import os
import re

from nexrad.s3 import S3Bucket

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

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

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_PRODUCT   = 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) != 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) != 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_PRODUCT.match(item.name)):
                                continue

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

                        parts.pop()

                    parts.pop()

                parts.pop()

            parts.pop()