#!/usr/bin/python3

# rain radar w/o 2GB of GUI browser - TWB (Trent W. Buck @ Linux Users Victoria ~ September 2020)

# PROBLEM:
#  * http://bom.gov.au is 90s style and very hard to use.
#    It also requires js, and is not SSL so COMPLETELY UNSAFE.
#  * http://m.bom.gov.au provided a GOOD option with two simple pages:
#      1. a full-screen rain radar for the last 15 minutes.
#         This tells me the heavy rainstorm is just starting, or just finishing.
#         This in turn tells me whether to leave now or wait 15 minutes.
#      2. For my station only (Melbourne CBD),
#          * min/max temp, rain chance forecasts for the rest of today
#          * severe weather warnings, in big letters, with a solid yellow background.
#  * m.bom.gov.au was shut down and replaced by an "app" that requires ios or dalvik.
#  * the backend data is now commercialized, so open source alternative interfaces to this data CANNOT EXIST ANYMORE.
#    i.e. bom.gov.au is trying to buck the govhack trend and make Australian weather MORE like American weather -- expensive and exclusive.
#
# So let's try to solve the most immediate problem: merge the rain GIF overlay onto the static map PNGs, as the javascript does.
# Then render that into a static png or webm, and view it.

# usage: radar [tmpdir1] [tmpdir2] [movie player and arguments]

import pwd
import os
import tempfile
import pathlib
import datetime
import subprocess
import shutil
import sys
import re

underlays = ('background', 'locations', 'range', 'topography')

primaries = ('IDR021', 'IDR023')
secondaries = ('IDR011', 'IDR013')
current = primaries

def radar(prefix,minute_offset_file,tempdir_path):
        now = datetime.datetime.utcnow()  # NOTE: TZ=UTC

        try:
                with open(minute_offset_file, 'r') as offsetfile:
                        minute_offset = int(offsetfile.read())
        except:
                minute_offset = 0

        new_offset=0
        while new_offset < 5:
                print (datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S'))
                proc = subprocess.run(args = [
                        # if reg becomes blocked, could fallback to `lynx -source`, but then we have to manage the forks ourselves
                        'puf', '-vvv', '-nc', '-U', 'Yes, keep trying to block those user agents BoM. It''s not like you''re the public service', '-P', tempdir_path,
                    # Try to get a rain image for every minute in the last hour.
                    # 1 in every 5 or 6 will work.  For now, just ignore that some fail.
                    *[then.strftime('http://reg.bom.gov.au/radar/'+prefix+'.T.%Y%m%d%H%M.png')
                      for i in range(60)
                      for then in [(now - datetime.timedelta(minutes=i))]
                      if (then.minute - minute_offset - new_offset) % 5 == 0],  # was 6, should now be 5
                    # The underlay images (NOTE: hardcode station to MEL (IDR021) for now).
                    *[f'http://reg.bom.gov.au/products/radar_transparencies/{prefix}.{u}.png'
                      for u in underlays]], universal_newlines = True, stderr = subprocess.PIPE)

                # for a complete non-match, you'd expect 12/12
                # failures for 5 minute intervals in an hour.  Set
                # threshold to require 4 successes?
                print ("proc.stderr = ", proc.stderr, datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S'), ": \"not found\" len = ", len(re.findall('not found', proc.stderr)))
                if len(re.findall('not found', proc.stderr)) < 8:
                        # successfully downloaded a set of images at offset minute_offset + new_offset
                        with open(minute_offset_file, 'w') as offsetfile:
                                offsetfile.write(str(minute_offset+new_offset))

                        break

                new_offset += 1

        # remove all but the last 12 images from each category
        subprocess.check_call(f"ls -tr {tempdir_path}/*.T.????????????.png 2>/dev/null | head -n -12 | xargs --no-run-if-empty rm --verbose", shell=True)
        subprocess.check_call(f"ls -tr {tempdir_path}/*.T.????????????.1.png 2>/dev/null | head -n -12 | xargs --no-run-if-empty rm --verbose", shell=True)
        subprocess.check_call(f"ls -tr {tempdir_path}/*.T.????????????.2.png 2>/dev/null | head -n -12 | xargs --no-run-if-empty rm --verbose", shell=True)
        subprocess.check_call(f"ls -tr {tempdir_path}/*.T.????????????.3.png 2>/dev/null | head -n -12 | xargs --no-run-if-empty rm --verbose", shell=True)
        subprocess.check_call(f"ls -tr {tempdir_path}/*.T.????????????.4.png 2>/dev/null | head -n -12 | xargs --no-run-if-empty rm --verbose", shell=True)

        regenerate = False

        # Merge the underlays and overlays into combined images.
        # We have to do this a bit at a time, because reasons.
        # For now just to the map overlay and skip land/sea &c
        for overlay_path in tempdir_path.glob(prefix+'*.T.????????????.png'):
            if not pathlib.Path(overlay_path.with_suffix(f'.4.png')).exists():
                subprocess.check_call(['gm', 'composite', overlay_path,                        tempdir_path / f'{prefix}.locations.png',   overlay_path.with_suffix(f'.1.png')])
                subprocess.check_call(['gm', 'composite', overlay_path.with_suffix(f'.1.png'), tempdir_path / f'{prefix}.range.png',       overlay_path.with_suffix(f'.2.png')])
                subprocess.check_call(['gm', 'composite', overlay_path.with_suffix(f'.2.png'), tempdir_path / f'{prefix}.topography.png',  overlay_path.with_suffix(f'.3.png')])
                subprocess.check_call(['gm', 'composite', overlay_path.with_suffix(f'.3.png'), tempdir_path / f'{prefix}.background.png',  overlay_path.with_suffix(f'.4.png')])
                regenerate = True

        # Convert to an animated gif.
        # FIXME: currently bugged -- it's not wiping the transparent cells between frames.
        #        When I add in the all-opaque underlay that should fix it.

        if regenerate:
            subprocess.check_call(['gm', 'convert',
                                   '-delay', '15',  # 1/6s per frame
                                   '-loop', '0',    # loop forever
                                   *sorted(tempdir_path.glob(prefix+'*.T.????????????.4.png')),
                                   tempdir_path / f'{prefix}.final.gif'])

args=()
if len(sys.argv) != 1:
    args=sys.argv[1:] # shift
    if ( args[0] == "--failover" ):
        # failover=true
        current = secondaries
        args = args[1:] # shift

provided_paths = False
if len(args) > 1:
    tempdir1_path = pathlib.Path(args.pop(0))
    tempdir2_path = pathlib.Path(args.pop(0))

    pathlib.Path(tempdir1_path).mkdir(parents=True, exist_ok=True)
    pathlib.Path(tempdir2_path).mkdir(parents=True, exist_ok=True)
    
    provided_paths = True
else:
    tempdir1_path = pathlib.Path(tempfile.mkdtemp(prefix="radar1."))
    tempdir2_path = pathlib.Path(tempfile.mkdtemp(prefix="radar2."))

print(f"path1={tempdir1_path},path2={tempdir2_path}")
if 0 == os.fork():
    radar(current[0], '/tmp/radar1.offset', tempdir1_path)
    os._exit(0)
else:
    radar(current[1], '/tmp/radar2.offset', tempdir2_path)
    os.wait()

subprocess.check_call(['ffmpeg', '-i', tempdir1_path / (current[0]+'.final.gif'), '-i', tempdir2_path / (current[1]+'.final.gif'), '-filter_complex', 'hstack', '-y', tempdir2_path / '.tmp.output.mp4'])
os.rename(tempdir2_path / '.tmp.output.mp4', tempdir2_path / 'output.mp4')

if len(args) == 0:
    args=['mpv', '-loop']
args+=[tempdir2_path / 'output.mp4']
print("Argument List:", str(args))
subprocess.check_call(args)

if not provided_paths:
    shutil.rmtree(tempdir1_path)
    shutil.rmtree(tempdir2_path)