package org.drools.guvnor.client.table;

import com.google.gwt.cell.client.ClickableTextCell;
import com.google.gwt.cell.client.ValueUpdater;
import com.google.gwt.core.client.GWT;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.user.cellview.client.Column;
import com.google.gwt.user.cellview.client.Header;
import com.google.gwt.user.client.ui.AbstractImagePrototype;

/**
 * Based on GWT bikeshed example.
 * @author Geoffrey De Smet
 */
public class SortableHeader<T, C extends Comparable> extends Header<String> {

    private static final TableImageResources TABLE_IMAGE_RESOURCES = GWT.create(TableImageResources.class);
    private static final String DOWN_ARROW = makeImage(TABLE_IMAGE_RESOURCES.downArrow());
    private static final String SMALL_DOWN_ARROW = makeImage(TABLE_IMAGE_RESOURCES.smallDownArrow());
    private static final String UP_ARROW = makeImage(TABLE_IMAGE_RESOURCES.upArrow());
    private static final String SMALL_UP_ARROW = makeImage(TABLE_IMAGE_RESOURCES.smallUpArrow());

    private static String makeImage(ImageResource resource) {
        AbstractImagePrototype prototype = AbstractImagePrototype.create(resource);
        return prototype.getHTML();
    }

    private final SortableHeaderGroup sortableHeaderGroup;
    private String text;
    private final Column<T, C> column;
    private SortDirection sortDirection = SortDirection.NONE;
    private int sortIndex = -1;

    public SortableHeader(SortableHeaderGroup sortableHeaderGroup, String text, Column<T, C> column) {
        super(new ClickableTextCell());
        this.sortableHeaderGroup = sortableHeaderGroup;
        this.text = text;
        this.column = column;
        setUpdater(new ValueUpdater<String>() {
            public void update(String s) {
                SortableHeader.this.sortableHeaderGroup.headerClicked(SortableHeader.this);
            }
        });
    }

    /**
     * @return the header label
     */
    public String getValue() {
        return text;
    }

    public Column<T, C> getColumn() {
        return column;
    }

    public SortDirection getSortDirection() {
        return sortDirection;
    }

    public void setSortDirection(SortDirection sortDirection) {
        this.sortDirection = sortDirection;
    }

    public int getSortIndex() {
        return sortIndex;
    }

    public void setSortIndex(int sortIndex) {
        this.sortIndex = sortIndex;
    }

    @Override
    public void render(SafeHtmlBuilder sb) {
        sb.appendHtmlConstant("<div style='position: relative; cursor: pointer; padding: 0px;'>");
        sb.appendHtmlConstant("<span style='padding-right: 10px'>");
        sb.appendEscaped(text);
        sb.appendHtmlConstant("</span>");
//        sb.appendHtmlConstant("<div style='position:absolute;right:0px;top:0px;'></div>");
        switch (sortDirection) {
            case NONE:
                // nothing
                break;
            case ASCENDING:
                sb.appendHtmlConstant(sortIndex == 0 ? UP_ARROW : SMALL_UP_ARROW);
                break;
            case DESCENDING:
                sb.appendHtmlConstant(sortIndex == 0 ? DOWN_ARROW : SMALL_DOWN_ARROW);
                break;
            default:
                throw new IllegalArgumentException("Unknown sortDirection (" + sortDirection + ").");
        }
        sb.appendHtmlConstant("</div>");
//        sb.appendHtmlConstant("<div>");
//        sb.appendHtmlConstant("</div></div>");
    }

}