/**
    * Copyright By Grandsoft Company Limited.  
    * 2014年5月19日 下午9:45:14
    */
   package gboat2.base.plugin.struts.freemarker;
   
   import java.io.File;
   import java.io.IOException;
   import java.util.List;
  
  import org.apache.commons.lang3.ObjectUtils;
  import org.apache.struts2.StrutsConstants;
  import org.apache.struts2.components.template.Template;
  import org.apache.struts2.components.template.TemplateEngine;
  import org.apache.struts2.views.freemarker.FreemarkerThemeTemplateLoader;
  
  import com.opensymphony.xwork2.inject.Inject;
  import com.opensymphony.xwork2.util.logging.Logger;
  import com.opensymphony.xwork2.util.logging.LoggerFactory;
  
  import freemarker.cache.FileTemplateLoader;
  import freemarker.cache.MultiTemplateLoader;
  import freemarker.cache.TemplateLoader;
  import gboat2.base.bridge.debug.DefaultDebugHook;
  import gboat2.base.bridge.exception.DefaultGboatNestedException;
  
  /**
   * Gboat 平台自定义 Struts2 标签模板管理器，需要结合 {@link GboatFreemarkerManager} 一起使用。
   * <pre>
   * 在 struts-plugin.xml 中添加了如下配置：
   * <code>&lt;bean class="gboat2.base.plugin.struts.freemarker.GboatThemeTemplateLoader" /&gt;</code>
   * </pre>
   * @date 2014年5月19日
   * @author <a href="mailto:[email protected]">何明旺</a>
   * @since 3.0.0-SNAPSHOT
   */
  public class GboatThemeTemplateLoader extends FreemarkerThemeTemplateLoader {
  
      protected String gboatViewResourcePath;
      protected MultiTemplateLoader sourceTemplateLoader;
      
      // Injected
      protected String themeExpansionToken;
      protected TemplateEngine templateEngine;
      
  
      private static final Logger LOG = LoggerFactory.getLogger(GboatThemeTemplateLoader.class);
  
      public GboatThemeTemplateLoader() {
          super();
          
          String view = "gboat2.base.view";
          DefaultDebugHook debugHook = DefaultDebugHook.getInstance();
          if(debugHook.isBundleDebugEnabled(view)) { // gboat2.base.view 开启了调试模式时，读取其资源文件存放的根目录
              gboatViewResourcePath = debugHook.getResourcesAbsolutPath(view);    
              try {
                  sourceTemplateLoader = new MultiTemplateLoader(new TemplateLoader[] {
                          new FileTemplateLoader(new File(gboatViewResourcePath), true)
                      });
              } catch (IOException e) {
                  throw new DefaultGboatNestedException(e);
              }
          }
      }
      
      @Override
      public Object findTemplateSource(String name) throws IOException {
          int tokenIndex = (name == null) ? -1 : name.indexOf(themeExpansionToken);
          if (tokenIndex < 0) {
              return  ObjectUtils.defaultIfNull(findTemplateSourceFromSourceFile(name), getParentTemplateLoader().findTemplateSource(name));
          }
  
          int themeEndIndex = name.indexOf('/', tokenIndex);
          if (themeEndIndex < 0) {
              return ObjectUtils.defaultIfNull(findTemplateSourceFromSourceFile(name), getParentTemplateLoader().findTemplateSource(name));
          }
  
          Template template = new Template(
              name.substring(0, tokenIndex - 1), 
              name.substring(tokenIndex + themeExpansionToken.length(), themeEndIndex), 
              name.substring(themeEndIndex + 1));
          
          List<Template> possibleTemplates = template.getPossibleTemplates(templateEngine);
          for (Template possibleTemplate : possibleTemplates) {
              Object templateSource = findTemplateSourceFromSourceFile(possibleTemplate.toString());
              if (templateSource != null)
                  return templateSource;
              
              templateSource = getParentTemplateLoader().findTemplateSource(
                      possibleTemplate.toString().substring(1));
              if (templateSource != null) {
                  return templateSource;
              }
          }
          String parentTheme = (String) templateEngine.getThemeProps(template).get("parent");
          if (parentTheme == null) {
              // no parent theme, no way to fetch parent template
              return null;
          }
         String parentName = "/" + template.getDir() + "/" + themeExpansionToken + parentTheme + "/" + template.getName();
         return ObjectUtils.defaultIfNull(findTemplateSourceFromSourceFile(name), this.findTemplateSource(parentName));
     }
     
     private Object findTemplateSourceFromSourceFile (String name) {
         // gboatViewResourcePath 为 null，表示没有开启调试模式
         if(gboatViewResourcePath == null)
             return null;
         
         File sourceFile = new File(gboatViewResourcePath, name);
         if(sourceFile.isFile()){ // 如果存在对应的源代码文件，则从源代码文件中读取
             try {
                 return  sourceTemplateLoader.findTemplateSource(name);
             } catch (IOException e) {
                 LOG.warn("读取标签模板的源文件 [#0] 失败。", e, sourceFile.getAbsolutePath());
             }
         }
         return null;
     }
 
     @Inject(StrutsConstants.STRUTS_UI_THEME_EXPANSION_TOKEN)
     public void setUIThemeExpansionToken(String token) {
         themeExpansionToken = token;
     }
 
     @Inject("ftl")
     public void setTemplateEngine(TemplateEngine templateEngine) {
         this.templateEngine = templateEngine;
     }
 
 }