package org.etk.core.rest.impl.header;

import java.util.List;
import java.util.Map;

import javax.ws.rs.core.CacheControl;
import javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate;


public class CacheControlHeaderDelegate extends AbstractHeaderDelegate<CacheControl> {

  /**
   * {@inheritDoc}
   */
  @Override
  public Class<CacheControl> support() {
    return CacheControl.class;
  }

  /**
   * {@inheritDoc}
   */
  public CacheControl fromString(String header) {
    throw new UnsupportedOperationException("CacheControl used only for response headers.");
  }

  /**
   * {@inheritDoc}
   */
  public String toString(CacheControl header) {
    StringBuffer buff = new StringBuffer();
    if (!header.isPrivate()) {
      appendString(buff, "public");
    }
    if (header.isPrivate()) {
      appendWithParameters(buff, "private", header.getPrivateFields());
    }
    if (header.isNoCache()) {
      appendWithParameters(buff, "no-cache", header.getNoCacheFields());
    }
    if (header.isNoStore()) {
      appendString(buff, "no-store");
    }
    if (header.isNoTransform()) {
      appendString(buff, "no-transform");
    }
    if (header.isMustRevalidate()) {
      appendString(buff, "must-revalidate");
    }
    if (header.isProxyRevalidate()) {
      appendString(buff, "proxy-revalidate");
    }
    if (header.getMaxAge() >= 0) {
      appendString(buff, header.getMaxAge() + "");
    }
    if (header.getSMaxAge() >= 0) {
      appendString(buff, header.getSMaxAge() + "");
    }
    for (Map.Entry<String, String> entry : header.getCacheExtension().entrySet()) {
      appendWithSingleParameter(buff, entry.getKey(), entry.getValue());
    }
    return buff.toString();
  }

  /**
   * Add single <code>String</code> to <code>StringBuffer</code> .
   * 
   * @param buff the StringBuffer
   * @param s single String
   */
  private static void appendString(StringBuffer buff, String s) {
    if (buff.length() > 0)
      buff.append(',').append(' ');
    
    buff.append(s);
  }

  /**
   * Add single pair key=value to <code>StringBuffer</code> . If value contains
   * whitespace then quotes will be added.
   * 
   * @param buff the StringBuffer
   * @param key the key
   * @param value the value
   */
  private static void appendWithSingleParameter(StringBuffer buff, String key, String value) {
    StringBuffer localBuff = new StringBuffer();
    localBuff.append(key);
    
    if (value != null && value.length() > 0)
      localBuff.append('=').append(HeaderHelper.addQuotesIfHasWhitespace(value));
    
    appendString(buff, localBuff.toString());
  }

  /**
   * Add to pair key="value1, value2" to <code>StringBuffer</code> .
   * 
   * @param buff the StringBuffer
   * @param key the key
   * @param values the collection of values
   */
  private static void appendWithParameters(StringBuffer buff, String key, List<String> values) {
    appendString(buff, key);
    if (values.size() > 0) {
      StringBuffer localBuff = new StringBuffer();
      buff.append('=');
      buff.append('"');
      
      for (String t : values)
        appendString(localBuff, t);
      
      buff.append(localBuff.toString());
      buff.append('"');
    }
  }

}