package org.madore.damlengine;

import java.util.regex.Pattern;
import java.util.regex.Matcher;
import org.w3c.dom.*;

public class TodoWrefAttr extends TodoAttr {

    public static class Factory extends TodoAttr.Factory {
	@Override
	public TodoWrefAttr newItem(Attr attr, Element owner,
				    Context ctx,
				    TodoItem caller) {
	    return new TodoWrefAttr(attr, owner, ctx, caller);
	}
    }

    public TodoWrefAttr(Attr attr, Element owner,
			Context ctx,
			TodoItem caller) {
	super(attr, owner, ctx, caller);
    }

    @Override
    public void handle() {
	final String wrefStr = attr.getValue();
	final Matcher wrefMatcher = Pattern.compile("^\\#d\\.(\\d{4})-(\\d{2})-(\\d{2})\\.(\\d{4})(|\\..*)$").matcher(wrefStr);
	if ( ! wrefMatcher.matches() )
	    throw new IllegalArgumentException("wref attribute must be of the form #d.YYYY-MM-DD.NNNN[.xxx]");
	final String wrefYearStr = wrefMatcher.group(1);
	final String wrefMonthStr = wrefMatcher.group(2);
	final String wrefDayStr = wrefMatcher.group(3);
	final String wrefNumberStr = wrefMatcher.group(4);
	final int wrefNumber = Integer.parseInt(wrefNumberStr);
	final String wrefSupplementStr = wrefMatcher.group(5);
	String wrefCat;
	if ( this.owner.hasAttributeNS(DamlEngine.DAML_NS, "wrefcat") ) {
	    wrefCat = this.owner.getAttributeNS(DamlEngine.DAML_NS, "wrefcat");
	    this.owner.removeAttributeNS(DamlEngine.DAML_NS, "wrefcat");
	} else {
	    wrefCat = null;
	}
	final String baseDir = (ctx.gc.uriToTop==null)?"":(ctx.gc.uriToTop+"weblog/");
	final WeblogSummary wsum = WeblogSummary.getSummary(ctx.dc);
	final WeblogSummary.EntrySummary esum;
	// Get entry for target link from weblog summary
	if ( wsum != null && wsum.entries != null )
	    esum = wsum.entries.get(wrefNumber);
	else
	    esum = null;
	// Check consistency if summary was available
	if ( esum != null ) {
	    if ( ! ((wrefYearStr+"-"+wrefMonthStr+"-"+wrefDayStr)
		    .equals(esum.date)) )
		throw new IllegalArgumentException("date mismatch for reference to entry "+wrefNumberStr);
	    if ( wrefCat != null && ! wrefCat.equals("@month")
		  && ! wrefCat.equals("@single") ) {
		if ( esum.catSet == null || ! esum.catSet.contains(wrefCat) )
		    throw new IllegalArgumentException("reference to entry "+wrefNumberStr+" in wrong category "+wrefCat);
	    }
	}
	// Prepare link object
	final WeblogLink lk;
	if ( esum != null && esum.specialName != null )
	    lk = new WeblogLink(wrefYearStr, wrefMonthStr, wrefDayStr,
				wrefNumberStr, wrefSupplementStr,
				esum.specialName);
	else
	    lk = new WeblogLink(wrefYearStr, wrefMonthStr, wrefDayStr,
				wrefNumberStr, wrefSupplementStr);
	// Decide whether link target is on this page
	final boolean onThisPage;
	if ( esum != null && esum.hasCut && ! lk.supplementStr.equals("") ) {
	    // Linking to a _fragment_ of an entry that has a cut-here element.
	    if ( ctx.wsc != null && ctx.wsc.sel != null
		 && ctx.wsc instanceof Context.WeblogSingleSelectionContext
		 && ((Context.WeblogSingleSelectionContext)ctx.wsc).number == wrefNumber )
		onThisPage = true;
	    else
		onThisPage = false;
	} else {
	    if ( ctx.wsc != null && ctx.wsc.sel != null
		 && ctx.wsc.sel.contains(wrefNumber) )
		onThisPage = true;
	    else
		onThisPage = false;
	}
	// Choose file portion of link target
	if ( onThisPage )
	    lk.setTypeRelative();
	else if ( wrefCat == null )
	    lk.setTypeStandard();
	else if ( wrefCat.equals("@month") )
	    lk.setTypeMonth();
	else if ( wrefCat.equals("@single") )
	    lk.setTypeSingle();
	else
	    lk.setTypeCat(wrefCat);
	// Construct full link target
	String target = lk.getTarget(baseDir);
	// Class and title attributes
	if ( ! this.owner.hasAttributeNS(null, "class") )
	    this.owner.setAttributeNS(null, "class", "weblog-internal-link");
	if ( wrefSupplementStr.equals("")
	     && ! this.owner.hasAttributeNS(null, "title")
	     && esum != null && esum.title != null )
	    this.owner.setAttributeNS(null, "title", esum.title);
	// Replace this attribute by computed target
	this.owner.removeAttributeNode(this.attr);
	this.owner.setAttributeNS(null, "href", target);
    }

}