package com.mysema.rdfbean.model.io;

import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import com.mysema.rdfbean.Namespaces;
import com.mysema.rdfbean.model.UID;

/**
 * @author tiwe
 * 
 */
public class TurtleStringWriter extends TurtleWriter {

    private final Map<String, String> prefixes = new HashMap<String, String>();

    private final StringBuilder prefixesString = new StringBuilder();

    public TurtleStringWriter() {
        this(false);
    }

    public TurtleStringWriter(boolean blankNodeAsURI) {
        super(new StringBuilder(), Collections.<String, String> emptyMap(), blankNodeAsURI);
    }

    @Override
    protected void appendPrefixed(UID uid) throws IOException {
        String prefix = prefixes.get(uid.ns());
        if (prefix == null) {
            prefix = Namespaces.DEFAULT.get(uid.ns());
            if (prefix == null) {
                prefix = "ns" + (prefixes.size() + 1);
            }
            prefixes.put(uid.ns(), prefix);
            prefixesString.append("@prefix " + prefix + ": <" + NTriplesUtil.escapeString(uid.ns()) + "> .\n");
        }
        appendable.append(prefix).append(":").append(uid.ln());
    }

    @Override
    public String toString() {
        ((StringBuilder) appendable).insert(0, prefixesString.toString());
        prefixesString.setLength(0);
        return appendable.toString();
    }

}