GUTSchedule/GUT.Schedule/GUTSchedule.Droid/Calendar.cs

using System.Collections.Generic;
using Android.App;
using Android.Content;
using Android.Database;
using Android.Net;
using Android.Provider;
using GUTSchedule.Droid.Activities;
using GUTSchedule.Models;
using Java.Util;

namespace GUTSchedule.Droid
{
	public static class Calendar
	{
		/// <summary>
		/// List of all existing Google calendars on the device
		/// </summary>
		public static List<(string Id, string Name)> Calendars { get; private set; } = new List<(string Id, string Name)>();

		/// <summary>
		/// Retrieves all Google Accounts' calendars existing on the device and puts them to <see cref="Calendars"/>
		/// </summary>
		public static void LoadCalendars()
		{
			Calendars = new List<(string, string)>();   // Resetting current calendars list

			// Building calendar data retrieval projections
			Uri calendarsUri = CalendarContract.Calendars.ContentUri;
			string[] calendarsProjection = {
				CalendarContract.Calendars.InterfaceConsts.Id,
				CalendarContract.Calendars.InterfaceConsts.CalendarDisplayName,
				CalendarContract.Calendars.InterfaceConsts.AccountName
			};

			// Retrieving calendars data
			ICursor cursor = Application.Context.ContentResolver.Query(calendarsUri, calendarsProjection, null, null, null);

			while (cursor.MoveToNext())
				Calendars.Add((cursor.GetString(0), $"{cursor.GetString(1)} ({cursor.GetString(2)})"));

			cursor.Close();
		}

		public static void Export(IEnumerable<Occupation> schedule)
		{
			foreach (Occupation item in schedule)
			{
				ContentValues eventValues = new ContentValues();

				eventValues.Put(CalendarContract.Events.InterfaceConsts.CalendarId, Calendars[MainActivity.SelectedCalendarIndex].Id);

				eventValues.Put(CalendarContract.Events.InterfaceConsts.Title, string.Format("{0}.{1} {2} ({3})",
					item.Order,
					MainActivity.AddGroupToTitle && !string.IsNullOrWhiteSpace(item.Group) ? $" [{item.Group}]" : "",
					item.Name,
					item.Type));

				eventValues.Put(CalendarContract.Events.InterfaceConsts.Description, item.Opponent);
				eventValues.Put(CalendarContract.Events.InterfaceConsts.EventLocation, item.Cabinet);

				eventValues.Put(CalendarContract.Events.InterfaceConsts.Availability, 0);

				eventValues.Put(CalendarContract.Events.InterfaceConsts.HasAlarm, MainActivity.Reminder != -5);
				// For some reason Google calendars ignore HasAlarm = false and set reminder for 30 minutes. Local calendars don't seem to have this issue

				eventValues.Put(CalendarContract.Events.InterfaceConsts.Dtstart, item.StartTime.ToUnixTime());
				eventValues.Put(CalendarContract.Events.InterfaceConsts.Dtend, item.EndTime.ToUnixTime());

				eventValues.Put(CalendarContract.Events.InterfaceConsts.EventTimezone, TimeZone.Default.ID);
				eventValues.Put(CalendarContract.Events.InterfaceConsts.EventEndTimezone, TimeZone.Default.ID);
				eventValues.Put(CalendarContract.Events.InterfaceConsts.CustomAppPackage, Application.Context.PackageName);

				Uri response = Application.Context.ContentResolver.Insert(CalendarContract.Events.ContentUri, eventValues);

				// Settings reminder
				if (MainActivity.Reminder != -5)
				{
					ContentValues reminderValues = new ContentValues();
					reminderValues.Put(CalendarContract.Reminders.InterfaceConsts.EventId, long.Parse(response.LastPathSegment));
					reminderValues.Put(CalendarContract.Reminders.InterfaceConsts.Minutes, MainActivity.Reminder);

					Application.Context.ContentResolver.Insert(CalendarContract.Reminders.ContentUri, reminderValues);
				}
			}
		}

		public static void Clear(bool keepPrevious = true)
		{
			Uri contentUri = CalendarContract.Events.ContentUri;
			string selector = $"({CalendarContract.Events.InterfaceConsts.CustomAppPackage} == \"{Application.Context.PackageName}\") AND (deleted != 1)";
			if (keepPrevious)
				selector += $" AND (dtstart > {System.DateTime.Now.ToUnixTime()})";

			string[] calendarsProjection = {
				CalendarContract.Events.InterfaceConsts.Id,
				CalendarContract.Events.InterfaceConsts.Dtstart,
				CalendarContract.Events.InterfaceConsts.CustomAppPackage,
			};

			// Retrieving calendars data
			ICursor cursor = Application.Context.ContentResolver.Query(contentUri, calendarsProjection, selector, null, null);
			while (cursor.MoveToNext())
				Application.Context.ContentResolver.Delete(ContentUris.WithAppendedId(CalendarContract.Events.ContentUri, cursor.GetLong(0)), null, null);

			cursor.Close();
		}
	}
}