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// Copyright 2015-2024 Nstream, inc.
//
// Licensed under the Redis Source Available License 2.0 (RSALv2) Agreement;
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://redis.com/legal/rsalv2-agreement/
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package nstream.adapter.common.provision;

import java.util.HashMap;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Properties;
import nstream.adapter.common.AdapterUtils;
import swim.structure.Item;
import swim.structure.Record;
import swim.structure.Value;
import swim.util.Log;

public final class ProvisionLoader {

  private static final Map> REGISTRY = new HashMap<>();

  private ProvisionLoader() {
  }

  @SuppressWarnings("unchecked")
  public static  AbstractProvision getProvision(String name) {
    final AbstractProvision result = REGISTRY.get(name);
    if (result == null) {
      throw new NoSuchElementException("No ProvisionLoader entry under " + name);
    }
    return (AbstractProvision) result;
  }

  public static int loadProvisions(Log log, Value config) {
    int errors = 0;
    for (Item provisionVal: config.get("provisions")) {
      try {
        loadFromItem(log, provisionVal);
      } catch (RuntimeException e) {
        errors++;
        e.printStackTrace();
      }
    }
    return errors;
  }

  @SuppressWarnings("unchecked")
  static  void loadFromItem(Log log, Item conf) {
    if (!(conf instanceof Record)) {
      log.warn("Ignored invalid Provision configuration " + conf);
      return;
    }
    final String name = conf.getAttr("provision").stringValue(null);
    if (name == null || name.isEmpty()) {
      log.warn("Ignored nameless Provision configuration " + conf);
      return;
    }
    final Class> provisionClass;
    try {
      provisionClass = (Class>) Class.forName(conf.get("class").stringValue());
    } catch (Exception e) {
      log.warn("Ignored Provision configuration " + conf + " with invalid class");
      return;
    }
    final Properties props = new Properties();
    AdapterUtils.loadPropsFromUse(log, "provision " + name, props, conf.get("use"));
    AdapterUtils.loadPropsFromDef(log, "provision " + name, props, conf.get("def"));
    final AbstractProvision collision = REGISTRY.get(name);
    loadFromProperties(log, name, provisionClass, props);
    if (collision != null) {
      log.warn("Existing " + collision.getClass().getName() + " under " + name
          + " will be unloaded to accommodate incoming same-named provision");
      collision.unload(log);
    }
  }

  private static  void loadFromProperties(Log log, String name,
                                             Class> provisionClass, Properties p) {
    try {
      loadProvision(log, name, provisionClass, p);
    } catch (ReflectiveOperationException e) {
      throw new RuntimeException("Provision " + name + " incurred issue during reflection", e);
    }
  }

  private static  void loadProvision(Log log, String name,
                                        Class> clazz, Properties properties)
      throws ReflectiveOperationException {
    final AbstractProvision result = clazz.getDeclaredConstructor().newInstance();
    result.load(log, properties);
    REGISTRY.put(name, result);
  }

  public static void debugProvisionNames(Log log) {
    log.info("Loaded provisions named: " + REGISTRY.keySet());
  }

  public static void logProvisionNames(Log log) {
    log.info("Loaded provisions named: " + REGISTRY.keySet());
  }

}