XStringLookup.java

/**
 * 
 */
package org.xmlsh.core;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.lang3.text.StrLookup;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.xmlsh.sh.shell.Shell;
import org.xmlsh.util.StringPair;
import org.xmlsh.util.Util;
import org.xmlsh.xpath.ThreadLocalShell;

/**
 * @author DLEE
 *
 */
public abstract class XStringLookup extends StrLookup<String> {

  private Map<String, XStringLookup> mSchemes;
  private static Map<String, XStringLookup> sDefaultSchemes = new HashMap<>();

  private XStringLookup mParent = null;

  static Logger mLogger = LogManager.getLogger();

  public XStringLookup() {
    this(null, getDefaultSchemes());
  }

  public XStringLookup(XStringLookup parent,
      Map<String, XStringLookup> schemes) {
    super();
    mSchemes = schemes;
    mParent = parent;
  }

  public static Map<String, XStringLookup> getDefaultSchemes() {
    synchronized(sDefaultSchemes) {
      if(sDefaultSchemes.isEmpty()) {
        sDefaultSchemes.put("env", new XStringLookup(null, null) {

          @Override
          protected XValue lookupXValue(String name) {
            Shell shell = ThreadLocalShell.get();
            if(shell != null)
              return shell.getEnv().getVarValue(name);
            return null;

          }
        });
        sDefaultSchemes.put("date", new XStringLookup(null, null) {

          @Override
          protected XValue lookupXValue(String name) {

            String ds = "";
            Date now = new Date();
            try {
              if(Util.isEmpty(name))
                ds = SimpleDateFormat.getDateInstance().format(now);
              else
                ds = new SimpleDateFormat(name).format(now);
            } catch (Exception e) {
              mLogger.catching(e);
              ds = "";
            }

            if(Util.isEmpty(ds))
              ds = (new Date()).toString();
            return XValue.newXValue(ds);

          }
        });

      }
    }

    return sDefaultSchemes;
  }

  /**
   * @param defaultSchemes
   */
  public XStringLookup(Map<String, XStringLookup> schemes) {
    this(null, schemes);
  }

  /**
   * @param parent
   */
  public XStringLookup(XStringLookup parent) {
    this(parent, getDefaultSchemes());
  }

  protected XStringLookup getScheme(String scheme) {
    if(mSchemes == null)
      return null;
    return mSchemes.get(scheme);
  }

  protected abstract XValue lookupXValue(String value)
      throws InvalidArgumentException, CoreException;

  protected XValue lookupXValue(String scheme, String name)
      throws CoreException {
    XValue value = null;

    // Scheme specific lookup
    if(scheme != null) {
      XStringLookup schemeLookup = getScheme(scheme);
      if(schemeLookup != null)
        value = schemeLookup.lookupXValue(name);
      if(value == null && mParent != null)
        value = mParent.lookupXValue(scheme, name);
      return value;
    }

    // no scheme
    value = lookupXValue(name);
    if(value == null && mParent != null)
      value = mParent.lookupXValue(name);
    return value;
  }

  @Override
  public final String lookup(String key) {

    mLogger.entry(key);
    StringPair pair = new StringPair(key, ':');
    String scheme = pair.getLeft();
    String name = pair.getRight();
    XValue value = null;
    try {
      value = lookupXValue(scheme, name);
    } catch (CoreException e) {
      // TODO Auto-generated catch block
      mLogger.catching(e);
    }
    if(value == null)
      return mLogger.exit(null);

    // TODO: Better determination of if to convert to string
    return mLogger.exit(value.toString());

  }

  public static XStringLookup newInstance(XValue def) {

    return new XStringLookup() {
      @Override
      protected XValue lookupXValue(String name)
          throws CoreException {
        return def.getNamedValue(name);
      }
    };

  }

}