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

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

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

    private final StringBuilder prefixesString = new StringBuilder();

    private final boolean delete;

    private final UID graph;

    public SPARQLUpdateWriter(UID graph, boolean delete) {
        this(graph, false, false);
    }

    public SPARQLUpdateWriter(UID graph, boolean delete, boolean blankNodeAsURI) {
        super(new StringBuilder(), Collections.<String, String> emptyMap(), blankNodeAsURI);
        this.graph = graph;
        this.delete = delete;
    }

    @Override
    protected void append(UID uid) {
        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");
        }
        try {
            appendable.append(prefix).append(":").append(uid.ln());
        } catch (IOException e) {
            throw new RepositoryException(e);
        }
    }

    @Override
    protected void appendPredicate(UID uid) {
        append(uid);
    }

    @Override
    public void begin() {
        try {
            if (delete) {
                appendable.append("DELETE DATA FROM <").append(graph.getId()).append("> {\n");
            } else {
                appendable.append("INSERT DATA INTO <").append(graph.getId()).append("> {\n");
            }
        } catch (IOException e) {
            throw new RepositoryException(e);
        }
    }

    @Override
    public void end() {
        try {
            if (last != null) {
                appendable.append(" .\n");
            }
            appendable.append("}\n");
        } catch (IOException e) {
            throw new RepositoryException(e);
        }
    }

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

}