mj 0.4.3

use chrono::prelude::*;
use regex::Regex;

const FORMAT: &'static str = "%Y-%m-%d";

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct JustDate(Date<Utc>);

impl JustDate {
  #[allow(dead_code)]
  pub fn date(&self) -> Date<Utc> {
    self.0
  }

  pub fn utc_now() -> Self {
    JustDate(Utc::now().date())
  }

  pub fn format(&self) -> String {
    self.0.format(FORMAT).to_string()
  }

  pub fn parse(input: &String) -> Option<Self> {
    if input == "today" {
      return Some(Self::utc_now());
    }
    match NaiveDate::parse_from_str(input.as_str(), FORMAT) {
      Ok(t) => {
        let date = Utc.ymd(t.year(), t.month(), t.day());
        Some(JustDate(date))
      },
      Err(_) => JustDate::parse_relative(input),
    }
  }

  fn parse_relative(input: &String) -> Option<Self> {
    let exp = Regex::new(r"(?P<days>\d+)d").unwrap();
    match exp.captures(input.as_str()) {
      Some(cap) => {
        match String::from(&cap["days"]).parse::<i64>() {
          Ok(days) => {
            let now = Utc::now().date();
            match now.checked_sub_signed(chrono::Duration::days(days)) {
              Some(date) => Some(JustDate(date)),
              None => None,
            }
          },
          Err(_) => None,
        }
      },
      None => None,
    }
  }
}