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**
** Copyright (C) 2017 The Qt Company Ltd.
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** This file is part of the Qt Labs Calendar module of the Qt Toolkit.
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****************************************************************************/

#include "qquickcalendarmodel_p.h"

#include <QtCore/private/qabstractitemmodel_p.h>

QT_BEGIN_NAMESPACE

/*!
    \qmltype CalendarModel
    \inherits QAbstractListModel
    \instantiates QQuickCalendarModel
    \inqmlmodule Qt.labs.calendar
    \brief A calendar model.

    CalendarModel provides a way of creating a range of MonthGrid
    instances. It is typically used as a model for a ListView that uses
    MonthGrid as a delegate.

    \snippet qtlabscalendar-calendarmodel.qml 1

    In addition to the \c index property, a list of model data roles
    are available in the context of each delegate:
    \table
        \row \li \b model.month : int \li The number of the month
        \row \li \b model.year : int \li The number of the year
    \endtable

    The Qt Labs Calendar module uses 0-based month numbers to be consistent
    with the JavaScript Date type, that is used by the QML language. This
    means that \c Date::getMonth() can be passed to the methods as is. When
    dealing with month numbers directly, it is highly recommended to use the
    following enumeration values to avoid confusion.

    \value Calendar.January January (0)
    \value Calendar.February February (1)
    \value Calendar.March March (2)
    \value Calendar.April April (3)
    \value Calendar.May May (4)
    \value Calendar.June June (5)
    \value Calendar.July July (6)
    \value Calendar.August August (7)
    \value Calendar.September September (8)
    \value Calendar.October October (9)
    \value Calendar.November November (10)
    \value Calendar.December December (11)

    \labs

    \sa MonthGrid, Calendar
*/

class QQuickCalendarModelPrivate : public QAbstractItemModelPrivate
{
    Q_DECLARE_PUBLIC(QQuickCalendarModel)

public:
    QQuickCalendarModelPrivate() : complete(false),
        from(1,1,1), to(275759, 9, 25), count(0)
    {
    }

    static int getCount(const QDate& from, const QDate &to);

    void populate(const QDate &from, const QDate &to, bool force = false);

    bool complete;
    QDate from;
    QDate to;
    int count;
};

int QQuickCalendarModelPrivate::getCount(const QDate& from, const QDate &to)
{
    if (!from.isValid() || !to.isValid())
        return 0;

    QDate f(from.year(), from.month(), 1);
    QDate t(to.year(), to.month(), to.daysInMonth());
    int days = f.daysTo(t);
    if (days < 0)
        return 0;

    QDate r = QDate(1, 1, 1).addDays(days);
    int years = r.year() - 1;
    int months = r.month() - 1;
    return 12 * years + months + (r.day() / t.day());
}

void QQuickCalendarModelPrivate::populate(const QDate &f, const QDate &t, bool force)
{
    Q_Q(QQuickCalendarModel);
    if (!force && f == from && t == to)
        return;

    int c = getCount(from, to);
    if (c != count) {
        q->beginResetModel();
        count = c;
        q->endResetModel();
        emit q->countChanged();
    } else {
        emit q->dataChanged(q->index(0, 0), q->index(c - 1, 0));
    }
}

QQuickCalendarModel::QQuickCalendarModel(QObject *parent) :
    QAbstractListModel(*(new QQuickCalendarModelPrivate), parent)
{
}

/*!
    \qmlproperty date Qt.labs.calendar::CalendarModel::from

    This property holds the start date.
*/
QDate QQuickCalendarModel::from() const
{
    Q_D(const QQuickCalendarModel);
    return d->from;
}

void QQuickCalendarModel::setFrom(const QDate &from)
{
    Q_D(QQuickCalendarModel);
    if (d->from != from) {
        if (d->complete)
            d->populate(from, d->to);
        d->from = from;
        emit fromChanged();
    }
}

/*!
    \qmlproperty date Qt.labs.calendar::CalendarModel::to

    This property holds the end date.
*/
QDate QQuickCalendarModel::to() const
{
    Q_D(const QQuickCalendarModel);
    return d->to;
}

void QQuickCalendarModel::setTo(const QDate &to)
{
    Q_D(QQuickCalendarModel);
    if (d->to != to) {
        if (d->complete)
            d->populate(d->from, to);
        d->to = to;
        emit toChanged();
    }
}

/*!
    \qmlmethod int Qt.labs.calendar::CalendarModel::monthAt(int index)

    Returns the month number at the specified model \a index.
*/
int QQuickCalendarModel::monthAt(int index) const
{
    Q_D(const QQuickCalendarModel);
    return d->from.addMonths(index).month() - 1;
}

/*!
    \qmlmethod int Qt.labs.calendar::CalendarModel::yearAt(int index)

    Returns the year number at the specified model \a index.
*/
int QQuickCalendarModel::yearAt(int index) const
{
    Q_D(const QQuickCalendarModel);
    return d->from.addMonths(index).year();
}

/*!
    \qmlmethod int Qt.labs.calendar::CalendarModel::indexOf(Date date)

    Returns the model index of the specified \a date.
*/
int QQuickCalendarModel::indexOf(const QDate &date) const
{
    Q_D(const QQuickCalendarModel);
    return d->getCount(d->from, date) - 1;
}

/*!
    \qmlmethod int Qt.labs.calendar::CalendarModel::indexOf(int year, int month)

    Returns the model index of the specified \a year and \a month.
*/
int QQuickCalendarModel::indexOf(int year, int month) const
{
    return indexOf(QDate(year, month + 1, 1));
}

QVariant QQuickCalendarModel::data(const QModelIndex &index, int role) const
{
    Q_D(const QQuickCalendarModel);
    if (index.isValid() && index.row() < d->count) {
        switch (role) {
        case MonthRole:
            return monthAt(index.row());
        case YearRole:
            return yearAt(index.row());
        default:
            break;
        }
    }
    return QVariant();
}

int QQuickCalendarModel::rowCount(const QModelIndex &parent) const
{
    Q_D(const QQuickCalendarModel);
    if (!parent.isValid())
        return d->count;
    return 0;
}

QHash<int, QByteArray> QQuickCalendarModel::roleNames() const
{
    QHash<int, QByteArray> roles;
    roles[MonthRole] = QByteArrayLiteral("month");
    roles[YearRole] = QByteArrayLiteral("year");
    return roles;
}

void QQuickCalendarModel::classBegin()
{
}

void QQuickCalendarModel::componentComplete()
{
    Q_D(QQuickCalendarModel);
    d->complete = true;
    d->populate(d->from, d->to, true);
}

QT_END_NAMESPACE