local syslog=require("syslog")
local math=require("math")
local cjson=require("cjson") 


-------------------------[全局参数定义]-------------------------

-------------------------[输入设备名称以及标识符]-------------------------
device="201955555555"
input_value_name="input"

-------------------------[输出设备名称以及标识符]-------------------------
output_value_name="output"

-------------------------[系统变量]------------------------
raw_data_cache_size=100  --缓存大小

syslog.openlog( string.format("%s syslog",device), syslog.LOG_PERROR + syslog.LOG_ODELAY, "LOG_USER")

function write_cache_to_file(path,ojb)
    local file=io.open(path, 'w+')
    file:seek('set')
    file:write(cjson.encode(ojb))
    file:flush()
    file:close()
end

function read_cache_from_file(path)
    local file=io.open(path, 'a+')
    local ojb={}
    file:seek('set')
    ojb = file:read()
    file:close()
    if(ojb == nil) then return nil end
    return cjson.decode(ojb)
end



function process_data(raw_data)
    local curr_timestamp=os.time()
        --排序去头去尾
        if #raw_data.list > 5 then  --数据长度大于一定值才只用去头去尾
        table.sort( raw_data.list )
        table.remove( raw_data.list,#raw_data.list)
        table.remove( raw_data.list,1)
        end
        --求平均
        local sum=0.0
        for i=1,#raw_data.list,1 do
            sum = sum + raw_data.list[i]
        end
        local out_data={}
        out_data['timestamp']=os.time()
        out_data[output_value_name]=sum/#raw_data.list
        local json_str=cjson.encode(out_data)
        syslog.syslog("LOG_WARNING", json_str .. #json_str)
        return 0,json_str,#json_str
end

function udef_process(data)
    local err_code=0
    local tmp_file=string.format("/tmp/%s.dat",device);
    local cache = read_cache_from_file(tmp_file)
    if not cache then     cache={}     cache.list={}     end
    if #cache.list > raw_data_cache_size then table.remove( cache.list, 1 ) end
    table.insert(cache.list, data ) 
    write_cache_to_file(tmp_file,cache)
    return process_data(cache)
end
        
function parser_input(obj)
    local source_a
    for i,v in pairs(obj["datas"]) do
        if(v["sn"] == device) then
            tag = v["tags"]
            if tag then
                source_a = tag[input_value_name]
            end
        end
    end
    return source_a
end

function protocol_decode(input_str, len)
  --出参格式化--
  local obj = cjson.decode(input_str)
  --获取输入变量--
local source_a = parser_input(obj)
if not source_a then
    return -1,0,0
end

err_code,out_str,out_len=udef_process(source_a)

return err_code,out_str,out_len
end
-- protocol_decode('{"datas":[{"sn":"201955555555","time":1574933970,"state":0,"quality":0,"identifier":"post","tags":{"input":10}}]}', 0)


syslog.closelog()