static CalendarItem Parse(IEnumerator <string> lines)
{
if (!lines.Current.StartsWith("BEGIN:"))
{
throw new ArgumentException("not a calendar item text");
}
var kind = lines.Current.Substring(6);
var item =
kind == CalendarDocument.Kind ? new CalendarDocument() :
kind == CalendarEvent.Kind ? new CalendarEvent() :
new CalendarItem(kind);
while (lines.MoveNext())
{
var i = lines.Current;
var idx = i.IndexOfAny(new[] { ':', ';' });
var key = i.Substring(0, idx);
var value = i.Substring(idx + 1);
switch (key)
{
case "BEGIN":
item.Items.Add(Parse(lines));
break;
case "END":
return(item);
default:
var values = i.StartsWith(key + ";") ? value.Split(new[] { ':' }, 2) : new[] { value };
var parameters = values.Take(values.Length - 1).Select(_ => _.Split(new[] { '=' }, 2)).SelectMany(_ => _.Last().Split(',').Select(v => new
{
Key = _.First(),
Value = CalendarValue.UnescapeValueString(v),
})).ToLookup(_ => _.Key, _ => _.Value);
var parsed = item.ParseValue(key, values.Last().Split(',').Select(CalendarValue.UnescapeValueString).ToArray(), parameters);
if (parsed != null)
{
item.Properties[key] = parsed;
}
break;
}
}
throw new InvalidOperationException("calendar item not properly ended");
}
protected virtual CalendarValue ParseValue(string key, IReadOnlyList <string> value, ILookup <string, string> parameters) => CalendarValue.Parse(value, parameters);