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package net.java.html.geo;

import java.util.logging.Level;

import java.util.logging.Logger;

import org.netbeans.html.geo.impl.JsG;

/** Class that represents a geolocation position provided as a callback

 * to {@link Handle#onLocation(net.java.html.geo.Position)} method. The

 * class getters mimic closely the structure of the position object as

 * specified by <a href="http://www.w3.org/TR/geolocation-API/">

 * W3C's Geolocation API</a>.

 *

 * @author Jaroslav Tulach

 */

public final class Position {

    static final Logger LOG = Logger.getLogger(Position.class.getName());

    private final long timestamp;

    private final Coordinates coords;

    Position(Object position) {

        Object obj = JsG.get(position, "timestamp");

        timestamp = obj instanceof Number ? ((Number)obj).longValue() : 0L;

        coords = new Coordinates(JsG.get(position, "coords"));

    }

    /** The actual location of the position.

     * @return non-null coordinates

     */

    public Coordinates getCoords() {

        return coords;

    }

    /** The time when the position has been recorded.

     * @return time in milliseconds since era (e.g. Jan 1, 1970).

     */

    public long getTimestamp() {

        return timestamp;

    }

    /** Actual location of a {@link Position}. 

     *  Mimics closely <a href="http://www.w3.org/TR/geolocation-API/">

     * W3C's Geolocation API</a>.

     */

    public static final class Coordinates {

        private final Object data;

        Coordinates(Object data) {

            this.data = data;

        }

        /**

         * @return geographic coordinate specified in decimal degrees.

         */

        public double getLatitude() {

            return ((Number)JsG.get(data, "latitude")).doubleValue(); // NOI18N

        }

        /**

         * @return geographic coordinate specified in decimal degrees.

         */

        public double getLongitude() {

            return ((Number)JsG.get(data, "longitude")).doubleValue(); // NOI18N

        } 

        /**

         * The accuracy attribute denotes the accuracy level of the latitude 

         * and longitude coordinates. It is specified in meters. 

         * The value of the accuracy attribute must be a non-negative number.

         * 

         * @return accuracy in meters

         */

        public double getAccuracy() {

            return ((Number)JsG.get(data, "accuracy")).doubleValue(); // NOI18N

        }

        /** Denotes the height of the position, specified in meters above the ellipsoid. 

         * If the implementation cannot provide altitude information, 

         * the value of this attribute must be null.

         * @return value in meters, may return null, if the information is not available 

         */

        public Double getAltitude() {

            return (Double)JsG.get(data, "altitude"); // NOI18N

        }

        /**  The altitude accuracy is specified in meters. 

         * If the implementation cannot provide altitude information, 

         * the value of this attribute must be null. Otherwise, the value 

         * must be a non-negative real number.

         * @return value in meters; may return null, if the information is not available 

         */

        public Double getAltitudeAccuracy() {

            return (Double)JsG.get(data, "altitudeAccuracy"); // NOI18N

        }

        /** @return may return null, if the information is not available */

        public Double getHeading() {

            return (Double)JsG.get(data, "heading"); // NOI18N

        }

        /** @return may return null, if the information is not available */

        public Double getSpeed() {

            return (Double)JsG.get(data, "speed"); // NOI18N

        }

    } // end of Coordinates

    /** Rather than subclassing this class directly consider using {@link OnLocation}

     * annotation. Such annotation will generate a subclass for you automatically

     * with two static methods <code>createQuery</code> and <code>createWatch</code>

     * which can be used to obtain instance of this class.

     */

    public static abstract class Handle {

        private final boolean oneTime;

        private boolean enableHighAccuracy;

        private long timeout;

        private long maximumAge;

        volatile JsH handle;

        /** Creates new instance of this handle.

         * 

         * @param oneTime <code>true</code> if the handle represents one time 

         *   <em>query</em>. <code>false</code> if it represents a <em>watch</em>

         */

        protected Handle(boolean oneTime) {

            super();

            this.oneTime = oneTime;

        }

        /** Callback from the implementation when a (new) position has been

         * received and identified

         * @param p the position

         * @throws Throwable if an exception is thrown, it will be logged by the system

         */

        protected abstract void onLocation(Position p) throws Throwable;

        /** Callback when an error occurs.

         * @param ex the exception describing what went wrong

         * @throws Throwable if an exception is thrown, it will be logged by the system

         */

        protected abstract void onError(Exception ex) throws Throwable;

        /** Check whether the location API is supported.

         * @return true, if one can call {@link #start}.

         */

        public final boolean isSupported() {

            return JsG.hasGeolocation();

        }

        /** Turns on high accuracy mode as specified by the 

         * <a href="http://www.w3.org/TR/2012/PR­geolocation­API­20120510/">

         * W3C's Geolocation API</a>. By default the mode is disabled.

         * @param enable <code>true</code> or <code>false</code>

         */

        public final void setHighAccuracy(boolean enable) {

            this.enableHighAccuracy = enable;

        }

        /** The amount of milliseconds to wait for a result.

         * By default infinity.

         * @param timeout time in milliseconds to wait for a result.

         */

        public final void setTimeout(long timeout) {

            this.timeout = timeout;

        }

        /** Sets maximum age of cached results which are acceptable to be

         * returned. By default maximum age is set to zero.

         * @param age time in milliseconds of acceptable cached results

         */

        public final void setMaximumAge(long age) {

            this.maximumAge = age;

        }

        /** Initializes the <em>query</em> or <em>watch</em> request(s) and

         * returns immediately. Has no effect if the query has already been

         * started. If a problem appears while starting the system,

         * it is immediately reported via the {@link #onError(java.lang.Exception)}

         * callback. For example, if the {@link #isSupported()} method

         * returns <code>false</code> an IllegalStateException is created

         * and sent to the {@link #onError(java.lang.Exception) callback} method.

         */

        public final void start() {

            if (handle != null) {

                return;

            }

            handle = new JsH();

            try {

                if (!isSupported()) {

                    throw new IllegalStateException("geolocation API not supported");

                }

                handle.start();

            } catch (Exception ex) {

                try {

                    onError(ex);

                } catch (Throwable thr) {

                    LOG.log(Level.INFO, "Problems delivering onError report", thr);

                }

            }

        }

        /** Stops all pending requests. After this call no further callbacks

         * can be obtained. Does nothing if no query or watch was in progress.

         */

        public final void stop() {

            JsH h = handle;

            if (h == null) {

                return;

            }

            handle = null;

            h.stop();

        }

        private final class JsH extends JsG {

            long watch;

            @Override

            public void onLocation(Object position) {

                if (handle != this) {

                    return;

                }

                if (oneTime) {

                    stop();

                }

                try {

                    Handle.this.onLocation(new Position(position));

                } catch (Throwable ex) {

                    LOG.log(Level.SEVERE, null, ex);

                }

            }

            @Override

            public void onError(final String message, int code) {

                if (handle != this) {

                    return;

                }

                if (oneTime) {

                    stop();

                }

                try {

                    final Exception err = new Exception(message + " errno: " + code) {

                        @Override

                        public String getLocalizedMessage() {

                            return message;

                        }

                    };

                    Handle.this.onError(err);

                } catch (Throwable ex) {

                    LOG.log(Level.SEVERE, null, ex);

                }

            }

            final void start() {

                watch = start(oneTime, enableHighAccuracy, timeout, maximumAge);

            }

            protected final void stop() {

                super.stop(watch);

            }

        }

    }

}