package org.metricshub.vcenter;
   
   /*-
    * ╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲
    * VCenter Java Client
    * ჻჻჻჻჻჻
    * Copyright (C) 2023 - 2025 MetricsHub
    * ჻჻჻჻჻჻
    * 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
   *
   *      http://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.
   * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
   */
  
  import com.vmware.vim25.HostServiceTicket;
  import com.vmware.vim25.InvalidLogin;
  import com.vmware.vim25.mo.Datacenter;
  import com.vmware.vim25.mo.Folder;
  import com.vmware.vim25.mo.HostSystem;
  import com.vmware.vim25.mo.InventoryNavigator;
  import com.vmware.vim25.mo.ManagedEntity;
  import com.vmware.vim25.mo.ServiceInstance;
  import java.net.InetAddress;
  import java.net.URL;
  import java.util.Arrays;
  import java.util.List;
  import java.util.function.Consumer;
  import java.util.function.Supplier;
  import java.util.stream.Collectors;
  
  /**
   * VCenterClient class for interacting with VMware vCenter server.
   */
  public final class VCenterClient {
  
  	private static final String ENTITY_HOST_SYSTEM = "HostSystem";
  	private static final String ENTITY_DATA_CENTER = "Datacenter";
  
  	private static Supplier<Boolean> isDebugEnabled;
  	private static Consumer<String> debug;
  
  	/**
  	 * Private constructor to prevent instantiation of this class
  	 */
  	private VCenterClient() {}
  
  	/**
  	 * Sets the debug methods to be used by the VCenterClient class.
  	 * <p>
  	 * The VCenterClient class may need to write debug information. However,
  	 * depending on whether it runs in the context of MatsyaEngine or as a CLI,
  	 * the debug will need to be handled differently.
  	 * <p>
  	 * In the case of MatsyaEngine, before making any further call to this class,
  	 * use setDebug(MatsyaEngine::getDebugMode, MatsyaEngine::debug).
  	 * <p>
  	 * In the case of CLI, use setDebug() with your own methods (which will probably
  	 * simply print to stdout).
  	 *
  	 * @param isDebugEnabledMethod The static method that returns a boolean whether the debug mode is enabled or not
  	 * @param debugMethod The static method that will print the debug message somewhere
  	 */
  	public static void setDebug(final Supplier<Boolean> isDebugEnabledMethod, final Consumer<String> debugMethod) {
  		isDebugEnabled = isDebugEnabledMethod;
  		debug = debugMethod;
  	}
  
  	/**
  	 * Request an authentication certificate for the specified hostname from the specified
  	 * VMware vCenter server. <p>
  	 * The specified hostname must be registered in VMware vCenter so we can get an authentication
  	 * "token" for it. <p>
  	 * To get this token, we first need to authenticate against VMware vCenter (using the good old
  	 * username and password mechanism). Then, we will be able to connect to the specified hostname
  	 * VMware ESX just using this "token"
  	 *
  	 * @param vCenterName The hostname of IP address of the VMware vCenter system
  	 * @param username Credentials to connect to VMware vCenter
  	 * @param password Associated password
  	 * @param hostname The hostname or IP address of the ESX host that we need an authentication token for
  	 * @return The authentication token in the form of a String
  	 * @throws InvalidLogin when the specified username/password is... well, invalid
  	 * @throws Exception when anything else happens
  	 */
  	public static String requestCertificate(
  		final String vCenterName,
  		final String username,
  		final String password,
  		final String hostname
  	) throws InvalidLogin, Exception {
  		ServiceInstance serviceInstance = null;
 
 		try {
 			// Connect to VCenter
 			URL vCenterURL = new URL("https://" + vCenterName + "/sdk");
 			debug.accept("Connecting to " + vCenterURL.toString() + "...");
 			serviceInstance = new ServiceInstance(vCenterURL, username, password, true);
 
 			// Try to find the specified host in VCenter
 
 			HostSystem hostSystem = getHostSystemManagedEntity(serviceInstance, hostname);
 
 			if (hostSystem == null) {
 				throw new Exception("Unable to find host " + hostname + " in VCenter " + vCenterName);
 			} else {
 				HostServiceTicket ticket = hostSystem.acquireCimServicesTicket();
 				return ticket.getSessionId();
 			}
 		} finally {
 			if (serviceInstance != null) {
 				serviceInstance.getServerConnection().logout();
 			}
 		}
 	}
 
 	/**
 	 * Retrieve in VCenter the managed entity that corresponds to the specified systemName
 	 * @param serviceInstance VCenter service instance
 	 * @param systemName The host name to be found in VCenter
 	 * @return The HostSystem instance that matches with specified systemName. <p>null if not found.
 	 * @throws Exception
 	 */
 	private static HostSystem getHostSystemManagedEntity(final ServiceInstance serviceInstance, final String systemName)
 		throws Exception {
 		// Declarations
 		String entityName;
 		String shortEntityName;
 		ManagedEntity[] managedEntities;
 
 		// Get the root folder (we'll search things from there)
 		Folder rootFolder = serviceInstance.getRootFolder();
 		if (rootFolder == null) {
 			throw new Exception("Couldn't get the root folder");
 		}
 
 		// First pass: Search for all managed entities in the root folder
 		// Try an exact match of the managed entity name with the specified hostname (case insensitive, of course)
 		InventoryNavigator inventoryNavigator = new InventoryNavigator(rootFolder);
 		managedEntities = inventoryNavigator.searchManagedEntities(ENTITY_HOST_SYSTEM);
 		if (managedEntities != null) {
 			// We did get a list of managed entities, let's parse them
 			for (ManagedEntity managedEntity : managedEntities) {
 				entityName = managedEntity.getName();
 				if (systemName.equalsIgnoreCase(entityName)) {
 					// Found it! Return immediately the corresponding HostSystem object
 					return (HostSystem) managedEntity;
 				}
 			}
 
 			// Second pass: try again, but compare with a "shortened" version of the hostname of the managed entities (i.e. what before the first dot)
 			if (systemName.indexOf('.') == -1) {
 				// Of course, we do this 2nd pass only if the specified system name doesn't have a dot, i.e. is a short name
 				for (ManagedEntity managedEntity : managedEntities) {
 					entityName = managedEntity.getName();
 					int dotIndex = entityName.indexOf('.');
 					if (dotIndex > 1) {
 						shortEntityName = entityName.substring(0, dotIndex);
 						if (systemName.equalsIgnoreCase(shortEntityName)) {
 							// Found it! Return immediately the corresponding HostSystem object
 							return (HostSystem) managedEntity;
 						}
 					}
 				}
 			}
 
 			// We're here, which means that we did get a list of managed entities, but none of them match with the specified hostname
 			if (isDebugEnabled.get()) {
 				String managedEntitiesString = "";
 				for (ManagedEntity managedEntity : managedEntities) {
 					managedEntitiesString = managedEntitiesString + " - " + managedEntity.getName() + "\n";
 				}
 				StringBuilder entityList = new StringBuilder();
 				for (ManagedEntity managedEntity : managedEntities) {
 					entityList.append(" - ").append(managedEntity.getName()).append("\n");
 				}
 				debug.accept(
 					"VCenterClient: Couldn't find host " +
 					systemName +
 					" in the list of managed entities in VCenter " +
 					serviceInstance.getServerConnection().getUrl().getHost() +
 					":\n" +
 					entityList
 				);
 				debug.accept("VCenterClient: Will now try with the IP address of " + systemName);
 			}
 		}
 
 		// Third pass: Try to find the host in another way, through the Datacenter entities
 		managedEntities = inventoryNavigator.searchManagedEntities(ENTITY_DATA_CENTER);
 		if (null == managedEntities || managedEntities.length == 0) {
 			throw new Exception("No Datacenter-type managed entity");
 		}
 
 		// And we will try that using the IP address instead of the host name
 		InetAddress[] hostIPaddresses;
 		try {
 			hostIPaddresses = InetAddress.getAllByName(systemName);
 		} catch (Exception e) {
 			throw new Exception("Couldn't resolve " + systemName + " into a valid IP address");
 		}
 
 		// Go through each datacenter
 		for (ManagedEntity datacenterEntity : managedEntities) {
 			// Go through each IP address of the specified system name
 			for (InetAddress hostIPaddress : hostIPaddresses) {
 				// Use the index to find the managed entity we want, by IP address
 				ManagedEntity[] managedEntitiesInDatacenter = serviceInstance
 					.getSearchIndex()
 					.findAllByIp((Datacenter) datacenterEntity, hostIPaddress.getHostAddress(), false);
 
 				// If we got something, return immediately the corresponding HostSystem instance, of the first match!
 				if (managedEntitiesInDatacenter != null && managedEntitiesInDatacenter.length != 0) {
 					return (HostSystem) managedEntitiesInDatacenter[0];
 				}
 			}
 		}
 
 		return null;
 	}
 
 	/**
 	 * Retrieve all managed entities of type "HostSystem" in the specified VCenter.
 	 * @param vCenterName The hostname of IP address of the VMware vCenter system
 	 * @param username Credentials to connect to VMware vCenter
 	 * @param password Associated password
 	 * @return The list of hostnames (or IP addresses) registered in the VCenter
 	 * @throws InvalidLogin for bad credentials
 	 * @throws Exception when anything else goes south
 	 */
 	public static List<String> getAllHostSystemManagedEntities(
 		final String vCenterName,
 		final String username,
 		final String password
 	) throws Exception {
 		ServiceInstance serviceInstance = null;
 
 		try {
 			// Connect to VCenter
 			URL vCenterURL = new URL("https://" + vCenterName + "/sdk");
 			debug.accept("Connecting to " + vCenterURL.toString() + "...");
 			serviceInstance = new ServiceInstance(vCenterURL, username, password, true);
 
 			// Get the root folder (we'll search things from there)
 			Folder rootFolder = serviceInstance.getRootFolder();
 			if (rootFolder == null) {
 				throw new Exception("Couldn't get the root folder");
 			}
 
 			// InventoryNavigator allows us to get all managed entities
 			InventoryNavigator inventoryNavigator = new InventoryNavigator(rootFolder);
 
 			// Get all entities of type "HostSystem" and return as a list of HostSystem
 			return Arrays
 				.stream(inventoryNavigator.searchManagedEntities(ENTITY_HOST_SYSTEM))
 				.map(ManagedEntity::getName)
 				.collect(Collectors.toList());
 		} finally {
 			if (serviceInstance != null) {
 				serviceInstance.getServerConnection().logout();
 			}
 		}
 	}
 }