001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.services.javascript;
016
017import java.util.Collections;
018import java.util.List;
019
020import org.apache.tapestry5.Asset;
021import org.apache.tapestry5.func.F;
022import org.apache.tapestry5.func.Flow;
023import org.apache.tapestry5.func.Mapper;
024import org.apache.tapestry5.func.Predicate;
025import org.apache.tapestry5.ioc.ServiceBinder;
026import org.apache.tapestry5.ioc.ServiceBindingOptions;
027import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
028import org.apache.tapestry5.ioc.internal.util.InternalUtils;
029import org.apache.tapestry5.services.AssetSource;
030
031/**
032 * An extensible implementation of {@link JavaScriptStack} that can be used as the implementation of a service.
033 * The contributions to the service are used to supply the libraries, stylesheets, and initialization for a
034 * JavaScriptStack, allowing the stack to be more dynamically configured. In practice, one will use
035 * {@link ServiceBinder#bind(Class, Class)} and {@link ServiceBindingOptions#withMarker(Class...)} to construct the
036 * service, then use the marker annotation to inject the service when contributing the service into to the
037 * {@link JavaScriptStackSource}.
038 * <p>
039 * A limitation of this implementation is that the contributed assets are not localized at all.
040 * 
041 * @since 5.3
042 * @see StackExtension
043 */
044@UsesOrderedConfiguration(StackExtension.class)
045public class ExtensibleJavaScriptStack implements JavaScriptStack
046{
047    private final AssetSource assetSource;
048
049    private final List<Asset> libraries;
050
051    private final List<StylesheetLink> stylesheets;
052
053    private final String initialization;
054
055    private final Predicate<StackExtension> by(final StackExtensionType type)
056    {
057        return new Predicate<StackExtension>()
058        {
059            public boolean accept(StackExtension element)
060            {
061                return element.type == type;
062            }
063        };
064    }
065
066    private final Mapper<StackExtension, String> extractValue = new Mapper<StackExtension, String>()
067    {
068        public String map(StackExtension element)
069        {
070            return element.value;
071        };
072    };
073
074    private final Mapper<String, Asset> stringToAsset = new Mapper<String, Asset>()
075    {
076        public Asset map(String value)
077        {
078            return assetSource.getExpandedAsset(value);
079        };
080    };
081
082    private final Mapper<Asset, StylesheetLink> assetToStylesheetLink = new Mapper<Asset, StylesheetLink>()
083    {
084        public StylesheetLink map(Asset asset)
085        {
086            return new StylesheetLink(asset);
087        };
088    };
089
090    public ExtensibleJavaScriptStack(AssetSource assetSource, List<StackExtension> configuration)
091    {
092        this.assetSource = assetSource;
093
094        Flow<StackExtension> extensions = F.flow(configuration);
095
096        libraries = extensions.filter(by(StackExtensionType.LIBRARY)).map(extractValue).map(stringToAsset).toList();
097
098        stylesheets = extensions.filter(by(StackExtensionType.STYLESHEET)).map(extractValue).map(stringToAsset)
099                .map(assetToStylesheetLink).toList();
100
101        List<String> initializations = extensions.filter(by(StackExtensionType.INITIALIZATION)).map(extractValue)
102                .toList();
103
104        initialization = initializations.isEmpty() ? null : InternalUtils.join(initializations, "\n");
105    }
106
107    public List<String> getStacks()
108    {
109        return Collections.emptyList();
110    }
111
112    public List<Asset> getJavaScriptLibraries()
113    {
114        return libraries;
115    }
116
117    public List<StylesheetLink> getStylesheets()
118    {
119        return stylesheets;
120    }
121
122    public String getInitialization()
123    {
124        return initialization;
125    }
126
127}