#!/usr/bin/env python3
#
############################################################################
#
# MODULE:       d.correlate for GRASS 6; based on dcorrelate.sh for GRASS 4,5
# AUTHOR(S):    CERL - Michael Shapiro; updated to GRASS 6 by Markus Neteler 5/2005
#               Converted to Python by Glynn Clements
# PURPOSE:      prints a graph of the correlation between data layers (in pairs)
#               derived from <grass5>/src.local/d.correlate.sh
# COPYRIGHT:    (C) 2005, 2008, 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: Prints a graph of the correlation between raster maps (in pairs).
# % keyword: display
# % keyword: statistics
# % keyword: raster
# % keyword: diagram
# % keyword: correlation
# %end
# %option G_OPT_R_MAPS
# %end

import sys
import os
from grass.script.utils import try_remove
from grass.script import core as gcore
from grass.exceptions import CalledModuleError


def main():
    layers = options["map"].split(",")

    if len(layers) < 2:
        gcore.error(_("At least 2 maps are required"))

    tmpfile = gcore.tempfile()

    for map in layers:
        if not gcore.find_file(map, element="cell")["file"]:
            gcore.fatal(_("Raster map <%s> not found") % map)

    try:
        gcore.write_command(
            "d.text", color="black", size=4, line=1, stdin="CORRELATION"
        )
    except CalledModuleError:
        return 1

    os.environ["GRASS_RENDER_FILE_READ"] = "TRUE"

    colors = "red black blue green gray violet".split()
    line = 2
    iloop = 0
    jloop = 0
    for iloop, i in enumerate(layers):
        for jloop, j in enumerate(layers):
            if i != j and iloop <= jloop:
                color = colors[0]
                colors = colors[1:]
                colors.append(color)
                gcore.write_command(
                    "d.text", color=color, size=4, line=line, stdin="%s %s" % (i, j)
                )
                line += 1

                ofile = open(tmpfile, "w")
                gcore.run_command("r.stats", flags="cnA", input=(i, j), stdout=ofile)
                ofile.close()

                ifile = open(tmpfile, "r")
                first = True
                for line in ifile:
                    f = line.rstrip("\r\n").split(" ")
                    x = float(f[0])
                    y = float(f[1])
                    if first:
                        minx = maxx = x
                        miny = maxy = y
                        first = False
                    if minx > x:
                        minx = x
                    if maxx < x:
                        maxx = x
                    if miny > y:
                        miny = y
                    if maxy < y:
                        maxy = y
                ifile.close()

                kx = 100.0 / (maxx - minx + 1)
                ky = 100.0 / (maxy - miny + 1)

                p = gcore.feed_command("d.graph", color=color)
                ofile = p.stdin

                ifile = open(tmpfile, "r")
                for line in ifile:
                    f = line.rstrip("\r\n").split(" ")
                    x = float(f[0])
                    y = float(f[1])
                    ofile.write(
                        b"icon + 0.1 %f %f\n"
                        % ((x - minx + 1) * kx, (y - miny + 1) * ky)
                    )
                ifile.close()

                ofile.close()
                p.wait()

    try_remove(tmpfile)

    return 0


if __name__ == "__main__":
    options, flags = gcore.parser()
    sys.exit(main())