-- Copyright 2016 Huawei Technologies Co., Ltd.

-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at

--     http://www.apache.org/licenses/LICENSE-2.0

-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
local _HEADER = "X-Driver-Parameter"

--extract driver header if present in request
function get_driver_header()
  local header = ""
  local driver_header = ngx.req.get_headers()[_HEADER]  
  if (driver_header ~= nil)
  then
    header = driver_header
  end
  return header
end

-- generate query url
function get_query_url(x_driver_header)
  local drivermgr_uri = '/openoapi/drivermgr/v1/drivers'
  local url = drivermgr_uri.."?".._HEADER.."="..tostring(ngx.escape_uri(x_driver_header)).."&service_url="..ngx.var.uri
  return url
end

-- generate driver url
function get_driver_url(driver_header)
  local cjson = require "cjson"
  local query_url = get_query_url(driver_header)
  local res = ngx.location.capture(query_url, { method = ngx.HTTP_GET})
  ngx.log (ngx.ERR, "Driver manager resp url : ", tostring(res.body))
  if (res.status == 200 and res.body ~= nil and res.body ~= '')
  then
    return tostring(cjson.new().decode(res.body).url)
  else
    return ''
  end
end

-- get headers
function get_headers()
  local headers = {}
  local h = ngx.req.get_headers()
  for k, value in pairs(h)
  do
     headers[k] = value
  end
  return headers
end

function get_body_params()
  ngx.req.read_body()
  local actual_body = ""  
  local body_param = ngx.req.get_body_data()
  if(body_param ~= nil)
  then
    actual_body = tostring(body_param)
  end
  return actual_body
end



ngx.log(ngx.INFO, "DRIVER MANAGER LUA", "***********************")

-- extract X-Driver-Parameter header param
local driver_header = get_driver_header()
ngx.log(ngx.ERR, "X-Driver-Parameter: ", driver_header)


-- ignore driver redirection if not driver manager request.
if (driver_header ~= "")
then 
  
  local driver_url = get_driver_url(driver_header)
  ngx.log (ngx.ERR, "Driver manager URl:: ", driver_url)
 
  local http = require "resty.http"
  local actual_headers = get_headers()
  local actual_body = get_body_params()

  ngx.log(ngx.ERR, "HTTP request to driver... ", " Request to driver manager")
  local res, err = http.new():request_uri(driver_url, {
        method = ngx.req.get_method(),
        body = actual_body,
        headers = actual_headers
      })

      if not res then
        ngx.say("Request to driver failed : ", err)
        return
      end
 ngx.log(ngx.ERR, "Response from driver : ", tostring(res.body))
 ngx.say(res.body)

else
  ngx.log(ngx.ERR, "X-Driver-Parameter not present", " Redirect to same url")
end