//  Copyright 2004 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry.form;

import java.text.DateFormatSymbols;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import org.apache.tapestry.ApplicationRuntimeException;
import org.apache.tapestry.IAsset;
import org.apache.tapestry.IEngine;
import org.apache.tapestry.IForm;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.IResourceLocation;
import org.apache.tapestry.IScript;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.engine.IScriptSource;
import org.apache.tapestry.html.Body;

/**
 * Provides a Form <tt>java.util.Date</tt> field component for selecting dates.
 *
 *  [<a href="../../../../../ComponentReference/DatePicker.html">Component Reference</a>]
 *
 * @author Paul Geerts
 * @author Malcolm Edgar
 * @version $Id$
 * @since 2.2
 * 
 */

public abstract class DatePicker extends AbstractFormComponent
{
    public abstract String getFormat();

    public abstract Date getValue();

    public abstract void setValue(Date value);

    public abstract boolean isDisabled();

    public abstract boolean getIncludeWeek();

    public abstract IAsset getIcon();

    private IScript _script;

    private static final String SYM_NAME = "name";
    private static final String SYM_FORMNAME = "formName";
    private static final String SYM_MONTHNAMES = "monthNames";
    private static final String SYM_SHORT_MONTHNAMES = "shortMonthNames";
    private static final String SYM_WEEKDAYNAMES = "weekDayNames";
    private static final String SYM_SHORT_WEEKDAYNAMES = "shortWeekDayNames";
    private static final String SYM_FIRSTDAYINWEEK = "firstDayInWeek";
    private static final String SYM_MINDAYSINFIRSTWEEK = "minimalDaysInFirstWeek";
    private static final String SYM_FORMAT = "format";
    private static final String SYM_INCL_WEEK = "includeWeek";
    private static final String SYM_VALUE = "value";
    private static final String SYM_BUTTONONCLICKHANDLER = "buttonOnclickHandler";

    // Output symbol

    private static final String SYM_BUTTONNAME = "buttonName";

    protected void finishLoad()
    {
        IEngine engine = getPage().getEngine();
        IScriptSource source = engine.getScriptSource();

        IResourceLocation location =
            getSpecification().getSpecificationLocation().getRelativeLocation("DatePicker.script");

        _script = source.getScript(location);
    }

    protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
    {
        IForm form = getForm(cycle);

        String name = form.getElementId(this);

        String format = getFormat();

        if (format == null)
            format = "dd MMM yyyy";

        SimpleDateFormat formatter = new SimpleDateFormat(format, getPage().getLocale());

        boolean disabled = isDisabled();

        if (!cycle.isRewinding())
        {
            Body body = Body.get(cycle);

            if (body == null)
                throw new ApplicationRuntimeException(
                    Tapestry.format("must-be-contained-by-body", "DatePicker"),
                    this,
                    null,
                    null);

            Locale locale = getPage().getLocale();
            DateFormatSymbols dfs = new DateFormatSymbols(locale);
            Calendar cal = Calendar.getInstance(locale);

            Date value = getValue();

            Map symbols = new HashMap();

            symbols.put(SYM_NAME, name);
            symbols.put(SYM_FORMAT, format);
            symbols.put(SYM_INCL_WEEK, getIncludeWeek() ? Boolean.TRUE : Boolean.FALSE);

            symbols.put(SYM_MONTHNAMES, makeStringList(dfs.getMonths(), 0, 12));
            symbols.put(SYM_SHORT_MONTHNAMES, makeStringList(dfs.getShortMonths(), 0, 12));
            symbols.put(SYM_WEEKDAYNAMES, makeStringList(dfs.getWeekdays(), 1, 8));
            symbols.put(SYM_SHORT_WEEKDAYNAMES, makeStringList(dfs.getShortWeekdays(), 1, 8));
            symbols.put(SYM_FIRSTDAYINWEEK, new Integer(cal.getFirstDayOfWeek() - 1));
            symbols.put(SYM_MINDAYSINFIRSTWEEK, new Integer(cal.getMinimalDaysInFirstWeek()));
            symbols.put(SYM_FORMNAME, form.getName());
            symbols.put(SYM_VALUE, value);

            _script.execute(cycle, body, symbols);

            writer.beginEmpty("input");
            writer.attribute("type", "text");
            writer.attribute("name", name);
            writer.attribute("title", formatter.toLocalizedPattern());

            if (value != null)
                writer.attribute("value", formatter.format(value));

            if (disabled)
                writer.attribute("disabled", "disabled");

            renderInformalParameters(writer, cycle);
            
            writer.printRaw("&nbsp;");

            if (!disabled)
            {
                writer.begin("a");
                writer.attribute("href", (String) symbols.get(SYM_BUTTONONCLICKHANDLER));
            }

            IAsset icon = getIcon();

            writer.beginEmpty("img");
            writer.attribute("src", icon.buildURL(cycle));
            writer.attribute("border", 0);

            if (!disabled)
                writer.end(); // <a>

        }

        if (form.isRewinding())
        {
            if (disabled)
                return;

            String textValue = cycle.getRequestContext().getParameter(name);

            if (Tapestry.isBlank(textValue))
                return;

            try
            {
                Date value = formatter.parse(textValue);

                setValue(value);
            }
            catch (ParseException ex)
            {
            }
        }

    }

    /**
     * Create a list of quoted strings. The list is suitable for
     * initializing a JavaScript array.
     */
    private String makeStringList(String[] a, int offset, int length)
    {
        StringBuffer b = new StringBuffer();
        for (int i = offset; i < length; i++)
        {
            // JavaScript is sensitive to some UNICODE characters. So for
            // the sake of simplicity, we just escape everything
            b.append('"');
            char[] ch = a[i].toCharArray();
            for (int j = 0; j < ch.length; j++)
            {
                if (ch[j] < 128)
                {
                    b.append(ch[j]);
                }
                else
                {
                    b.append(escape(ch[j]));
                }
            }

            b.append('"');
            if (i < length - 1)
            {
                b.append(", ");
            }
        }
        return b.toString();

    }

    /**
     * Create an escaped Unicode character
     * @param c
     * @return The unicode character in escaped string form
     */
    private static String escape(char c)
    {
        StringBuffer b = new StringBuffer();
        for (int i = 0; i < 4; i++)
        {
            b.append(Integer.toHexString(c & 0x000F).toUpperCase());
            c >>>= 4;
        }
        b.append("u\\");
        return b.reverse().toString();
    }

}