#!/usr/bin/env python

############################################################################
#
# MODULE:       r.rgb
# AUTHOR(S):	Glynn Clements
# PURPOSE:	Split a raster map into red, green and blue maps
# COPYRIGHT:	(C) 2009 Glynn Clements and the GRASS Development Team
#
#		This program is free software under the GNU General Public
#		License (>=v2). Read the file COPYING that comes with GRASS
#		for details.
#
#############################################################################

#%module
#% description: Splits a raster map into red, green and blue maps.
#% keyword: raster
#% keyword: RGB
#% keyword: separate
#% keyword: split
#%end
#%option G_OPT_R_INPUT
#%end
#%option G_OPT_R_OUTPUT
#% key: red
#% description: Red channel raster map name
#% required: no
#%end
#%option G_OPT_R_OUTPUT
#% key: green
#% description: Green channel raster map name
#% required: no
#%end
#%option G_OPT_R_OUTPUT
#% key: blue
#% description: Blue channel raster map name
#% required: no
#%end
#%rules
#% required: red, green, blue
#%end

import grass.script as gscript


def main():
    options, unused = gscript.parser()
    input = options['input']
    red = options['red']
    green = options['green']
    blue = options['blue']

    if not gscript.find_file(input)['file']:
        gscript.fatal(_("Raster map <%s> not found") % input)

    expressions = []
    maps = []
    if red:
        expressions.append('%s = r#${input}' % red)
        maps.append(red)
    if green:
        expressions.append('%s = g#${input}' % green)
        maps.append(green)
    if blue:
        expressions.append('%s = b#${input}' % blue)
        maps.append(blue)
    expr = ';'.join(expressions)
    gscript.mapcalc(expr, input=input)

    for name in maps:
        gscript.run_command('r.colors', map=name, color='grey255')
        gscript.raster_history(name)


if __name__ == "__main__":
    main()
