off -= 1;
}
Some((date, *observed))
}
}
}
}
}
}
#[derive(Clone, Serialize, Deserialize, Default, Debug)]
struct Calendar {
description: String,
dow: HashSet<Weekday>,
public: bool,
excluded: Vec<DateSpec>,
inherits: Vec<String>,
}
impl Calendar {
fn adjust_holidays(&self, holidays: &Vec<(NaiveDate, AdjustmentPolicy)>) -> HashSet<NaiveDate> {
let mut observed = HashSet::new();
for (date, policy) in holidays.iter() {
match self.adjust_holiday(*date, policy, &observed) {
Some(holiday) => {
observed.insert(holiday);
}
None => {}
}
}
observed
}
/// Adjust a date given existing holidays and adjustment policy
fn adjust_holiday(
&self,
date: NaiveDate,
policy: &AdjustmentPolicy,
holidays: &HashSet<NaiveDate>,
) -> Option<NaiveDate> {
let mut actual = date.clone();
println!("Adjusting {:?}", date);
let is_blocked =
|x: NaiveDate| -> bool { (!self.dow.contains(&x.weekday())) || holidays.contains(&x) };
use AdjustmentPolicy::*;
match policy {
Next => {
while is_blocked(actual) {
actual = actual.succ();
}
Some(actual)
}
Prev => {
while is_blocked(actual) {
actual = actual.pred();
}
Some(actual)
}
Closest => {
let prev = self
.adjust_holiday(date, &AdjustmentPolicy::Prev, holidays)
.unwrap();
let next = self
.adjust_holiday(date, &AdjustmentPolicy::Next, holidays)
.unwrap();
if (date - prev) < (next - date) {
Some(prev)
} else {
Some(next)
}
}
NoAdjustment => {
if is_blocked(actual) {
None
} else {
Some(actual)
}
}
}
}
/// Get the set of all holidays in a given year
pub fn get_holidays(&self, date: NaiveDate) -> HashSet<NaiveDate> {
let holidays: Vec<(NaiveDate, AdjustmentPolicy)> = self
.excluded
.iter()
.map(|x| x.resolve(date.year()))
.filter(|x| x.is_some())
.map(|x| x.unwrap())
.collect();
self.adjust_holidays(&holidays)
}
/// Returns true if the given date is a holiday / non-business day
fn is_holiday(&self, date: NaiveDate) -> bool {
self.get_holidays(date).contains(&date)
}
/// Returns the set of valid calendar dates within the specified range
pub fn date_range(&self, from: NaiveDate, to: NaiveDate) -> Vec<NaiveDate> {
let mut result = Vec::new();
let mut cur = from.pred();
let year = from.year();
let mut holidays = self.get_holidays(cur);
while cur <= to {
cur = cur.succ();
if cur.year() != year {
holidays = self.get_holidays(cur);
}
if !self.dow.contains(&cur.weekday()) || holidays.contains(&cur) {
continue;
}
result.push(cur);
}
result
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn check_double_observed() {
use chrono::Month::*;
use chrono::Weekday::*;
let cal = Calendar {
description: "Test description".to_owned(),
dow: HashSet::from([Mon, Tue, Wed, Thu, Fri]),
public: false,
excluded: vec![
DateSpec::MonthDay {
month: December,
day: 25u32,
observed: AdjustmentPolicy::Next,
description: "Christmas".to_owned(),
since: None,
until: None,
},
DateSpec::MonthDay {
month: December,
day: 26u32,
observed: AdjustmentPolicy::Next,
description: "Boxing Day".to_owned(),
since: None,
until: None,
},
],
inherits: vec![],
};
// Christmas falls on a Saturday, observed was Monday
assert!(cal.is_holiday(NaiveDate::from_ymd(2021, 12, 27)));
// Boxing Day falls on a Sunday, observed is a Tuesday
assert!(cal.is_holiday(NaiveDate::from_ymd(2021, 12, 28)));
assert!(!cal.is_holiday(NaiveDate::from_ymd(2021, 12, 24)));
}
#[test]
fn check_crossing_years() {
use chrono::Month::*;
use chrono::Weekday::*;
let cal = Calendar {
description: "Test description".to_owned(),
dow: HashSet::from([Mon, Tue, Wed, Thu, Fri]),
public: false,
excluded: vec![
DateSpec::MonthDay {
month: December,
day: 25u32,
observed: AdjustmentPolicy::Next,
description: "Christmas".to_owned(),
since: None,
until: None,
},
DateSpec::MonthDay {
month: December,
day: 26u32,
observed: AdjustmentPolicy::Next,
description: "Boxing Day".to_owned(),
since: None,
until: None,
},
DateSpec::MonthDay {
month: January,
day: 1u32,
observed: AdjustmentPolicy::Next,
description: "New Years Day".to_owned(),
since: None,
until: None,
},
],
inherits: vec![],
};
let myrange = cal.date_range(
NaiveDate::from_ymd(2021, 12, 15),
NaiveDate::from_ymd(2022, 01, 15),
);
assert_eq!(myrange.len(), 20);
}
}