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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2011, Open Source Geospatial Foundation (OSGeo)
 *    (C) 2003-2005, Open Geospatial Consortium Inc.
 *
 *    All Rights Reserved. http://www.opengis.org/legal/
 */
package org.opengis.geometry.coordinate;

import static org.opengis.annotation.Obligation.*;
import static org.opengis.annotation.Specification.*;

import java.util.List;
import org.opengis.annotation.UML;
import org.opengis.geometry.primitive.CurveInterpolation;
import org.opengis.geometry.primitive.CurveSegment;

/**
 * Similar to a {@linkplain LineString line string} except that the interpolation is by circular
 * arcs. Since it requires 3 points to determine a circular arc, the {@linkplain #getControlPoints
 * control points} are treated as a sequence of overlapping sets of 3 {@linkplain Position
 * positions}, the start of each arc, some point between the start and end, and the end of each arc.
 * Since the end of each arc is the start of the next, this {@linkplain Position position} is not
 * repeated in the {@linkplain #getControlPoints control points} sequence.
 *
 * @version ISO 19107
 * @author Martin Desruisseaux (IRD)
 * @since GeoAPI 1.0
 * @see GeometryFactory#createArcString
 * @see ArcStringByBulge#asArcString
 */
@UML(identifier = "GM_ArcString", specification = ISO_19107)
public interface ArcString extends CurveSegment {
    /**
     * Returns the number of circular arcs in the string. Since the interpolation method requires
     * overlapping sets of 3 positions, the number of arcs determines the number of {@linkplain
     * #getControlPoints control points}:
     *
     * 
     *
     * numArc = ({@link #getControlPoints controlPoints}.length - 1)/2
     *
     * 
     *
     * @return The number of circular arcs.
     */
    @UML(identifier = "numArc", obligation = MANDATORY, specification = ISO_19107)
    int getNumArc();

    /**
     * Returns the sequence of points used to control the arcs in this string. The first three
     * {@linkplain Position positions} in the sequence determines the first arc. Any three
     * consecutive {@linkplain Position positions} beginning with an odd offset, determine another
     * arc in the string.
     *
     * @return The control points. The array size is 2*{@link #getNumArc numArc} +1
     *     .
     */
    @UML(identifier = "controlPoints", obligation = MANDATORY, specification = ISO_19107)
    PointArray getControlPoints();

    /**
     * The interpolation for a {@code ArcString} is "{@linkplain
     * CurveInterpolation#CIRCULAR_ARC_3_POINTS circular arc by 3 points}".
     *
     * @return Always {@link CurveInterpolation#CIRCULAR_ARC_3_POINTS}.
     */
    @UML(identifier = "interpolation", obligation = MANDATORY, specification = ISO_19107)
    CurveInterpolation getInterpolation();

    /**
     * Constructs a sequence of arcs that is the geometric equivalent of this arc string.
     *
     * @return The sequence of arcs.
     */
    @UML(identifier = "asGM_Arc", obligation = MANDATORY, specification = ISO_19107)
    List asArcs();
}