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package ucar.nc2.ft2.simpgeometry;

import ucar.nc2.Attribute;
import ucar.nc2.Variable;
import ucar.nc2.constants.CF;
import ucar.nc2.dataset.NetcdfDataset;

/**
 * A class which given a dataset, will read from the dataset one of the simple geometry types. Those being polygon,
 * line, or point.
 * 
 * @author [email protected]
 *
 */
public class SimpleGeometryReader {

  private NetcdfDataset ds;

  /**
   * Returns a Polygon given a variable name and the geometric index. If the Polygon is not found it will return null.
   * If the Polygon is a part of the Multi-Polygon, it will return the head
   * (the first Polygon in the series which constitutes the Multi-Polygon).
   * 
   * @param name of the variable which holds the Polygon
   * @param index of the Polygon within the variable
   * @return a new polygon with all associated information
   */
  public Polygon readPolygon(String name, int index) {

    Variable polyvar = ds.findVariable(name);
    if (polyvar == null)
      return null;

    Polygon poly = null;

    // CFConvention
    if (ds.findGlobalAttribute(CF.CONVENTIONS) != null)
      if (ucar.nc2.dataset.conv.CF1Convention.getVersion(ds.findGlobalAttribute(CF.CONVENTIONS).getStringValue()) >= 8)
        poly = new CFPolygon();

    if (poly == null)
      return null;
    else
      return poly.setupPolygon(ds, polyvar, index);
  }

  /**
   * Returns a Line given a variable name and the geometric index. If the Line is not found it will return null. If the
   * Line is a part of the Multi-Line, it will return the head
   * (the first Line in the series which constitutes the Multi-Line).
   * 
   * @param name of the variable which holds the Line
   * @param index of the Line within the variable
   * @return a new line with all associated information
   */
  public Line readLine(String name, int index) {

    Variable linevar = ds.findVariable(name);
    if (linevar == null)
      return null;
    Line line = null;

    // CFConvention
    if (ds.findGlobalAttribute(CF.CONVENTIONS) != null)
      if (ucar.nc2.dataset.conv.CF1Convention.getVersion(ds.findGlobalAttribute(CF.CONVENTIONS).getStringValue()) >= 8)
        line = new CFLine();

    if (line == null)
      return null;
    else
      return line.setupLine(ds, linevar, index);
  }

  /**
   * Returns a Point given a variable name and the geometric index. If the Point is not found it will return null. If
   * the Point is a part of the Multi-Point, it will return the head
   * (the first Point in the series which constitutes the Multi-Point).
   * 
   * @param name of the variable which holds the Point
   * @param index of the Point within the variable
   * @return a new Point with all associated information
   */
  public Point readPoint(String name, int index) {

    Variable pointvar = ds.findVariable(name);
    if (pointvar == null)
      return null;
    Point pt = null;

    // CFConvention
    if (ds.findGlobalAttribute(CF.CONVENTIONS) != null)
      if (ucar.nc2.dataset.conv.CF1Convention.getVersion(ds.findGlobalAttribute(CF.CONVENTIONS).getStringValue()) >= 8)
        pt = new CFPoint();

    if (pt == null)
      return pt;
    else
      return pt.setupPoint(ds, pointvar, index);
  }

  /**
   * Given a variable name, returns the geometry type which that variable is associated with.
   * If the variable has no simple geometry information, null will be returned.
   * 
   * @param name variable name which will have geometry type be checked
   * @return Geometry Type if holds geometry information, null if not
   */
  public GeometryType getGeometryType(String name) {
    Variable geometryVar = ds.findVariable(name);
    if (geometryVar == null)
      return null;

    // CFConvention
    if (ds.findGlobalAttribute(CF.CONVENTIONS) != null)
      if (ucar.nc2.dataset.conv.CF1Convention
          .getVersion(ds.findGlobalAttribute(CF.CONVENTIONS).getStringValue()) >= 8) {
        Attribute geometryTypeAttr;
        String geometry_type;

        geometryTypeAttr = geometryVar.findAttribute(CF.GEOMETRY_TYPE);
        if (geometryTypeAttr == null)
          return null;
        geometry_type = geometryTypeAttr.getStringValue();

        switch (geometry_type) {
          case CF.POLYGON:
            return GeometryType.POLYGON;
          case CF.LINE:
            return GeometryType.LINE;
          case CF.POINT:
            return GeometryType.POINT;
          default:
            return null;
        }
      }

    return null;
  }

  /**
   * Constructs a new Simple Geometry Reader over the specified dataset.
   * 
   * @param ds - the specified dataset
   */
  public SimpleGeometryReader(NetcdfDataset ds) {
    this.ds = ds;
  }

}