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Homekit Accessory Protocol for Java
package io.github.hapjava.characteristics.impl.base;
import io.github.hapjava.characteristics.Characteristic;
import io.github.hapjava.characteristics.EventableCharacteristic;
import io.github.hapjava.characteristics.HomekitCharacteristicChangeCallback;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.function.Consumer;
import javax.json.Json;
import javax.json.JsonArrayBuilder;
import javax.json.JsonObject;
import javax.json.JsonObjectBuilder;
import javax.json.JsonValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Base class for implementing {@link Characteristic}.
*
* @author Andy Lintner
*/
public abstract class BaseCharacteristic implements Characteristic, EventableCharacteristic {
private final Logger logger = LoggerFactory.getLogger(BaseCharacteristic.class);
private final String type;
private final String shortType;
private final String format;
private final String description;
private final boolean isReadable;
private final boolean isWritable;
private final Optional> subscriber;
private final Optional unsubscriber;
/**
* Default constructor
*
* @param type a string containing a UUID that indicates the type of characteristic. Apple defines
* a set of these, however implementors can create their own as well.
* @param format a string indicating the value type, which must be a recognized type by the
* consuming device.
* @param isWritable indicates whether the value can be changed.
* @param isReadable indicates whether the value can be retrieved.
* @param description a description of the characteristic to be passed to the consuming device.
* @param subscriber subscribes to changes
* @param unsubscriber unsubscribes to changes
*/
public BaseCharacteristic(
String type,
String format,
String description,
boolean isReadable,
boolean isWritable,
Optional> subscriber,
Optional unsubscriber) {
if (type == null || format == null || description == null) {
throw new NullPointerException();
}
this.type = type;
this.shortType = this.type.replaceAll("^0*([0-9a-fA-F]+)-0000-1000-8000-0026BB765291$", "$1");
this.format = format;
this.description = description;
this.isReadable = isReadable;
this.isWritable = isWritable;
this.subscriber = subscriber;
this.unsubscriber = unsubscriber;
}
@Override
/** {@inheritDoc} */
public final CompletableFuture toJson(int iid) {
return makeBuilder(iid).thenApply(builder -> builder.build());
}
/**
* Creates the JSON serialized form of the accessory for use over the HomeKit Accessory Protocol.
*
* @param instanceId the static id of the accessory.
* @return a future that will complete with the JSON builder for the object.
*/
protected CompletableFuture makeBuilder(int instanceId) {
CompletableFuture futureValue = getValue();
if (futureValue == null) {
futureValue = CompletableFuture.completedFuture(getDefault());
}
return futureValue
.exceptionally(
t -> {
logger.warn("Could not retrieve value " + this.getClass().getName(), t);
return null;
})
.thenApply(
value -> {
JsonArrayBuilder perms = Json.createArrayBuilder();
if (isReadable) {
perms.add("pr");
}
if (isWritable) {
perms.add("pw");
}
if (subscriber.isPresent()) {
perms.add("ev");
}
JsonObjectBuilder builder =
Json.createObjectBuilder()
.add("iid", instanceId)
.add("type", shortType)
.add("perms", perms.build())
.add("format", format)
.add("description", description);
if (isReadable) setJsonValue(builder, value);
return builder;
});
}
/** {@inheritDoc} */
@Override
public final void setValue(JsonValue jsonValue) {
try {
setValue(convert(jsonValue));
} catch (Exception e) {
logger.warn("Error while setting JSON value", e);
}
}
/** {@inheritDoc} */
@Override
public void supplyValue(JsonObjectBuilder builder) {
try {
setJsonValue(builder, getValue().get());
} catch (InterruptedException | ExecutionException e) {
logger.warn("Error retrieving value", e);
setJsonValue(builder, getDefault());
}
}
/** {@inheritDoc} */
@Override
public void subscribe(HomekitCharacteristicChangeCallback callback) {
subscriber.get().accept(callback);
}
/** {@inheritDoc} */
@Override
public void unsubscribe() {
unsubscriber.get().run();
}
/**
* Converts from the JSON value to a Java object of the type T
*
* @param jsonValue the JSON value to convert from.
* @return the converted Java object.
*/
protected abstract T convert(JsonValue jsonValue);
/**
* Update the characteristic value using a new value supplied by the connected client.
*
* @param value the new value to set.
* @throws Exception if the value cannot be set.
*/
protected abstract void setValue(T value) throws Exception;
/**
* Retrieves the current value of the characteristic.
*
* @return a future that will complete with the current value.
*/
protected abstract CompletableFuture getValue();
/**
* Supplies a default value for the characteristic to send to connected clients when the real
* value. cannot be retrieved.
*
* @return a sensible default value.
*/
protected abstract T getDefault();
/**
* Writes the value key to the serialized characteristic
*
* @param builder The JSON builder to add the value to
* @param value The value to add
*/
protected void setJsonValue(JsonObjectBuilder builder, T value) {
// I don't like this - there should really be a way to construct a disconnected JSONValue...
if (value instanceof Boolean) {
builder.add("value", (Boolean) value);
} else if (value instanceof Double) {
builder.add("value", (Double) value);
} else if (value instanceof Integer) {
builder.add("value", (Integer) value);
} else if (value instanceof Long) {
builder.add("value", (Long) value);
} else if (value instanceof BigInteger) {
builder.add("value", (BigInteger) value);
} else if (value instanceof BigDecimal) {
builder.add("value", (BigDecimal) value);
} else if (value == null) {
builder.addNull("value");
} else {
builder.add("value", value.toString());
}
}
}