Lighttpd rewrite conditions written in Lua for WP Super Cache

rewrite.lua

function serve_html(cached_page)
  if (lighty.stat(cached_page)) then
    lighty.env["physical.path"] = cached_page
    return true
  else
    return false
  end
end
 
function serve_gzip(cached_page)
  if (lighty.stat(cached_page .. ".gz")) then
    lighty.header["Content-Encoding"] = "gzip"
    lighty.header["Content-Type"] = ""
    lighty.header["X-Powered-By"] = "Lua Super Cache"
    lighty.env["physical.path"] = cached_page .. ".gz"
    return true
  else
    return false
  end
end

function file_exists(path)
  local attr = lighty.stat(path)
  if (attr) then
    return true
  else
    return false
  end
end

function go_php()
  lighty.env["uri.path"] = "/index.php"
  lighty.env["physical.rel-path"] = lighty.env["uri.path"]
  lighty.env["physical.path"] = lighty.env["physical.doc-root"] .. lighty.env["physical.rel-path"]
end

function is_root()
  if (lighty.env["physical.path"] == lighty.env["physical.doc-root"] .. "/") then
    return true
  else
    return false
  end
end

if (is_root() or not file_exists(lighty.env["physical.path"])) then
  if (string.match(lighty.env["uri.path"],"^/([%w%_%-]+)/(wp%-.*)")) then
    n, a = string.match(lighty.env["uri.path"], "^/([%w%_%-]+)/(wp%-.*)")
    if a then
      lighty.env["physical.path"] = lighty.env["physical.doc-root"] .. "/" .. a
    else
      n, a = string.match(lighty.env["uri.path"], "^([%w%_%-%/]+)(.*%.php)$")
      if a then
        lighty.env["physical.path"] = lighty.env["physical.doc-root"] .. "/" .. a
      end
    end
  else
    query = (lighty.env["uri.query"] and string.find(lighty.env["uri.query"], ".*s=.*"))
    post = (lighty.env["request.method"] == "POST")
    if (not query and not post) then
      accept_encoding = lighty.request["Accept-Encoding"] or "no_acceptance"
      cached_page = lighty.env["physical.doc-root"] .. "/wp-content/cache/supercache/" .. lighty.request["Host"] .. lighty.env["request.uri"] .. "/index.html"
      cached_page = string.gsub(cached_page, "//", "/")
      if (file_exists(cached_page)) then
        if (string.find(accept_encoding, "gzip")) then
          if (not serve_gzip(cached_page)) then
            serve_html(cached_page)
          end
        else
          serve_html(cached_page)
        end
      else
        go_php()
      end
    else
      go_php()
    end
  end
end