import csv
import datetime
import decimal
import io
import logging
from collections.abc import Iterable, Mapping, Sequence
from decimal import Decimal

import requests
import requests_cache
from frozendict import frozendict

logger = logging.getLogger(__name__)

try:
    import cfscrape
except ImportError:
    cfscrape = None
    logger.warning('cfscrape not installed: Certain fetchers might not work')

try:
    import browsercookie
except ImportError:
    logger.warning('browsercookie not installed: Certain fetchers might not work')
    browsercookie = None


import personal_data.data
import personal_data.fetchers

from . import mailgun

CSV_DIALECT = 'one_true_dialect'
csv.register_dialect(CSV_DIALECT, lineterminator='\n', skipinitialspace=True)

logging.basicConfig()
logger.setLevel('INFO')


def try_value(fn, s: str) -> object:
    try:
        return fn(s)
    except (ValueError, decimal.InvalidOperation):
        return None


def to_value(s: str) -> object:
    s = s.strip()
    if len(s) == 0:
        return None
    if (v := try_value(Decimal, s)) is not None:
        return v
    if v := try_value(datetime.date.fromisoformat, s):
        return v
    if v := try_value(datetime.datetime.fromisoformat, s):
        return v
    if s.lower() == 'false':
        return False
    if s.lower() == 'true':
        return True
    if s.lower() == 'none':
        return None
    return s


def equals_without_fields(
    a: Mapping[str, object],
    b: Mapping[str, object],
    fields: Iterable[str] = frozenset(),
) -> bool:
    a = dict(a)
    b = dict(b)

    for f in fields:
        del a[f], b[f]

    return frozendict(a) == frozendict(b)


def deduplicate_dicts(
    dicts: Sequence[dict],
    deduplicate_mode: personal_data.data.DeduplicateMode,
    deduplicate_ignore_columns: list[str],
) -> tuple[Sequence[dict], list[str]]:
    fieldnames = []
    for d in dicts:
        for k in d.keys():
            if k not in fieldnames:
                fieldnames.append(k)
            del k
        del d

    if deduplicate_mode == personal_data.data.DeduplicateMode.ONLY_LATEST:
        while len(dicts) >= 2 and equals_without_fields(
            dicts[-1],
            dicts[-2],
            deduplicate_ignore_columns,
        ):
            del dicts[-1]
    elif deduplicate_mode == personal_data.data.DeduplicateMode.BY_ALL_COLUMNS:
        to_remove = set()
        for idx1, first in enumerate(dicts):
            for second in dicts[idx1 + 1 :]:
                if equals_without_fields(first, second, deduplicate_ignore_columns):
                    to_remove.add(second)
        dicts = set(dicts) - to_remove
    elif deduplicate_mode != personal_data.data.DeduplicateMode.NONE:
        dicts = set(dicts)

    dicts = sorted(dicts, key=lambda d: tuple(str(d.get(fn, '')) for fn in fieldnames))
    return dicts, fieldnames


def normalize_dict(d: dict) -> frozendict:
    return frozendict(
        {k: to_value(str(v)) for k, v in d.items() if to_value(str(v)) is not None},
    )


def extend_csv_file(
    filename: str,
    new_dicts: list[dict],
    deduplicate_mode: personal_data.data.DeduplicateMode,
    deduplicate_ignore_columns: list[str],
) -> dict:
    dicts = []
    try:
        with open(filename) as csvfile:
            reader = csv.DictReader(csvfile, dialect=CSV_DIALECT)
            for row in reader:
                for k in list(row.keys()):
                    orig = row[k]
                    row[k] = to_value(orig)
                    if row[k] is None:
                        del row[k]
                    del k, orig
                dicts.append(frozendict(row))
                del row
            del csvfile
    except FileNotFoundError as e:
        logger.info('Creating file: %s', filename)

    original_num_dicts = len(dicts)
    dicts += [normalize_dict(d) for d in new_dicts]
    del new_dicts

    dicts, fieldnames = deduplicate_dicts(
        dicts,
        deduplicate_mode,
        deduplicate_ignore_columns,
    )

    csvfile_in_memory = io.StringIO()
    writer = csv.DictWriter(
        csvfile_in_memory,
        fieldnames=fieldnames,
        dialect=CSV_DIALECT,
    )
    writer.writeheader()
    for d in dicts:
        writer.writerow(d)
    output_csv = csvfile_in_memory.getvalue()
    del writer, csvfile_in_memory

    with open(filename, 'w') as csvfile:
        csvfile.write(output_csv)
        del csvfile
    logger.info(
        'Extended CSV "%s" from %d to %d lines',
        filename,
        original_num_dicts,
        len(dicts),
    )

    return {
        'extended': original_num_dicts != len(dicts),
        'input_lines': original_num_dicts,
        'output_lines': len(dicts),
        'dicts': dicts,
    }


STANDARD_HEADERS = {
    'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64; rv:122.0) Gecko/20100101 Firefox/122.0',
    # "Accept": "application/json, text/plain, */*",
    'Accept-Language': 'en-US,en;q=0.5',
    'Accept-Encoding': 'gzip, deflate, br',
}


if cfscrape:

    class CachedCfScrape(requests_cache.CacheMixin, cfscrape.CloudflareScraper):
        pass


def get_session(cookiejar, *, with_cfscrape: bool) -> requests.Session:
    assert isinstance(with_cfscrape, bool)
    session_class = requests_cache.CachedSession
    if cfscrape:
        session_class = CachedCfScrape
    session = session_class('output/web_cache', cookies=cookiejar)
    for cookie in cookiejar:
        session.cookies.set_cookie(cookie)
    return session


def send_notification(
    session: requests.Session,
    scraper_name: str,
    latest_dict: frozendict,
):
    body = ['A new update has occured for ', scraper_name, '\n']
    for k, v in latest_dict.items():
        body.append(f'{k}: {v}\n')
    mailgun.send_email(session, f'Updated {scraper_name}', ''.join(body))


def available_scrapers() -> list[type[personal_data.data.Scraper]]:
    return personal_data.data.Scraper.__subclasses__()


def available_scraper_names() -> list[str]:
    return [scraper_cls.__name__ for scraper_cls in available_scrapers()]


def main(
    scraper_filter: frozenset[str],
    *,
    use_cookiejar: bool,
    send_email_notification: bool = False,
) -> None:
    if use_cookiejar:
        cookiejar = browsercookie.firefox()
        logger.info('Got cookiejar from firefox: %s cookies', len(cookiejar))
    else:
        cookiejar = []
        logger.warning('No cookiejar is used')

    if not send_email_notification:
        logger.info('Email not enabled: Notifications will not be sent!')

    for scraper_cls in available_scrapers():
        session = get_session(cookiejar, with_cfscrape=scraper_cls.requires_cfscrape())
        scraper = scraper_cls(session)
        if scraper_cls.__name__ not in scraper_filter:
            continue
        logger.info(
            'Running %s, appending to "%s"',
            scraper_cls.__name__,
            scraper.dataset_name,
        )
        result_rows = []
        try:
            for result in scraper.scrape():
                result_rows.append(result)
                del result
        except requests.exceptions.HTTPError:
            logger.exception('Failed in running %s', scraper_cls.__name__)
            continue
        status = extend_csv_file(
            f'output/{scraper.dataset_name}.csv',
            result_rows,
            deduplicate_mode=scraper.deduplicate_mode,
            deduplicate_ignore_columns=scraper.deduplicate_ignore_columns,
        )
        logger.info('Scraper done: %s', scraper.dataset_name)

        if status['extended'] and send_email_notification:
            send_notification(session, scraper_cls.__name__, status['dicts'][-1])

        del scraper, session