#!/usr/bin/env python

############################################################################
#
# MODULE:	r.blend for GRASS 5.7; based on blend.sh for GRASS 5
# AUTHOR(S):	CERL?; updated to GRASS 5.7 by Michael Barton
#               Converted to Python by Glynn Clements
# PURPOSE:	To redraw current displayed maps to 24 bit PNG output
# COPYRIGHT:	(C) 2004-2012 by 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: Blends color components of two raster maps by a given ratio.
#% keyword: raster
#% keyword: composite
#%end
#%option G_OPT_R_INPUT
#% key: first
#% description: Name of first raster map for blending
#%end
#%option G_OPT_R_INPUT
#% key: second
#% description: Name of second raster map for blending
#%end
#%option G_OPT_R_BASENAME_OUTPUT
#% description: Basename for red, green and blue output raster maps
#%end
#%option
#% key: percent
#% type: double
#% answer: 50
#% options : 0-100
#% description: Percentage weight of first map for color blending
#% required : no
#%end
#% flag
#% key: c
#% description: Combine resulting R,G,B layers into single output map
#%end

import os
import string
import grass.script as gscript


def main():
    first = options['first']
    second = options['second']
    output = options['output']
    percent = options['percent']

    mapset = gscript.gisenv()['MAPSET']

    if not gscript.overwrite():
        for ch in ['r', 'g', 'b']:
            map = '%s.%s' % (output, ch)
            if gscript.find_file(map, element='cell', mapset=mapset)['file']:
                gscript.fatal(_("Raster map <%s> already exists.") % map)

    percent = float(percent)
    perc_inv = 100.0 - percent

    frac1 = percent / 100.0
    frac2 = perc_inv / 100.0

    gscript.message(_("Calculating the three component maps..."))

    template = string.Template("$$output.$ch = "
                               "if(isnull($$first), $ch#$$second, "
                               "if(isnull($$second), $ch#$$first, "
                               "$$frac1 * $ch#$$first + "
                               "$$frac2 * $ch#$$second))")
    cmd = [template.substitute(ch=ch) for ch in ['r', 'g', 'b']]
    cmd = ';'.join(cmd)

    gscript.mapcalc(cmd, output=output, first=first, second=second,
                    frac1=frac1, frac2=frac2)

    for ch in ['r', 'g', 'b']:
        map = "%s.%s" % (output, ch)
        gscript.run_command('r.colors', map=map, color='grey255')
        gscript.run_command('r.support', map=map, history="",
                            title="Color blend of %s and %s" % (first, second),
                            description="generated by r.blend")
        gscript.run_command('r.support', map=map,
                            history="r.blend %s channel." % ch)
        gscript.run_command('r.support', map=map,
                            history="  %d%% of %s, %d%% of %s" %
                                    (percent, first, perc_inv, second))
        gscript.run_command('r.support', map=map, history="")
        gscript.run_command('r.support', map=map, history=os.environ['CMDLINE'])

    if flags['c']:
        gscript.run_command('r.composite', r='%s.r' % output,
                            g='%s.g' % output, b='%s.b' % output,
                            output=output)

        gscript.run_command('r.support', map=output, history="",
                            title="Color blend of %s and %s" % (first, second),
                            description="generated by r.blend")
        gscript.run_command('r.support', map=output,
                            history="  %d%% of %s, %d%% of %s" %
                                    (percent, first, perc_inv, second))
        gscript.run_command('r.support', map=output, history="")
        gscript.run_command('r.support', map=output,
                            history=os.environ['CMDLINE'])
    else:
        gscript.message(_("Done. Use the following command to visualize "
                          "the result:"))
        gscript.message(_("d.rgb r=%s.r g=%s.g b=%s.b") %
                        (output, output, output))


if __name__ == "__main__":
    options, flags = gscript.parser()
    main()