/*
 * Copyright 2013-present the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 com.alibaba.cloud.nacos.annotation;

import java.util.Set;

import com.alibaba.nacos.api.config.ConfigChangeEvent;
import com.alibaba.nacos.api.config.ConfigChangeItem;
import com.alibaba.nacos.common.utils.CollectionUtils;
import org.jspecify.annotations.Nullable;

public abstract class NacosPropertiesKeyListener extends AbstractConfigChangeListener {

	@Nullable Set<String> interestedKeys;

	@Nullable Set<String> interestedKeyPrefixes;

	NacosPropertiesKeyListener(Object target) {
		super(target);
	}

	NacosPropertiesKeyListener(Object target, Set<String> interestedKeys) {
		this(target);
		this.interestedKeys = interestedKeys;
	}

	public NacosPropertiesKeyListener(Object target, Set<String> interestedKeys, Set<String> interestedKeyPrefixes) {
		this(target);
		this.interestedKeys = interestedKeys;
		this.interestedKeyPrefixes = interestedKeyPrefixes;
	}

	@Override
	public final void receiveConfigChange(ConfigChangeEvent event) {
		if (CollectionUtils.isNotEmpty(interestedKeys) || CollectionUtils.isNotEmpty(interestedKeyPrefixes)) {
			boolean foundInterested = false;
			for (ConfigChangeItem changeItem : event.getChangeItems()) {
				if (interestedKeys != null && matchesInterestedKey(changeItem.getKey(), interestedKeys)) {
					foundInterested = true;
					break;
				}
				if (interestedKeyPrefixes != null) {
					for (String prefix : interestedKeyPrefixes) {
						if (changeItem.getKey().startsWith(prefix)) {
							foundInterested = true;
							break;
						}
					}
				}
			}
			if (!foundInterested) {
				return;
			}
		}
		configChanged(event);
	}

	/**
	 * Check whether the changed key matches any of the interested keys.
	 *
	 * For YAML array/list configurations, the config change parser flattens keys
	 * with array indices (e.g. {@code myList[0]}, {@code myList[1]}), but users
	 * typically register interest in the base key ({@code myList}). This method
	 * handles both exact matches and array-indexed key matches by stripping the
	 * first {@code [index]} suffix and checking against the interested keys.
	 *
	 * @param changedKey the key from the {@link ConfigChangeItem}
	 * @param interestedKeys the set of keys the listener is interested in
	 * @return {@code true} if the changed key matches any interested key
	 */
	private boolean matchesInterestedKey(String changedKey, Set<String> interestedKeys) {
		if (interestedKeys.contains(changedKey)) {
			return true;
		}
		// Handle array-indexed keys: "key[0]" or "key[0].nested" should match "key"
		int bracketIndex = changedKey.indexOf('[');
		if (bracketIndex > 0) {
			String baseKey = changedKey.substring(0, bracketIndex);
			return interestedKeys.contains(baseKey);
		}
		return false;
	}

	@Override
	public String toString() {
		return "NacosPropertiesKeyListener{" + "interestedKeys=" + interestedKeys + ", interestedKeyPrefixes="
				+ interestedKeyPrefixes + '}' + "@" + hashCode();
	}

	public abstract void configChanged(ConfigChangeEvent event);
}
