import gzip
import csv
import datetime

from nexrad.coord import Coord, COORD_SYSTEM

def time_from_str(time: str):
    size = len(time)

    if size <= 2:
        return (
            int(time) % 24,
            0
        )

    return (
        int(time[0:size-2]) % 24,
        int(time[size-2:])  % 60
    )

def timestamp_from_parts(yearmonth: str, day: str, time: str) -> datetime.datetime:
    hour, minute = time_from_str(time)

    return datetime.datetime(
        year   = int(yearmonth[0:4]),
        month  = int(yearmonth[4:6]),
        day    = int(day),
        hour   = hour,
        minute = minute
    )

def coord_from_str(text_lat: str, text_lon: str):
    lat = 0.0 if text_lat == '' else float(text_lat)
    lon = 0.0 if text_lon == '' else float(text_lon)

    return Coord(lat, lon)

class StormReport():
    __slots__ = (
        'timestamp_start', 'timestamp_end', 'episode_id', 'event_id',
        'state', 'event_type', 'wfo', 'coord_start', 'coord_end',
        'locale_start', 'locale_end', 'tornado_f_rating'
    )

    timestamp_start:  datetime.datetime
    timestamp_end:    datetime.datetime
    episode_id:       int
    event_id:         int
    state:            str
    event_type:       str
    wfo:              str
    coord_start:      Coord
    coord_end:        Coord
    locale_start:     str
    locale_end:       str
    tornado_f_rating: str

    @staticmethod
    def from_csv_row(row: dict):
        report = StormReport()

        report.timestamp_start  = timestamp_from_parts(row['BEGIN_YEARMONTH'], row['BEGIN_DAY'], row['BEGIN_TIME'])
        report.timestamp_end    = timestamp_from_parts(row['END_YEARMONTH'],   row['END_DAY'],   row['END_TIME'])
        report.episode_id       = int(row['EPISODE_ID'])
        report.event_id         = int(row['EVENT_ID'])
        report.state            = row['STATE']
        report.event_type       = row['EVENT_TYPE']
        report.wfo              = row['WFO']
        report.coord_start      = coord_from_str(row['BEGIN_LAT'], row['BEGIN_LON'])
        report.coord_end        = coord_from_str(row['END_LAT'],   row['END_LON'])
        report.locale_start     = row['BEGIN_LOCATION']
        report.locale_end       = row['END_LOCATION']
        report.tornado_f_rating = row['TOR_F_SCALE']

        return report

    @staticmethod
    def each_from_csv_file(file: str):
        with gzip.open(file, 'rt') as fh:
            reader = csv.DictReader(fh, dialect='excel')

            for row in reader:
                yield StormReport.from_csv_row(row)

    RADAR_SIGNIFICANT_EVENT_TYPES = {
        'Blizzard':                 True,
        'Coastal Flood':            True,
        'Debris Flow':              True,
        'Dust Storm':               True,
        'Flash Flood':              True,
        'Flood':                    True,
        'Funnel Cloud':             True,
        'Hail':                     True,
        'Heavy Rain':               True,
        'Heavy Snow':               True,
        'Hurricane (Typhoon)':      True,
        'Ice Storm':                True,
        'Lake-Effect Snow':         True,
        'Lightning':                True,
        'Marine Hail':              True,
        'Marine Strong Wind':       True,
        'Marine Thunderstorm Wind': True,
        'Seiche':                   True,
        'Storm Surge/Tide':         True,
        'Thunderstorm Wind':        True,
        'Tornado':                  True,
        'Tropical Depression':      True,
        'Tropical Storm':           True,
        'Waterspout':               True,
        'Winter Storm':             True,
    }

    def is_radar_significant(self):
        return self.event_type in self.RADAR_SIGNIFICANT_EVENT_TYPES

    def nearest_radars(self, db):
        sql = """
            select
                id,
                call,
                ST_Distance(coord, MakePoint(?, ?, %d), true) as distance
            from
                nexrad_radar
            where
                distance <= 460000
            order by
                distance asc
            limit 3
        """ % (COORD_SYSTEM)

        st = db.execute(sql, (self.coord_start.lon,
                              self.coord_start.lat))

        return st.fetchone()