/**
 * Author: Sven Gothel <sgothel@jausoft.com>
 * Copyright (c) 2020 Gothel Software e.K.
 * Copyright (c) 2020 ZAFENA AB
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package direct_bt.tinyb;

import java.util.Arrays;
import java.util.List;

import org.tinyb.BluetoothException;
import org.tinyb.BluetoothGattCharacteristic;
import org.tinyb.BluetoothGattDescriptor;
import org.tinyb.BluetoothGattService;
import org.tinyb.BluetoothManager;
import org.tinyb.BluetoothNotification;
import org.tinyb.BluetoothType;
import org.tinyb.BluetoothUtils;
import org.tinyb.GATTCharacteristicListener;

public class DBTGattCharacteristic extends DBTObject implements BluetoothGattCharacteristic
{
    private static final boolean DEBUG = DBTManager.DEBUG;

    /* pp */ final DBTGattService service;

    /**
     * Characteristic Handle of this instance.
     * <p>
     * Attribute handles are unique for each device (server) (BT Core Spec v5.2: Vol 3, Part F Protocol..: 3.2.2 Attribute Handle).
     * </p>
     */
    private final short handle;

    /* Characteristics Property */
    private final String[] properties;
    // private final boolean hasNotify;
    // private final boolean hasIndicate;

    /* Characteristics Value Type UUID */
    private final String value_type_uuid;

    /**
     * Characteristics Value Handle.
     * <p>
     * Attribute handles are unique for each device (server) (BT Core Spec v5.2: Vol 3, Part F Protocol..: 3.2.2 Attribute Handle).
     * </p>
     */
    private final short value_handle;

    /* Optional Client Characteristic Configuration index within descriptorList */
    private final int clientCharacteristicsConfigIndex;

    private final List<BluetoothGattDescriptor> descriptorList;

    private byte[] cachedValue = null;
    private BluetoothNotification<byte[]> valueNotificationCB = null;

    private boolean updateCachedValue(final byte[] value, final boolean notify) {
        boolean valueChanged = false;
        if( null == cachedValue || cachedValue.length != value.length ) {
            cachedValue = new byte[value.length];
            valueChanged = true;
        } else if( !Arrays.equals(value, cachedValue) ) {
            valueChanged = true;
        }
        if( valueChanged ) {
            System.arraycopy(value, 0, cachedValue, 0, value.length);
            if( notify && null != valueNotificationCB ) {
                valueNotificationCB.run(cachedValue);
            }
        }
        return valueChanged;
    }

    private final GATTCharacteristicListener characteristicListener = new GATTCharacteristicListener() {

        @Override
        public void notificationReceived(final BluetoothGattCharacteristic charDecl, final byte[] value, final long timestamp) {
            final DBTGattCharacteristic cd = (DBTGattCharacteristic)charDecl;
            if( !cd.equals(DBTGattCharacteristic.this) ) {
                throw new InternalError("Filtered GATTCharacteristicListener.notificationReceived: Wrong Characteristic: Got "+charDecl+
                                        ", expected "+DBTGattCharacteristic.this.toString());
            }
            final boolean valueChanged = updateCachedValue(value, true);
            if( DEBUG ) {
                System.err.println("GATTCharacteristicListener.notificationReceived: "+charDecl+
                                   ", value[changed "+valueChanged+", data "+BluetoothUtils.bytesHexString(value, true, true)+"]");
            }
        }

        @Override
        public void indicationReceived(final BluetoothGattCharacteristic charDecl, final byte[] value, final long timestamp,
                                       final boolean confirmationSent) {
            final DBTGattCharacteristic cd = (DBTGattCharacteristic)charDecl;
            if( !cd.equals(DBTGattCharacteristic.this) ) {
                throw new InternalError("Filtered GATTCharacteristicListener.indicationReceived: Wrong Characteristic: Got "+charDecl+
                                        ", expected "+DBTGattCharacteristic.this.toString());
            }
            final boolean valueChanged = updateCachedValue(value, true);
            if( DEBUG ) {
                System.err.println("GATTCharacteristicListener.indicationReceived: "+charDecl+
                                   ", value[changed "+valueChanged+", data "+BluetoothUtils.bytesHexString(value, true, true)+"]");
            }
        }

    };

   /* pp */ DBTGattCharacteristic(final long nativeInstance, final DBTGattService service,
                                  final short handle, final String[] properties,
                                  final String value_type_uuid, final short value_handle,
                                  final int clientCharacteristicsConfigIndex)
    {
        super(nativeInstance, handle /* hash */);
        this.service = service;
        this.handle = handle;

        this.properties = properties;
        /** {
            boolean hasNotify = false;
            boolean hasIndicate = false;
            for(int i=0; !hasNotify && !hasIndicate && i<properties.length; i++) {
                if( "notify".equals(properties[i]) ) {
                    hasNotify = true;
                }
                if( "indicate".equals(properties[i]) ) {
                    hasIndicate = true;
                }
            }
            this.hasNotify = hasNotify;
            this.hasIndicate = hasIndicate;
        } */

        this.value_type_uuid = value_type_uuid;
        this.value_handle = value_handle;
        this.clientCharacteristicsConfigIndex = clientCharacteristicsConfigIndex;
        this.descriptorList = getDescriptorsImpl();
        this.addCharacteristicListener(characteristicListener, false); // silent, don't enable native GATT ourselves
    }

    @Override
    public synchronized void close() {
        if( !isValid() ) {
            return;
        }
        removeAllCharacteristicListener();
        disableValueNotifications();
        super.close();
    }

    @Override
    public boolean equals(final Object obj)
    {
        if (obj == null || !(obj instanceof DBTGattCharacteristic)) {
            return false;
        }
        final DBTGattCharacteristic other = (DBTGattCharacteristic)obj;
        return handle == other.handle; /** unique attribute handles */
    }

    @Override
    public String getUUID() { return value_type_uuid; }

    @Override
    public BluetoothType getBluetoothType() { return class_type(); }

    static BluetoothType class_type() { return BluetoothType.GATT_CHARACTERISTIC; }

    @Override
    public BluetoothGattCharacteristic clone()
    { throw new UnsupportedOperationException(); } // FIXME

    @Override
    public BluetoothGattDescriptor find(final String UUID, final long timeoutMS) {
        final BluetoothManager manager = DBTManager.getBluetoothManager();
        return (BluetoothGattDescriptor) manager.find(BluetoothType.GATT_DESCRIPTOR,
                null, UUID, this, timeoutMS);
    }

    @Override
    public BluetoothGattDescriptor find(final String UUID) {
        return find(UUID, 0);
    }

    @Override
    public final BluetoothGattService getService() { return service; }

    @Override
    public final String[] getFlags() { return properties; }

    @Override
    public final byte[] getValue() { return cachedValue; }

    @Override
    public final byte[] readValue() throws BluetoothException {
        final byte[] value = readValueImpl();
        updateCachedValue(value, true);
        return cachedValue;
    }

    @Override
    public final boolean writeValue(final byte[] value) throws BluetoothException {
        final boolean res = writeValueImpl(value);
        if( res ) {
            updateCachedValue(value, false);
        }
        return res;
    }

    @Override
    public final List<BluetoothGattDescriptor> getDescriptors() { return descriptorList; }

    @Override
    public final synchronized void enableValueNotifications(final BluetoothNotification<byte[]> callback) {
        final boolean res = enableValueNotificationsImpl(true);
        if( DEBUG ) {
            System.err.println("GATTCharacteristicListener.enableValueNotifications: GATT Native: "+res);
        }
        valueNotificationCB = callback;
    }

    @Override
    public final synchronized void disableValueNotifications() {
        final boolean res = enableValueNotificationsImpl(false);
        if( DEBUG ) {
            System.err.println("GATTCharacteristicListener.disableValueNotifications: GATT Native: "+res);
        }
        valueNotificationCB = null;
    }

    @Override
    public final boolean getNotifying() {
        return null != valueNotificationCB;
    }

    @Override
    public final boolean addCharacteristicListener(final GATTCharacteristicListener listener) {
        return addCharacteristicListener(listener, true);
    }
    private final boolean addCharacteristicListener(final GATTCharacteristicListener listener, final boolean nativeEnable) {
        if( nativeEnable ) {
            final boolean res = enableValueNotificationsImpl(true);
            if( DEBUG ) {
                System.err.println("GATTCharacteristicListener.addCharacteristicListener: GATT Native: "+res);
            }
        }
        return service.device.addCharacteristicListener(listener, this);
    }

    @Override
    public final boolean removeCharacteristicListener(final GATTCharacteristicListener l) {
        return service.device.removeCharacteristicListener(l);
    }

    @Override
    public final int removeAllCharacteristicListener() {
        return service.device.removeAllCharacteristicListener();
    }

    /**
     * Characteristic Handle of this instance.
     * <p>
     * Attribute handles are unique for each device (server) (BT Core Spec v5.2: Vol 3, Part F Protocol..: 3.2.2 Attribute Handle).
     * </p>
     */
    public final short getHandle() { return handle; }

    /**
     * Returns Characteristics Value Handle.
     * <p>
     * Attribute handles are unique for each device (server) (BT Core Spec v5.2: Vol 3, Part F Protocol..: 3.2.2 Attribute Handle).
     * </p>
     */
    public final short getValueHandle() { return value_handle; }

    /** Returns optional Client Characteristic Configuration index within descriptorList */
    public final int getClientCharacteristicsConfigIndex() { return clientCharacteristicsConfigIndex; }

    @Override
    public final String toString() { return toStringImpl(); }

    /* Native method calls: */

    private native String toStringImpl();

    private native byte[] readValueImpl() throws BluetoothException;

    private native boolean writeValueImpl(byte[] argValue) throws BluetoothException;

    private native List<BluetoothGattDescriptor> getDescriptorsImpl();

    /**
     * Enables disables GATT notification and/or indication.
     */
    private native boolean enableValueNotificationsImpl(boolean v);

    @Override
    protected native void deleteImpl();

}