SimpleConkyScript/lua/system.lua

-- HorlogeSkynet's Lua script (for Conky) -- System module
-- <https://git.forestier.app/HorlogeSkynet/SimpleConkyScript.git>


local json = require('cjson.safe')


local system = {}


-- `config` object is passed as parameter here.
local _settings = (...).get_entries('settings')


-- Handy wrapper to `io.popen` to execute, read output from and pre-format the passed command.
function system.get_subcommand_output(command)
    local handle = io.popen(command)
    local output = handle:read('*all')
    io.close(handle)

    -- No output could be fetched from STDOUT.
    if #output == 0 then return end

    -- Replace new-lines characters by regular space.
    output = string.gsub(output, '\n', ' ')
    -- Right-trim the final output.
    output = string.gsub(output, "^(.-) *$", '%1')

    return output
end


-- Simple function to extract and return screen dimensions from a subcommand output as `${WIDTH}x${HEIGHT}`.
function system.get_screen_resolution()
    local xdpyinfo_output = system.get_subcommand_output(_settings.display.resolution_exec)
    local width, height = string.match(xdpyinfo_output, "(%d+)x(%d+)")

    return tonumber(width), tonumber(height)
end


-- Compute and return the average value measured from the specified sensor chip sub-features values.
-- `is_fan` is a boolean that MUST be set to `true` when dealing with a fan control chip.
function system.compute_avg_chip_value(chip_name, is_fan)
    -- Due to <https://github.com/lm-sensors/lm-sensors/pull/196>, we won't use LM-SENSORS's `-f` option at the moment.
    local sensors_output = system.get_subcommand_output(
            string.format("sensors -A -j \'%s\'", chip_name))
    if not sensors_output then
        io.stderr:write("Couldn\'t execute `sensors` subcommand.\n")
        return
    end

    local chip_output, error_message = json.decode(sensors_output)
    if not chip_output then
        io.stderr:write(
                string.format("Couldn\'t decode `sensors` JSON output : %s.\n", error_message))
        return
    end

    if not chip_output[chip_name] then
        io.stderr:write(
                string.format("Specified sensor (\'%s\') could not be found.\n", chip_name))
        return
    end

    local count, average_value = 0, 0.0
    for _, subfeatures in pairs(chip_output[chip_name]) do
        for name, value in pairs(subfeatures) do
            -- These conditions check whether this sub-feature value is a correct candidate, as :
            -- * It might be an input value for an unwanted control chip type ;
            -- * Some chips/adapters might return null (temperatures) values.
            -- According to LM-SENSORS, sub-features input values are labeled as `{fan,temp}\d_input`.
            if name:match(((is_fan and 'fan') or 'temp') .. "%d_input") and (value ~= 0.0 or is_fan) then
                count, average_value = count + 1, average_value + value
                -- There is only one `${chip_type}*_input` field per sub-feature.
                -- We may stop stop the current iteration at this step.
                break
            end
        end
    end

    if count == 0 then
        io.stderr:write(string.format("Couldn\'t retrieve any value from \'%s\' chip.\n", chip_name))
        return
    end

    -- For temperature, and when Fahrenheit unit is specified, let's perform a manual conversion.
    if not is_fan and string.upper(_settings.temperature.unit) == 'F' then
        average_value = (average_value * (9 / 5.)) + 32
    end

    return (average_value / count)
end


-- Return the temperature of the passed drive name.
function system.get_drive_temp(drive_name, wake_up)
    local hddtemp_output = system.get_subcommand_output(
            string.format(
                    "hddtemp \'%s\' -n -u \'%s\' %s",
                    drive_name,
                    _settings.temperature.unit,
                    ((wake_up and '-w') or '')))

    return tonumber(hddtemp_output)
end


-- Specific function to compute the ratio percentage between current and maximum brightness values.
function system.get_brightness_value(cur_file, max_file)
    local handle

    handle = io.open(cur_file)
    local cur_brightness = tonumber(handle:read('*all'))
    io.close(handle)

    handle = io.open(max_file)
    local max_brightness = tonumber(handle:read('*all'))
    io.close(handle)

    return (cur_brightness / max_brightness) * 100
end


-- Simple function to ask Conky about a network interface status (up/down).
-- See `if_up_strictness` Conky configuration option, as the result hard-depends on it.
function system.is_network_interface_up(if_name)
    local if_up = conky_parse(string.format("${if_up %s}1${else}0${endif}", if_name))

    return (if_up == '1')
end


return system