#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
skyview2svg -- Create an SVG image of GPS satellites sky view.

Read from file or stdin the JSON data produced by gpsd,
example usage:

    gpspipe -w | skyview2svg > skyview.svg

For GPSD JSON format see: http://www.catb.org/gpsd/gpsd_json.html
"""
# This code runs compatibly under Python 2 and 3.x for x >= 2.
# Preserve this property!
#
# This file is Copyright (c) 2010-2018 by the GPSD project
# SPDX-License-Identifier: BSD-2-clause
from __future__ import absolute_import, print_function, division

import datetime
import json
import math
import sys

__author__ = "Niccolo Rigacci"
__copyright__ = "Copyright 2018 Niccolo Rigacci <niccolo@rigacci.org>"
__license__ = "BSD-2-clause"
__email__ = "niccolo@rigacci.org"
__version__ = "3.19-dev"


# ------------------------------------------------------------------------
# ------------------------------------------------------------------------
def polar2cart(azimuth, elevation, r_max):
    """Convert polar coordinates in cartesian ones."""
    radius = r_max * (1 - elevation / 90.0)
    theta = math.radians(float(azimuth - 90))
    return (
        int(radius * math.cos(theta) + 0.5),
        int(radius * math.sin(theta) + 0.5)
    )


# ------------------------------------------------------------------------
# ------------------------------------------------------------------------
def cutoff_err(err, err_min, err_max):
    """Cut-off Estimated Error between min and max."""
    if err is None or err >= err_max:
        return err_max, '&gt;'
    if err <= err_min:
        return err_min, '&lt;'
    else:
        return err, ''


# ------------------------------------------------------------------------
# Read JSON data from file or stdin, search a {'class': 'SKY'} line.
# ------------------------------------------------------------------------
EXIT_CODE = 0
SKY = None
TPV = None
try:
    if len(sys.argv) > 1:
        with open(sys.argv[1]) as f:
            while True:
                SENTENCE = json.loads(f.readline())
                if 'class' in SENTENCE and SENTENCE['class'] == 'SKY':
                    SKY = SENTENCE
                if 'class' in SENTENCE and SENTENCE['class'] == 'TPV':
                    TPV = SENTENCE
                if SKY is not None and TPV is not None:
                    break
    else:
        while True:
            SENTENCE = json.loads(sys.stdin.readline())
            if 'class' in SENTENCE and SENTENCE['class'] == 'SKY':
                SKY = SENTENCE
            if 'class' in SENTENCE and SENTENCE['class'] == 'TPV':
                TPV = SENTENCE
            if SKY is not None and TPV is not None:
                sys.stdin.close()
                break
except (IOError, ValueError):
    # Assume empty data and write msg to stderr.
    EXIT_CODE = 100
    sys.stderr.write("Error reading JSON data from file or stdin."
                     " Creating an empty or partial skyview image.\n")

if SKY is None:
    SKY = {}
if TPV is None:
    TPV = {}

# ------------------------------------------------------------------------
# Colors for the SVG styles.
# ------------------------------------------------------------------------
# Background and label colors.
BACKGROUND_COLOR = '#323232'
LBL_FONT_COLOR = 'white'
FONT_FAMILY = 'Verdana,Arial,Helvetica,sans-serif'
# Compass dial.
COMPASS_STROKE_COLOR = '#9d9d9d'
DIAL_POINT_COLOR = COMPASS_STROKE_COLOR
# Satellites constellation.
SAT_USED_FILL_COLOR = '#00ff00'
SAT_UNUSED_FILL_COLOR = '#d0d0d0'
SAT_USED_STROKE_COLOR = '#0b400b'
SAT_UNUSED_STROKE_COLOR = '#101010'
SAT_USED_TEXT_COLOR = '#000000'
SAT_UNUSED_TEXT_COLOR = '#000000'
# Sat signal/noise ratio box and bars.
BARS_AREA_FILL_COLOR = '#646464'
BARS_AREA_STROKE_COLOR = COMPASS_STROKE_COLOR
BAR_USED_FILL_COLOR = '#00ff00'
BAR_UNUSED_FILL_COLOR = '#ffffff'
BAR_USED_STROKE_COLOR = '#324832'
BAR_UNUSED_STROKE_COLOR = BACKGROUND_COLOR

# ------------------------------------------------------------------------
# Size and position of elements.
# ------------------------------------------------------------------------
IMG_WIDTH = 528
IMG_HEIGHT = 800
STROKE_WIDTH = int(IMG_WIDTH * 0.007)

# Scale graph bars to accomodate at least MIN_SAT values.
MIN_SAT = 12
NUM_SAT = MIN_SAT

# Auto-scale: reasonable values for Signal/Noise Ratio and Error.
SNR_MAX = 30.0  # Do not autoscale below this value.
# Auto-scale horizontal and vertical error, in meters.
ERR_MIN = 5.0
ERR_MAX = 75.0

# Create an empty list, if satellites list is missing.
if 'satellites' not in SKY.keys():
    SKY['satellites'] = []

if len(SKY['satellites']) < MIN_SAT:
    NUM_SAT = MIN_SAT
else:
    NUM_SAT = len(SKY['satellites'])

# Make a sortable array and autoscale SNR.
SATELLITES = {}
for sat in SKY['satellites']:
    SATELLITES[sat['PRN']] = sat
    if float(sat['ss']) > SNR_MAX:
        SNR_MAX = float(sat['ss'])

# Compass dial and satellites placeholders.
CIRCLE_X = int(IMG_WIDTH * 0.50)
CIRCLE_Y = int(IMG_WIDTH * 0.49)
CIRCLE_R = int(IMG_HEIGHT * 0.22)
SAT_WIDTH = int(CIRCLE_R * 0.24)
SAT_HEIGHT = int(CIRCLE_R * 0.14)

# GPS position.
POS_LBL_X = int(IMG_WIDTH * 0.50)
POS_LBL_Y = int(IMG_HEIGHT * 0.62)

# Sat signal/noise ratio box and bars.
BARS_BOX_WIDTH = int(IMG_WIDTH * 0.82)
BARS_BOX_HEIGHT = int(IMG_HEIGHT * 0.14)
BARS_BOX_X = int((IMG_WIDTH - BARS_BOX_WIDTH) * 0.5)
BARS_BOX_Y = int(IMG_HEIGHT * 0.78)
BAR_HEIGHT_MAX = int(BARS_BOX_HEIGHT * 0.72)
BAR_SPACE = int((BARS_BOX_WIDTH - STROKE_WIDTH) / NUM_SAT)
BAR_WIDTH = int(BAR_SPACE * 0.70)
BAR_RADIUS = int(BAR_WIDTH * 0.20)

# Error box and bars.
ERR_BOX_X = int(IMG_WIDTH * 0.65)
ERR_BOX_Y = int(IMG_HEIGHT * 0.94)
ERR_BOX_WIDTH = int((BARS_BOX_X + BARS_BOX_WIDTH) - ERR_BOX_X)
ERR_BOX_HEIGHT = BAR_SPACE * 2
ERR_BAR_HEIGHT_MAX = int(ERR_BOX_WIDTH - STROKE_WIDTH*2)

# Timestamp
TIMESTAMP_X = int(IMG_WIDTH * 0.50)
TIMESTAMP_Y = int(IMG_HEIGHT * 0.98)

# Text labels.
LBL_FONT_SIZE = int(IMG_WIDTH * 0.036)
LBL_COMPASS_POINTS_SIZE = int(CIRCLE_R * 0.12)
LBL_SAT_SIZE = int(SAT_HEIGHT * 0.75)
LBL_SAT_BAR_SIZE = int(BAR_WIDTH * 0.90)

# Get timestamp from GPS or system.
if 'time' in SKY:
    UTC = datetime.datetime.strptime(SKY['time'], '%Y-%m-%dT%H:%M:%S.%fZ')
elif 'time' in TPV:
    UTC = datetime.datetime.strptime(TPV['time'], '%Y-%m-%dT%H:%M:%S.%fZ')
else:
    UTC = datetime.datetime.utcnow()
TIME_STR = UTC.strftime('%Y-%m-%d %H:%M:%S UTC')

# ------------------------------------------------------------------------
# Output the SGV image.
# ------------------------------------------------------------------------
print('''<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
          "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg
   xmlns="http://www.w3.org/2000/svg"
   width="%d"
   height="%d">''' % (IMG_WIDTH, IMG_HEIGHT))

# NOTICE: librsvg v.2.40 has a bug with "chain" multiple class selectors:
# it does not handle a selector like text.label.title and a
# tag class="label title".
print('<style type="text/css">')
# Labels.
print('    text              '
      '{ font-family: Verdana,Arial,Helvetica,sans-serif; font-weight: bold;}')
print('    text.label        { fill: %s; font-size: %dpx; }' %
      (LBL_FONT_COLOR, LBL_FONT_SIZE))
print('    text.label-title  { font-size: %dpx; text-anchor: middle; }' %
      (int(LBL_FONT_SIZE * 1.4),))
print('    text.label-prn    { font-size: %dpx; text-anchor: end; }' %
      (LBL_SAT_BAR_SIZE,))
print('    text.label-center { text-anchor: middle; }')
print('    text.label-snr    { text-anchor: start; }')
print('    text.label-err    { text-anchor: end; }')
# Compass dial.
print('    circle.compass    '
      '{ stroke: %s; stroke-width: %d; fill-opacity: 0; }' %
      (COMPASS_STROKE_COLOR, STROKE_WIDTH,))
print('    line.compass      { stroke: %s; stroke-width: %d; }' %
      (COMPASS_STROKE_COLOR, STROKE_WIDTH))
print('    text.compass      '
      '{ fill: %s; font-size: %dpx; text-anchor: middle; }' %
      (DIAL_POINT_COLOR, LBL_COMPASS_POINTS_SIZE))
# Satellites constellation.
print('    rect.sats         { stroke-width: %d; fill-opacity: 1.0; }' %
      (STROKE_WIDTH,))
print('    rect.sats-used    { stroke: %s; fill: %s; }' %
      (SAT_USED_STROKE_COLOR, SAT_USED_FILL_COLOR))
print('    rect.sats-unused  { stroke: %s; fill: %s; }' %
      (SAT_UNUSED_STROKE_COLOR, SAT_UNUSED_FILL_COLOR))
print('    text.sats         { font-size: %dpx; text-anchor: middle; }' %
      (LBL_SAT_SIZE,))
print('    text.sats-used    { fill: %s; }' % (SAT_USED_TEXT_COLOR,))
print('    text.sats-unused  { fill: %s; }' % (SAT_UNUSED_TEXT_COLOR,))
# Box containing bars graph.
print('    rect.box          { fill: %s; stroke: %s; stroke-width: %d; }' %
      (BARS_AREA_FILL_COLOR, BARS_AREA_STROKE_COLOR, STROKE_WIDTH))
# Graph bars.
print('    rect.bars         { stroke-width: %d; opacity: 1.0; }' %
      (STROKE_WIDTH,))
print('    rect.bars-used    { stroke: %s; fill: %s; }' %
      (BAR_USED_STROKE_COLOR, BAR_USED_FILL_COLOR))
print('    rect.bars-unused  { stroke: %s; fill: %s; }' %
      (BAR_UNUSED_STROKE_COLOR, BAR_UNUSED_FILL_COLOR))
print('</style>')
# Background and title.
print('<rect width="100%%" height="100%%" fill="%s" />' %
      (BACKGROUND_COLOR,))
print('<text class="label label-title" x="%d" y="%d">'
      'Sky View of GPS Satellites</text>' %
      (int(IMG_WIDTH * 0.5), int(LBL_FONT_SIZE * 1.5)))
# Sky circle with cardinal points.
print('<circle class="compass" cx="%d" cy="%d" r="%d" />' %
      (CIRCLE_X, CIRCLE_Y, CIRCLE_R))
print('<circle class="compass" cx="%d" cy="%d" r="%d" />' %
      (CIRCLE_X, CIRCLE_Y, int(CIRCLE_R / 2)))
print('<line class="compass" x1="%d" y1="%d" x2="%d" y2="%d" />' %
      (CIRCLE_X, CIRCLE_Y - CIRCLE_R, CIRCLE_X, CIRCLE_Y + CIRCLE_R))
print('<line class="compass" x1="%d" y1="%d" x2="%d" y2="%d" />' %
      (CIRCLE_X - CIRCLE_R, CIRCLE_Y, CIRCLE_X + CIRCLE_R, CIRCLE_Y))
print('<text x="%d" y="%d" class="compass">%s</text>' %
      (CIRCLE_X, CIRCLE_Y - CIRCLE_R - LBL_COMPASS_POINTS_SIZE, 'N'))
print('<text x="%d" y="%d" class="compass">%s</text>' %
      (CIRCLE_X, CIRCLE_Y + CIRCLE_R + LBL_COMPASS_POINTS_SIZE, 'S'))
print('<text x="%d" y="%d" class="compass">%s</text>' %
      (CIRCLE_X - CIRCLE_R - LBL_COMPASS_POINTS_SIZE,
       CIRCLE_Y + int(LBL_COMPASS_POINTS_SIZE*0.4), 'W'))
print('<text x="%d" y="%d" class="compass">%s</text>' %
      (CIRCLE_X + CIRCLE_R + LBL_COMPASS_POINTS_SIZE,
       CIRCLE_Y + int(LBL_COMPASS_POINTS_SIZE*0.4), 'E'))
# Lat/lon.
POS_LAT = "%.5f" % (float(TPV['lat']),) if 'lat' in TPV else 'Unknown'
POS_LON = "%.5f" % (float(TPV['lon']),) if 'lon' in TPV else 'Unknown'
print('<text class="label label-center" x="%d" y="%d">Lat/Lon: %s %s</text>' %
      (POS_LBL_X, POS_LBL_Y, POS_LAT, POS_LON))
# Satellites signal/noise ratio box.
print('<rect class="box" x="%d" y="%d" rx="%d" ry="%d" '
      'width="%d" height="%d" />' %
      (BARS_BOX_X, BARS_BOX_Y - BARS_BOX_HEIGHT, BAR_RADIUS,
       BAR_RADIUS, BARS_BOX_WIDTH, BARS_BOX_HEIGHT))
SS_LBL_X = int(BARS_BOX_X + STROKE_WIDTH * 1.5)
SS_LBL_Y = int(BARS_BOX_Y - BARS_BOX_HEIGHT + LBL_FONT_SIZE +
               STROKE_WIDTH * 1.5)
print('<text class="label label-snr" x="%d" y="%d">'
      'Satellites Signal/Noise Ratio</text>' % (SS_LBL_X, SS_LBL_Y))
# Box for horizontal and vertical estimated error.
if 'epx' in TPV and 'epy' in TPV:
    EPX = float(TPV['epx'])
    EPY = float(TPV['epy'])
    EPH = math.sqrt(EPX**2 + EPY**2)
elif 'eph' in TPV:
    EPH = float(TPV['eph'])
else:
    EPH = ERR_MAX
EPV = float(TPV['epv']) if 'epv' in TPV else ERR_MAX
ERR_H, SIGN_H = cutoff_err(EPH, ERR_MIN, ERR_MAX)
ERR_V, SIGN_V = cutoff_err(EPV, ERR_MIN, ERR_MAX)
ERR_LBL_X = int(ERR_BOX_X - STROKE_WIDTH * 2.0)
ERR_LBL_Y_OFFSET = STROKE_WIDTH + BAR_WIDTH * 0.6
print('<rect class="box" x="%d" y="%d" rx="%d" ry="%d" '
      'width="%d" height="%d" />' %
      (ERR_BOX_X, ERR_BOX_Y - ERR_BOX_HEIGHT, BAR_RADIUS,
       BAR_RADIUS, ERR_BOX_WIDTH, ERR_BOX_HEIGHT))
# Horizontal error.
POS_X = ERR_BOX_X + STROKE_WIDTH
POS_Y = ERR_BOX_Y - ERR_BOX_HEIGHT + int((BAR_SPACE - BAR_WIDTH) * 0.5)
ERR_H_BAR_HEIGHT = int(ERR_H / ERR_MAX * ERR_BAR_HEIGHT_MAX)
print('<text class="label label-err" x="%d" y="%d">'
      'Horizontal error %s%.1f m</text>' %
      (ERR_LBL_X, ERR_LBL_Y_OFFSET + POS_Y, SIGN_H, ERR_H))
print('<rect class="bars bars-used" x="%d" y="%d" rx="%d" '
      ' ry="%d" width="%d" height="%d" />' %
      (POS_X, POS_Y, BAR_RADIUS, BAR_RADIUS, ERR_H_BAR_HEIGHT, BAR_WIDTH))
# Vertical error.
POS_Y = POS_Y + BAR_SPACE
ERR_V_BAR_HEIGHT = int(ERR_V / ERR_MAX * ERR_BAR_HEIGHT_MAX)
print('<text class="label label-err" x="%d" y="%d">'
      'Vertical error %s%.1f m</text>' %
      (ERR_LBL_X, ERR_LBL_Y_OFFSET + POS_Y, SIGN_V, ERR_V))
print('<rect class="bars bars-used" x="%d" y="%d" rx="%d" '
      ' ry="%d" width="%d" height="%d" />' %
      (POS_X, POS_Y, BAR_RADIUS, BAR_RADIUS, ERR_V_BAR_HEIGHT, BAR_WIDTH))
# Satellites and Signal/Noise bars.
i = 0
for prn in sorted(SATELLITES):
    sat = SATELLITES[prn]
    BAR_HEIGHT = int(BAR_HEIGHT_MAX * (float(sat['ss']) / SNR_MAX))
    (sat_x, sat_y) = polar2cart(float(sat['az']), float(sat['el']), CIRCLE_R)
    sat_x = int(CIRCLE_X + sat_x)
    sat_y = int(CIRCLE_Y + sat_y)
    rect_radius = int(SAT_HEIGHT * 0.25)
    sat_rect_x = int(sat_x - (SAT_WIDTH) / 2)
    sat_rect_y = int(sat_y - (SAT_HEIGHT) / 2)
    sat_class = 'used' if sat['used'] else 'unused'
    print('<rect class="sats sats-%s" x="%d" y="%d" width="%d" '
          ' height="%d" rx="%d" ry="%d" />' %
          (sat_class, sat_rect_x, sat_rect_y, SAT_WIDTH, SAT_HEIGHT,
           rect_radius, rect_radius))
    print('<text class="sats %s" x="%d" y="%d">%s</text>' %
          (sat_class, sat_x, sat_y + int(LBL_SAT_SIZE*0.4), sat['PRN']))
    pos_x = (int(BARS_BOX_X + (STROKE_WIDTH * 0.5) +
             (BAR_SPACE - BAR_WIDTH) * 0.5 + BAR_SPACE * i))
    pos_y = int(BARS_BOX_Y - BAR_HEIGHT - (STROKE_WIDTH * 1.5))
    print('<rect class="bars bars-%s" x="%d" y="%d" rx="%d" ry="%d" '
          'width="%d" height="%d" />' %
          (sat_class, pos_x, pos_y, BAR_RADIUS, BAR_RADIUS,
           BAR_WIDTH, BAR_HEIGHT))
    x = int(pos_x + BAR_WIDTH * 0.5)
    y = int(BARS_BOX_Y + (STROKE_WIDTH * 1.5))
    print('<text class="label label-prn" x="%d" y="%d" '
          'transform="rotate(270, %d, %d)">%s</text>' %
          (x, y, x, y, sat['PRN']))
    i = i + 1
print('<text class="label label-center" x="%d" y="%d">%s</text>' %
      (TIMESTAMP_X, TIMESTAMP_Y, TIME_STR))
print('</svg>')

sys.exit(EXIT_CODE)