#!/usr/bin/env python
#
#########################################################################
#
# MODULE:       v.sort.points
#
# AUTHOR(S):    Moritz Lennert
#
# PURPOSE:      Takes a point map and creates a new point map with the points
#               sorted according to a chosen numeric column with largest 
#               values first
#
# DATE:         Wed May  4 18:44:05 2016
#
#########################################################################

#%module
#% description: Sorts a vector point map according to a numeric column
#%end
#%option G_OPT_V_INPUT
#% required: yes
#%end
#%option G_OPT_V_FIELD
#% required: yes
#% answer: 1
#%end
#%option G_OPT_V_OUTPUT
#% required: yes
#%end
#%option G_OPT_DB_COLUMN
#% description: Name of attribute column used for sorting
#% required: yes
#%end
#%flag
#% key: r
#% description: do not reverse sort
#%end

import sys
import os

import grass.script as gscript

def num(s):
    try:
        return int(s)
    except ValueError:
        try:
            return float(s)
        except:
            return s

def main():
    options, flags = gscript.parser()
    inputmap = options['input']
    layer = options['layer']
    outputmap = options['output']
    sort_column = options['column']
    reverse = True
    if flags['r']:
        reverse = False

    columns = gscript.vector_columns(inputmap)
    key_column = gscript.vector_layer_db(inputmap, layer)['key']
    sort_index = columns[sort_column]['index']+2
    sorted_cols = sorted(iter(columns.items()), key=lambda x_y: x_y[1]['index'])
    column_def="x DOUBLE PRECISION, y DOUBLE PRECISION, cat INTEGER"
    colnames = []
    for colcount in range(1,len(sorted_cols)):
        name = sorted_cols[colcount][0]
        type = sorted_cols[colcount][1]['type']
        if name == sort_column and (type != 'INTEGER' and type != 'DOUBLE PRECISION'):
            gscript.fatal('Sort column must be numeric')
        if name == key_column:
            continue
        colnames.append(name)
        column_def += ", %s %s" % (name, type)

    inpoints=gscript.read_command('v.out.ascii',
                            in_=inputmap,
                            columns=colnames,
                            quiet=True)

    points=[]
    for line in inpoints.splitlines():
        data = [num(x) for x in line.split('|')]
        points.append(data)

    points_sorted=sorted(points, key=lambda x: x[sort_index], reverse=reverse)

    outpoints = ""
    for list in points_sorted:
        outpoints+="|".join([str(x) for x in list])+"\n"

    gscript.write_command('v.in.ascii',
                        input='-',
                        stdin=outpoints,
                        output=outputmap,
                        x=1,
                        y=2,
                        cat=3,
                        columns=column_def,
                        quiet=True)

    gscript.run_command('v.db.dropcolumn',
                        map=outputmap,
                        columns='x,y',
                        quiet=True)

    return 0

if __name__ == "__main__":
    sys.exit(main())