import os
import re
import enum
import datetime

from nexrad.db    import Database
from nexrad.s3    import S3Bucket, S3_KEY_RE
from nexrad.radar import RADAR_RANGE

class ArchiveDateError(Exception):
    def __init__(self, supplied: str, missing: str):
        self.supplied = supplied
        self.missing  = missing

    def __str__(self):
        return "Archive {self.supplied} was supplied, but required {self.missing} is missing"

class ArchiveProductType(enum.Enum):
    DEFAULT = 1
    V03     = 3
    V04     = 4

class ArchiveProduct():
    __slots__ = 'typeof', 'radar', 'timestamp',

    typeof:    ArchiveProductType
    radar:     str
    timestamp: datetime.datetime

    def __parts__(self):
        return [
            "%04d" % (self.timestamp.year),
            "%02d" % (self.timestamp.month),
            "%02d" % (self.timestamp.day),
            self.radar,
            "%4s%04d%02d%02d_%02d%02d%02d" % (
                self.radar,
                self.timestamp.year, self.timestamp.month,  self.timestamp.day,
                self.timestamp.hour, self.timestamp.minute, self.timestamp.second
            )
        ]

    def __str__(self):
        ret = '/'.join(self.__parts__())

        if self.typeof == ArchiveProductType.V03:
            ret += "_V03"
        elif self.typeof == ArchiveProductType.V04:
            ret += "_V04"

        ret += ".gz"

        return ret

    def path(self):
        parts = self.__parts__()
        ret   = os.path.join(*parts)

        if self.typeof == ArchiveProductType.V03:
            ret += "_V03"
        elif self.typeof == ArchiveProductType.V04:
            ret += "_V04"

        ret += ".gz"

        return ret

    def key(self):
        return str(self)

    @staticmethod
    def from_s3_key(key: str):
        product = ArchiveProduct()
        match   = S3_KEY_RE.match(key)

        product.timestamp = datetime.datetime(
            year   = int(match[6]),
            month  = int(match[7]),
            day    = int(match[8]),
            hour   = int(match[9]),
            minute = int(match[10]),
            second = int(match[11]),
            tzinfo = datetime.UTC
        )

        product.radar  = match[4]
        product.typeof = ArchiveProductType.V03 \
                if key[-7:] == '_V03.gz' else ArchiveProductType.DEFAULT

        return product

    def is_downloaded(self, path: str):
        return os.path.isfile(os.path.join(path, self.path()))

    def is_reported(self, db: Database):
        sql = """select count((
                     select ST_Distance(MakeLine(event.coord_start, event.coord_end),
                                        radar.coord,
                                        true) as distance
                     from
                         nexrad_storm_event as event,
                         nexrad_radar as radar
                     where
                         distance <= :radius
                         and :timestamp between event.timestamp_start and event.timestamp_end
                         and radar.call = :call)) as num
        """

        st = db.execute(sql, {
            'radius':    RADAR_RANGE,
            'timestamp': self.timestamp,
            'call':      self.radar
        })

        result = st.fetchone()

        return result['num'] == 1

class Archive():
    path:   str
    bucket: S3Bucket

    def __init__(self, path: str, bucket: S3Bucket):
        self.path   = path
        self.bucket = bucket

    def is_downloaded(self, key: str):
        return os.path.exists(os.path.join(self.path, key))

    def download(self, key: str):
        path   = os.path.join(self.path, key)
        parent = os.path.dirname(path)

        os.makedirs(parent, exist_ok=True)

        with open(path, 'wb') as fh:
            self.bucket.s3.download_fileobj(self.bucket.name, key, fh)

    RE_YEAR      = re.compile(r'^\d{4}$')
    RE_MONTH_DAY = re.compile(r'^\d{2}$')
    RE_CALL      = re.compile(r'^[A-Z]{4}$')
    RE_FILE      = re.compile(r'^([A-Z]{4})(\d{4})(\d{2})(\d{2})_(\d{2})(\d{2})(\d{2})')

    def each_downloaded_key(self,
                            year:  int=None,
                            month: int=None,
                            day:   int=None):
        parts = [self.path]

        if day is not None and month is None:
            raise ArchiveDateError('day', 'month')

        if month is not None and year is None:
            raise ArchiveDateError('month', 'year')

        for cur_year in os.scandir(os.path.join(*parts)):
            if not (cur_year.is_dir() and self.RE_YEAR.match(cur_year.name)):
                continue

            if year is not None and int(cur_year.name) != year:
                continue

            parts.append(cur_year.name)

            for cur_month in os.scandir(os.path.join(*parts)):
                if not (cur_month.is_dir() and self.RE_MONTH_DAY.match(cur_month.name)):
                    continue

                if month is not None and int(cur_month.name) != month:
                    continue

                parts.append(cur_month.name)

                for cur_day in os.scandir(os.path.join(*parts)):
                    if not (cur_day.is_dir() and self.RE_MONTH_DAY.match(cur_day.name)):
                        continue

                    if day is not None and int(cur_day.name) != day:
                        continue

                    parts.append(cur_day.name)

                    for call in os.scandir(os.path.join(*parts)):
                        if not (call.is_dir() and self.RE_CALL.match(call.name)):
                            continue

                        parts.append(call.name)

                        for item in os.scandir(os.path.join(*parts)):
                            if not (item.is_file() and self.RE_FILE.match(item.name)):
                                continue

                            yield '/'.join([*parts[1:], item.name])

                        parts.pop()

                    parts.pop()

                parts.pop()

            parts.pop()

    def each_downloaded_product(self,
                                year:  int=None,
                                month: int=None,
                                day:   int=None):
        for key in self.each_downloaded_key(year, month, day):
            yield ArchiveProduct.from_s3_key(key)