package org.argeo.cms.ui.util;
   
   import static java.nio.charset.StandardCharsets.UTF_8;
   
   import java.io.BufferedReader;
   import java.io.IOException;
   import java.io.InputStreamReader;
   import java.net.URL;
   import java.util.ArrayList;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.stream.Collectors;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.argeo.cms.CmsException;
  import org.eclipse.rap.rwt.RWT;
  import org.eclipse.rap.rwt.application.Application;
  import org.eclipse.rap.rwt.service.ResourceLoader;
  import org.osgi.framework.Bundle;
  import org.osgi.framework.BundleContext;
  
  /**
   * Simplifies the theming of an app (only RAP is supported at this stage).<br>
   * 
   * Additional fonts listed in <code>/fonts.txt</code>.<br>
   * Additional (standard CSS) header in <code>/header.css</code>.<br>
   * RAP specific CSS files in <code>/rap/*.css</code>.<br>
   * All images added as additional resources based on extensions
   * <code>/ ** /*.{png,gif,jpeg,...}</code>.<br>
   */
  public class CmsTheme {
  	private final static Log log = LogFactory.getLog(CmsTheme.class);
  
  	private String themeId;
  	private Map<String, ResourceLoader> css = new HashMap<>();
  	private Map<String, ResourceLoader> resources = new HashMap<>();
  
  	private String headerCss;
  	private List<String> fonts = new ArrayList<>();
  
  	private String basePath;
  	private String cssPath;
  
  	public CmsTheme(BundleContext bundleContext) {
  		this(bundleContext, null);
  	}
  
  	public CmsTheme(BundleContext bundleContext, String symbolicName) {
  		Bundle themeBundle;
  		if (symbolicName == null) {
  			themeBundle = bundleContext.getBundle();
  //			basePath = "/theme/";
  //			cssPath = basePath;
  		} else {
  			themeBundle = ThemeUtils.findThemeBundle(bundleContext, symbolicName);
  		}
  		basePath = "/";
  		cssPath = "/rap/";
  		this.themeId = RWT.DEFAULT_THEME_ID;
  		addStyleSheets(themeBundle, new BundleResourceLoader(themeBundle));
  		BundleResourceLoader themeBRL = new BundleResourceLoader(themeBundle);
  		addResources(themeBRL, "*.png");
  		addResources(themeBRL, "*.gif");
  		addResources(themeBRL, "*.jpg");
  		addResources(themeBRL, "*.jpeg");
  		addResources(themeBRL, "*.svg");
  		addResources(themeBRL, "*.ico");
  
  		// fonts
  		URL fontsUrl = themeBundle.getEntry(basePath + "fonts.txt");
  		if (fontsUrl != null) {
  			loadFontsUrl(fontsUrl);
  		}
  
  		// common CSS header (plain CSS)
  		URL headerCssUrl = themeBundle.getEntry(basePath + "header.css");
  		if (headerCssUrl != null) {
  			try (BufferedReader buffer = new BufferedReader(new InputStreamReader(headerCssUrl.openStream(), UTF_8))) {
  				headerCss = buffer.lines().collect(Collectors.joining("\n"));
  			} catch (IOException e) {
  				throw new CmsException("Cannot read " + headerCssUrl, e);
  			}
  		}
  
  	}
  
  	public void apply(Application application) {
  		resources: for (String name : resources.keySet()) {
  			if (name.startsWith("target/"))
  				continue resources; // skip maven output
  			application.addResource(name, resources.get(name));
  			if (log.isTraceEnabled())
  				log.trace("Added resource " + name);
  		}
  		for (String name : css.keySet()) {
  			application.addStyleSheet(themeId, name, css.get(name));
 			if (log.isDebugEnabled())
 				log.debug("Added RAP CSS " + name);
 		}
 	}
 
 	public String getAdditionalHeaders() {
 		StringBuilder sb = new StringBuilder();
 		if (headerCss != null) {
 			sb.append("<style type='text/css'>\n");
 			sb.append(headerCss);
 			sb.append("\n</style>\n");
 		}
 		for (String link : fonts) {
 			sb.append("<link rel='stylesheet' href='");
 			sb.append(link);
 			sb.append("'/>\n");
 		}
 		if (sb.length() == 0)
 			return null;
 		else
 			return sb.toString();
 	}
 
 	void addStyleSheets(Bundle themeBundle, ResourceLoader ssRL) {
 		Enumeration<URL> themeResources = themeBundle.findEntries(cssPath, "*.css", true);
 		if (themeResources == null)
 			return;
 		while (themeResources.hasMoreElements()) {
 			String resource = themeResources.nextElement().getPath();
 			// remove first '/' so that RWT registers it
 			resource = resource.substring(1);
 			if (!resource.endsWith("/")) {
 				if (css.containsKey(resource))
 					log.warn("Overriding " + resource + " from " + themeBundle.getSymbolicName());
 				css.put(resource, ssRL);
 			}
 
 		}
 
 	}
 
 	void loadFontsUrl(URL url) {
 		try (BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream(), UTF_8))) {
 			String line = null;
 			while ((line = in.readLine()) != null) {
 				line = line.trim();
 				if (!line.equals("") && !line.startsWith("#")) {
 					fonts.add(line);
 				}
 			}
 		} catch (IOException e) {
 			throw new CmsException("Cannot load URL " + url, e);
 		}
 	}
 
 	void addResources(BundleResourceLoader themeBRL, String pattern) {
 		Bundle themeBundle = themeBRL.getBundle();
 		Enumeration<URL> themeResources = themeBundle.findEntries(basePath, pattern, true);
 		if (themeResources == null)
 			return;
 		while (themeResources.hasMoreElements()) {
 			String resource = themeResources.nextElement().getPath();
 			// remove first '/' so that RWT registers it
 			resource = resource.substring(1);
 			if (!resource.endsWith("/")) {
 				if (resources.containsKey(resource))
 					log.warn("Overriding " + resource + " from " + themeBundle.getSymbolicName());
 				resources.put(resource, themeBRL);
 			}
 
 		}
 
 	}
 
 	public String getThemeId() {
 		return themeId;
 	}
 
 	public void setThemeId(String themeId) {
 		this.themeId = themeId;
 	}
 
 	public String getBasePath() {
 		return basePath;
 	}
 
 	public void setBasePath(String basePath) {
 		this.basePath = basePath;
 	}
 
 	public String getCssPath() {
 		return cssPath;
 	}
 
 	public void setCssPath(String cssPath) {
 		this.cssPath = cssPath;
 	}
 
 }