--[[

A script to change MorphOS skin prefs. Use at your own risk.

Usage: LuaX changeskin.lua <location> <screen> <skin>

- The "location" argument can be ENV, ENVARC, or BOTH. It defines where
  the "screens.txt" file is modified.
- If the "skin" argument is omitted, the default skin is used.
- The "make_backup" setting creates a "screens.txt.bak" file
  to the corresponding location.
- The "screen" argument is case sensitive!

Examples:
 LuaX changeskin.lua ENV Ambient Ater
 LuaX changeskin.lua BOTH Ambient Default

]]

require 'io'
require 'os'
require 'string'


-- CONFIG BEGINS (Use true or false values)

make_backup = true

-- CONFIG ENDS


function change_skin(loc)
	if make_backup then os.execute('Copy ' .. loc .. ':MUI/screens.txt ' .. loc .. ':MUI/screens.txt.bak CLONE') end
	local file = io.open(loc .. ':MUI/screens.txt','r')
	if file then
		local found
		local content = file:read('*a')
		io.close(file)
		content, found = string.gsub(content, '(N="?' .. screen .. '.-S="?)(%w+)', "%1" .. skin)
		if found > 0 then
			file = io.open(loc .. ':MUI/screens.txt','w+')
			if file then
				file:write(content)
				io.close(file)
			else
				io.write('Failed to write the file in ' .. loc .. '.\n')
			end
		else
			io.write('Failed to change the skin.\n')
		end
	else
		io.write('Failed to read the file in ' .. loc .. '.\n')
	end
end


if #arg > 1 then
	location = string.upper(arg[1])
	screen = arg[2]
	if arg[3] then skin = arg[3] else skin = 'Default' end
	if location == 'BOTH' then
		change_skin('ENVARC')
		change_skin('ENV')
	elseif location == 'ENV' then
		change_skin('ENV')
	elseif location == 'ENVARC' then
		change_skin('ENVARC')
	else
		io.write('The first argument must be "ENV", "ENVARC", or "BOTH"!\n')
	end
else
	io.write('At least two arguments (location and screen name) are required.\n')
end