local socket = require('socket') --luasocket

local function trim(s)
   return s:gsub("^%s*(.-)%s*$", "%1")
end

local function split(s, sep)
    local t = {}
    for str in string.gmatch(s, "([^"..sep.."]+)") do
        table.insert(t, str)
    end
    return t
end


local Inverter = {}
Inverter.__index = Inverter

function Inverter.create(host, port)
    assert(host ~= nil, 'host cannot be nil')
    assert(type(port) == 'number', 'port must be a number')

    local client = {}
    client.host = host
    client.port = port
    client.tcp = socket.tcp()

    setmetatable(client, Inverter)
    return client
end

function Inverter:connect()
    local ok, err = self.tcp:connect(self.host, self.port)
    if not ok then
        return ok, err
    end

    self:format('json')
    return true
end

function Inverter:disconnect()
    self.tcp:close()
end

function Inverter:format(format)
    data = 'format ' .. format
    if not self:_write(data) then
        return nil
    end
    return self:_read_response()    
end

function Inverter:exec(command, arguments)
    data = 'exec ' .. command
    if arguments then
        data = data .. ' ' .. table.concat(arguments, ' ')
    end
    if not self:_write(data) then
        return nil
    end
    return self:_read_response()
end


function Inverter:_write(data)
    return self.tcp:send(data .. '\r\n')
end

function Inverter:_read_response()
    buf = ''
    while (true) do
        readed = self.tcp:receive()
        if readed == '' then
            break
        end
        buf = buf .. readed .. '\r\n'
    end

    buf = trim(buf)
    response = split(buf, '\r\n')
    
    status = response[1]
    table.remove(response, 1)
    
    body = table.concat(response, '\r\n')
    return status == 'ok', body
end

return Inverter