001// Copyright 2007, 2008, 2010 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.internal.services;
016
017import org.apache.tapestry5.ComponentResources;
018import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
019import org.apache.tapestry5.ioc.services.SymbolSource;
020import org.apache.tapestry5.ioc.services.TypeCoercer;
021import org.apache.tapestry5.services.InvalidationListener;
022import org.apache.tapestry5.services.MetaDataLocator;
023
024import java.util.Map;
025
026public class MetaDataLocatorImpl implements MetaDataLocator, InvalidationListener
027{
028    private final SymbolSource symbolSource;
029
030    private final TypeCoercer typeCoercer;
031
032    private final ComponentModelSource modelSource;
033
034    private final Map<String, Map<String, String>> defaultsByFolder = CollectionFactory
035            .newCaseInsensitiveMap();
036
037    private final Map<String, String> cache = CollectionFactory.newConcurrentMap();
038
039    private interface ValueLocator
040    {
041        String valueForKey(String key);
042    }
043
044    public MetaDataLocatorImpl(SymbolSource symbolSource, TypeCoercer typeCoercer,
045            ComponentModelSource modelSource, Map<String, String> configuration)
046    {
047        this.symbolSource = symbolSource;
048        this.typeCoercer = typeCoercer;
049        this.modelSource = modelSource;
050
051        loadDefaults(configuration);
052    }
053
054    public void objectWasInvalidated()
055    {
056        cache.clear();
057    }
058
059    private void loadDefaults(Map<String, String> configuration)
060    {
061        for (Map.Entry<String, String> e : configuration.entrySet())
062        {
063            String key = e.getKey();
064
065            int colonx = key.indexOf(':');
066
067            String folderKey = colonx < 0 ? "" : key.substring(0, colonx);
068
069            Map<String, String> forFolder = defaultsByFolder.get(folderKey);
070
071            if (forFolder == null)
072            {
073                forFolder = CollectionFactory.newCaseInsensitiveMap();
074                defaultsByFolder.put(folderKey, forFolder);
075            }
076
077            String defaultKey = colonx < 0 ? key : key.substring(colonx + 1);
078
079            forFolder.put(defaultKey, e.getValue());
080        }
081    }
082
083    public <T> T findMeta(String key, final ComponentResources resources, Class<T> expectedType)
084    {
085        String value = getSymbolExpandedValueFromCache(key, resources.getCompleteId() + "/" + key,
086                new ValueLocator()
087                {
088                    public String valueForKey(String key)
089                    {
090                        return locate(key, resources);
091                    }
092                });
093
094        return typeCoercer.coerce(value, expectedType);
095    }
096
097    public <T> T findMeta(String key, final String pageName, Class<T> expectedType)
098    {
099        String value = getSymbolExpandedValueFromCache(key, pageName + "/" + key,
100                new ValueLocator()
101                {
102                    public String valueForKey(String key)
103                    {
104                        String result = modelSource.getPageModel(pageName).getMeta(key);
105
106                        return result != null ? result : locateInDefaults(key, pageName);
107                    }
108                });
109
110        return typeCoercer.coerce(value, expectedType);
111    }
112
113    private String getSymbolExpandedValueFromCache(String key, String cacheKey,
114            ValueLocator valueLocator)
115    {
116        if (cache.containsKey(cacheKey))
117            return cache.get(cacheKey);
118
119        String value = valueLocator.valueForKey(key);
120
121        if (value == null)
122        {
123            value = symbolSource.valueForSymbol(key);
124        }
125        else
126        {
127            value = symbolSource.expandSymbols(value);
128        }
129
130        cache.put(cacheKey, value);
131
132        return value;
133    }
134
135    private String locate(String key, ComponentResources resources)
136    {
137        ComponentResources cursor = resources;
138
139        while (true)
140        {
141            String value = cursor.getComponentModel().getMeta(key);
142
143            if (value != null)
144                return value;
145
146            ComponentResources next = cursor.getContainerResources();
147
148            if (next == null)
149                return locateInDefaults(key, cursor.getPageName());
150
151            cursor = next;
152        }
153    }
154
155    private String locateInDefaults(String key, String pageName)
156    {
157
158        // We're going to peel this apart, slash by slash. Thus for
159        // "mylib/myfolder/mysubfolder/MyPage" we'll be checking: "mylib/myfolder/mysubfolder",
160        // then "mylib/myfolder", then "mylib", then "".
161
162        String path = pageName;
163
164        while (true)
165        {
166            int lastSlashx = path.lastIndexOf('/');
167
168            String folderKey = lastSlashx < 0 ? "" : path.substring(0, lastSlashx);
169
170            Map<String, String> forFolder = defaultsByFolder.get(folderKey);
171
172            if (forFolder != null && forFolder.containsKey(key))
173                return forFolder.get(key);
174
175            if (lastSlashx < 0)
176                break;
177
178            path = path.substring(0, lastSlashx);
179        }
180
181        // Perhaps from here into the symbol sources? That may come later.
182
183        return null;
184    }
185}