#!/usr/bin/env python
# -*- coding: utf-8 -*-
############################################################################
#
# MODULE:       v.median
# AUTHOR(S):    Luca Delucchi, Fondazione E. Mach (Italy)
#
# PURPOSE:      Return the barycenter of a cloud of point
# COPYRIGHT:    (C) 2011 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: Return the barycenter of a cloud of point.
#% keyword: vector
#%end
#%option
#% key: input
#% type: string
#% gisprompt: old,vector,vector
#% description: Name of vector map to pack up
#% key_desc: name
#% required : yes
#%end
#%option
#% key: output
#% type: string
#% gisprompt: new_file,file,output
#% description: Name for output file ('-' for standard output)
#% answer: -
#% required : no
#%end

import sys, os
from grass.script.utils import try_remove
from grass.script import core as grass
from grass.exceptions import CalledModuleError
from numpy import transpose, genfromtxt, median


def point_med(filetmp):
    # function to return the median point, x and y
    point_list = transpose(genfromtxt(filetmp, delimiter='|',usecols=(0,1)))
    return median(point_list[0]), median(point_list[1])

def main():
    # check if input file exists
    infile = options['input']
    gfile = grass.find_file(infile, element = 'vector')
    if not gfile['name']:
        grass.fatal(_("Vector map <%s> not found") % infile)    
    # create tempfile and write ascii file of input
    temp_in = grass.tempfile()
    try:
        grass.run_command('v.out.ascii', overwrite = True, input=gfile['name'], 
                          output = temp_in)
    except CalledModuleError:
        grass.fatal(_("Failed to export vector in a temporary file"))
    # x and y of median point
    medx, medy = point_med(temp_in)   
    try_remove(temp_in)
    # prepare the output
    output = "%f|%f" % (medx, medy)
    map_name = options['output']
    overwrite = os.getenv('GRASS_OVERWRITE')
    # if output is not set return to stdout
    if map_name == '-':
        grass.message(output)
    # else
    else:
        # output file
        goutfile = grass.find_file(name = map_name, element = 'vector',
                            mapset = '.')
        # output tempfile
        temp_out = grass.tempfile()
        file_out = open(temp_out,'w')
        file_out.write(output)
        file_out.close()
        # output file exists and not overwrite
        if goutfile['file'] and overwrite != '1':
            grass.fatal(_("Vector map <%s> already exists") % map_name)
        # output file exists and overwrite
        elif goutfile['file'] and overwrite == '1':
            grass.warning(_("Vector map <%s> already exists and will be overwritten") % map_name)
            grass.run_command('v.in.ascii', overwrite = True, input=temp_out, 
                                        output = map_name)
        # output file not exists
        else:
            grass.run_command('v.in.ascii', input=temp_out, output = map_name)
        try_remove(temp_out)
   
if __name__ == "__main__":
    options, flags = grass.parser()
    sys.exit(main())