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OfficeFloor plug-in for Web
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/*
 * OfficeFloor - http://www.officefloor.net
 * Copyright (C) 2005-2018 Daniel Sagenschneider
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see .
 */
package net.officefloor.web.state;

import java.util.LinkedList;
import java.util.List;

import net.officefloor.compile.impl.util.CompileUtil;
import net.officefloor.frame.api.build.None;
import net.officefloor.frame.api.managedobject.CoordinatingManagedObject;
import net.officefloor.frame.api.managedobject.ManagedObject;
import net.officefloor.frame.api.managedobject.ObjectRegistry;
import net.officefloor.frame.api.managedobject.source.ManagedObjectSource;
import net.officefloor.frame.api.managedobject.source.impl.AbstractManagedObjectSource;
import net.officefloor.frame.api.source.PrivateSource;
import net.officefloor.server.http.HttpHeader;
import net.officefloor.server.http.HttpRequest;
import net.officefloor.server.http.ServerHttpConnection;
import net.officefloor.web.build.HttpObjectParser;
import net.officefloor.web.build.HttpObjectParserFactory;
import net.officefloor.web.build.WebArchitect;

/**
 * {@link ManagedObjectSource} to provide an {@link Object} from the
 * {@link HttpObjectParser} instances.
 * 
 * @author Daniel Sagenschneider
 */
@PrivateSource
public class HttpObjectManagedObjectSource
		extends AbstractManagedObjectSource {

	/**
	 * Dependency keys.
	 */
	public static enum HttpObjectDependencies {
		SERVER_HTTP_CONNECTION
	}

	/**
	 * {@link Object} {@link Class}.
	 */
	private final Class objectClass;

	/**
	 * Accepted content-type values.
	 */
	private final String[] acceptedContentTypes;

	/**
	 * {@link List} of {@link HttpObjectParserFactory} instances that are loaded by
	 * the {@link WebArchitect}.
	 */
	private final List parserFactories;

	/**
	 * {@link HttpObjectParser} instances.
	 */
	private HttpObjectParser[] parsers;

	/**
	 * Instantiate.
	 * 
	 * @param objectClass
	 *            {@link Object} {@link Class}.
	 * @param acceptedContentTypes
	 *            Accepted content-type values.
	 * @param parserFactories
	 *            {@link List} of {@link HttpObjectParserFactory} instances that are
	 *            loaded by the {@link WebArchitect}.
	 */
	public HttpObjectManagedObjectSource(Class objectClass, String[] acceptedContentTypes,
			List parserFactories) {
		this.objectClass = objectClass;
		this.acceptedContentTypes = acceptedContentTypes;
		this.parserFactories = parserFactories;
	}

	/*
	 * ==================== ManagedObjectSource ==========================
	 */

	@Override
	protected void loadSpecification(SpecificationContext context) {
	}

	@Override
	@SuppressWarnings("unchecked")
	protected void loadMetaData(MetaDataContext context) throws Exception {

		// Load the meta-data
		context.setObjectClass(this.objectClass);
		context.setManagedObjectClass(HttpObjectManagedObject.class);
		context.addDependency(HttpObjectDependencies.SERVER_HTTP_CONNECTION, ServerHttpConnection.class);

		// Create filter message
		String acceptContentTypeMessage = " in any Content-Type";
		if ((this.acceptedContentTypes != null) && (this.acceptedContentTypes.length > 0)) {
			acceptContentTypeMessage = " for accepting Content-Type"
					+ ((this.acceptedContentTypes.length > 2) ? "s " : " ")
					+ String.join(", ", this.acceptedContentTypes);
		}

		// Create the list of parsers
		List> objectParsers = new LinkedList<>();
		NEXT_PARSER: for (HttpObjectParserFactory parserFactory : this.parserFactories) {

			// Obtain the content type
			String contentType = parserFactory.getContentType();

			// Determine if accept Content-Type
			if ((this.acceptedContentTypes != null) && (this.acceptedContentTypes.length > 0)) {
				// Ensure one of the accepted content types
				boolean isAcceptableContentType = false;
				for (String acceptedContentType : this.acceptedContentTypes) {
					if (acceptedContentType.equals(contentType)) {
						isAcceptableContentType = true;
					}
				}
				if (!isAcceptableContentType) {
					// Not acceptable Content-Type
					continue NEXT_PARSER;
				}
			}

			// Create the parser for the object class
			try {
				HttpObjectParser parser = parserFactory.createHttpObjectParser(this.objectClass);
				if (parser == null) {
					continue NEXT_PARSER; // parser not able to handle object
				}

				// Include the parser
				objectParsers.add(parser);

			} catch (Exception ex) {
				// Propagate failure about creating object parser
				String errorMessage = ex.getMessage();
				errorMessage = CompileUtil.isBlank(errorMessage) ? "" : " (cause: " + errorMessage + ")";
				throw new Exception("Failed to create " + HttpObjectParser.class.getSimpleName() + " for Content-Type "
						+ contentType + " for object " + this.objectClass.getName() + errorMessage, ex);
			}
		}
		this.parsers = objectParsers.toArray(new HttpObjectParser[objectParsers.size()]);

		// Ensure have at least one object parser
		if (this.parsers.length == 0) {
			throw new Exception("No " + HttpObjectParser.class.getSimpleName() + " available for object "
					+ this.objectClass.getName() + acceptContentTypeMessage);
		}
	}

	@Override
	protected ManagedObject getManagedObject() throws Throwable {
		return new HttpObjectManagedObject();
	}

	/**
	 * HTTP Object {@link ManagedObject}.
	 */
	private class HttpObjectManagedObject implements CoordinatingManagedObject {

		/**
		 * HTTP object.
		 */
		private Object httpObject;

		/*
		 * ================= ManagedObject =========================
		 */

		@Override
		public void loadObjects(ObjectRegistry registry) throws Throwable {

			// Obtain the server HTTP connection
			ServerHttpConnection connection = (ServerHttpConnection) registry
					.getObject(HttpObjectDependencies.SERVER_HTTP_CONNECTION);

			// Obtain the content type
			HttpRequest request = connection.getRequest();
			HttpHeader header = request.getHeaders().getHeader("content-type");
			if (header == null) {
				// No content-type so can not parse out object
				this.httpObject = null;
				return;
			}
			String contentType = header.getValue();

			// Search the parsers for matching content type
			for (int i = 0; i < HttpObjectManagedObjectSource.this.parsers.length; i++) {
				HttpObjectParser parser = HttpObjectManagedObjectSource.this.parsers[i];

				// Determine if can handle content-type
				if (contentType.equals(parser.getContentType())) {
					// Found parser for the object
					this.httpObject = parser.parse(connection);
					return; // parsed out the object
				}
			}

			// As here, no HTTP object
			this.httpObject = null;
		}

		@Override
		public Object getObject() throws Throwable {
			return this.httpObject;
		}
	}

}