From bee5dd259a4438d45ecd1bcc26dfba12875236d6 Mon Sep 17 00:00:00 2001
From: Thomas Lenz <thomas.lenz@egiz.gv.at>
Date: Tue, 26 Jun 2018 11:03:48 +0200
Subject: initial commit

---
 .../impl/idp/auth/modules/ModuleRegistration.java  | 151 +++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/auth/modules/ModuleRegistration.java

(limited to 'eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/auth/modules/ModuleRegistration.java')

diff --git a/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/auth/modules/ModuleRegistration.java b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/auth/modules/ModuleRegistration.java
new file mode 100644
index 00000000..cb4a055a
--- /dev/null
+++ b/eaaf_core/src/main/java/at/gv/egiz/eaaf/core/impl/idp/auth/modules/ModuleRegistration.java
@@ -0,0 +1,151 @@
+/*******************************************************************************
+ *******************************************************************************/
+package at.gv.egiz.eaaf.core.impl.idp.auth.modules;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.ServiceLoader;
+
+import javax.annotation.PostConstruct;
+
+import org.apache.commons.lang3.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ApplicationContext;
+import org.springframework.core.io.Resource;
+
+import at.gv.egiz.eaaf.core.api.idp.auth.modules.AuthModule;
+import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext;
+import at.gv.egiz.eaaf.core.api.idp.process.ProcessEngine;
+import at.gv.egiz.eaaf.core.impl.idp.process.ProcessDefinitionParserException;
+
+/**
+ * This class handles registering modules. The modules are detected either with
+ * the ServiceLoader mechanism or via Spring. All detected modules are ranked
+ * according to their priority.
+ */
+public class ModuleRegistration {
+
+	private static ModuleRegistration instance = new ModuleRegistration();
+
+	private List<AuthModule> priorizedModules = new ArrayList<>();
+
+	@Autowired
+	private ApplicationContext ctx;
+
+	@Autowired
+	private ProcessEngine processEngine;
+
+	private Logger log = LoggerFactory.getLogger(getClass());
+
+	public static ModuleRegistration getInstance() {
+		return instance;
+	}
+
+	private ModuleRegistration() {
+	}
+
+	@PostConstruct
+	private void init() {
+		// load modules via the ServiceLoader
+		initServiceLoaderModules();
+
+		// load modules via Spring
+		initSpringModules();
+
+		// order modules according to their priority
+		sortModules();
+	}
+	
+	/**
+	 * Discovers modules which use the ServiceLoader mechanism.
+	 */
+	private void initServiceLoaderModules() {
+		log.info("Looking for auth modules.");
+		ServiceLoader<AuthModule> loader = ServiceLoader.load(AuthModule.class);
+		Iterator<AuthModule> modules = loader.iterator();
+		while (modules.hasNext()) {
+			AuthModule module = modules.next();
+			log.info("Detected module {}", module.getClass().getName());
+			registerModuleProcessDefinitions(module);
+			priorizedModules.add(module);
+		}
+	}
+
+	/**
+	 * Discovers modules which use Spring.
+	 */
+	private void initSpringModules() {
+		log.debug("Discovering Spring modules.");
+		Map<String, AuthModule> modules = ctx.getBeansOfType(AuthModule.class);
+		for (AuthModule module : modules.values()) {
+			registerModuleProcessDefinitions(module);
+			priorizedModules.add(module);
+		}
+	}
+
+	/**
+	 * Registers the resource uris for the module.
+	 * 
+	 * @param module
+	 *            the module.
+	 */
+	private void registerModuleProcessDefinitions(AuthModule module) {
+		for (String uri : module.getProcessDefinitions()) {
+			Resource resource = ctx.getResource(uri);
+			if (resource.isReadable()) {
+				log.info("Registering process definition '{}'.", uri);
+				try (InputStream processDefinitionInputStream = resource.getInputStream()) {
+					processEngine.registerProcessDefinition(processDefinitionInputStream);
+				} catch (IOException e) {
+					log.error("Process definition '{}' could NOT be read.", uri, e);
+				} catch (ProcessDefinitionParserException e) {
+					log.error("Error while parsing process definition '{}'", uri, e);
+				}
+			} else {
+				log.error("Process definition '{}' cannot be read.", uri);
+			}
+		}
+	}
+
+	/**
+	 * Order the modules in descending order according to their priority.
+	 */
+	private void sortModules() {
+		Collections.sort(priorizedModules, new Comparator<AuthModule>() {
+			@Override
+			public int compare(AuthModule thisAuthModule, AuthModule otherAuthModule) {
+				int thisOrder = thisAuthModule.getPriority();
+				int otherOrder = otherAuthModule.getPriority();
+				return (thisOrder < otherOrder ? 1 : (thisOrder == otherOrder ? 0 : -1));
+			}
+		});
+	}
+
+	/**
+	 * Returns the process description id of the first process, in the highest ranked
+	 * module, which is able to work with the given execution context.
+	 * 
+	 * @param context
+	 *            the {@link ExecutionContext}.
+	 * @return the process id or {@code null}
+	 */
+	public String selectProcess(ExecutionContext context) {
+		for (AuthModule module : priorizedModules) {
+			String id = module.selectProcess(context);
+			if (StringUtils.isNotEmpty(id)) {
+				log.debug("Process with id '{}' selected, for context '{}'.", id, context);
+				return id;
+			}
+		}
+		log.info("No process is able to handle context '{}'.", context);
+		return null;
+	}
+}
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