local _M = {}

function test_output(content, status)
 ngx.header.content_type = 'application/json;charset=UTF-8';
 ngx.say(content)
 ngx.status = status
 ngx.exit(status)
end

function split(str, delimiter)
 if str==nil or str=='' or delimiter==nil then
 return nil
 end
 
 local result = {}
 for match in (str..delimiter):gmatch("(.-)"..delimiter) do
 table.insert(result, match)
 end
 return result
end

function rewrite(request_uri, reg, original_uri)
	i, j = string.find(request_uri, reg)
	if i ~= nil then
		local real_uri, index=string.gsub(request_uri, reg, original_uri, 1)
		return real_uri
	end
	return nil
end

function _M.dispatch()
 local cjson = require "cjson"
 local cache = ngx.shared.cache
 local config_str=cache:get(ngx.var.host);
 if config_str == nil then
 config_str=cache:get("localhost");
 if config_str == nil then
 ngx.exit(404)
 end
 end

 local config = cjson.decode(config_str)

 local real_uri = nil
 local api_info = nil
 local api_uri_array = config["api_uri_array"]
 local api_uri_map = config["api_uri_map"]
 local uri = ngx.var.uri
 if ngx.var.args ~= nil then
 uri = uri.."?"..ngx.var.args
 end

 for k,uri_regx in pairs(api_uri_array) do
 local api_info_t = api_uri_map[uri_regx];
 real_uri = rewrite(uri, api_info_t["request_uri"], api_info_t["original_uri"]);
 if(real_uri ~= nil) then
 api_info = api_info_t
 break;
 end
 end

 if api_info == nil then
 ngx.exit(404)
 end

 local servers = api_info["servers"]
 local server_count = table.getn(servers)

 if server_count == 0 then
 ngx.exit(503)
 end

 local request_index_cache_key = ngx.var.host.."_request_index_"..api_info["request_uri"]
 local request_index = cache:get(request_index_cache_key)
 if request_index == nil then
 request_index = 1
 end
 cache:set(request_index_cache_key, request_index+1)
 local server = servers[request_index%server_count+1];

 if api_info["host"] == "localhost" then
 api_info["host"] = ngx.var.host
 end

 if server["protocol"] ~= nil and server["protocol"] ~= "" then
 ngx.var.upstream = server["protocol"].."servers"
 end

 ngx.var.backend_host = server["ip"]
 ngx.var.backend_port = server["port"]
 ngx.var.newhost = api_info["host"]
 ngx.req.set_header("Host", api_info["host"])

 local uri_t = split(real_uri, "?")
 ngx.req.set_uri(uri_t[1])
 if table.getn(uri_t) == 2 then
 local uri_args = uri_t[2]
 ngx.req.set_uri_args(uri_args)
 else
 ngx.req.set_uri_args({})
 end
end

return _M