1 files changed, 251 insertions, 4 deletions
diff --git a/src/repeatrule.cpp b/src/repeatrule.cpp
index df16c5e..cc11c91 100644
--- a/src/repeatrule.cpp
+++ b/src/repeatrule.cpp
@@ -18,7 +18,254 @@
 
 #include "repeatrule.h"
 
-RepeatRule RepeatRule::fromRRule(const QString &, const QDate &) { return {}; }
-QString RepeatRule::toRRule(const QString &) const { return {}; }
-QString RepeatRule::describe() const { return {}; }
-bool RepeatRule::operator==(const RepeatRule &) const { return false; }
+#include <QCoreApplication>
+#include <QLocale>
+#include <QMap>
+
+#include <algorithm>
+
+namespace {
+
+// iCalendar weekday codes, indexed by Qt::DayOfWeek - 1.
+const char *const kDays[] = { "MO", "TU", "WE", "TH", "FR", "SA", "SU" };
+
+int dayFromCode(const QString &code)
+{
+    for (int i = 0; i < 7; ++i)
+        if (code == QLatin1String(kDays[i]))
+            return i + 1;
+    return 0;
+}
+
+/// Splits "-1FR" into ordinal -1 and Friday. A plain "FR" gives ordinal 0.
+bool splitByDay(const QString &token, int *ordinal, int *day)
+{
+    if (token.size() < 2)
+        return false;
+    *day = dayFromCode(token.right(2));
+    const QString head = token.left(token.size() - 2);
+    bool ok = true;
+    *ordinal = head.isEmpty() ? 0 : head.toInt(&ok);
+    return *day != 0 && ok;
+}
+
+// Array literals have no enclosing class, so the context must be named on each
+// literal (AGENTS.md: QT_TR_NOOP here compiles and extracts nothing).
+const char *const kOrdinals[] = {
+    QT_TRANSLATE_NOOP("RepeatRule", "first"),
+    QT_TRANSLATE_NOOP("RepeatRule", "second"),
+    QT_TRANSLATE_NOOP("RepeatRule", "third"),
+    QT_TRANSLATE_NOOP("RepeatRule", "fourth"),
+};
+
+QString tr(const char *text) { return QCoreApplication::translate("RepeatRule", text); }
+
+QString ordinalWord(int ordinal)
+{
+    if (ordinal == -1)
+        return tr("last");
+    return (ordinal >= 1 && ordinal <= 4) ? tr(kOrdinals[ordinal - 1]) : QString();
+}
+
+} // namespace
+
+RepeatRule RepeatRule::fromRRule(const QString &value, const QDate &start)
+{
+    RepeatRule rule;
+    auto markCustom = [&]() {
+        RepeatRule custom;
+        custom.custom = true;
+        custom.customText = value;
+        return custom;
+    };
+
+    QMap<QString, QString> parts;
+    for (const QString &pair : value.split(QLatin1Char(';'), Qt::SkipEmptyParts)) {
+        const int eq = pair.indexOf(QLatin1Char('='));
+        if (eq <= 0)
+            return markCustom();
+        parts.insert(pair.left(eq).toUpper(), pair.mid(eq + 1).toUpper());
+    }
+
+    const QString freq = parts.take(QStringLiteral("FREQ"));
+    if (freq == QLatin1String("DAILY")) rule.freq = Freq::Daily;
+    else if (freq == QLatin1String("WEEKLY")) rule.freq = Freq::Weekly;
+    else if (freq == QLatin1String("MONTHLY")) rule.freq = Freq::Monthly;
+    else if (freq == QLatin1String("YEARLY")) rule.freq = Freq::Yearly;
+    else return markCustom();
+
+    if (parts.contains(QStringLiteral("INTERVAL"))) {
+        rule.interval = parts.take(QStringLiteral("INTERVAL")).toInt();
+        if (rule.interval < 1)
+            return markCustom();
+    }
+    if (parts.contains(QStringLiteral("COUNT"))) {
+        rule.end = End::Count;
+        rule.count = parts.take(QStringLiteral("COUNT")).toInt();
+        if (rule.count < 1)
+            return markCustom();
+    }
+    if (parts.contains(QStringLiteral("UNTIL"))) {
+        const QString until = parts.take(QStringLiteral("UNTIL"));
+        rule.end = End::Until;
+        rule.until = QDate::fromString(until.left(8), QStringLiteral("yyyyMMdd"));
+        if (!rule.until.isValid())
+            return markCustom();
+    }
+    rule.wkst = parts.take(QStringLiteral("WKST"));
+
+    const QStringList byDay = parts.contains(QStringLiteral("BYDAY"))
+        ? parts.take(QStringLiteral("BYDAY")).split(QLatin1Char(',')) : QStringList();
+    const QStringList byMonthDay = parts.contains(QStringLiteral("BYMONTHDAY"))
+        ? parts.take(QStringLiteral("BYMONTHDAY")).split(QLatin1Char(',')) : QStringList();
+    const QStringList byMonth = parts.contains(QStringLiteral("BYMONTH"))
+        ? parts.take(QStringLiteral("BYMONTH")).split(QLatin1Char(',')) : QStringList();
+
+    if (!parts.isEmpty())  // BYSETPOS, BYWEEKNO, BYHOUR, ... : outside the table.
+        return markCustom();
+
+    switch (rule.freq) {
+    case Freq::Daily:
+        if (!byDay.isEmpty() || !byMonthDay.isEmpty() || !byMonth.isEmpty())
+            return markCustom();
+        break;
+    case Freq::Weekly:
+        if (!byMonthDay.isEmpty() || !byMonth.isEmpty())
+            return markCustom();
+        for (const QString &token : byDay) {
+            int ordinal = 0, day = 0;
+            if (!splitByDay(token, &ordinal, &day) || ordinal != 0)
+                return markCustom();
+            rule.weekdays.append(day);
+        }
+        if (rule.weekdays.isEmpty())
+            rule.weekdays.append(start.dayOfWeek());
+        std::sort(rule.weekdays.begin(), rule.weekdays.end());
+        break;
+    case Freq::Monthly:
+    case Freq::Yearly: {
+        const bool yearly = rule.freq == Freq::Yearly;
+        if (!byMonthDay.isEmpty() && !byDay.isEmpty())
+            return markCustom();
+        if (!byDay.isEmpty()) {
+            int ordinal = 0, day = 0;
+            if (byDay.size() != 1 || !splitByDay(byDay.first(), &ordinal, &day)
+                || !(ordinal == -1 || (ordinal >= 1 && ordinal <= 4)))
+                return markCustom();
+            if (yearly && byMonth.size() != 1)
+                return markCustom();
+            rule.by = By::Weekday;
+            rule.ordinal = ordinal;
+            rule.weekday = day;
+            if (yearly)
+                rule.month = byMonth.first().toInt();
+        } else if (yearly) {
+            if (!byMonth.isEmpty() || !byMonthDay.isEmpty())
+                return markCustom();  // "on the start date" writes neither
+        } else {
+            if (!byMonth.isEmpty() || byMonthDay.size() > 1)
+                return markCustom();
+            rule.monthDay = byMonthDay.isEmpty() ? start.day() : byMonthDay.first().toInt();
+            if (rule.monthDay < 1 || rule.monthDay > 31)
+                return markCustom();
+        }
+        break;
+    }
+    case Freq::None:
+        break;
+    }
+    return rule;
+}
+
+QString RepeatRule::toRRule(const QString &untilValue) const
+{
+    if (custom)
+        return customText;
+    if (freq == Freq::None)
+        return {};
+
+    QStringList parts;
+    static const char *const kFreq[] = { "", "DAILY", "WEEKLY", "MONTHLY", "YEARLY" };
+    parts << QStringLiteral("FREQ=%1").arg(QLatin1String(kFreq[static_cast<int>(freq)]));
+    if (interval > 1)
+        parts << QStringLiteral("INTERVAL=%1").arg(interval);
+
+    auto byDayToken = [](int ordinal, int day) {
+        return (ordinal ? QString::number(ordinal) : QString()) + QLatin1String(kDays[day - 1]);
+    };
+    if (freq == Freq::Weekly && !weekdays.isEmpty()) {
+        QStringList days;
+        for (int d : weekdays)
+            days << QLatin1String(kDays[d - 1]);
+        parts << QStringLiteral("BYDAY=%1").arg(days.join(QLatin1Char(',')));
+    } else if (freq == Freq::Monthly) {
+        if (by == By::Weekday)
+            parts << QStringLiteral("BYDAY=%1").arg(byDayToken(ordinal, weekday));
+        else
+            parts << QStringLiteral("BYMONTHDAY=%1").arg(monthDay);
+    } else if (freq == Freq::Yearly && by == By::Weekday) {
+        parts << QStringLiteral("BYMONTH=%1").arg(month)
+              << QStringLiteral("BYDAY=%1").arg(byDayToken(ordinal, weekday));
+    }
+
+    if (end == End::Count)
+        parts << QStringLiteral("COUNT=%1").arg(count);
+    else if (end == End::Until)
+        parts << QStringLiteral("UNTIL=%1").arg(untilValue);
+    if (!wkst.isEmpty())
+        parts << QStringLiteral("WKST=%1").arg(wkst);
+    return parts.join(QLatin1Char(';'));
+}
+
+QString RepeatRule::describe() const
+{
+    if (custom)
+        return tr("Custom rule");
+    if (freq == Freq::None)
+        return tr("Does not repeat");
+
+    const QLocale locale;
+    QString text;
+    switch (freq) {
+    case Freq::Daily:
+        text = interval == 1 ? tr("Daily") : tr("Every %1 days").arg(interval);
+        break;
+    case Freq::Weekly: {
+        QStringList days;
+        for (int d : weekdays)
+            days << locale.dayName(d, QLocale::ShortFormat);
+        text = (interval == 1 ? tr("Weekly") : tr("Every %1 weeks").arg(interval))
+               + tr(", on %1").arg(days.join(QStringLiteral(", ")));
+        break;
+    }
+    case Freq::Monthly:
+        text = interval == 1 ? tr("Monthly") : tr("Every %1 months").arg(interval);
+        text += by == By::Weekday
+            ? tr(", on the %1 %2").arg(ordinalWord(ordinal), locale.dayName(weekday))
+            : tr(", on day %1").arg(monthDay);
+        break;
+    case Freq::Yearly:
+        text = interval == 1 ? tr("Yearly") : tr("Every %1 years").arg(interval);
+        if (by == By::Weekday)
+            text += tr(", on the %1 %2 of %3")
+                        .arg(ordinalWord(ordinal), locale.dayName(weekday),
+                             locale.monthName(month));
+        break;
+    case Freq::None:
+        break;
+    }
+    if (end == End::Count)
+        text += tr(", %1 times").arg(count);
+    else if (end == End::Until)
+        text += tr(", until %1").arg(locale.toString(until, QLocale::ShortFormat));
+    return text;
+}
+
+bool RepeatRule::operator==(const RepeatRule &o) const
+{
+    return freq == o.freq && interval == o.interval && weekdays == o.weekdays
+        && by == o.by && monthDay == o.monthDay && ordinal == o.ordinal
+        && weekday == o.weekday && month == o.month && end == o.end
+        && until == o.until && count == o.count && wkst == o.wkst
+        && custom == o.custom && customText == o.customText;
+}