"""
Parse documents (often application/pdf).
"""

import logging
import re
from datetime import datetime
from typing import Optional, Union

from tika import parser

from ..models import ResourceError, ResourceRedirect, Site, TextResource
from ..utils.durl import Durl
from ..utils.http import get_header_links
from ..utils.lang import extract_content_language
from .plaintext import annotate_text

logger = logging.getLogger(__name__)
logger_debug = logging.getLogger(__name__ + '.debug')
logger_debug.setLevel(logging.INFO)


re_url = re.compile(
    r'((http|https)://[\w_-]+\.[\w_-]+(:[0-9]+)?'
    r'([\w.,@?^=%&:/~+#-]*[\w@?^=%&/~+#-])?)'
)


async def parse_document(
    durl: Durl,
    resp: dict,
    site: Optional[Site],
) -> Optional[Union[TextResource, ResourceError, ResourceRedirect]]:
    """
    Extract plain text from documents in various formats.
    """
    content = resp['content']

    # HTTP headers, canonical URL, shortlink
    header_links = await get_header_links(resp['headers'], durl, site)
    if canonical := header_links.get('canonical'):
        if canonical != durl.url():
            return ResourceRedirect(resp['redirects'] + [canonical])
    shortlink = header_links.get('shortlink')

    # use tika to extract text
    doc = parser.from_buffer(content)
    # logger.debug(pformat(doc))
    if doc.get('status') != 200:
        msg = f'Analyzing document failed: {durl.url()}'
        return ResourceError(msg)

    # collect meta data
    meta = doc.get('metadata', {})
    content_type = meta.get('Content-Type')
    if isinstance(content_type, list):
        content_type = content_type[-1]
    title = concat(meta.get('title'))
    concat(meta.get('creator'))
    last_change = extract_latest(meta.get('date') or meta.get('created'))
    keywords = None

    # text content
    text = (doc.get('content') or '').strip()

    # links
    links_int: dict[Durl, tuple[list[str], str]] = {}
    links_ext: dict[Durl, tuple[list[str], str]] = {}
    for url in re_url.findall(text):
        link_durl = await Durl(url[0])
        if link_durl:
            if link_durl.site() == durl.site():
                links_int[link_durl] = [], link_durl.url()
            else:
                links_ext[link_durl] = [], link_durl.url()

    # annotations
    text, annotations = annotate_text(text)

    return TextResource(
        content_type=content_type,
        last_change=last_change,
        text_len=len(text),
        lang=extract_content_language(text),
        title=title,
        init_fields={
            'durl': durl,
            'site': site,
            'headers': resp['headers'],
            'redirects': resp['redirects'],
            'links_int': links_int,
            'links_ext': links_ext,
            'shortlink': shortlink,
            'canonical': None,
        },
        search_fields={
            'title': title,
            'pub_date': last_change,
            'keywords': keywords,
            'text': text,
            'annotations': annotations,
        },
    )


def extract_latest(s: Optional[Union[str, list]]) -> Optional[datetime]:
    """
    Extract the lastest date (if any) from a string or list of strings.
    """
    if not s:
        return None
    if not isinstance(s, list):
        s = [s]
    dt = []
    for t in s:
        try:
            dt.append(datetime.fromisoformat(t.rstrip('Z')))
        except:
            pass
    return max(dt) if dt else None


def concat(s: Optional[Union[str, list]]) -> Optional[str]:
    """
    Helper function for joining strings together.
    """
    if not s:
        return None
    if not isinstance(s, list):
        s = [s]
    return ' '.join(s)