/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module org.eclipse.swt.widgets.DateTime;

import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.internal.gtk.OS;
import org.eclipse.swt.internal.Compatibility;

import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.TypedListener;

import java.lang.all;

version(Tango){
    import tango.util.Convert;

    static import tango.text.Util;
    //static import tango.text.locale.Core;
    static import tango.time.Time;
    static import tango.time.WallClock;
    static import tango.time.chrono.Gregorian;
    static import tango.time.chrono.Calendar;
} else { // Phobos
    import std.conv;
    static import std.datetime;
}


private class Calendar{
    enum {
        AM,
        PM
    }
    enum {
        AM_PM,
        HOUR,
        MINUTE,
        SECOND,
        MONTH,
        YEAR,
        DAY_OF_MONTH,
        DAY_SELECTED,
        MONTH_CHANGED,
        HOUR_OF_DAY,
    }
    private static const int[] MONTH_DAYS = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];
    static private Calendar instance;

    private int second;
    private int minute;
    private int hour;
    private int dayofmonth;
    private int month;
    private int year;

    static Calendar getInstance(){
        if( instance is null ){
            synchronized {
                if( instance is null ){
                    instance = new Calendar;
                }
            }
        }
        return instance;
    }

    public this(){
        version(Tango){
            tango.time.Time.Time time = tango.time.WallClock.WallClock.now();
            tango.time.Time.TimeSpan span = time.time.span;
            this.second = span.seconds % 60;
            this.minute = span.minutes % 60;
            this.hour   = span.hours;
            auto greg = tango.time.chrono.Gregorian.Gregorian.generic;
            this.dayofmonth = greg.getDayOfMonth( time );
            this.month      = greg.getMonth( time );
            this.year       = greg.getYear( time );
        } else { // Phobos
            auto time = std.datetime.Clock.currTime();
            this.second     = time.second;
            this.minute     = time.minute;
            this.hour       = time.hour;
            this.dayofmonth = time.day;
            this.month      = time.month;
            this.year       = time.year;
        }
    }
    int getActualMaximum(int field){
        switch( field ){
        case YEAR:
            return 2100;
        case MONTH:
            return cast(int)MONTH_DAYS.length -1;
        case DAY_OF_MONTH:
            return MONTH_DAYS[month];
        case HOUR:
            return 11;
        case HOUR_OF_DAY:
            return 23;
        case MINUTE:
            return 59;
        case SECOND:
            return 59;
        case AM_PM:
            return PM;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }

    int getActualMinimum(int field){
        switch( field ){
        case YEAR:
            return 1900;
        case MONTH:
            return 0;
        case DAY_OF_MONTH:
            return 1;
        case HOUR:
        case HOUR_OF_DAY:
            return 0;
        case MINUTE:
            return 0;
        case SECOND:
            return 0;
        case AM_PM:
            return AM;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }

    int getMaximum(int field){
        switch( field ){
        case YEAR:
            return 2100;
        case MONTH:
            return 11;
        case DAY_OF_MONTH:
            return 31;
        case HOUR:
            return 11;
        case HOUR_OF_DAY:
            return 23;
        case MINUTE:
            return 59;
        case SECOND:
            return 59;
        case AM_PM:
            return PM;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }

    int getMinimum(int field){
        switch( field ){
        case YEAR:
            return 1900;
        case MONTH:
            return 0;
        case DAY_OF_MONTH:
            return 1;
        case HOUR:
        case HOUR_OF_DAY:
            return 0;
        case MINUTE:
            return 0;
        case SECOND:
            return 0;
        case AM_PM:
            return AM;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }
    int get(int field){
        switch( field ){
        case YEAR:
            return year;
        case MONTH:
            return month;
        case DAY_OF_MONTH:
            return dayofmonth;
        case HOUR:
            return hour;
        case HOUR_OF_DAY:
            return hour % 12;
        case MINUTE:
            return minute;
        case SECOND:
            return second;
        case AM_PM:
            return ( hour < 12 ) ? AM : PM;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }
    void set( int year, int month, int day ){
        this.year = year;
        this.month = month;
        this.dayofmonth = day;
    }
    void set(int field, int value){
        switch( field ){
        case YEAR:
            year = value;
            break;
        case MONTH:
            assert( value >= 0 && value < 12 );
            month = value;
            break;
        case DAY_OF_MONTH:
            assert( value > 0 && value <= getActualMaximum( DAY_OF_MONTH ) );
            dayofmonth = value;
            break;
        case HOUR:
            assert( value >= 0 && value < 12 );
            hour = value;
            break;
        case HOUR_OF_DAY:
            assert( value >= 0 && value < 24 );
            hour = value;
            break;
        case MINUTE:
            assert( value >= 0 && value < 60 );
            minute = value;
            break;
        case SECOND:
            assert( value >= 0 && value < 60 );
            second = value;
            break;
        case AM_PM:
            if( get(field) is AM ){
                if( value is AM ){
                    return;
                }
                else{
                    hour += 12;
                }
            }
            else{ // PM
                if( value is AM ){
                    hour -= 12;
                }
                else{
                    return;
                }
            }
            break;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }

    void roll(int field, int value){
        switch( field ){
        case YEAR:
            year = value;
            break;
        case MONTH:
            month += value;
            month %= 12;
            break;
        case DAY_OF_MONTH:
            dayofmonth += value;
            dayofmonth %= getActualMaximum( DAY_OF_MONTH );
            break;
        case HOUR:
        case HOUR_OF_DAY:
            hour += value;
            hour %= 24;
            break;
        case MINUTE:
            minute += value;
            minute %= 60;
            break;
        case SECOND:
            second += value;
            second %= 60;
            break;
        case AM_PM:
            set( AM_PM, get( AM_PM ) is AM ? PM : AM );
            break;
        default: assert( false, Format( "no matching switch case for field {}.", field ));
        }
    }
}


private class DateFormatSymbols {
    private enum String[] ampm = [ "AM"[], "PM" ];
    TryConst!(String[]) getAmPmStrings(){
        return ampm;
    }
}


/**
 * Instances of this class are selectable user interface
 * objects that allow the user to enter and modify date
 * or time values.
 * <p>
 * Note that although this class is a subclass of <code>Composite</code>,
 * it does not make sense to add children to it, or set a layout on it.
 * </p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>DATE, TIME, CALENDAR, SHORT, MEDIUM, LONG</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles DATE, TIME, or CALENDAR may be specified,
 * and only one of the styles SHORT, MEDIUM, or LONG may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see <a href="http://www.eclipse.org/swt/snippets/#datetime">DateTime snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 *
 * @since 3.3
 */
public class DateTime : Composite {
    int day, month, year, hours, minutes, seconds;

    static const int MIN_YEAR = 1752; // Gregorian switchover in North America: September 19, 1752
    static const int MAX_YEAR = 9999;

    /* Emulated DATE and TIME variables */
    Calendar calendar;
    DateFormatSymbols formatSymbols;
    Button down, up;
    Text text;
    String format;
    Point[] fieldIndices;
    int[] fieldNames;
    int fieldCount, currentField = 0, characterCount = 0;
    bool ignoreVerify = false;
    static const String DEFAULT_SHORT_DATE_FORMAT = "MM/YYYY";
    static const String DEFAULT_MEDIUM_DATE_FORMAT = "MM/DD/YYYY";
    static const String DEFAULT_LONG_DATE_FORMAT = "MM/DD/YYYY";
    static const String DEFAULT_SHORT_TIME_FORMAT = "HH:MM AM";
    static const String DEFAULT_MEDIUM_TIME_FORMAT = "HH:MM:SS AM";
    static const String DEFAULT_LONG_TIME_FORMAT = "HH:MM:SS AM";



/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>SWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>SWT</code> style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a composite control which will be the parent of the new instance (cannot be null)
 * @param style the style of control to construct
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see SWT#DATE
 * @see SWT#TIME
 * @see SWT#CALENDAR
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public this (Composite parent, int style) {
    super (parent, checkStyle (style));
    if ((this.style & SWT.CALENDAR) is 0) {
        /* SWT.DATE and SWT.TIME */
        calendar = Calendar.getInstance();
        formatSymbols = new DateFormatSymbols();

        text = new Text(this, SWT.SINGLE);
        /* disable the native drag and drop for the date/time text field */
        OS.gtk_drag_dest_unset(text.handle);
        if ((this.style & SWT.DATE) !is 0) {
            setFormat((this.style & SWT.SHORT) !is 0 ? DEFAULT_SHORT_DATE_FORMAT : (this.style & SWT.LONG) !is 0 ? DEFAULT_LONG_DATE_FORMAT : DEFAULT_MEDIUM_DATE_FORMAT);
        } else { // SWT.TIME
            setFormat((this.style & SWT.SHORT) !is 0 ? DEFAULT_SHORT_TIME_FORMAT : (this.style & SWT.LONG) !is 0 ? DEFAULT_LONG_TIME_FORMAT : DEFAULT_MEDIUM_TIME_FORMAT);
        }
        text.setText(getFormattedString(this.style));
        Listener listener = new class () Listener {
            public void handleEvent(Event event) {
                switch(event.type) {
                    case SWT.KeyDown: onKeyDown(event); break;
                    case SWT.FocusIn: onFocusIn(event); break;
                    case SWT.FocusOut: onFocusOut(event); break;
                    case SWT.MouseDown: onMouseClick(event); break;
                    case SWT.MouseUp: onMouseClick(event); break;
                    case SWT.Verify: onVerify(event); break;
                    default:
                }
            }
        };
        text.addListener(SWT.KeyDown, listener);
        text.addListener(SWT.FocusIn, listener);
        text.addListener(SWT.FocusOut, listener);
        text.addListener(SWT.MouseDown, listener);
        text.addListener(SWT.MouseUp, listener);
        text.addListener(SWT.Verify, listener);
        up = new Button(this, SWT.ARROW | SWT.UP);
        //up.setToolTipText(SWT.getMessage ("SWT_Up")); //$NON-NLS-1$
        down = new Button(this, SWT.ARROW | SWT.DOWN);
        //down.setToolTipText(SWT.getMessage ("SWT_Down")); //$NON-NLS-1$
        up.addListener(SWT.Selection, new class() Listener {
            public void handleEvent(Event event) {
                incrementField(+1);
                text.setFocus();
            }
        });
        down.addListener(SWT.Selection, new class() Listener {
            public void handleEvent(Event event) {
                incrementField(-1);
                text.setFocus();
            }
        });
        addListener(SWT.Resize, new class() Listener {
            public void handleEvent(Event event) {
                onResize(event);
            }
        });
    }
}

static int checkStyle (int style) {
    /*
    * Even though it is legal to create this widget
    * with scroll bars, they serve no useful purpose
    * because they do not automatically scroll the
    * widget's client area.  The fix is to clear
    * the SWT style.
    */
    style &= ~(SWT.H_SCROLL | SWT.V_SCROLL);
    style = checkBits (style, SWT.DATE, SWT.TIME, SWT.CALENDAR, 0, 0, 0);
    return checkBits (style, SWT.MEDIUM, SWT.SHORT, SWT.LONG, 0, 0, 0);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the control is selected by the user, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * <code>widgetSelected</code> is called when the user changes the control's value.
 * <code>widgetDefaultSelected</code> is not called.
 * </p>
 *
 * @param listener the listener which should be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener (SelectionListener listener) {
    checkWidget ();
    if (listener is null) error (SWT.ERROR_NULL_ARGUMENT);
    TypedListener typedListener = new TypedListener (listener);
    addListener (SWT.Selection, typedListener);
    addListener (SWT.DefaultSelection, typedListener);
}

override
protected void checkSubclass () {
    if (!isValidSubclass ()) error (SWT.ERROR_INVALID_SUBCLASS);
}

override
public Point computeSize (int wHint, int hHint, bool changed) {
    checkWidget ();
    int width = 0, height = 0;
    if (wHint is SWT.DEFAULT || hHint is SWT.DEFAULT) {
        if ((style & SWT.CALENDAR) !is 0) {
            // TODO: CALENDAR computeSize
            width = 300;
            height = 200;
        } else {
            /* SWT.DATE and SWT.TIME */
            GC gc = new GC(text);
            Point textSize = gc.stringExtent(getComputeSizeString(style));
            gc.dispose();
            Rectangle trim = text.computeTrim(0, 0, textSize.x, textSize.y);
            Point buttonSize = up.computeSize(SWT.DEFAULT, SWT.DEFAULT, changed);
            width = trim.width + buttonSize.x;
            height = Math.max(trim.height, buttonSize.y);
        }
    }
    if (width is 0) width = DEFAULT_WIDTH;
    if (height is 0) height = DEFAULT_HEIGHT;
    if (wHint !is SWT.DEFAULT) width = wHint;
    if (hHint !is SWT.DEFAULT) height = hHint;
    int border = getBorderWidth ();
    width += border * 2; height += border * 2;
    return new Point (width, height);
}

override
void createHandle (int index) {
    if ((style & SWT.CALENDAR) !is 0) {
        state |= HANDLE;
        fixedHandle = cast(GtkWidget*)OS.g_object_new (display.gtk_fixed_get_type (), null);
        if (fixedHandle is null) error (SWT.ERROR_NO_HANDLES);
        OS.gtk_fixed_set_has_window (fixedHandle, true);
        handle = cast(GtkWidget*)OS.gtk_calendar_new ();
        if (handle is null) error (SWT.ERROR_NO_HANDLES);
        OS.gtk_container_add (fixedHandle, handle);
        if (OS.GTK_VERSION >= OS.buildVERSION(2, 4, 0)) {
            OS.gtk_calendar_set_display_options(handle, OS.GTK_CALENDAR_SHOW_HEADING | OS.GTK_CALENDAR_SHOW_DAY_NAMES);
        } else {
            OS.gtk_calendar_display_options(handle, OS.GTK_CALENDAR_SHOW_HEADING | OS.GTK_CALENDAR_SHOW_DAY_NAMES);
        }
    } else {
        super.createHandle(index);
    }
}

override
void createWidget (int index) {
    super.createWidget (index);
    if ((style & SWT.CALENDAR) !is 0) {
        getDate();
    }
}

void commitCurrentField() {
    if (characterCount > 0) {
        characterCount = 0;
        int fieldName = fieldNames[currentField];
        int start = fieldIndices[currentField].x;
        int end = fieldIndices[currentField].y;
        String value = text.getText(start, end - 1);
        int s = value.lastIndexOf(' ');
        if (s !is -1) value = value.substring(s + 1);
        int newValue = unformattedIntValue(fieldName, value, characterCount is 0, calendar.getActualMaximum(fieldName));
        if (newValue !is -1) setTextField(fieldName, newValue, true, true);
    }
}

String formattedStringValue(int fieldName, int value, bool adjust) {
    if (fieldName is Calendar.AM_PM) {
        return formatSymbols.getAmPmStrings()[value];
    }
    if (adjust) {
        if (fieldName is Calendar.HOUR && value is 0) {
            return to!(String)(12);
        }
        if (fieldName is Calendar.MONTH) {
            return to!(String)(value + 1);
        }
    }
    return to!(String)(value);
}

String getComputeSizeString(int style) {
    if ((style & SWT.DATE) !is 0) {
        return (style & SWT.SHORT) !is 0 ? DEFAULT_SHORT_DATE_FORMAT : (style & SWT.LONG) !is 0 ? DEFAULT_LONG_DATE_FORMAT : DEFAULT_MEDIUM_DATE_FORMAT;
    }
    // SWT.TIME
    return (style & SWT.SHORT) !is 0 ? DEFAULT_SHORT_TIME_FORMAT : (style & SWT.LONG) !is 0 ? DEFAULT_LONG_TIME_FORMAT : DEFAULT_MEDIUM_TIME_FORMAT;
}

int getFieldIndex(int fieldName) {
    for (int i = 0; i < fieldCount; i++) {
        if (fieldNames[i] is fieldName) {
            return i;
        }
    }
    return -1;
}

String getFormattedString(int style) {
    if ((style & SWT.TIME) !is 0) {
        auto ampm = formatSymbols.getAmPmStrings();
        int h = calendar.get(Calendar.HOUR); if (h is 0) h = 12;
        int m = calendar.get(Calendar.MINUTE);
        int s = calendar.get(Calendar.SECOND);
        int a = calendar.get(Calendar.AM_PM);
        if ((style & SWT.SHORT) !is 0) return "" ~ (h < 10 ? " " : "") ~ to!(String)(h) ~ ":" ~ (m < 10 ? "0" : "") ~ to!(String)(m) ~ " " ~ ampm[a];
        return "" ~ (h < 10 ? " " : "") ~ to!(String)(h) ~ ":" ~ (m < 10 ? "0" : "") ~ to!(String)(m) ~ ":" ~ (s < 10 ? "0" : "") ~ to!(String)(s) ~ " " ~ ampm[a];
    }
    /* SWT.DATE */
    int y = calendar.get(Calendar.YEAR);
    int m = calendar.get(Calendar.MONTH) + 1;
    int d = calendar.get(Calendar.DAY_OF_MONTH);
    if ((style & SWT.SHORT) !is 0) return "" ~ (m < 10 ? " " : "") ~ to!(String)(m) ~ "/" ~ to!(String)(y);
    return "" ~ (m < 10 ? " " : "") ~ to!(String)(m) ~ "/" ~ (d < 10 ? " " : "") ~ to!(String)(d) ~ "/" ~ to!(String)(y);
}

void getDate() {
    uint y;
    uint m;
    uint d;
    OS.gtk_calendar_get_date(handle, &y, &m, &d);
    year = y;
    month = m;
    day = d;
}

/**
 * Returns the receiver's date, or day of the month.
 * <p>
 * The first day of the month is 1, and the last day depends on the month and year.
 * </p>
 *
 * @return a positive integer beginning with 1
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getDay () {
    checkWidget ();
    if ((style & SWT.CALENDAR) !is 0) {
        getDate();
        return day;
    } else {
        return calendar.get(Calendar.DAY_OF_MONTH);
    }
}

/**
 * Returns the receiver's hours.
 * <p>
 * Hours is an integer between 0 and 23.
 * </p>
 *
 * @return an integer between 0 and 23
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getHours () {
    checkWidget ();
    if ((style & SWT.CALENDAR) !is 0) {
        return hours;
    } else {
        return calendar.get(Calendar.HOUR_OF_DAY);
    }
}

/**
 * Returns the receiver's minutes.
 * <p>
 * Minutes is an integer between 0 and 59.
 * </p>
 *
 * @return an integer between 0 and 59
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getMinutes () {
    checkWidget ();
    if ((style & SWT.CALENDAR) !is 0) {
        return minutes;
    } else {
        return calendar.get(Calendar.MINUTE);
    }
}

/**
 * Returns the receiver's month.
 * <p>
 * The first month of the year is 0, and the last month is 11.
 * </p>
 *
 * @return an integer between 0 and 11
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getMonth () {
    checkWidget ();
    if ((style & SWT.CALENDAR) !is 0) {
        getDate();
        return month;
    } else {
        return calendar.get(Calendar.MONTH);
    }
}

override
String getNameText() {
    if((style & SWT.TIME) !is 0){
        return Format( "{}:{}:{}", getHours(), getMinutes(), getSeconds() );
    }
    else{
        return Format( "{}/{}/{}", (getMonth() + 1), getDay(), getYear() );
    }
}

/**
 * Returns the receiver's seconds.
 * <p>
 * Seconds is an integer between 0 and 59.
 * </p>
 *
 * @return an integer between 0 and 59
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getSeconds () {
    checkWidget ();
    if ((style & SWT.CALENDAR) !is 0) {
        return seconds;
    } else {
        return calendar.get(Calendar.SECOND);
    }
}

/**
 * Returns the receiver's year.
 * <p>
 * The first year is 1752 and the last year is 9999.
 * </p>
 *
 * @return an integer between 1752 and 9999
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getYear () {
    checkWidget ();
    if ((style & SWT.CALENDAR) !is 0) {
        getDate();
        return year;
    } else {
        return calendar.get(Calendar.YEAR);
    }
}

override int gtk_day_selected (GtkWidget* widget) {
    sendSelectionEvent ();
    return 0;
}

override int gtk_month_changed (GtkWidget* widget) {
    sendSelectionEvent ();
    return 0;
}

override
void hookEvents () {
    super.hookEvents();
    if ((style & SWT.CALENDAR) !is 0) {
        OS.g_signal_connect_closure (handle, OS.day_selected.ptr, display.closures [DAY_SELECTED], false);
        OS.g_signal_connect_closure (handle, OS.month_changed.ptr, display.closures [MONTH_CHANGED], false);
    }
}

bool isValid(int fieldName, int value) {
    Calendar validCalendar;
    if ((style & SWT.CALENDAR) !is 0) {
        validCalendar = Calendar.getInstance();
        validCalendar.set(Calendar.YEAR, year);
        validCalendar.set(Calendar.MONTH, month);
    } else {
        validCalendar = calendar;
    }
    int min = validCalendar.getActualMinimum(fieldName);
    int max = validCalendar.getActualMaximum(fieldName);
    return value >= min && value <= max;
}

bool isValid(int year, int month, int day) {
    Calendar valid = Calendar.getInstance();
    valid.set(year, month, day);
    return valid.get(Calendar.YEAR) is year && valid.get(Calendar.MONTH) is month && valid.get(Calendar.DAY_OF_MONTH) is day;
}

void incrementField(int amount) {
    int fieldName = fieldNames[currentField];
    int value = calendar.get(fieldName);
    if (fieldName is Calendar.HOUR) {
        int max = calendar.getMaximum(Calendar.HOUR);
        int min = calendar.getMinimum(Calendar.HOUR);
        if ((value is max && amount is 1) || (value is min && amount is -1)) {
            int temp = currentField;
            currentField = getFieldIndex(Calendar.AM_PM);
            setTextField(Calendar.AM_PM, (calendar.get(Calendar.AM_PM) + 1) % 2, true, true);
            currentField = temp;
        }
    }
    setTextField(fieldName, value + amount, true, true);
}

void onKeyDown(Event event) {
    int fieldName;
    switch (event.keyCode) {
        case SWT.ARROW_RIGHT:
        case SWT.KEYPAD_DIVIDE:
            // a right arrow or a valid separator navigates to the field on the right, with wraping
            selectField((currentField + 1) % fieldCount);
            break;
        case SWT.ARROW_LEFT:
            // navigate to the field on the left, with wrapping
            int index = currentField - 1;
            selectField(index < 0 ? fieldCount - 1 : index);
            break;
        case SWT.ARROW_UP:
        case SWT.KEYPAD_ADD:
            // set the value of the current field to value + 1, with wrapping
            commitCurrentField();
            incrementField(+1);
            break;
        case SWT.ARROW_DOWN:
        case SWT.KEYPAD_SUBTRACT:
            // set the value of the current field to value - 1, with wrapping
            commitCurrentField();
            incrementField(-1);
            break;
        case SWT.HOME:
            // set the value of the current field to its minimum
            fieldName = fieldNames[currentField];
            setTextField(fieldName, calendar.getActualMinimum(fieldName), true, true);
            break;
        case SWT.END:
            // set the value of the current field to its maximum
            fieldName = fieldNames[currentField];
            setTextField(fieldName, calendar.getActualMaximum(fieldName), true, true);
            break;
        default:
            switch (event.character) {
                case '/':
                case ':':
                case '-':
                case '.':
                    // a valid separator navigates to the field on the right, with wraping
                    selectField((currentField + 1) % fieldCount);
                    break;
                default:
            }
    }
}

void onFocusIn(Event event) {
    selectField(currentField);
}

void onFocusOut(Event event) {
    commitCurrentField();
}

void onMouseClick(Event event) {
    if (event.button !is 1) return;
    Point sel = text.getSelection();
    for (int i = 0; i < fieldCount; i++) {
        if (sel.x >= fieldIndices[i].x && sel.x <= fieldIndices[i].y) {
            currentField = i;
            break;
        }
    }
    selectField(currentField);
}

void onResize(Event event) {
    Rectangle rect = getClientArea ();
    int width = rect.width;
    int height = rect.height;
    Point buttonSize = up.computeSize(SWT.DEFAULT, height);
    int buttonHeight = buttonSize.y / 2;
    text.setBounds(0, 0, width - buttonSize.x, height);
    up.setBounds(width - buttonSize.x, 0, buttonSize.x, buttonHeight);
    down.setBounds(width - buttonSize.x, buttonHeight, buttonSize.x, buttonHeight);
}

void onVerify(Event event) {
    if (ignoreVerify) return;
    event.doit = false;
    int fieldName = fieldNames[currentField];
    int start = fieldIndices[currentField].x;
    int end = fieldIndices[currentField].y;
    int length_ = end - start;
    String newText = event.text;
    if (fieldName is Calendar.AM_PM) {
        auto ampm = formatSymbols.getAmPmStrings();
        if (newText.equalsIgnoreCase(ampm[Calendar.AM].substring(0, 1)) || newText.equalsIgnoreCase(ampm[Calendar.AM])) {
            setTextField(fieldName, Calendar.AM, true, false);
        } else if (newText.equalsIgnoreCase(ampm[Calendar.PM].substring(0, 1)) || newText.equalsIgnoreCase(ampm[Calendar.PM])) {
            setTextField(fieldName, Calendar.PM, true, false);
        }
        return;
    }
    if (characterCount > 0) {
        try {
            Integer.parseInt(newText);
        } catch (NumberFormatException ex) {
            return;
        }
        String value = text.getText(start, end - 1);
        int s = value.lastIndexOf(' ');
        if (s !is -1) value = value.substring(s + 1);
        newText = value ~ newText;
    }
    ptrdiff_t newTextLength = newText.length;
    bool first = characterCount is 0;
    characterCount = (newTextLength < length_) ? cast(int)/*64bit*/newTextLength : 0;
    int max = calendar.getActualMaximum(fieldName);
    int min = calendar.getActualMinimum(fieldName);
    int newValue = unformattedIntValue(fieldName, newText, characterCount is 0, max);
    if (newValue is -1) {
        characterCount = 0;
        return;
    }
    if (first && newValue is 0 && length_ > 1) {
        setTextField(fieldName, newValue, false, false);
    } else if (min <= newValue && newValue <= max) {
        setTextField(fieldName, newValue, characterCount is 0, characterCount is 0);
    } else {
        if (newTextLength >= length_) {
            newText = newText.substring(cast(int)/*64bit*/(newTextLength - length_ + 1));
            newValue = unformattedIntValue(fieldName, newText, characterCount is 0, max);
            if (newValue !is -1) {
                characterCount = length_ - 1;
                if (min <= newValue && newValue <= max) {
                    setTextField(fieldName, newValue, characterCount is 0, true);
                }
            }
        }
    }
}

override
void releaseWidget () {
    super.releaseWidget();
    //TODO: need to do anything here?
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the control is selected by the user.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #addSelectionListener
 */
public void removeSelectionListener (SelectionListener listener) {
    checkWidget ();
    if (listener is null) error (SWT.ERROR_NULL_ARGUMENT);
    if (eventTable is null) return;
    eventTable.unhook (SWT.Selection, listener);
    eventTable.unhook (SWT.DefaultSelection, listener);
}

void selectField(int index) {
    if (index !is currentField) {
        commitCurrentField();
    }
    int start = fieldIndices[index].x;
    int end = fieldIndices[index].y;
    Point pt = text.getSelection();
    if (index is currentField && start is pt.x && end is pt.y) return;
    currentField = index;
    display.asyncExec(new class( start, end ) Runnable {
        int start, end;
        this( int start, int end ){
            this.start = start; this.end = end;
        }
        public void run() {
            if (!text.isDisposed()) {
                String value = text.getText(start, end - 1);
                int s = value.lastIndexOf(' ');
                if (s is -1 ) s = start;
                else s = start + s + 1;
                text.setSelection(s, end);
            }
        }
    });
}

void sendSelectionEvent () {
    uint y;
    uint m;
    uint d;
    OS.gtk_calendar_get_date(handle, &y, &m, &d);
    //TODO: hours, minutes, seconds?
    if (d !is day ||
        m !is month ||
        y !is year) {
        year = y;
        month = m;
        day = d;
        postEvent (SWT.Selection);
    }
}

override
public void setBackground(Color color) {
    checkWidget();
    super.setBackground(color);
    if (text !is null) text.setBackground(color);
}

override
public void setFont(Font font) {
    checkWidget();
    super.setFont(font);
    if (text !is null) text.setFont(font);
    redraw();
}

override
public void setForeground(Color color) {
    checkWidget();
    super.setForeground(color);
    if (text !is null) text.setForeground(color);
}

/*public*/ void setFormat(String string) {
    checkWidget();
    // TODO: this needs to be locale sensitive
    fieldCount = (style & SWT.DATE) !is 0 ? ((style & SWT.SHORT) !is 0 ? 2 : 3) : ((style & SWT.SHORT) !is 0 ? 3 : 4);
    fieldIndices = new Point[fieldCount];
    fieldNames = new int[fieldCount];
    if ((style & SWT.DATE) !is 0) {
        fieldNames[0] = Calendar.MONTH;
        fieldIndices[0] = new Point(0, 2);
        if ((style & SWT.SHORT) !is 0) {
            fieldNames[1] = Calendar.YEAR;
            fieldIndices[1] = new Point(3, 7);
        } else {
            fieldNames[1] = Calendar.DAY_OF_MONTH;
            fieldIndices[1] = new Point(3, 5);
            fieldNames[2] = Calendar.YEAR;
            fieldIndices[2] = new Point(6, 10);
        }
    } else { /* SWT.TIME */
        fieldNames[0] = Calendar.HOUR;
        fieldIndices[0] = new Point(0, 2);
        fieldNames[1] = Calendar.MINUTE;
        fieldIndices[1] = new Point(3, 5);
        if ((style & SWT.SHORT) !is 0) {
            fieldNames[2] = Calendar.AM_PM;
            fieldIndices[2] = new Point(6, 8);
        } else {
            fieldNames[2] = Calendar.SECOND;
            fieldIndices[2] = new Point(6, 8);
            fieldNames[3] = Calendar.AM_PM;
            fieldIndices[3] = new Point(9, 11);
        }
    }
}

void setField(int fieldName, int value) {
    if (calendar.get(fieldName) is value) return;
    if (fieldName is Calendar.AM_PM) {
        calendar.roll(Calendar.HOUR_OF_DAY, 12); // TODO: needs more work for setFormat and locale
    }
    calendar.set(fieldName, value);
    postEvent(SWT.Selection);
}

void setTextField(int fieldName, int value, bool commit, bool adjust) {
    if (commit) {
        int max = calendar.getActualMaximum(fieldName);
        int min = calendar.getActualMinimum(fieldName);
        if (fieldName is Calendar.YEAR) {
            max = MAX_YEAR;
            min = MIN_YEAR;
            /* Special case: convert 1 or 2-digit years into reasonable 4-digit years. */
            int currentYear = Calendar.getInstance().get(Calendar.YEAR);
            int currentCentury = (currentYear / 100) * 100;
            if (value < (currentYear + 30) % 100) value += currentCentury;
            else if (value < 100) value += currentCentury - 100;
        }
        if (value > max) value = min; // wrap
        if (value < min) value = max; // wrap
    }
    int start = fieldIndices[currentField].x;
    int end = fieldIndices[currentField].y;
    text.setSelection(start, end);
    String newValue = formattedStringValue(fieldName, value, adjust);
    StringBuffer buffer = new StringBuffer(newValue);
    /* Convert leading 0's into spaces. */
    int prependCount = end - start - buffer.length();
    for (int i = 0; i < prependCount; i++) {
        switch (fieldName) {
        case Calendar.MINUTE:
        case Calendar.SECOND:
            buffer.insert(0, 0);
        break;
        default:
            buffer.insert(0, ' ');
        break;
        }
    }
    newValue = buffer.toString();
    ignoreVerify = true;
    text.insert(newValue);
    ignoreVerify = false;
    selectField(currentField);
    if (commit) setField(fieldName, value);
}

/**
 * Sets the receiver's year, month, and day in a single operation.
 * <p>
 * This is the recommended way to set the date, because setting the year,
 * month, and day separately may result in invalid intermediate dates.
 * </p>
 *
 * @param year an integer between 1752 and 9999
 * @param month an integer between 0 and 11
 * @param day a positive integer beginning with 1
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.4
 */
public void setDate (int year, int month, int day) {
    checkWidget ();
    if (!isValid(year, month, day)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.year = year;
        this.month = month;
        this.day = day;
        OS.gtk_calendar_select_month(handle, month, year);
        OS.gtk_calendar_select_day(handle, day);
    } else {
        calendar.set(Calendar.YEAR, year);
        calendar.set(Calendar.MONTH, month);
        calendar.set(Calendar.DAY_OF_MONTH, day);
        updateControl();
    }
}

/**
 * Sets the receiver's date, or day of the month, to the specified day.
 * <p>
 * The first day of the month is 1, and the last day depends on the month and year.
 * </p>
 *
 * @param day a positive integer beginning with 1
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setDay (int day) {
    checkWidget ();
    if (!isValid(Calendar.DAY_OF_MONTH, day)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.day = day;
        OS.gtk_calendar_select_day(handle, day);
    } else {
        calendar.set(Calendar.DAY_OF_MONTH, day);
        updateControl();
    }
}

/**
 * Sets the receiver's hours.
 * <p>
 * Hours is an integer between 0 and 23.
 * </p>
 *
 * @param hours an integer between 0 and 23
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setHours (int hours) {
    checkWidget ();
    if (!isValid(Calendar.HOUR_OF_DAY, hours)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.hours = hours;
    } else {
        calendar.set(Calendar.HOUR_OF_DAY, hours);
        updateControl();
    }
}

/**
 * Sets the receiver's minutes.
 * <p>
 * Minutes is an integer between 0 and 59.
 * </p>
 *
 * @param minutes an integer between 0 and 59
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinutes (int minutes) {
    checkWidget ();
    if (!isValid(Calendar.MINUTE, minutes)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.minutes = minutes;
    } else {
        calendar.set(Calendar.MINUTE, minutes);
        updateControl();
    }
}

/**
 * Sets the receiver's month.
 * <p>
 * The first month of the year is 0, and the last month is 11.
 * </p>
 *
 * @param month an integer between 0 and 11
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMonth (int month) {
    checkWidget ();
    if (!isValid(Calendar.MONTH, month)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.month = month;
        OS.gtk_calendar_select_month(handle, month, year);
    } else {
        calendar.set(Calendar.MONTH, month);
        updateControl();
    }
}

/**
 * Sets the receiver's seconds.
 * <p>
 * Seconds is an integer between 0 and 59.
 * </p>
 *
 * @param seconds an integer between 0 and 59
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setSeconds (int seconds) {
    checkWidget ();
    if (!isValid(Calendar.SECOND, seconds)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.seconds = seconds;
    } else {
        calendar.set(Calendar.SECOND, seconds);
        updateControl();
    }
}

/**
 * Sets the receiver's hours, minutes, and seconds in a single operation.
 *
 * @param hours an integer between 0 and 23
 * @param minutes an integer between 0 and 59
 * @param seconds an integer between 0 and 59
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @since 3.4
 */
public void setTime (int hours, int minutes, int seconds) {
    checkWidget ();
    if (!isValid(Calendar.HOUR_OF_DAY, hours)) return;
    if (!isValid(Calendar.MINUTE, minutes)) return;
    if (!isValid(Calendar.SECOND, seconds)) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.hours = hours;
        this.minutes = minutes;
        this.seconds = seconds;
    } else {
        calendar.set(Calendar.HOUR_OF_DAY, hours);
        calendar.set(Calendar.MINUTE, minutes);
        calendar.set(Calendar.SECOND, seconds);
        updateControl();
    }
}

/**
 * Sets the receiver's year.
 * <p>
 * The first year is 1752 and the last year is 9999.
 * </p>
 *
 * @param year an integer between 1752 and 9999
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setYear (int year) {
    checkWidget ();
    //if (!isValid(Calendar.YEAR, year)) return;
    if (year < MIN_YEAR || year > MAX_YEAR) return;
    if ((style & SWT.CALENDAR) !is 0) {
        this.year = year;
        OS.gtk_calendar_select_month(handle, month, year);
    } else {
        calendar.set(Calendar.YEAR, year);
        updateControl();
    }
}

int unformattedIntValue(int fieldName, String newText, bool adjust, int max) {
    int newValue;
    try {
        newValue = Integer.parseInt(newText);
    } catch (NumberFormatException ex) {
        return -1;
    }
    if (fieldName is Calendar.MONTH && adjust) {
        newValue--;
        if (newValue is -1) newValue = max;
    }
    if (fieldName is Calendar.HOUR && adjust) {
        if (newValue is 12) newValue = 0; // TODO: needs more work for setFormat and locale
    }
    return newValue;
}

public void updateControl() {
    if (text !is null) {
        String string = getFormattedString(style);
        ignoreVerify = true;
        text.setText(string);
        ignoreVerify = false;
    }
    redraw();
}
}