1 /**
2 * This file Copyright (c) 2016-2018 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.ui.framework.ioc;
35
36 import info.magnolia.objectfactory.guice.GuiceComponentProvider;
37 import info.magnolia.objectfactory.guice.GuiceUtils;
38
39 import java.util.Optional;
40
41 import javax.inject.Inject;
42
43 import com.google.inject.Injector;
44 import com.google.inject.Key;
45 import com.google.inject.Provider;
46 import com.google.inject.name.Names;
47
48 /**
49 * <p>
50 * Special {@link Provider} implementation which is used
51 * when a certain type is bound differently in different contexts.
52 * </p>
53 * <p>
54 * This would be the case when e.g. app <b>bar</b> configures a type
55 * {@code Foo} to be implemented by {@code FooBarImpl} and app
56 * <b>baz</b> has a binding of {@code Foo} to {@code FooBazImpl}.
57 * </p>
58 * <p>
59 * In order to support such cases we assume that {@code Foo} is bound
60 * in a special way. It is expected that two concrete implementations
61 * of it are bound using a {@link com.google.inject.BindingAnnotation
62 * binding annotation} such as e.g.
63 * {@link info.magnolia.ui.api.ioc.App App}.
64 * </p>
65 * <p>
66 * By binding the un-annotated type to this provider we allow the developers
67 * to inject types like {@code Foo} without explicitly
68 * mentioning the binding annotations.
69 * This provider will use {@link CurrentUiContextReference} to fetch all the
70 * relevant UI contexts and will produce the possible Guice {@link Key keys}.
71 * The most suitable key is then picked, i.e. we pick the binding
72 * which is closest to the current UI context.
73 * </p>
74 *
75 * <p>
76 * For more information on binding annotations, see
77 * <a href="https://github.com/google/guice/wiki/BindingAnnotations">Guice Binding Annotations tutorial</a>.
78 * </p>
79 *
80 * @param <T> type of the provided instance.
81 *
82 * @see UiContextReference
83 * @see UiContextBoundComponentProvider
84 */
85 class UiContextApplyingProvider<T> implements Provider<T> {
86
87 public static <U> UiContextApplyingProvider<U> of(Class<U> type) {
88 return new UiContextApplyingProvider<>(type);
89 }
90
91 private @Inject Injector injector;
92
93 private final Class<T> type;
94
95 UiContextApplyingProvider(Class<T> type) {
96 this.type = type;
97 }
98
99 @Override
100 public T get() {
101 final CurrentUiContextReference currentUiContext = injector.getInstance(CurrentUiContextReference.class);
102
103 // get all the UI contexts that are reachable from the current one
104 return currentUiContext.getAvailableContextReferences()
105 .stream()
106 // produce a Guice type Key relevant to the UI context
107 .map(uiContextReference -> Key.get(type, uiContextReference.getAnnotation()))
108 // check whether such Key is bound to anything
109 .filter(key -> GuiceUtils.hasExplicitBindingFor(injector, key))
110 .findFirst().map(injector::getInstance)
111 // in most of the cases - there should be a UI-annotated variation to be used
112 .orElseGet(() -> getDefault(currentUiContext));
113 }
114
115 private T getDefault(CurrentUiContextReference context) {
116 return Optional.ofNullable(
117 SessionStore.access().getBeanStore(context.getUiContextReference()).get(type))
118 .orElseGet(() -> {
119 try {
120 return this.injector.getInstance(GuiceComponentProvider.class).newInstance(type);
121 } catch (Exception e) {
122 return this.injector.getInstance(Key.get(GuiceComponentProvider.class, Names.named("main"))).getComponent(type);
123 }
124 });
125 }
126 }