package de.intevation.flys.exports;

import java.io.BufferedWriter;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;

import org.apache.log4j.Logger;

import de.intevation.flys.artifacts.model.WstLine;


/**
 * A writer that creates WSTs.
 *
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public class WstWriter {

    /** The logger used in this class.*/
    private static Logger logger = Logger.getLogger(WstWriter.class);


    /** The default unit that is written into the header of the WST.*/
    public static final String DEFAULT_UNIT = "Wassserstand [NN + m]";


    /** The lines that need to be included for the export.*/
    protected Map<Double, WstLine> lines;

    /** The column names.*/
    protected List<String> columnNames;

    /** The locale used to format the values.*/
    protected Locale locale;

    /** The number of discharge columns.*/
    protected int cols;

    /** The last Q values.*/
    protected double[] qs;



    /**
     * This constructor creates a new WstWriter with an OutputStream and a
     * number of Q columns.
     *
     * @param out The output stream where the WST is written to.
     * @param cols The number of columns of the resulting WST.
     */
    public WstWriter(int cols) {
        this.columnNames = new ArrayList<String>(cols);
        this.lines       = new HashMap<Double, WstLine>();
        this.qs          = new double[cols];
        this.locale      = Locale.US;
        this.cols        = cols;

    }


    /**
     * This method is used to create the WST from the data that has been
     * inserted using add(double[]) before.
     */
    public void write(OutputStream out) {
        logger.info("WstWriter.write");

        PrintWriter writer = new PrintWriter(
            new BufferedWriter(
                new OutputStreamWriter(out)));

        writeHeader(writer);

        Collection<WstLine> collection = new TreeMap(lines).values();

        for (WstLine line: collection) {
            writeWLine(writer, line);
        }

        writer.flush();
        writer.close();
    }


    /**
     * This method is used to add a new line to the WST.
     *
     * @param wqkms A 3dim double array with [W,Q, KM].
     */
    public void add(double[] wqkms) {
        Double km = wqkms[2];

        WstLine line = lines.get(km);

        if (line == null) {
            line = new WstLine(km.doubleValue());
            lines.put(km, line);
        }

        line.add(wqkms[0], wqkms[1]);
    }


    /**
     * Adds a further column name.
     *
     * @param name The name of the new column.
     */
    public void addColumn(String name) {
        if (name != null) {
            columnNames.add(name);
        }
    }


    /**
     * This method writes the header of the WST.
     *
     * @param writer The PrintWriter that creates the output.
     */
    protected void writeHeader(PrintWriter writer) {
        logger.debug("WstWriter.writeHeader");

        writer.println(cols);
        writer.print("        ");

        for (String columnName: columnNames) {
            writer.printf(locale, "%9s", columnName);
        }

        writer.println();

        writer.write("*   KM     ");
        writer.write(DEFAULT_UNIT);
        writer.println();
    }


    /**
     * This method writes a line with W values and a certain kilometer.
     *
     * @param writer The PrintWriter that is used to create the output.
     * @param line The WstLine that should be written to the output.
     */
    protected void writeWLine(PrintWriter writer, WstLine line) {
        double   km  = line.getKm();
        double[] qs  = line.getQs();
        int      num = line.getSize();

        if (dischargesChanged(qs)) {
            writeQLine(writer, qs);
        }

        writer.printf(locale, "%8.3f", km);

        for (int i = 0; i < num; i++) {
            writer.printf(locale, "%9.2f", line.getW(i));
        }

        writer.println();
    }


    /**
     * Writes a discharge line (Q values) into a WST.
     *
     * @param qs the Q values for the next range.
     */
    protected void writeQLine(PrintWriter writer, double[] qs) {
        writer.write("*\u001f      ");

        for (int i = 0; i < cols; i++) {
            this.qs[i] = qs[i];

            writer.printf(locale, "%9.2f", qs[i]);
        }

        writer.println();
    }


    /**
     * This method determines if a Q has changed from the last line to the
     * current one.
     *
     * @param newQs The Q values of the next line.
     *
     * @return true, if a Q value have changed, otherwise false.
     */
    protected boolean dischargesChanged(double[] newQs) {
        // XXX maybe there is a way to do this faster
        for (int i = 0; i < cols; i++) {
            if (Math.abs(newQs[i] - qs[i]) >= 0.001) {
                return true;
            }
        }

        return false;
    }
}
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