sCCripts/jlib/log.lua

-- Created by Jef Roosens
--
-- Module to add logging to a program. This module is integrated in all jlib
-- functions.


local module = {}


-- Define class with default values
local Logger = {
    level = 2,
    level_colors = {
        colors.red, colors.orange, colors.yellow, colors.blue, colors.white},
    prefixes = { "CRIT", "ERROR", "WARN", "INFO", "DEBUG" },
    filename = nil
}


-- Return a new logger 'object'.
--
-- @param level log level:
-- (0) critical, (1) errors, (2) warnings, (3) info,(4) debug
-- @param level_colors table containing color names for messages; order is
-- { critical, errors, warnings, info, debug }. Only colors for the needed log
-- level need to be provided: e.g. if the log level is (2) warnings, then only
-- two colors need to be provided. If not provided, defaults to
-- { red, orange, yellow, blue, white }.
-- @param prefixes prefix to show for each log level
-- @param filename log file to write to. If not supplied, log will only be
-- outputted to stdout
-- @return a logger 'object'
function Logger:new(o)
    o = o or {}
    setmetatable(o, self)
    self.__index = self

    -- Open file handler
    if o.filename then
        o._file = open(filename, "a")
    end

    return o
end

-- Log a message with the given level
--
-- @param level log level; levels higher than logger level get discarded
-- @param message message to log
-- @return wether or not the message was actually logged
function Logger:log(level, message)
    -- Exit if the level is too high
    if level > self.level then return false end

    -- Log to screen
    local cur_color = term.getTextColor()
    term.setTextColor(self.colors[level + 1])
    term.write("[" .. self.prefixes[level + 1] .. "] ")
    term.setTextColor(cur_color)
    print(message)

    -- Log to file
    if self._file then
        local line = "[" .. self.prefixes[level + 1] .. "] " .. message .. '\n'
        self._file.write(line)
        self._file.flush()

    end
end

-- Just some convenience functions; wrappers around Logger:log
function Logger:critical(message) self:log(0, message) end
function Logger:error(message) self:log(1, message) end
function Logger:warning(message) self:log(2, message) end
function Logger:info(message) self:log(3, message) end
function Logger:debug(message) self:log(4, message) end

-- Close the logger a.k.a. close the log file handler
function Logger:close()
    if self._file then self._file.close() end
end


module.Logger = Logger
return module