--[[

    Copyright (C) 2016 ZTE, Inc. and others. All rights reserved. (ZTE)

    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 msbConf   =  require('conf.msbinit')
local dbclient  =  require('dao.db_access')
local tbl_util  =  require('lib.utils.table_util')
local svc_util  =  require('lib.utils.svc_util')
local log_util  =  require('lib.utils.log_util')
local error_handler  =  require('lib.utils.error_handler')

local tbl_concat = table.concat
local tbl_isempty = tbl_util.isempty
local svc_isactive = svc_util.isactive
local svc_get_url = svc_util.get_url
local svc_get_backend_protocol = svc_util.get_backend_protocol
local svc_use_own_upstream = svc_util.use_own_upstream
local svc_get_key_prefix = svc_util.get_key_prefix
local str_low = string.lower
local ngx_var = ngx.var
local ngx_ctx = ngx.ctx
local log = log_util.log
local error_svc_not_found = error_handler.svc_not_found
local error_upstream_not_found = error_handler.upstream_not_found

local enablerefercheck = msbConf.systemConf.enablerefercheck
local useconsultemplate = msbConf.systemConf.useconsultemplate

---------------------------------------------------------------
--preCheck:
--     determine whether it is websocket request 
--     and do internal redirect
---------------------------------------------------------------
if ngx.var.uri == "/" then
	local m, err = ngx.re.match(ngx.var.host, "^((25[0-5]|2[0-4]\\d|[01]?\\d\\d?)\\.){3}(25[0-5]|2[0-4]\\d|[01]?\\d\\d?)$","o")
	if m then
		return ngx.exec("@defaultpage")
	end
end

local http_upgrade = ngx_var.http_upgrade
if(ngx_var.websocket_internal_redirect == "on") and http_upgrade and str_low(http_upgrade)== "websocket" then
	--ngx.log(ngx.ERR, "Websocket request and redirect to @customwebsocket")
	return ngx.exec("@customwebsocket")
end

---------------------------------------------------------------
--step0:Preparation
--      svcnames:service names registered under this port
---------------------------------------------------------------
local req_res  = ngx_var.uri
local svc_type = ngx_var.svc_type
local key_prefix = svc_get_key_prefix()

local custom_svc_keypattern = tbl_concat({key_prefix,"custom","*"},":")

local get_svckey_custom = function(svcname)
	return tbl_concat({key_prefix,"custom",svcname},":")
end

local svcnames,err = dbclient.load_customsvcnames(custom_svc_keypattern)
if not svcnames then
	error_svc_not_found("Failed to load the route table!","keypattern--"..custom_svc_keypattern)
end

---------------------------------------------------------------
--step1:run the match process(check whether the request 
--      match the name in the svcnames one by one) 
--      and return the matched serice info
---------------------------------------------------------------
local matchedsvcname
local svcinfo
local svc_key = ""
--add by wangyg:20160418 special handler for refer
local matched_usingrefer = false
--end of add by wangyg:20160418 special handler for refer
for _, svcname in ipairs(svcnames) do
	if (svcname == "/") then
		svc_key = get_svckey_custom(svcname)
		local svc_info,err = dbclient.load_serviceinfo(svc_key)
		if svc_info and svc_isactive(svc_info)then
			matchedsvcname = svcname
			svcinfo = svc_info
			break
		end
	end
	local from, to, err = ngx.re.find(req_res, "^"..svcname.."(/(.*))?$", "jo")
	--check whether svcname is the prefix of the req uri
	if from then
		svc_key = get_svckey_custom(svcname)
		local svc_info,err = dbclient.load_serviceinfo(svc_key)
		if svc_info and svc_isactive(svc_info) then 
			matchedsvcname = svcname
			svcinfo = svc_info
			break
		end
	else
		--do nothing
	end
end
---------------------------------------------------------------
--step1.1:additional process,test against the refer 
--        similar to step1
---------------------------------------------------------------
--add by wangyg:20160418 special handler for refer
if not matchedsvcname and enablerefercheck then 
	local refer =  ngx_var.http_referer
	if(refer and refer~="") then
		for _, svcname in ipairs(svcnames) do
			local urlreg ="^(https://|http://|)(([1-9]|([1-9]\\d)|(1\\d\\d)|(2([0-4]\\d|5[0-5])))\\.)(([0-9]|([1-9]\\d)|(1\\d\\d)|(2([0-4]\\d|5[0-5])))\\.){2}([1-9]|([1-9]\\d)|(1\\d\\d)|(2([0-4]\\d|5[0-5])))(:\\d{1,5})?"..svcname.."(/(.*))?$";
			local from, to, err = ngx.re.find(refer, urlreg, "jo")
			----check whether svcname is the prefix of the req refer
			if from then
				svc_key = get_svckey_custom(svcname)
				local svc_info,err = dbclient.load_serviceinfo(svc_key)
				if svc_info and svc_isactive(svc_info) then 
					matchedsvcname = svcname
					svcinfo = svc_info
					matched_usingrefer = true
					break
				end
			end
		end
	end
end
--end of add by wangyg:20160418 special handler for refer

if not matchedsvcname or tbl_isempty(svcinfo) then
	error_svc_not_found("No route found for this request!","custom not match")
end

local svc_url = svc_get_url(svcinfo,svc_type)

---------------------------------------------------------------
--step2:rewrite the request uri using the svcinfo
---------------------------------------------------------------
local rewrited_uri =""
if (matchedsvcname == "/") then
	--special handling: if "/" matched, contact directly
	rewrited_uri = svc_url..req_res
else
	--rewrited_uri = ngx.re.sub(req_res, "^"..matchedsvcname.."(.*)", svc_url.."$1", "o")
	local newuri,n,err = ngx.re.sub(req_res, "^"..matchedsvcname.."(/.*)?", svc_url.."$1", "o")
	--add by wangyg:20160418 special handler for refer
	if(n==0 and matched_usingrefer) then newuri = svc_url..req_res end --special handling if matched using refer
	--end of add by wangyg:20160418 special handler for refer
	rewrited_uri = newuri
end
--if (rewrited_uri == "") then rewrited_uri = "/" end --avoid throws internal error when it is empty
if (rewrited_uri == "") then return ngx.redirect(ngx.var.uri.."/") end 
ngx.req.set_uri(rewrited_uri)

--set the matched service info,used in the proxy_redirect directive 
ngx_var.svc_name = matchedsvcname
ngx_var.svc_url =  svc_url

--log the route info
log("matched",matchedsvcname)
if(matched_usingrefer) then log("matched_usingrefer",true) end 
--log("rewrited_uri",rewrited_uri)

---------------------------------------------------------------
--step2.1:store the svcinfo in the context, plugins may use it
---------------------------------------------------------------
ngx_ctx.svcinfo = svcinfo

---------------------------------------------------------------
--step3:process the proxy upstream part
-- con1-using consul template:set the upstream name
-- con2-using msb balancer:query the backserver list and store in the ctx
---------------------------------------------------------------
--set the http_protocol used by proxy_pass directive
ngx_var.http_protocol = svc_get_backend_protocol(svcinfo)

if svc_use_own_upstream(svcinfo) then
	local consul_servicename = svcinfo.spec["consulServiceName"]
	if not consul_servicename or consul_servicename == "" then
		error_upstream_not_found()
	end
	ngx_var.backend = consul_servicename
	ngx.ctx.use_ownupstream = true
else
	local backservers = svcinfo.spec.nodes
	if tbl_isempty(backservers) then
		error_svc_not_found("No active backend server found!","key--"..svc_key)
	end
	ngx_ctx.backservers = backservers
	ngx_ctx.svc_key = svc_key
end