#!/data/data/com.termux/files/usr/bin/python3

import datetime as dt
import json
import os
import pytz
import subprocess
import sys
import yaml


def to_iso6801_basic(dt):
    return dt.isoformat().replace(':', '').replace('-', '') \
        .replace('+0000', 'Z')


class Position:

    def __init__(self, timestamp, latitude, longitude, altitude):
        self.timestamp = timestamp
        self.latitude = latitude
        self.longitude = longitude
        self.altitude = altitude

    @classmethod
    def from_termux_location(cls, provider='network'):
        loc_json = subprocess.check_output(['termux-location', '-p', provider]) \
            .decode(sys.stdout.encoding)
        req_ts = dt.datetime.now(pytz.utc)
        loc_attr = yaml.load(loc_json)
        if not loc_attr:
            return None
        else:
            print(loc_attr)
            return cls(
                timestamp=req_ts -
                    dt.timedelta(milliseconds=loc_attr['elapsedMs']),
                latitude=loc_attr['latitude'],
                longitude=loc_attr['longitude'],
                altitude=loc_attr['altitude'],
            )


def symlink(src, dst, force=False):
    if force and os.path.lexists(dst):
        os.unlink(dst)
    os.symlink(src=src, dst=dst)


def compute(target_dir_path):
    cur = Position.from_termux_location()
    target_name = '{}.yml'.format(to_iso6801_basic(cur.timestamp))
    with open(os.path.join(target_dir_path, target_name), 'w') as f:
        f.write(yaml.dump(
            {
                'lat': cur.latitude,
                'lon': cur.longitude,
                'alt': cur.altitude,
            },
            default_flow_style=False,
        ))
    symlink(
        src=target_name,
        dst=os.path.join(target_dir_path, 'last.yml'),
        force=True,
    )


def _init_argparser():
    import argparse
    argparser = argparse.ArgumentParser(description=None)
    argparser.add_argument(
        '--target-dir',
        metavar='PATH',
        dest='target_dir_path',
        default='.',
    )
    return argparser


def main(argv):
    argparser = _init_argparser()
    try:
        import argcomplete
        argcomplete.autocomplete(argparser)
    except ImportError:
        pass
    args = argparser.parse_args(argv)
    compute(**vars(args))
    return 0

if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))