--
--  lua-logfile.lua -- Lua Logfile Abstraction (language: Lua)
--  Copyright (c) 2007 Ralf S. Engelschall <address@hidden>
--
--  You can redistribute and/or modify this file under the terms of
--  the GNU General Public License as published by the Free Software
--  Foundation; either version 2 of the License, or (at your option) any
--  later version.
--
--  This file is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
--  General Public License for more details.
--
--  You should have received a copy of the GNU General Public License
--  along with this program; if not, write to the Free Software
--  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
--  USA, or contact Ralf S. Engelschall <address@hidden>.
--

--  create namespace
Logfile = {}

--  object constructor
Logfile.new = function (class, logfile, tag)
    --  create new object
    local self = {}
    setmetatable(self, class)
    class.__index = class

    --  initialize object
    self.fd = nil
    self.tag = nil
    self.log_level = "info"
    self.log_levels = { ["error"] = 1, ["warning"] = 2, ["info"] = 3, ["debug"] = 4 }

    --  handle convenience argument to constructor
    if logfile ~= nil then
        self:open(logfile, tag)
    end

    --  return new object
    return self
end

--  object method: logfile opening
Logfile.open = function (self, logfile, tag)
    self.fd = io.open(logfile, "a")
    if self.fd == nil then
        io.stderr:write("ERROR: logfile:open: failed to open file \"" .. logfile .. "\"\n")
        return false
    end
    self.tag = tag
    return true
end

--  object method: logfile level configuration
Logfile.level = function (self, level)
    if self.log_levels[level] == nil then
        io.stderr:write("ERROR: logfile:level: invalid logging level \"" .. level .. "\"\n")
        return
    end
    self.log_level = level
    return
end

--  object method: logfile writing
Logfile.entry = function (self, level, msg)
    if self.log_levels[level] == nil then
        io.stderr:write("ERROR: logfile:entry: invalid logging level \"" .. level .. "\"\n")
        return
    end
    if self.log_levels[level] <= self.log_levels[self.log_level] then
        if level == "error" then
            if self.tag then
                io.stderr:write(tag .. ":ERROR: " .. msg .. "\n")
            else
                io.stderr:write("ERROR: " .. msg .. "\n")
            end
        end
        if self.fd ~= nil then
            local date = os.date("%Y-%m-%dT%H:%M:%S ")
            local txt = date
            if self.tag then
                txt = txt .. self.tag .. ": "
            end
            txt = txt .. level .. ": "
            txt = txt .. msg .. "\n"
            self.fd:write(txt)
            self.fd:flush()
        end
    end
    return
end

--  object method: logfile closing
Logfile.close = function (self)
    if self.fd ~= nil then
        self.fd:close()
        self.fd = nil
    end
    return
end