package org.infinispan.commons.util;

import java.io.File;
import java.util.Map;
import java.util.Properties;

import org.infinispan.commons.logging.Log;
import org.infinispan.commons.logging.LogFactory;

/**
 * A utility class for replacing properties in strings.
 *
 * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @author <a href="Scott.Stark@jboss.org">Scott Stark</a>
 * @author <a href="claudio.vesco@previnet.it">Claudio Vesco</a>
 * @author <a href="mailto:adrian@jboss.com">Adrian Brock</a>
 * @author <a href="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
 * @since 4.2
 */
public class StringPropertyReplacer {
   private static final Log log = LogFactory.getLog(StringPropertyReplacer.class);
   /**
    * New line string constant
    */
   public static final String NEWLINE = System.getProperty("line.separator", "\n");

   /**
    * File separator value
    */
   private static final String FILE_SEPARATOR = File.separator;

   /**
    * Path separator value
    */
   private static final String PATH_SEPARATOR = File.pathSeparator;

   /**
    * File separator alias
    */
   private static final String FILE_SEPARATOR_ALIAS = "/";

   /**
    * Path separator alias
    */
   private static final String PATH_SEPARATOR_ALIAS = ":";

   // States used in property parsing
   private static final int NORMAL = 0;
   private static final int SEEN_DOLLAR = 1;
   private static final int IN_BRACKET = 2;

   /**
    * Go through the input string and replace any occurance of ${p} with the
    * System.getProperty(p) value. If there is no such property p defined, then
    * the ${p} reference will remain unchanged.
    * <p/>
    * If the property reference is of the form ${p:v} and there is no such
    * property p, then the default value v will be returned.
    * <p/>
    * If the property reference is of the form ${p1,p2} or ${p1,p2:v} then the
    * primary and the secondary properties will be tried in turn, before
    * returning either the unchanged input, or the default value.
    * <p/>
    * The property ${/} is replaced with System.getProperty("file.separator")
    * value and the property ${:} is replaced with System.getProperty("path.separator").
    * <p/>
    * Environment variables are referenced by the <code>env.</code> prefix, for example ${env.PATH}
    *
    * @param string - the string with possible ${} references
    * @return the input string with all property references replaced if any. If
    *         there are no valid references the input string will be returned.
    */
   public static String replaceProperties(final String string) {
      return replaceProperties(string, null);
   }

   /**
    * Go through the input string and replace any occurance of ${p} with the
    * props.getProperty(p) value. If there is no such property p defined, then
    * the ${p} reference will remain unchanged.
    * <p/>
    * If the property reference is of the form ${p:v} and there is no such
    * property p, then the default value v will be returned.
    * <p/>
    * If the property reference is of the form ${p1,p2} or ${p1,p2:v} then the
    * primary and the secondary properties will be tried in turn, before
    * returning either the unchanged input, or the default value.
    * <p/>
    * The property ${/} is replaced with System.getProperty("file.separator")
    * value and the property ${:} is replaced with System.getProperty("path.separator").
    *
    * @param string - the string with possible ${} references
    * @param props  - the source for ${x} property ref values, null means use
    *               System.getProperty()
    * @return the input string with all property references replaced if any. If
    *         there are no valid references the input string will be returned.
    */
   public static String replaceProperties(final String string, final Properties props) {
      if (string == null)
         return null;
      final char[] chars = string.toCharArray();
      StringBuilder buffer = new StringBuilder();
      boolean properties = false;
      int state = NORMAL;
      int start = 0;
      for (int i = 0; i < chars.length; ++i) {
         char c = chars[i];

         // Dollar sign outside brackets
         if (c == '$' && state != IN_BRACKET)
            state = SEEN_DOLLAR;

            // Open bracket immediatley after dollar
         else if (c == '{' && state == SEEN_DOLLAR) {
            buffer.append(string, start, i - 1);
            state = IN_BRACKET;
            start = i - 1;
         }

         // No open bracket after dollar
         else if (state == SEEN_DOLLAR)
            state = NORMAL;

            // Closed bracket after open bracket
         else if (c == '}' && state == IN_BRACKET) {
            // No content
            if (start + 2 == i) {
               buffer.append("${}"); // REVIEW: Correct?
            } else // Collect the system property
            {
               String value;

               String key = string.substring(start + 2, i);

               // check for alias
               if (FILE_SEPARATOR_ALIAS.equals(key)) {
                  value = FILE_SEPARATOR;
               } else if (PATH_SEPARATOR_ALIAS.equals(key)) {
                  value = PATH_SEPARATOR;
               } else {
                  // check from the properties
                  value = resolveKey(key, props);

                  if (value == null) {
                     // Check for a default value ${key:default}
                     int colon = key.indexOf(':');
                     if (colon > 0) {
                        String realKey = key.substring(0, colon);
                        value = resolveKey(realKey, props);

                        if (value == null) {
                           // Check for a composite key, "key1,key2"
                           value = resolveCompositeKey(realKey, props);

                           // Not a composite key either, use the specified default
                           if (value == null)
                              value = key.substring(colon + 1);
                        }
                     } else {
                        // No default, check for a composite key, "key1,key2"
                        value = resolveCompositeKey(key, props);
                     }
                  }
               }

               if (value != null) {
                  properties = true;
                  buffer.append(value);
               } else {
                  buffer.append("${");
                  buffer.append(key);
                  buffer.append('}');
                  log.propertyCouldNotBeReplaced(key);
               }

            }
            start = i + 1;
            state = NORMAL;
         }
      }

      // No properties
      if (!properties)
         return string;

      // Collect the trailing characters
      if (start != chars.length)
         buffer.append(string, start, chars.length);

      // Done
      return buffer.toString();
   }

   public static void replaceProperties(Map<String, String> map, Properties properties) {
      map.replaceAll((k, v) -> replaceProperties(v, properties));
   }

   /**
    * Try to resolve a "key" from the provided properties by checking if it is
    * actually a "key1,key2", in which case try first "key1", then "key2". If
    * all fails, return null.
    * <p/>
    * It also accepts "key1," and ",key2".
    *
    * @param key   the key to resolve
    * @param props the properties to use
    * @return the resolved key or null
    */
   private static String resolveCompositeKey(String key, Properties props) {
      String value = null;

      // Look for the comma
      int comma = key.indexOf(',');
      if (comma > -1) {
         // If we have a first part, try resolve it
         if (comma > 0) {
            // Check the first part
            String key1 = key.substring(0, comma);
            value = resolveKey(key1, props);
         }
         // Check the second part, if there is one and first lookup failed
         if (value == null && comma < key.length() - 1) {
            String key2 = key.substring(comma + 1);
            value = resolveKey(key2, props);
         }
      }
      // Return whatever we've found or null
      return value;
   }

   private static String resolveKey(String key, Properties props) {
      if (key.startsWith("env.")) {
         return System.getenv(key.substring(4));
      } else if (props != null) {
         return props.getProperty(key);
      } else {
         return System.getProperty(key);
      }
   }
}
