/**
 * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
 */

package net.sourceforge.pmd.renderers;

import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import java.util.List;

/**
 * A generic writer that formats input items into rows and columns per the
 * provided column descriptors.
 *
 * @author Brian Remedios
 * @param <T>
 */
public class CSVWriter<T extends Object> {

    private final String separator; // e.g., the comma
    private final String lineSeparator; // cr
    private final List<ColumnDescriptor<T>> columns;

    public CSVWriter(List<ColumnDescriptor<T>> theColumns, String theSeparator, String theLineSeparator) {
        columns = theColumns;
        separator = theSeparator;
        lineSeparator = theLineSeparator;
    }

    public void writeTitles(Writer writer) throws IOException {
        StringBuilder buf = new StringBuilder(300);
        for (int i = 0; i < columns.size() - 1; i++) {
            quoteAndCommify(buf, columns.get(i).title);
        }

        quote(buf, columns.get(columns.size() - 1).title);

        buf.append(lineSeparator);
        writer.write(buf.toString());
    }

    public void writeData(Writer writer, Iterator<T> items) throws IOException {

        int count = 1;

        StringBuilder buf = new StringBuilder(300);

        T rv;
        final int lastColumnIdx = columns.size() - 1;

        while (items.hasNext()) {
            buf.setLength(0);
            rv = items.next();

            for (int i = 0; i < lastColumnIdx; i++) {
                quoteAndCommify(buf, columns.get(i).accessor.get(count, rv, separator));
            }

            quote(buf, columns.get(lastColumnIdx).accessor.get(count, rv, separator));

            buf.append(lineSeparator);
            writer.write(buf.toString());
            count++;
        }
    }

    private void quote(StringBuilder buffer, String s) {
        if (s == null) {
            return;
        }
        buffer.append('"').append(s).append('"');
    }

    private void quoteAndCommify(StringBuilder buffer, String s) {
        quote(buffer, s);
        buffer.append(separator);
    }
}