function file_exists(path)
  local attr = lighty.stat(path)
  if (attr and attr["is_file"]) then
      return true
   else
      return false
  end
end
function removePrefix(str, prefix)
  return str:sub(1,#prefix+1) == prefix.."/" and str:sub(#prefix+2)
end
function string.starts(x,y)
 return string.sub(x,1,string.len(y)) == y
end

local prefix = ''

if (not file_exists(lighty.env["physical.path"]))  then   -- if this is not an existing file
lighty.header["Expires"] = "Sun, 19 Nov 1978 05:00:00 GMT"
lighty.header["Cache-Control"] = "no-store, no-cache, must-revalidate, post-check=0, pre-check=0"
local FINAL_PATH = "empty"
local req_uri = lighty.env["request.uri"]
local SERVE_CACHED_FLAG = (string.find((lighty.request["Cookie"] or "NOCOOKIE"), "DRUPAL_UID") == nil) and (lighty.env["uri.query"] == nil) and (lighty.env["request.method"] == "GET") -- 1st filter (anon+no_uriquery+GET) to qualify boost caching
 if (SERVE_CACHED_FLAG == true) then  -- qualifies for boost cache type
 local boost_path_uribase = lighty.env["physical.doc-root"] .. "/cache/" .. lighty.request["Host"] .. "/0" .. req_uri
  if (req_uri == "/") then  -- if path is front page
   local boost_path_frontpg = boost_path_uribase .. "index.html"  -- path for boost cached file
   if (file_exists(boost_path_frontpg)) then
    FINAL_PATH = boost_path_frontpg       -- serve boost cached path for front page
    end
  else
   local RESTRICTED_PATHS = (string.starts(req_uri,"/user")) or (string.starts(req_uri,"/cache")) or (string.starts(req_uri,"/admin"))  -- 2nd filter to qualify boosted paths
   if (RESTRICTED_PATHS == false) then
    FINAL_PATH = ((file_exists(boost_path_uribase .. ".html") and (boost_path_uribase .. ".html")) or (file_exists(boost_path_uribase .. "/index.html") and (boost_path_uribase .. "/index.html")) or "empty")
      -- assign FINAL_PATH to file based on uribase being a file or base dir
   end
  end
 end
 if (FINAL_PATH == "empty") then       -- file still missing. pass it to the fastcgi backend
    local request_uri = removePrefix(lighty.env["uri.path"], prefix)
    if request_uri then
      lighty.env["uri.path"]          = prefix .. "/index.php"
      local uriquery = lighty.env["uri.query"] or ""
      lighty.env["uri.query"] = uriquery .. (uriquery ~= "" and "&" or "") .. "q=" .. request_uri
      lighty.env["physical.rel-path"] = lighty.env["uri.path"]
      lighty.env["request.orig-uri"]  = lighty.env["request.uri"]
      FINAL_PATH = lighty.env["physical.doc-root"] .. lighty.env["physical.rel-path"]
    end
 end
 lighty.env["physical.path"] = FINAL_PATH
end