implement base functionality for chat commands

Chat commands alwys start with `/mtimer` and then the player defines
what action to perform and adds a payload.

    /mtimer help
    /mtimer show
    /mtimer set setting value

Issue: https://github.com/dsohler/mtimer/issues/1

init.lua

@@ -1,7 +1,10 @@
--- Load default configuration andf functions
+-- Load default configuration
 local modpath = minetest.get_modpath(minetest.get_current_modname())..DIR_DELIM
 local config = dofile(modpath..'system'..DIR_DELIM..'get_options.lua')
+
+-- Load functions
 dofile(modpath..'system'..DIR_DELIM..'timer_function.lua')
+dofile(modpath..'system'..DIR_DELIM..'chat_commands.lua')
 
 
 -- Set custom player attribute if not set

system/chat_commands.lua

@@ -0,0 +1,63 @@
+-- Colorize a string in the given color
+--
+-- Colorizes a string in a given hexadecimal color coded color. The string will
+-- be returned including a reset color escape (assumably white text color)
+local colorize = function (color, string)
+    local c = minetest.get_color_escape_sequence('#'..string.upper(color))
+    local r = minetest.get_color_escape_sequence('#FFFFFF')
+    return c..string..r
+end
+
+
+-- Show the configuration to the player
+--
+-- Gathers all settable variables and prints them to the player
+--
+-- @param player The player object of the player to print to
+local show_configuration = function (player)
+    local name = player:get_player_name()
+    local result_string = colorize('729fcf', 'MTimer configuration')..'\n'
+    local font_color = player:get_attribute('mtimer:font_color')
+
+    local configuration = {
+        runtime = player:get_attribute('mtimer:runtime'),
+        offset = player:get_attribute('mtimer:offset'),
+        ingame_time = player:get_attribute('mtimer:ingame_time'),
+        current_time = player:get_attribute('mtimer:current_time'),
+        font_color = colorize(font_color, font_color),
+        start = player:get_attribute('mtimer:start'),
+        show = player:get_attribute('mtimer:show'),
+        locale = player:get_attribute('mtimer:locale'),
+        position = player:get_attribute('mtimer:position'),
+        format = player:get_attribute('mtimer:format'),
+        alignment = player:get_attribute('mtimer:alignment')
+    }
+
+    for setting,value in pairs(configuration) do
+        local s = colorize('73d216', setting)
+        result_string = result_string..'  '..s..' = '..value..'\n'
+    end
+
+    minetest.chat_send_player(name, result_string)
+end
+
+
+-- Register the chat command that will be used to interact with MTimer.
+--
+-- The chat command has three actions:
+--
+-- help   Show help to the user via the regular chat
+-- show   Show the current configuration to the user
+-- set    Set the given setting to the given value
+minetest.register_chatcommand('mtimer', {
+    params = '<help>, <show>, <set setting value>',
+    description = 'Manage MTimer display',
+    func = function(name, parameters)
+        local player = minetest.get_player_by_name(name)
+        local action = parameters:match('%a+')
+        local payload = parameters:gsub('^%a+ ', '')
+        if action == 'show' then show_configuration(player) end
+        if action == 'help' then show_help(player) end
+        if action == 'set' and payload ~= nil then set(player, payload) end
+    end
+})