Fixes TigerCenter Calendars on the macOS calendar app

fix-calendar.swift

#!/usr/bin/env swift

import EventKit

let eventStore = EKEventStore()

extension String: Error {}

func deleteBadEvents(calendarName: String) throws {
    // Make dates for Fall Semester 2017 before exams
    let startDate = Calendar.current.date(from:
        DateComponents(year: 2017, month: 8, day: 28))!
    let endDate = Calendar.current.date(from:
        DateComponents(year: 2017, month: 12, day: 12))!

    // Find the specified RIT calendar
    let calendars = eventStore.calendars(for: .event)
    guard let rit = calendars.first(where: { $0.title == calendarName }) else {
        throw "Unknown calendar '\(calendarName)'"
    }

    // Get all events within the date range
    let eventPredicate = eventStore.predicateForEvents(withStart: startDate,
                                                       end: endDate,
                                                       calendars: [rit])
    let events = eventStore.events(matching: eventPredicate)

    // Events with no occurrenceDate are standalone as they aren't
    // considered repeating.
    let toDelete = events.filter { $0.occurrenceDate == nil }
    guard !toDelete.isEmpty else {
        throw "No events to delete"
    }
    print("This will delete the following \(toDelete.count) events:")
    for event in toDelete {
        print("  \(event.title!): \(event.startDate!)")
    }
    print("Are you sure you wish to delete these events? [y|N]")
    let line = readLine(strippingNewline: true)!
    if line.lowercased().contains("y") {
        for event in toDelete {
            // Remove all standalone events.
            try eventStore.remove(event, span: .thisEvent, commit: false)
        }
        try eventStore.commit()
    } else {
        print("Not deleting events")
    }
}

func err(_ value: Any) -> Never {
    print("error: \(value)")
    exit(-1)
}

let semaphore = DispatchSemaphore(value: 0)

eventStore.requestAccess(to: .event) { granted, error in
    defer { semaphore.signal() }
    if let error = error {
        err(error)
    }
    guard granted else {
        err("You need to grant calendar access to use this script")
    }
    do {
        print("RIT Calendar Name: ", terminator: "")
        let name = readLine(strippingNewline: true)!
        try deleteBadEvents(calendarName: name)
    } catch {
        err(error)
    }
}

// Keep the main queue alive long enough to run the completion.
semaphore.wait()