#!/usr/bin/env python3
#
# thumbnails.py: Create thumbnail images of the GRASS color tables
#
#  AUTHOR: Vaclav Petras (non-PPM version using r.mapcalc)
#          Glynn Clements (Python version)
#      Earlier Bourne script version by Hamish Bowman,
#      https://grasswiki.osgeo.org/wiki/Talk:Color_tables
#
#   (C) 2009-2017 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.
#

import sys
import os
import atexit
import grass.script as grass


tmp_grad_abs = None
tmp_grad_rel = None


def cleanup():
    if tmp_grad_rel:
        grass.run_command('g.remove', flags='f', type='raster',
                          name=tmp_grad_rel, quiet=True)
    if tmp_grad_abs:
        grass.run_command('g.remove', flags='f', type='raster',
                          name=tmp_grad_abs, quiet=True)


def make_gradient(path):
    fh = open(path)
    text = fh.read()
    fh.close()

    lines = text.splitlines()
    records = list()
    for line in lines:
        if line.startswith("#"):
            # skip comments
            continue
        if len(line) == 0:
            # skip empty lines
            continue
        records.append(line.split())
    records = [record for record in records
               if record[0] != 'nv' and record[0] != 'default']
    relative = False
    absolute = False
    for record in records:
        if record[0].endswith("%"):
            relative = True
            record[0] = record[0].rstrip("%")
        else:
            absolute = True

    if absolute:
        if relative:
            minval = -0.04
            maxval = 0.04
        else:
            minval = float(records[0][0])
            # shift min up for floating point values so that
            # first color in color table is visible
            if '.' in records[0][0]:
                # assumes that 1% of min does not go to the next value
                # and is still represented as float and does not make
                # too much difference in color
                # works better than 1% of the difference to the next value
                minval += abs(minval / 100)
            maxval = float(records[-1][0])
            maxval = min(maxval, 2500000)
        if os.path.basename(path) in ('ndvi', 'ndwi', 'ndwi2'):
            minval = -1.0
            maxval = 1.0
        if os.path.basename(path) == 'ndvi_MODIS':
            minval = -10000.0
            maxval = 10000.0
        if os.path.basename(path) == 'population_dens':
            maxval = 1000.0
        if os.path.basename(path) == 'precipitation':
            maxval = 2000.0
        if os.path.basename(path) in ('terrain', 'srtm', 'srtm_plus'):
            minval = -500.0
            maxval = 3000.0
        grad = tmp_grad_abs
        grass.mapcalc("$grad = "
                      " float($min) + (col() - 1) * "
                      "  (float($max) - float($min)) / ncols()",
                      grad=tmp_grad_abs, min=minval, max=maxval, quiet=True)
    else:
        grad = tmp_grad_rel

    return grad


def make_image(output_dir, table, grad, height, width):
    outfile = os.path.join(output_dir, "colortables", "%s.png" % table)
    os.environ['GRASS_RENDER_FILE'] = outfile

    grass.run_command("r.colors", map=grad, color=table, quiet=True)
    os.environ['GRASS_RENDER_FRAME'] = '%f,%f,%f,%f' % (0, height, 2, width - 2)
    grass.run_command("d.rast", map=grad, quiet=True)
    if 1:
        os.environ['GRASS_RENDER_FRAME'] = '%f,%f,%f,%f' % (0, height, 0, width)
        grass.write_command("d.graph", quiet=True, flags='m', stdin="""
        width 1
        color {outcolor}
        polyline
        {x1} {y1}
        {x2} {y1}
        {x2} {y2}
        {x1} {y2}
        {x1} {y1}
        color {incolor}
        polyline
        {x3} {y3}
        {x4} {y3}
        {x4} {y4}
        {x3} {y4}
        {x3} {y3}
        """.format(x1=1, x2=width, y1=0, y2=height - 1,
                   x3=2, x4=width - 1, y3=1, y4=height - 2,
                   outcolor='white', incolor='black'))


def main():
    global tmp_img, tmp_grad_abs, tmp_grad_rel

    height = 15
    width = 85

    os.environ['GRASS_OVERWRITE'] = '1'

    color_dir = os.path.join(os.environ['GISBASE'], "etc", "colors")
    output_dir = os.path.join(os.environ['GISBASE'], "docs", "html")

    if not os.path.exists(output_dir):
        os.makedirs(output_dir)

    pid = os.getpid()
    tmp_grad_abs = "tmp_grad_abs_%d" % pid
    tmp_grad_rel = "tmp_grad_rel_%d" % pid

    os.environ['GRASS_RENDER_WIDTH'] = '%d' % width
    os.environ['GRASS_RENDER_HEIGHT'] = '%d' % height
    os.environ['GRASS_RENDER_TRUECOLOR'] = 'TRUE'
    # for multiple d commands (requires to delete/move image each time)
    os.environ['GRASS_RENDER_FILE_READ'] = 'TRUE'
    os.environ['GRASS_RENDER_FILE_MAPPED'] = 'FALSE'
    os.environ['GRASS_RENDER_TRANSPARENT'] = 'FALSE'
    os.environ['GRASS_RENDER_BACKGROUNDCOLOR'] = 'ffffff'
    os.environ['GRASS_RENDER_IMMEDIATE'] = 'cairo'
    # for one pixel wide lines
    os.environ['GRASS_RENDER_ANTIALIAS'] = 'none'

    for var in ['GRASS_RENDER_LINE_WIDTH']:
        if var in os.environ:
            del os.environ[var]

    os.environ['GRASS_ANTIALIAS'] = 'none'

    grass.use_temp_region()
    grass.run_command('g.region', s=0, w=0, n=height, e=width,
                      rows=height, cols=width, res=1, flags='a')

    grass.mapcalc("$grad = float(col())", grad=tmp_grad_rel, quiet=True)

    for table in os.listdir(color_dir):
        path = os.path.join(color_dir, table)
        grad = make_gradient(path)
        make_image(output_dir, table, grad,
                   height=height, width=width)

    grass.mapcalc("$grad = col()", grad=tmp_grad_abs, quiet=True)
    for table in ['grey.eq', 'grey.log', 'random']:
        make_image(output_dir, table, tmp_grad_abs,
                   height=height, width=width)


if __name__ == "__main__":
    atexit.register(cleanup)
    main()