package javax.microedition.sensor;

import java.security.Permission;

import javax.microedition.io.GCFPermission;

/**
 <p>This class represents an access right to a connection/connections 
 via the "sensor" protocol. The <code>SensorProtocolPermission</code> 
 grants the permission to either sensors measuring a certain quantity 
 or to private/protected sensors. If the name given is a sensor URI 
 then the access for sensors pointed by this URI is granted.
 Because a valid sensor URI always contains a quantity, 
 <code>SensorProtocolPermissions</code> constructed with a URI 
 will always address sensors of one quantity.
 The sensor URI is defined in {@link SensorConnection}.</p>
  
 <p>{@link #PRIVATE} and {@link #PROTECTED} constants
 are for private and protected sensors; the access is granted for 
 the whole group of such sensors. The sensors of the group are most
 probably measuring different quantities.</p> 
 
 <p>In the Mobile Sensor API the only security control points  
 are opening a connection and registering for push, no other methods are protected. 
 That is why no actions are listed here.</p>
 
 <p>Note: the sensor URI as a name may refer to one or more sensors, 
 including private and protected sensors.
 If the policy prevents opening any of these sensors, the permission
 must not be granted.</p>
 */
public final class SensorProtocolPermission extends GCFPermission {

     /**
     *<p>
     The name for the permission targeted to private sensors.
     </p>
     */
     public final static String PRIVATE    
         = "javax.microedition.sensor.PrivateSensor";

    /**
     *<p>
     The name for the permission targeted to protected sensor.
     </p>
     */
     public final static String PROTECTED    
         = "javax.microedition.sensor.ProtectedSensor";



    /**
     <p>The method creates a new <code>SensorProtocolPermission</code>,
     the name of which may be:</p>
     <ul>
     <li>the sensor URI</li>
     <li>{@link #PRIVATE}</li>
     <li>{@link #PROTECTED}</li>
     </ul> 
     @param name the permission name
     @throws IllegalArgumentException if the <code>uri</code> is zero length
     or not a valid name
     @throws NullPointerException if <code>uri</code> is <code>null</code>
     */
    public SensorProtocolPermission(java.lang.String name){
    	if (name==null)
    	   throw new NullPointerException(
		   "SensorProtocolPermission called with a null value");
    	if (name.length() == 0)
    	   throw new IllegalArgumentException(
    	   "SensorProtocolPermission called with a zero-length name");
    	try{
    	   SensorManager.findSensors(name);
    	}catch (IllegalArgumentException e) {
    	   throw new IllegalArgumentException(
	   "SensorProtocolPermission called with an invalid name "+name);
	}
    			
    }


	/**<p>
	 The method checks two <code>SensorProtocolPermission</code> objects 
	 for equality. Checks that given <i>object</i> is
	 a <code>SensorProtocolPermission</code> and has the same name as this object.</p>
	 
	 @param object the object we are testing for equality with this object.
	 @return <code>true</code> if object is a <code>SensorProtocolPermission</code>, 
	 and has the same name as this <code>SensorProtocolPermission</code> object.
	 */
	public boolean equals(Object object) {
		if (object == this)
			return true;
		if (! (object instanceof SensorProtocolPermission))	
			return false;
		return getName().equals(((SensorProtocolPermission)object).getName());
	}

	/**<p>
	 The method returns actions, for this permission 
	 the method returns always <code>null</code> since no actions are defined.</p>
	 @return <code>null</code>
	 */
	public String getActions()
	{
		return null;
	}

	/**<p>
	 The method returns the hash code value for this object.
	 The value returned complies with the requirements of the
	 the hashCode method of the superclass.</p>
	 @return a hash code value for this object.
	 */
	public int hashCode() {
		return this.getName().hashCode();
	}

	
	/**<p>
	 The method checks if this <code>SensorProtocolPermission</code> 
	 object "implies" the specified
	 permission. More specifically, this method returns <code>true</code> if:</p>
	 <ul>
	 <li><i>p</i> is an instanceof <code>SensorProtocolPermission</code>, and</li>
	 <li><i>p</i>'s actions return <code>null</code>, and</li>
	 <li><i>p</i>'s name equals this object's name, or if</li>
	 <li><i>p</i>'s sensor URI defines a subset of the category
	 (private/protected), or if</li>
	 <li><i>p</i>'s sensor URI defines a subset of sensors of this object's URI</li>
	 </ul>
	 
	 @param p the permission to check against.
	 *
	 @return <code>true</code> if the specified permission is implied by this object,
	 <code>false</code> if not.
	 */

	public boolean implies(Permission p) {
		if (!(p instanceof SensorProtocolPermission)) return false;


		// Check of this SensorProtocolPermission's name implies the other's name
		String name = getName();
		String name2 = p.getName();
		if (name.equals(name2)) return true;
		

		// URI defines a subset of sensors of this object's category (private/protected)
		String[] categories = {PRIVATE, PROTECTED};
		SensorInfo[] infos2 = SensorManager.findSensors(name2);
		for (int i=0; i<categories.length; i++){
			if (!name.equals(categories[i])) continue;
			if (name2.equals(categories[i])) return false;
			
			for (int j=0; j<infos2.length; j++){
				String category = null;
				if (infos2[j].getProperty(SensorInfo.PROP_PERMISSION)!=null){
					category = (String)infos2[j].getProperty(SensorInfo.PROP_PERMISSION);
				}
				if (category == null) return false;
				if (category.indexOf(categories[i])==-1) return false;	
			}
			// true only if sensors were found
			return (infos2.length>0);
		}
		
		
		// URI defines a subset of sensors of this object's URI
		SensorInfo[] infos = SensorManager.findSensors(name);
		
		//infos2 must be a subset of infos
		for (int i=0; i<infos2.length; i++){
			String tmpUrl2 = infos2[i].getUrl();
			int j=0;
			for (; j<infos.length && !(infos[i].getUrl().equals(tmpUrl2)); j++);
			if (j==infos.length) return false;
		}
		// true only if sensors were found
		return (infos2.length>0);
	}
}