package dalclient;

import java.util.*;
import java.net.*;
import java.io.*;


/**
 * Query record class.  Holds a table row or dataset descriptor containing
 * a set of keyword=value pairs for the record.
 */
public class QueryRecord {
    LinkedHashMap params = new LinkedHashMap();

    QueryRecord(LinkedHashMap m) {
	params = m;
    }

    /* Get the number of fields in the query response record. */
    public int getAttributeCount() {
	return (params.size());
    }

    /* Get an attribute given its keyword name. */
    public QRAttribute getAttribute(String key) {
	String value = (String) params.get(key);
	return ((value == null) ? null : new QRAttribute(value));
    }

    /* Get the map itself. */
    public LinkedHashMap getMap() {
	return (params);
    }

    /* Fetch the referenced dataset to a generated filename.  By default
     * we try to create the file in the current working directory.  We
     * try to guess the file extension from the "Format" dataset attribute,
     * if given.
     */
    public String getDataset() throws Exception {
	QRAttribute v = getAttribute("Format");
	File cwd = new File(".");
	String suffix = null;

	if (v != null) {
	    String s = v.stringValue();
	    int last = s.lastIndexOf('/');
	    if (last > 0)
		suffix = "." + s.substring(last + 1);
	}

	File path = cwd.createTempFile("data", suffix, cwd);
	return (getDataset(path.toString()) ? path.toString() : null);
    }

    /* Get the dataset pointed to by the AccessReference attribute.
     * Returns true if the download is successful, false if there is
     * no AccessReference attribute for the dataset.
     */
    public boolean getDataset(String path) throws Exception {
	QRAttribute v = getAttribute("AccessReference");
	if (v == null)
	    return (false);

	readURL(v.stringValue(), path);
	return (true);
    }

    /* ReadURL -- Copy the contents of a URL to the named output file as a 
     * binary stream.
     */
    public long readURL(String url, String path) throws Exception {
	URL link = new URL(url);
	InputStream in = link.openStream();
	FileOutputStream out = new FileOutputStream(path);

	byte buf[] = new byte[4096];  int n;  long size;
	for (size=0;  (n = in.read(buf, 0, buf.length)) > 0;  size += n)
	    out.write(buf, 0, n);

	return (size);
    }
}