feat: parse one calendar event with libical (item 206)

1 files changed, 73 insertions, 0 deletions

diff --git a/src/repeatrule.h b/src/repeatrule.h
new file mode 100644
index 0000000..59dfceb
--- /dev/null
+++ b/src/repeatrule.h
@@ -0,0 +1,73 @@
+/*
+ * qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include <QDate>
+#include <QList>
+#include <QString>
+
+/// The repeat control's model, and its RRULE value text in both directions.
+///
+/// No libical: an RRULE value is `KEY=VALUE;KEY=VALUE`, which is simpler to
+/// read and write as text than through icalrecurrencetype, and keeping it pure
+/// is what lets every row of the spec's repeat table be tested as a string.
+struct RepeatRule
+{
+    enum class Freq { None, Daily, Weekly, Monthly, Yearly };
+    /// Monthly and Yearly only: on a day of the month, or on the Nth weekday.
+    enum class By { MonthDay, Weekday };
+    enum class End { Never, Until, Count };
+
+    Freq freq = Freq::None;
+    int interval = 1;
+    /// Weekly: Qt::DayOfWeek values, 1 (Monday) to 7 (Sunday), sorted.
+    QList<int> weekdays;
+    By by = By::MonthDay;
+    int monthDay = 0;   ///< Monthly, By::MonthDay: 1 to 31.
+    int ordinal = 0;    ///< By::Weekday: 1 to 4, or -1 for "last".
+    int weekday = 0;    ///< By::Weekday: Qt::DayOfWeek.
+    int month = 0;      ///< Yearly, By::Weekday: 1 to 12.
+    End end = End::Never;
+    QDate until;        ///< End::Until: the last day an occurrence may fall on.
+    int count = 0;      ///< End::Count.
+    /// Carried through a rewrite untouched, per the spec: several existing
+    /// rules carry it and it changes nothing for the modes above.
+    QString wkst;
+
+    /// A rule outside the control's table. `customText` is the value exactly
+    /// as read, and an edit never rewrites it.
+    bool custom = false;
+    QString customText;
+
+    /// Parses an RRULE value (no "RRULE:" prefix). `start` is the event's
+    /// first day, which fills in what an RRULE leaves implicit (a weekly rule
+    /// with no BYDAY repeats on the start's weekday).
+    static RepeatRule fromRRule(const QString &value, const QDate &start);
+
+    /// The RRULE value, or an empty string for Freq::None. `untilValue` is
+    /// the whole UNTIL value, `20261231` for an all-day event or
+    /// `20261231T225959Z` for a timed one, computed by the caller because
+    /// only it knows the event's zone. Ignored unless end is End::Until.
+    QString toRRule(const QString &untilValue = QString()) const;
+
+    /// "Monthly, on the last Friday", translated. Custom rules say so.
+    QString describe() const;
+
+    bool operator==(const RepeatRule &other) const;
+};