package com.exalead;

import com.exalead.mercury.component.*;
import com.exalead.mercury.component.config.CVComponentConfig;
import com.exalead.papi.framework.connectors.Connector;
import com.exalead.papi.framework.connectors.ConnectorConfig;
import com.exalead.papi.framework.connectors.introspection.UpgradeConfig;

import exa.bee.KeyValue;

@IntrospectableComponent(
// register the {@link MyUpgradableConnector.Introspector} class to handle introspection queries
introspectorClass=MyUpgradableConnector.Introspector.class,
// tells CloudView this connector supports the config upgrade capability
supportedQueries={ @SupportedQuery(queryClass=UpgradeConfig.class)})
public class MyUpgradableConnector extends Connector {
public MyUpgradableConnector(final ConnectorConfig config) throws Exception {
super(config);
}

public static class Introspector implements CVComponentIntrospector {
// Member method called to process introspection queries.
@Override
public Object execute(
final CVComponentConfig componentConfig,
final IntrospectionQuery query) throws Exception {
if (query instanceof UpgradeConfig) {
final UpgradeConfig up = (UpgradeConfig) query;
System.out.println("Updating configuration of connector " + up.getConnectorName());
//Specify the component versions explicitly and the dependencies to perform the upgrade
//The following example shows how to upgrade from version 1.0 to 2.0 if you need
// an intermediary upgrade to version 1.1
//You can either upgrade from 1.0 to 2.0 OR from 1.1 to 2.0
//CAUTION: As by default CloudView is not able to provide the previous connector version (1.0 or 1.1)
//to this method, if you choose to migrate from 1.1 to 2.0, the same code will be called.
//In our example, it will execute the upgrade operation starting from 1.0.
applyChangesFrom_1_0To1_1(up.getCurrentConfig());
applyChangesFrom_1_1To2_0(up.getCurrentConfig());
return up.getCurrentConfig();
}
return null;
}
void applyChangesFrom_1_0To1_1(final KeyValue config) {
renameKey(config, "Foo", "Bar");
}
void applyChangesFrom_1_1To2_0(final KeyValue config) {
// [...] apply required changes. For example, if version 2.0 is multithreaded and
// you need to set up the threadPoolSize property...
}

/**
* Recursively look for a key in the connector configuration, and rename it to another value.
* @param config The configuration to upgrade
* @param prevKey The configuration key name to replace
* @param newKey The new key value
* @return The updated configuration
*/
public KeyValue renameKey(final KeyValue config, final String prevKey, String newKey) {
if (config.getKey() != null) {
if (config.getKey().equals(prevKey)) {
config.setKey(newKey);
}
}
for (int i = 0; i < config.getKeyValue().size(); ++i) {
config.getKeyValue().set(i, renameKey(config.getKeyValue().get(i), prevKey, newKey));
}
return config;
}
}
}