Files
banner/src/bot/commands/ics.rs

380 lines
13 KiB
Rust

//! ICS command implementation for generating calendar files.
use crate::banner::{Course, MeetingDays, MeetingScheduleInfo, WeekdayExt};
use crate::bot::{Context, Error, utils};
use chrono::{Datelike, Duration, NaiveDate, Utc, Weekday};
use serenity::all::CreateAttachment;
use tracing::info;
/// Find the nth occurrence of a weekday in a given month/year (1-based).
fn nth_weekday_of_month(year: i32, month: u32, weekday: Weekday, n: u32) -> Option<NaiveDate> {
let first = NaiveDate::from_ymd_opt(year, month, 1)?;
let days_ahead = (weekday.num_days_from_monday() as i64
- first.weekday().num_days_from_monday() as i64)
.rem_euclid(7) as u32;
let day = 1 + days_ahead + 7 * (n - 1);
NaiveDate::from_ymd_opt(year, month, day)
}
/// Compute a consecutive range of dates starting from `start` for `count` days.
fn date_range(start: NaiveDate, count: i64) -> Vec<NaiveDate> {
(0..count)
.filter_map(|i| start.checked_add_signed(Duration::days(i)))
.collect()
}
/// Compute university holidays for a given year.
///
/// Federal holidays use weekday-of-month rules so they're correct for any year.
/// University-specific breaks (Fall Break, Spring Break, Winter Holiday) are derived
/// from anchoring federal holidays or using UTSA's typical scheduling patterns.
fn compute_holidays_for_year(year: i32) -> Vec<(&'static str, Vec<NaiveDate>)> {
let mut holidays = Vec::new();
// Labor Day: 1st Monday of September
if let Some(d) = nth_weekday_of_month(year, 9, Weekday::Mon, 1) {
holidays.push(("Labor Day", vec![d]));
}
// Fall Break: Mon-Tue of Columbus Day week (2nd Monday of October + Tuesday)
if let Some(mon) = nth_weekday_of_month(year, 10, Weekday::Mon, 2) {
holidays.push(("Fall Break", date_range(mon, 2)));
}
// Day before Thanksgiving: Wednesday before 4th Thursday of November
if let Some(thu) = nth_weekday_of_month(year, 11, Weekday::Thu, 4)
&& let Some(wed) = thu.checked_sub_signed(Duration::days(1))
{
holidays.push(("Day Before Thanksgiving", vec![wed]));
}
// Thanksgiving: 4th Thursday of November + Friday
if let Some(thu) = nth_weekday_of_month(year, 11, Weekday::Thu, 4) {
holidays.push(("Thanksgiving", date_range(thu, 2)));
}
// Winter Holiday: Dec 23-31
if let Some(start) = NaiveDate::from_ymd_opt(year, 12, 23) {
holidays.push(("Winter Holiday", date_range(start, 9)));
}
// New Year's Day: January 1
if let Some(d) = NaiveDate::from_ymd_opt(year, 1, 1) {
holidays.push(("New Year's Day", vec![d]));
}
// MLK Day: 3rd Monday of January
if let Some(d) = nth_weekday_of_month(year, 1, Weekday::Mon, 3) {
holidays.push(("MLK Day", vec![d]));
}
// Spring Break: full week (Mon-Sat) starting the 2nd or 3rd Monday of March
// UTSA typically uses the 2nd full week of March
if let Some(mon) = nth_weekday_of_month(year, 3, Weekday::Mon, 2) {
holidays.push(("Spring Break", date_range(mon, 6)));
}
holidays
}
/// Generate an ICS file for a course
#[poise::command(slash_command, prefix_command)]
pub async fn ics(
ctx: Context<'_>,
#[description = "Course Reference Number (CRN)"] crn: i32,
) -> Result<(), Error> {
ctx.defer().await?;
let course = utils::get_course_by_crn(&ctx, crn).await?;
let term = course.term.clone();
// Get meeting times
let meeting_times = ctx
.data()
.app_state
.banner_api
.get_course_meeting_time(&term, &crn.to_string())
.await?;
if meeting_times.is_empty() {
ctx.say("No meeting times found for this course.").await?;
return Ok(());
}
// Sort meeting times by start time
let mut sorted_meeting_times = meeting_times.to_vec();
MeetingScheduleInfo::sort_by_start_time(&mut sorted_meeting_times);
// Generate ICS content
let (ics_content, excluded_holidays) =
generate_ics_content(&course, &term, &sorted_meeting_times)?;
// Create file attachment
let filename = format!(
"{subject}_{number}_{section}.ics",
subject = course.subject.replace(" ", "_"),
number = course.course_number,
section = course.sequence_number,
);
let file = CreateAttachment::bytes(ics_content.into_bytes(), filename.clone());
// Build response content
let mut response_content = format!(
"📅 Generated ICS calendar for **{}**\n\n**Meeting Times:**\n{}",
course.display_title(),
sorted_meeting_times
.iter()
.enumerate()
.map(|(i, m)| {
let time_info = match &m.time_range {
Some(range) => format!(
"{} {}",
m.days_string().unwrap_or("TBA".to_string()),
range.format_12hr()
),
None => m.days_string().unwrap_or("TBA".to_string()),
};
format!("{}. {}", i + 1, time_info)
})
.collect::<Vec<_>>()
.join("\n")
);
// Add holiday exclusion information
if !excluded_holidays.is_empty() {
let count = excluded_holidays.len();
let count_text = if count == 1 {
"1 date was".to_string()
} else {
format!("{} dates were", count)
};
response_content.push_str(&format!("\n\n{} excluded from the ICS file:\n", count_text));
response_content.push_str(
&excluded_holidays
.iter()
.map(|s| format!("- {}", s))
.collect::<Vec<_>>()
.join("\n"),
);
}
ctx.send(
poise::CreateReply::default()
.content(response_content)
.attachment(file),
)
.await?;
info!(crn = %crn, "ics command completed");
Ok(())
}
/// Generate ICS content for a course and its meeting times
fn generate_ics_content(
course: &Course,
term: &str,
meeting_times: &[MeetingScheduleInfo],
) -> Result<(String, Vec<String>), anyhow::Error> {
let mut ics_content = String::new();
let mut excluded_holidays = Vec::new();
// ICS header
ics_content.push_str("BEGIN:VCALENDAR\r\n");
ics_content.push_str("VERSION:2.0\r\n");
ics_content.push_str("PRODID:-//Banner Bot//Course Calendar//EN\r\n");
ics_content.push_str("CALSCALE:GREGORIAN\r\n");
ics_content.push_str("METHOD:PUBLISH\r\n");
// Calendar name
ics_content.push_str(&format!(
"X-WR-CALNAME:{} - {}\r\n",
course.display_title(),
term
));
// Generate events for each meeting time
for (index, meeting_time) in meeting_times.iter().enumerate() {
let (event_content, holidays) = generate_event_content(course, meeting_time, index)?;
ics_content.push_str(&event_content);
excluded_holidays.extend(holidays);
}
// ICS footer
ics_content.push_str("END:VCALENDAR\r\n");
Ok((ics_content, excluded_holidays))
}
/// Generate ICS event content for a single meeting time
fn generate_event_content(
course: &Course,
meeting_time: &MeetingScheduleInfo,
index: usize,
) -> Result<(String, Vec<String>), anyhow::Error> {
let course_title = course.display_title();
let instructor_name = course.primary_instructor_name();
let location = meeting_time.place_string();
// Create event title with meeting index if multiple meetings
let event_title = if index > 0 {
format!("{} (Meeting {})", course_title, index + 1)
} else {
course_title
};
// Create event description
let description = format!(
"CRN: {}\\nInstructor: {}\\nDays: {}\\nMeeting Type: {}",
course.course_reference_number,
instructor_name,
meeting_time.days_string().unwrap_or("TBA".to_string()),
meeting_time.meeting_type.description()
);
// Get start and end times
let (start_dt, end_dt) = meeting_time.datetime_range();
// Format datetimes for ICS (UTC format)
let start_utc = start_dt.with_timezone(&Utc);
let end_utc = end_dt.with_timezone(&Utc);
let start_str = start_utc.format("%Y%m%dT%H%M%SZ").to_string();
let end_str = end_utc.format("%Y%m%dT%H%M%SZ").to_string();
// Generate unique ID for the event
let uid = format!(
"{}-{}-{}@banner-bot.local",
course.course_reference_number,
index,
start_utc.timestamp()
);
let mut event_content = String::new();
// Event header
event_content.push_str("BEGIN:VEVENT\r\n");
event_content.push_str(&format!("UID:{}\r\n", uid));
event_content.push_str(&format!("DTSTART:{}\r\n", start_str));
event_content.push_str(&format!("DTEND:{}\r\n", end_str));
event_content.push_str(&format!("SUMMARY:{}\r\n", escape_ics_text(&event_title)));
event_content.push_str(&format!(
"DESCRIPTION:{}\r\n",
escape_ics_text(&description)
));
event_content.push_str(&format!("LOCATION:{}\r\n", escape_ics_text(&location)));
// Add recurrence rule if there are specific days and times
if !meeting_time.days.is_empty() && meeting_time.time_range.is_some() {
let days_of_week = meeting_time.days_of_week();
let by_day: Vec<String> = days_of_week
.iter()
.map(|day| day.to_short_string().to_uppercase())
.collect();
if !by_day.is_empty() {
let until_date = meeting_time
.date_range
.end
.format("%Y%m%dT000000Z")
.to_string();
event_content.push_str(&format!(
"RRULE:FREQ=WEEKLY;BYDAY={};UNTIL={}\r\n",
by_day.join(","),
until_date
));
// Add holiday exceptions (EXDATE) if the class would meet on holiday dates
let holiday_exceptions = get_holiday_exceptions(meeting_time);
if let Some(exdate_property) = generate_exdate_property(&holiday_exceptions, start_utc)
{
event_content.push_str(&format!("{}\r\n", exdate_property));
}
// Collect holiday names for reporting
let start_year = meeting_time.date_range.start.year();
let end_year = meeting_time.date_range.end.year();
let all_holidays: Vec<_> = (start_year..=end_year)
.flat_map(compute_holidays_for_year)
.collect();
let mut holiday_names = Vec::new();
for (holiday_name, holiday_dates) in &all_holidays {
for &exception_date in &holiday_exceptions {
if holiday_dates.contains(&exception_date) {
holiday_names.push(format!(
"{} ({})",
holiday_name,
exception_date.format("%a, %b %d")
));
}
}
}
holiday_names.sort();
holiday_names.dedup();
event_content.push_str("END:VEVENT\r\n");
return Ok((event_content, holiday_names));
}
}
// Event footer
event_content.push_str("END:VEVENT\r\n");
Ok((event_content, Vec::new()))
}
/// Check if a class meets on a specific date based on its meeting days
fn class_meets_on_date(meeting_time: &MeetingScheduleInfo, date: NaiveDate) -> bool {
let day: MeetingDays = date.weekday().into();
meeting_time.days.contains(day)
}
/// Get holiday dates that fall within the course date range and would conflict with class meetings
fn get_holiday_exceptions(meeting_time: &MeetingScheduleInfo) -> Vec<NaiveDate> {
let start_year = meeting_time.date_range.start.year();
let end_year = meeting_time.date_range.end.year();
(start_year..=end_year)
.flat_map(compute_holidays_for_year)
.flat_map(|(_, dates)| dates)
.filter(|&date| {
date >= meeting_time.date_range.start
&& date <= meeting_time.date_range.end
&& class_meets_on_date(meeting_time, date)
})
.collect()
}
/// Generate EXDATE property for holiday exceptions
fn generate_exdate_property(
exceptions: &[NaiveDate],
start_time: chrono::DateTime<Utc>,
) -> Option<String> {
if exceptions.is_empty() {
return None;
}
let mut exdate_values = Vec::new();
for &exception_date in exceptions {
// Create a datetime for the exception using the same time as the start time
let exception_datetime = exception_date.and_time(start_time.time()).and_utc();
let exdate_str = exception_datetime.format("%Y%m%dT%H%M%SZ").to_string();
exdate_values.push(exdate_str);
}
Some(format!("EXDATE:{}", exdate_values.join(",")))
}
/// Escape text for ICS format
fn escape_ics_text(text: &str) -> String {
text.replace("\\", "\\\\")
.replace(";", "\\;")
.replace(",", "\\,")
.replace("\n", "\\n")
.replace("\r", "")
}