-- lpack=require("lua_pack")
-- require("bit")
-- cjson=require("cjson")

----------------------[MODBUS read data]--------------------------
local function read_multi_register(obj,id)
    return bpack("CC",0x01,0x33)
end

----------------------[MODBUS write data]--------------------------
local function write_multi_register(obj,id,data)
    return bpack("CC",0x01,0x11)
end


local function response_distance(raw_data, len)
    obj={}
    local _,id,data= bunpack(raw_data,"CC")
    if data == 0x00 then
        obj.open = 0
    elseif data == 0x11 then
        obj.open = 1
    else
        obj.open = 2
    end
    return obj
end


----------------------[test control demo]--------------------------
local function response_test_demo(raw_data, len)
    local obj={}
    obj.error = 0
    return obj
end


global_identifier_func_tab = {
    {
        identifier="fetchFeedback",
        create_bin_func=read_multi_register,
        create_bin_args={0X80,1},
        parser_bin_func=response_distance
    },
    {
        identifier="Control",
        create_bin_func=write_multi_register,
        create_bin_args={0X8A,1},
        parser_bin_func=response_test_demo
    }
}


local function crc8(data)
    local crc=0x0;
    for k=1,  #data do
        crc = bit.bxor(crc, string.byte(data,k))
    end
    return tonumber(string.format("%u", bit.band(crc,0xFF) ))
end

function protocol_encode(json_str, len)
    local err_code=0

    --取出入参--
    local obj=cjson.decode(json_str)
    local id=obj.identifier
    local addr=tonumber(obj.term_addr,16)
    --编码--
    -- print(json_str)
    if id == "null" then
        return 0, "", 0
    end
    local raw_data=nil
    for i,v in pairs(global_identifier_func_tab) do
        if v.identifier == id then
            local call_func = v.create_bin_func
            local data = call_func(obj,v.create_bin_args[2])
            local bin=nil

            raw_data = bpack("CC",v.create_bin_args[1],addr)
            for i = 1, #data do raw_data = raw_data .. bpack("C",data:byte(i)) end
            local bcc = crc8(raw_data)
            raw_data = raw_data .. bpack("C",bcc)
            local t_str=''
            for i=1, #raw_data do
                t_str=t_str .. (string.format("%02X", string.byte(string.sub(raw_data, i, i))))
            end

            print(t_str,#t_str)
            return err_code, t_str, #t_str
        end
    end
    return -1, nil, 0
end

function protocol_decode(input_str, len)
    local err_code=0

    -- print(input_str)

    --取出入参--
    local obj={}
    local input_obj=cjson.decode(input_str)
    local bin_str=input_obj.raw_data
    local id=input_obj.identifier
    --入参中的raw_data的二进制转换--
    if not bin_str or #bin_str < 5 then
        print(string.format( "Input args failed,args:%s",input_str))
        return nil
    end
    local t_str=''
    for i=1,#bin_str,2 do
        t_str=t_str .. string.char(tonumber(string.sub(bin_str, i, i+1),16))
    end

    raw_data=t_str
    local crc = crc8(string.sub(raw_data,1,#raw_data - 1))
    _,_,crc_pack = bunpack(raw_data,"IC")
    if (crc ~= crc_pack) then
        print(string.format( "Data crc check failed cal:%02X packet:%02X",crc,crc_pack))
        return nil
    end
    _,head,addr = bunpack(raw_data,"CC")
    if addr ~= 0x01 then
        print(string.format( "Data addr check failed cal:%02X",addr))
        return nil
    end
    for i,v in pairs(global_identifier_func_tab) do
        if v.identifier == id then
            local call_func = v.parser_bin_func
            local data,data_len = nil,0
            data = string.sub(raw_data,3,4)

            local json_obj = call_func(data,#data)-- 调用不同的函数执行解析数据
            json_obj.identifier=id                             -- 返回调用标识
            json_obj.term_addr=string.format("%02X",addr)
            local json_str=cjson.encode(json_obj)
            print(err_code, json_str, #json_str)
            return err_code,json_str,#json_str
        end
    end
    return nil

end



-- raw_data = bpack("CCCC",0X8A,1,1,0x11)
-- local bcc = crc8(raw_data)
-- print(string.format("BCC %X",bcc))
-- raw_data = raw_data .. bpack("C",bcc)
-- local t_str=''
-- for i=1, #raw_data do
--     t_str=t_str .. (string.format("%02X", string.byte(string.sub(raw_data, i, i))))
-- end

-- print(t_str,#t_str)
-- protocol_decode('{"raw_data":"8001011191","identifier":"fetchFeedback"}')