Hijri calendar

use hijri.qweruse hijri_from_date, hijri_to_date from hijri      // Quillo 0.6: only these

icu_calendar = "=1.5.2"chrono = { version = "0.4", default-features = false, features = ["std", "clock"] }serde_json = { version = "1", features = ["preserve_order"] }

// A mosque's website: today's Hijri date in the header, Ramadan's dates, and the year's holy days.////   quillo run hijri.qwe      then open http://localhost:8080/calendaruse "hijri.qwer"route GET /calendar {    {        today: hijri_from_date("today", "")?.text,        date: hijri_from_date("2026-10-29", "")?,        civil: hijri_from_date("2026-10-29", "civil")?.text,        ramadan: hijri_month(1448, 9, "")?,        back: hijri_to_date(1447, 10, 1, "")?,        bad: hijri_month(1448, 13, "").error,    }}route GET /holy-days/:year(int) = hijri_holy_days(year, "")?route GET / {    let h = hijri_from_date("today", "")?    <html><body>        <header>{h.weekday}, {h.text} · <span dir="rtl" lang="ar">{h.weekday_ar} {h.text_ar}</span></header>    </body></html>}

//! Islamic (Hijri) calendar dates: today's date in Umm al-Qura (Saudi Arabia's official calendar), the civil tabular or the observational calendar, written in English and Arabic; a Hijri date back to the Gregorian one; a month's first and last days; and the year's holy days.//! version: 1.0.0//!//! [dependencies]//! icu_calendar = "=1.5.2"//! chrono = { version = "0.4", default-features = false, features = ["std", "clock"] }//! serde_json = { version = "1", features = ["preserve_order"] }use chrono::{Datelike, NaiveDate};use icu_calendar::islamic::{IslamicCivil, IslamicObservational, IslamicTabular, IslamicUmmAlQura};use icu_calendar::{Date, Iso};use serde_json::{json, Value};const MONTHS: [&str; 12] = ["Muharram", "Safar", "Rabi al-Awwal", "Rabi al-Thani", "Jumada al-Awwal", "Jumada al-Thani", "Rajab", "Shaban", "Ramadan", "Shawwal", "Dhu al-Qadah", "Dhu al-Hijjah"];const MONTHS_AR: [&str; 12] = ["محرم", "صفر", "ربيع الأول", "ربيع الآخر", "جمادى الأولى", "جمادى الآخرة", "رجب", "شعبان", "رمضان", "شوال", "ذو القعدة", "ذو الحجة"];const WEEKDAYS: [&str; 7] = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"];const WEEKDAYS_AR: [&str; 7] = ["الاثنين", "الثلاثاء", "الأربعاء", "الخميس", "الجمعة", "السبت", "الأحد"];#[derive(Clone, Copy)]enum Kind { UmmAlQura, Civil, Tabular, Observational }fn kind(name: &str) -> Result<Kind, String> {    Ok(match name.trim().to_lowercase().replace(['-', ' '], "_").as_str() {        "" | "umm_al_qura" | "ummalqura" | "saudi" => Kind::UmmAlQura,        "civil" => Kind::Civil,        "tabular" => Kind::Tabular,        "observational" | "sighting" => Kind::Observational,        other => return Err(format!("`{}` is not a Hijri calendar: umm_al_qura, civil, tabular or observational", other)),    })}fn iso_of(date: &str) -> Result<(NaiveDate, Date<Iso>), String> {    let t = date.trim();    let d = if t.is_empty() || t == "today" { chrono::Utc::now().date_naive() } else {        NaiveDate::parse_from_str(t.get(..10).unwrap_or(t), "%Y-%m-%d").map_err(|_| format!("`{}` is not a date (2026-10-29)", date))?    };    let iso = Date::try_new_iso_date(d.year(), d.month() as u8, d.day() as u8).map_err(|e| format!("{}: {:?}", date, e))?;    Ok((d, iso))}// (year, month, day, days in month) of an ISO date.fn to_hijri(iso: &Date<Iso>, k: Kind) -> (i32, u8, u8, u8) {    macro_rules! conv { ($cal:expr) => {{ let h = iso.to_calendar($cal); (h.year().number, h.month().ordinal as u8, h.day_of_month().0 as u8, h.days_in_month()) }} }    match k {        Kind::UmmAlQura => conv!(IslamicUmmAlQura::new()),        Kind::Civil => conv!(IslamicCivil::new()),        Kind::Tabular => conv!(IslamicTabular::new()),        Kind::Observational => conv!(IslamicObservational::new()),    }}fn to_gregorian(y: i32, m: u8, d: u8, k: Kind) -> Result<NaiveDate, String> {    let bad = |e: icu_calendar::CalendarError| format!("{}-{}-{} is not a Hijri date: {:?}", y, m, d, e);    let iso = match k {        Kind::UmmAlQura => Date::try_new_ummalqura_date(y, m, d, IslamicUmmAlQura::new()).map_err(bad)?.to_iso(),        Kind::Civil => Date::try_new_islamic_civil_date_with_calendar(y, m, d, IslamicCivil::new()).map_err(bad)?.to_iso(),        Kind::Tabular => Date::try_new_islamic_tabular_date_with_calendar(y, m, d, IslamicTabular::new()).map_err(bad)?.to_iso(),        Kind::Observational => Date::try_new_observational_islamic_date(y, m, d, IslamicObservational::new()).map_err(bad)?.to_iso(),    };    NaiveDate::from_ymd_opt(iso.year().number, iso.month().ordinal, iso.day_of_month().0).ok_or_else(|| "the date is out of range".to_string())}fn arabic_digits(n: i64) -> String {    n.to_string().chars().map(|c| match c.to_digit(10) { Some(d) => char::from_u32(0x0660 + d).unwrap(), None => c }).collect()}fn check(y: i64, m: i64) -> Result<(), String> {    if !(1..=9999).contains(&y) || !(1..=12).contains(&m) {        return Err(format!("{}-{} is not a Hijri year and month (months 1 to 12)", y, m));    }    Ok(())}/// A Gregorian date (`"2026-10-29"`, or `"today"`) in the Hijri calendar `calendar` (`"umm_al_qura"`, the default when `""`; `"civil"`, `"tabular"` or `"observational"`):/// `{ year, month, day, month_name, month_name_ar, weekday, weekday_ar, days_in_month, text, text_ar }`, `text` as "18 Jumada al-Awwal 1448 AH".pub fn hijri_from_date(date: &str, calendar: &str) -> Result<Value, String> {    let k = kind(calendar)?;    let (g, iso) = iso_of(date)?;    let (y, m, d, dim) = to_hijri(&iso, k);    let wd = g.weekday().num_days_from_monday() as usize;    let mi = (m as usize).clamp(1, 12) - 1;    Ok(json!({        "year": y, "month": m, "day": d,        "month_name": MONTHS[mi], "month_name_ar": MONTHS_AR[mi],        "weekday": WEEKDAYS[wd], "weekday_ar": WEEKDAYS_AR[wd],        "days_in_month": dim,        "text": format!("{} {} {} AH", d, MONTHS[mi], y),        "text_ar": format!("{} {} {} هـ", arabic_digits(d as i64), MONTHS_AR[mi], arabic_digits(y as i64)),    }))}/// The Gregorian date (`"2027-03-09"`) of a Hijri date in `calendar` (`""` for Umm al-Qura).pub fn hijri_to_date(year: i64, month: i64, day: i64, calendar: &str) -> Result<String, String> {    check(year, month)?;    if !(1..=30).contains(&day) { return Err(format!("day {} is not 1 to 30", day)) }    Ok(to_gregorian(year as i32, month as u8, day as u8, kind(calendar)?)?.to_string())}/// A Hijri month in Gregorian dates: `{ year, month, month_name, first, last, days }`; `hijri_month(1448, 9, "")` is Ramadan 1448.pub fn hijri_month(year: i64, month: i64, calendar: &str) -> Result<Value, String> {    check(year, month)?;    let k = kind(calendar)?;    let first = to_gregorian(year as i32, month as u8, 1, k)?;    let (_, iso) = iso_of(&first.to_string())?;    let days = to_hijri(&iso, k).3 as i64;    Ok(json!({        "year": year, "month": month, "month_name": MONTHS[month as usize - 1],        "first": first.to_string(), "last": (first + chrono::Duration::days(days - 1)).to_string(), "days": days,    }))}/// The holy days of Hijri year `year` with their Gregorian dates: Islamic New Year, Ashura, the Mawlid, Isra and Mi'raj, the start of Ramadan, Laylat al-Qadr, Eid al-Fitr, the Day of Arafah and Eid al-Adha./// By calculation: where a day is fixed by sighting the moon, it may come a day later.pub fn hijri_holy_days(year: i64, calendar: &str) -> Result<Vec<Value>, String> {    check(year, 1)?;    let k = kind(calendar)?;    let days: [(&str, u8, u8); 9] = [        ("Islamic New Year", 1, 1), ("Ashura", 1, 10), ("Mawlid", 3, 12), ("Isra and Mi'raj", 7, 27), ("First day of Ramadan", 9, 1),        ("Laylat al-Qadr", 9, 27), ("Eid al-Fitr", 10, 1), ("Day of Arafah", 12, 9), ("Eid al-Adha", 12, 10),    ];    days.iter().map(|(name, m, d)| {        let g = to_gregorian(year as i32, *m, *d, k)?;        Ok(json!({ "name": name, "date": g.to_string(), "hijri": format!("{} {} {}", d, MONTHS[*m as usize - 1], year) }))    }).collect()}