import asyncio
import functools
import pathlib
import re
from datetime import datetime
from typing import List, Tuple, Dict

from libzim import Entry
from sqlalchemy.orm import Session
from sqlalchemy.orm.exc import NoResultFound  # noqa

from modules.zim import kiwix
from modules.zim.errors import UnknownZim, UnknownZimSubscription
from modules.zim.kiwix import KIWIX_CATALOG
from modules.zim.models import Zim, Zims, TagZimEntry, ZimSubscription
from wrolpi import flags
from wrolpi.common import register_modeler, logger, extract_html_text, extract_headlines, get_media_directory, walk, \
    register_refresh_cleanup, background_task
from wrolpi.db import get_db_session, optional_session, get_db_curs
from wrolpi.downloader import DownloadFrequency
from wrolpi.files.lib import refresh_files
from wrolpi.files.models import FileGroup
from wrolpi.vars import PYTEST, DOCKERIZED

logger = logger.getChild(__name__)

__all__ = [
    'flag_outdated_zim_files',
    'get_all_entries_tags',
    'get_entries_tags',
    'get_entry',
    'get_kiwix_catalog',
    'get_unique_paths',
    'get_zim',
    'get_zims',
    'zim_modeler',
    'zim_download_url_to_name',
]


@register_modeler
async def zim_modeler():
    while True:
        with get_db_session(commit=True) as session:
            file_groups = session.query(FileGroup, Zim) \
                .filter(FileGroup.indexed != True,  # noqa
                        FileGroup.primary_path.ilike('%.zim'),
                        ) \
                .outerjoin(Zim, Zim.file_group_id == FileGroup.id) \
                .limit(10)
            file_groups: List[Tuple[FileGroup, Zim]] = list(file_groups)

            processed = 0
            for file_group, zim in file_groups:
                processed += 1

                zim_id = None
                try:
                    if not zim:
                        zim = Zim(file_group=file_group, path=file_group.primary_path)
                        session.add(zim)
                        session.flush([zim])
                    zim_id = zim.id
                    file_group.indexed = True
                except Exception as e:
                    if PYTEST:
                        raise
                    logger.error(f'Unable to model Zim {zim_id=} {file_group.primary_path=}', exc_info=e)

            logger.debug(f'Modeled {processed} zim files')

            if processed < 10:
                # Did not reach limit, do not query again.
                break

        # Sleep to catch cancel.
        await asyncio.sleep(0)


def get_all_entries_tags():
    """Returns a dict of dicts which contain the names of all Tags of each Entry's path.

    Example:
        {
            1: {
                    'path1': ['tag1', 'tag2'],
            },
            2: {
                    'path2': ['tag1'],
            },
        """
    stmt = '''
        SELECT tz.zim_id, tz.zim_entry, array_agg(t.name)::TEXT[]
        FROM
            tag t
            LEFT JOIN tag_zim tz on t.id = tz.tag_id
        GROUP BY 1, 2
    '''
    with get_db_curs() as curs:
        curs.execute(stmt)
        entries = dict()
        for zim_id, zim_entry, tag_names in curs.fetchall():
            if not zim_id:
                continue
            try:
                entries[zim_id][zim_entry] = tag_names
            except KeyError:
                entries[zim_id] = {zim_entry: tag_names}
    return entries


def get_entries_tags(paths: List[str], zim_id: int):
    all_entries_tags = get_all_entries_tags()
    entries = dict()
    for path in paths:
        zim_tag_entries = all_entries_tags.get(zim_id, dict())
        entries[path] = zim_tag_entries.get(path, list())

    return entries


def get_unique_paths(*paths: str) -> List[str]:
    """Return a new list which contains unique Zim paths."""
    new_paths = list()
    simple_paths = list()
    for path in paths:
        simple_path = path.replace('-', '').replace('_', '').replace('/', '').lower()
        if simple_path not in simple_paths:
            new_paths.append(path)
            simple_paths.append(simple_path)
    return new_paths


@optional_session
def headline_zim(search_str: str, zim_id: int, tag_names: List[str] = None, offset: int = 0, limit: int = 10,
                 session: Session = None) -> Dict:
    zim_id = int(zim_id)
    zim = get_zim(zim_id, session=session)

    if tag_names:
        # TODO what is the count goes over the limit?
        entries = zim.entries_with_tags(tag_names, offset=offset, limit=1_000, session=session)
        estimate = 0
    elif search_str:
        # Get suggested results (this searches titles).
        results = zim.suggest(search_str, offset, limit)
        search_results = zim.search(search_str, offset, limit)
        # Remove duplicate entries (disambiguation or redirect).
        results = get_unique_paths(*results, *search_results)
        results = results[:limit]
        entries = [zim.get_entry(i) for i in results]
        estimate = zim.estimate(search_str)
    else:
        raise RuntimeError('Must provide search_str or tag_names.')

    articles = [bytes(i.get_item().content).decode('UTF-8') for i in entries]
    articles = [extract_html_text(i) for i in articles]

    entries_tag_names = get_entries_tags([i.path for i in entries], zim_id)

    # Always get headlines even if there is no search_str.  This is because Postgres will return the start of each
    # article.
    headlines = extract_headlines(articles, search_str)

    search = list()
    if search_str:
        # `search_str` allows us to headline the title.
        titles = [i.title for i in entries]
        headline_titles = extract_headlines(titles, search_str)

        for entry in entries:
            title_headline, title_rank = headline_titles.pop(0)
            headline, rank = headlines.pop(0)
            if rank > 0 or title_rank > 0:
                # The result for each Entry.
                path = entry.path
                entry_tag_names = entries_tag_names[path] if path in entries_tag_names else list()
                search.append(dict(
                    headline=headline,
                    path=path,
                    rank=max(rank, title_rank),
                    tag_names=entry_tag_names,
                    title=title_headline,
                ))
                if tag_names:
                    estimate += 1
    else:
        # No `search_str`, we return all entries.
        for entry in entries:
            headline, _ = headlines.pop(0)
            path = entry.path
            entry_tag_names = entries_tag_names[path] if path in entries_tag_names else list()
            search.append(dict(
                headline=headline,
                path=path,
                rank=0,
                tag_names=entry_tag_names,
                title=entry.title,
            ))
        estimate = len(entries)

    results = dict(
        path=zim.path,
        metadata=zim.zim_metadata,
        search=search,
        estimate=estimate,
    )
    return results


@optional_session
def get_zim(zim_id: int, session: Session = None) -> Zim:
    """Return the Zim record of the provided path.

    @raise UnknownZim: When no record exists with the id.
    @warning: Results are cached."""
    try:
        zim: Zim = session.query(Zim) \
            .join(FileGroup, FileGroup.id == Zim.file_group_id) \
            .filter(Zim.id == zim_id) \
            .one()
        return zim
    except Exception as e:
        raise UnknownZim() from e


@functools.lru_cache(maxsize=1_000)
def get_entry(path: str, zim_id: int) -> Entry:
    with get_db_session() as session:
        zim = get_zim(zim_id, session=session)
        entry = zim.get_entry(path, throw=True)
    return entry


@optional_session
def get_zims(ids: List[int] = None, session: Session = None) -> List[Zim]:
    if ids:
        zims = session.query(Zim).filter(Zim.id.in_(ids)).all()
    else:
        zims = Zims.get_all(session=session)

    return zims


@optional_session(commit=True)
def delete_zims(ids: List[int], session: Session = None):
    zims = get_zims(ids, session=session)
    for zim in zims:
        zim.delete()


@optional_session
async def add_tag(tag_name: str, zim_id: int, zim_entry: str, session: Session = None) -> TagZimEntry:
    zim = session.query(Zim).filter_by(id=zim_id).one()
    tag_zim_entry = zim.tag_entry(tag_name, zim_entry)
    session.commit()
    return tag_zim_entry


@optional_session
async def untag(tag_name: str, zim_id: int, zim_entry: str, session: Session = None):
    zim: Zim = session.query(Zim).filter_by(id=zim_id).one()
    zim.untag_entry(tag_name, zim_entry)
    session.commit()


def get_kiwix_catalog():
    return KIWIX_CATALOG.copy()


@optional_session
def get_kiwix_subscriptions(session: Session = None) -> Dict[str, ZimSubscription]:
    subscriptions = session.query(ZimSubscription)
    subscriptions_by_name = {i.name: i for i in subscriptions}
    return subscriptions_by_name


@optional_session(commit=True)
async def subscribe(name: str, language: str, session: Session = None,
                    frequency: int = DownloadFrequency.days180) -> ZimSubscription:
    subscription = ZimSubscription.get_or_create(name, session=session)
    subscription.language = language

    if name == 'Wikipedia (with images)':
        url = f'https://download.kiwix.org/zim/wikipedia/wikipedia_{language}_all_maxi_'
    elif name == 'Wikipedia (mini)':
        url = f'https://download.kiwix.org/zim/wikipedia/wikipedia_{language}_all_mini_'
    elif name == 'Wikipedia (no images)':
        url = f'https://download.kiwix.org/zim/wikipedia/wikipedia_{language}_all_nopic_'
    elif name == 'Wikiversity (with images)':
        url = f'https://download.kiwix.org/zim/wikiversity/wikiversity_{language}_all_maxi_'
    elif name == 'Wikiversity (no images)':
        url = f'https://download.kiwix.org/zim/wikiversity/wikiversity_{language}_all_nopic_'
    elif name == 'Wikitionary (no images)':
        url = f'https://download.kiwix.org/zim/wiktionary/wiktionary_{language}_all_nopic_'
    elif name == 'Wikitionary (with images)':
        url = f'https://download.kiwix.org/zim/wikiversity/wikiversity_{language}_all_maxi_'
    elif name == 'Wikibooks (no images)':
        url = f'https://download.kiwix.org/zim/wikibooks/wikibooks_{language}_all_nopic_'
    elif name == 'Wikibooks (with images)':
        url = f'https://download.kiwix.org/zim/wikibooks/wikibooks_{language}_all_maxi_'
    elif name == 'Wikisource':
        url = f'https://download.kiwix.org/zim/wikisource/wikisource_{language}_all_maxi_'
    elif name == 'Raspberry Pi (Stack Exchange)':
        url = f'https://download.kiwix.org/zim/stack_exchange/raspberrypi.stackexchange.com_{language}_all_'
    elif name == 'Vikidia':
        url = f'https://download.kiwix.org/zim/vikidia/vikidia_{language}_all_maxi_'
    elif name == 'Stackoverflow (Stack Exchange)':
        url = f'https://download.kiwix.org/zim/stack_exchange/{language}.stackoverflow.com_{language}_all_'
    elif name == 'Superuser (Stack Exchange)':
        url = f'https://download.kiwix.org/zim/stack_exchange/superuser.com_{language}_all_'
    elif name == 'iFixit':
        url = f'https://download.kiwix.org/zim/ifixit/ifixit_{language}_all_'
    elif name == 'Gutenberg':
        url = f'https://download.kiwix.org/zim/gutenberg/gutenberg_{language}_all_'
    elif name == 'Amateur Radio (Stack Exchange)':
        url = f'https://download.kiwix.org/zim/stack_exchange/ham.stackexchange.com_{language}_all_'
    else:
        raise ValueError(f'{name} not a valid Kiwix subscription name!')

    if language not in kiwix.KIWIX_CATALOG_BY_NAME[name]['languages']:
        raise ValueError(f'Language {repr(str(language))} is invalid for {name}')

    subscription.change_download(url, frequency, session=session)
    session.add(subscription)
    session.flush([subscription])
    session.commit()
    return subscription


@optional_session
async def unsubscribe(subscription_id: int, session: Session = None):
    subscription: ZimSubscription = session.query(ZimSubscription).filter_by(id=subscription_id).one_or_none()
    if subscription:
        session.delete(subscription)
        if subscription.download:
            session.delete(subscription.download)
        session.commit()
    else:
        raise UnknownZimSubscription(f'{subscription_id=}')


KIWIX_URL_PARSER = re.compile(r'https:\/\/download\.kiwix\.org\/zim\/(.+?)\/(.+?)_(\w{2,3})(_.+)')


def zim_download_url_to_name(url: str) -> Tuple[str, str]:
    _, project, language, flavor = KIWIX_URL_PARSER.match(url).groups()
    if project == 'wikipedia' and flavor == '_all_maxi_':
        name = 'Wikipedia (with images)'
    elif project == 'wikipedia' and flavor == '_all_nopic_':
        name = 'Wikipedia (no images)'
    elif project == 'wikipedia' and flavor == '_all_mini_':
        name = 'Wikipedia (mini)'
    elif project == 'wikiversity' and flavor == '_all_maxi_':
        name = 'Wikiversity (with images)'
    elif project == 'wikiversity' and flavor == '_all_nopic_':
        name = 'Wikiversity (no images)'
    elif project == 'wiktionary' and flavor == '_all_maxi_':
        name = 'Wikitionary (with images)'
    elif project == 'wiktionary' and flavor == '_all_nopic_':
        name = 'Wikitionary (no images)'
    elif project == 'wikibooks' and flavor == '_all_maxi_':
        name = 'Wikibooks (with images)'
    elif project == 'wikibooks' and flavor == '_all_nopic_':
        name = 'Wikibooks (no images)'
    elif project == 'wikisource' and flavor == '_all_maxi_':
        name = 'Wikisource'
    elif project == 'raspberrypi.stackexchange.com' and flavor == '_all_':
        name = 'Raspberry Pi (Stack Exchange)'
    elif project == 'vikidia' and flavor == '_all_maxi_':
        name = 'Vikidia'
    elif 'stackoverflow.com' in project and flavor == '_all_':
        name = 'Stackoverflow (Stack Exchange)'
    elif project == 'superuser.com' and flavor == '_all_':
        name = 'Superuser (Stack Exchange)'
    elif project == 'ifixit' and flavor == '_all_':
        name = 'iFixit'
    elif project == 'gutenberg' and flavor == '_all_':
        name = 'Gutenberg'
    elif project == 'ham.stackexchange.com' and flavor == '_all_':
        name = 'Amateur Radio (Stack Exchange)'
    else:
        raise RuntimeError(f'Could not find name for Zim URL: {url} {project=} {flavor=}')

    if language not in kiwix.KIWIX_CATALOG_BY_NAME[name]['languages']:
        raise ValueError(f'Language {repr(str(language))} is invalid for {name}')

    return name, language


def get_zim_directory() -> pathlib.Path:
    media_directory = get_media_directory()
    zim_directory = media_directory / 'zims'
    return zim_directory


async def check_zim(path: pathlib.Path) -> int:
    """
    Runs `zimcheck` against the Zim file.  Zim is valid only if this returns `0`.

    @warning: Only performs the checksum check!
    """
    cmd = f'zimcheck -C {path.absolute()}'
    proc = await asyncio.create_subprocess_shell(cmd)
    stdout, stderr = await proc.communicate()
    logger.debug(f'zimcheck returned {proc.returncode}')
    if proc.returncode != 0 and stderr:
        logger.debug(stderr)
    return proc.returncode


ZIM_NAME_PARSER = re.compile(r'(.+?)_(\d{4}-\d{2}).zim')


def parse_name(path: pathlib.Path) -> Tuple[str, datetime]:
    name, date = ZIM_NAME_PARSER.match(path.name).groups()
    date = datetime.strptime(date, '%Y-%m')
    return name, date


def find_outdated_zim_files(path: pathlib.Path = None) -> Tuple[List[pathlib.Path], List[pathlib.Path]]:
    """Search the Zim directory for outdated Zim files.  Returns a list of outdated, and a list of current Zim files."""
    path = path or get_zim_directory()
    if not path.is_dir():
        logger.error(f'Cannot search for outdated Zim files because the directory does not exist: {path}')
        return list(), list()

    # Find all non-empty Zim files.
    files = [i for i in walk(path) if i.is_file() and i.stat().st_size and i.suffix == '.zim']
    zims = list()
    for file in files:
        try:
            name, date = parse_name(file)
        except Exception as e:
            logger.warning(f'Found Zim {file} but its name does not match.', exc_info=e)
            continue

        zims.append((name, date, file))

    # Order by newest first.
    zims = sorted(zims, key=lambda i: i[1], reverse=True)
    outdated_files = list()
    current_files = list()
    newest_names = list()
    for name, date, file in zims:
        if name in newest_names:
            # Already saw this name, this date is older.
            outdated_files.append(file)
        else:
            newest_names.append(name)
            current_files.append(file)

    return sorted(outdated_files), sorted(current_files)


async def remove_outdated_zim_files(path: pathlib.Path = None) -> int:
    """Deletes all old Zim files."""
    outdated, _ = find_outdated_zim_files(path)
    logger.info(f'Deleting {len(outdated)} outdated Zim files: {outdated}')
    deleted_count = 0
    for file in outdated:
        file.unlink()
        deleted_count += 1

    if PYTEST:
        await refresh_files(outdated)
    else:
        background_task(refresh_files(outdated))

    await restart_kiwix()

    return deleted_count


@register_refresh_cleanup
def flag_outdated_zim_files():
    """Set the `outdated_zims` Flag if outdated Zim files can be found, otherwise clear it."""
    outdated, _ = find_outdated_zim_files()
    if outdated:
        logger.info('Outdated Zims were found')
        flags.outdated_zims.set()
    else:
        logger.info('Outdated Zims were not found')
        flags.outdated_zims.clear()


async def restart_kiwix():
    if PYTEST:
        logger.warning('Unable to restart Kiwix serve because we are testing')
        return
    if DOCKERIZED:
        logger.warning('Setting Kiwix restart because this is in a docker container')
        flags.kiwix_restart.set()
        return

    logger.info('Restarting Kiwix serve')

    cmd = f'sudo /usr/bin/systemctl restart wrolpi-kiwix.service'
    proc = await asyncio.create_subprocess_shell(cmd)
    stdout, stderr = await proc.communicate()
    logger.debug(f'systemctl returned {proc.returncode}')
    if proc.returncode != 0 and stderr:
        logger.debug(stderr)
    return proc.returncode