Redirect filter

<filter>
  <filter-name>RedirectFilter</filter-name>
  <filter-class>org.akhikhl.gretty.RedirectFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>RedirectFilter</filter-name>
  <url-pattern>/*</url-pattern>
  <dispatcher>REQUEST</dispatcher>
  <dispatcher>FORWARD</dispatcher>
</filter-mapping>

// here we forward context root path to "index.html"
filter relPath: '/', {
  forward 'index.html'
}

// here we redirect old path to a new path
filter relPath: '/old/path', {
  redirect contextPath + '/new/path'
}

// here we convert path parameter to query parameter
filter relPath: ~'/path/(.*)', { matches ->
  redirect new URIBuilder(requestURI).setPath(contextPath + '/anotherPath').setQuery(matches.relPath[0][1])
}

// here we redirect all HTTP traffic to HTTPS scheme and port
filter scheme: 'http', {
  redirect new URIBuilder(requestURI).setScheme('https').setPort(httpsPort)
}

/**
 * Adds new filter to filter chain.
 * Must be called in the top scope of "filter.groovy" script.
 * options - contains one or more filter criteria.
 * closure - represents filter handler, which is invoked only when all criteria are fulfilled.
 */

void filter(Map options, Closure closure)

/**
 * Redirects current HTTP request to the specified destination.
 * Must be called only within closure of filter function.
 * destination - can be URI, URIBuilder or String.
 */
void redirect(destination)

/**
 * Forwards current HTTP request to the specified destination.
 * Must be called only within closure of filter function.
 * destination - can be URI, URIBuilder or String.
 */
void forward(destination)

filter relPath: '/path', scheme: 'http', {
  // ...
}

filter relPath: ~'/path/(*.)', query: ~'x=(.*)', { matches ->
  // if we get here, then matches.relPath[0][1] will contain first capture group for relPath regex,
  // while matches.query[0][1] will contain first capture group for query regex.
}