import re
import json as pyjson


from typing import List, Optional, Any
from inspect import signature
from functools import wraps
from hashlib import sha256
from urllib.parse import urlparse, quote, unquote
from html import escape, unescape
from datetime import datetime
from dateparser import parse as dateparser

import requests
from base32_crockford import encode as base32_encode                            # type: ignore
from w3lib.encoding import html_body_declared_encoding, http_content_type_encoding

try:
    import chardet
    detect_encoding = lambda rawdata: chardet.detect(rawdata)["encoding"]
except ImportError:
    detect_encoding = lambda rawdata: "utf-8"

### Parsing Helpers

# All of these are (str) -> str
# shortcuts to: https://docs.python.org/3/library/urllib.parse.html#url-parsing
scheme = lambda url: urlparse(url).scheme.lower()
without_scheme = lambda url: urlparse(url)._replace(scheme='').geturl().strip('//')
without_query = lambda url: urlparse(url)._replace(query='').geturl().strip('//')
without_fragment = lambda url: urlparse(url)._replace(fragment='').geturl().strip('//')
without_path = lambda url: urlparse(url)._replace(path='', fragment='', query='').geturl().strip('//')
path = lambda url: urlparse(url).path
basename = lambda url: urlparse(url).path.rsplit('/', 1)[-1]
domain = lambda url: urlparse(url).netloc
query = lambda url: urlparse(url).query
fragment = lambda url: urlparse(url).fragment
extension = lambda url: basename(url).rsplit('.', 1)[-1].lower() if '.' in basename(url) else ''
base_url = lambda url: without_scheme(url)  # uniq base url used to dedupe links

without_www = lambda url: url.replace('://www.', '://', 1)
without_trailing_slash = lambda url: url[:-1] if url[-1] == '/' else url.replace('/?', '?')
hashurl = lambda url: base32_encode(int(sha256(base_url(url).encode('utf-8')).hexdigest(), 16))[:20]

urlencode = lambda s: s and quote(s, encoding='utf-8', errors='replace')
urldecode = lambda s: s and unquote(s)
htmlencode = lambda s: s and escape(s, quote=True)
htmldecode = lambda s: s and unescape(s)

short_ts = lambda ts: str(parse_date(ts).timestamp()).split('.')[0]
ts_to_date = lambda ts: ts and parse_date(ts).strftime('%Y-%m-%d %H:%M')
ts_to_iso = lambda ts: ts and parse_date(ts).isoformat()


URL_REGEX = re.compile(
    r'http[s]?://'                    # start matching from allowed schemes
    r'(?:[a-zA-Z]|[0-9]'              # followed by allowed alphanum characters
    r'|[$-_@.&+]|[!*\(\),]'           #    or allowed symbols
    r'|(?:%[0-9a-fA-F][0-9a-fA-F]))'  #    or allowed unicode bytes
    r'[^\]\[\(\)<>\""\'\s]+',         # stop parsing at these symbols
    re.IGNORECASE,
)

COLOR_REGEX = re.compile(r'\[(?P<arg_1>\d+)(;(?P<arg_2>\d+)(;(?P<arg_3>\d+))?)?m')

def is_static_file(url: str):
    # TODO: the proper way is with MIME type detection + ext, not only extension
    from .config import STATICFILE_EXTENSIONS
    return extension(url).lower() in STATICFILE_EXTENSIONS


def enforce_types(func):
    """
    Enforce function arg and kwarg types at runtime using its python3 type hints
    """
    # TODO: check return type as well

    @wraps(func)
    def typechecked_function(*args, **kwargs):
        sig = signature(func)

        def check_argument_type(arg_key, arg_val):
            try:
                annotation = sig.parameters[arg_key].annotation
            except KeyError:
                annotation = None

            if annotation is not None and annotation.__class__ is type:
                if not isinstance(arg_val, annotation):
                    raise TypeError(
                        '{}(..., {}: {}) got unexpected {} argument {}={}'.format(
                            func.__name__,
                            arg_key,
                            annotation.__name__,
                            type(arg_val).__name__,
                            arg_key,
                            str(arg_val)[:64],
                        )
                    )

        # check args
        for arg_val, arg_key in zip(args, sig.parameters):
            check_argument_type(arg_key, arg_val)

        # check kwargs
        for arg_key, arg_val in kwargs.items():
            check_argument_type(arg_key, arg_val)

        return func(*args, **kwargs)

    return typechecked_function


def docstring(text: Optional[str]):
    """attach the given docstring to the decorated function"""
    def decorator(func):
        if text:
            func.__doc__ = text
        return func
    return decorator


@enforce_types
def str_between(string: str, start: str, end: str=None) -> str:
    """(<abc>12345</def>, <abc>, </def>)  ->  12345"""

    content = string.split(start, 1)[-1]
    if end is not None:
        content = content.rsplit(end, 1)[0]

    return content


@enforce_types
def parse_date(date: Any) -> Optional[datetime]:
    """Parse unix timestamps, iso format, and human-readable strings"""
    
    if date is None:
        return None

    if isinstance(date, datetime):
        return date
    
    if isinstance(date, (float, int)):
        date = str(date)

    if isinstance(date, str):
        return dateparser(date)

    raise ValueError('Tried to parse invalid date! {}'.format(date))


@enforce_types
def download_url(url: str, timeout: int=None) -> str:
    """Download the contents of a remote url and return the text"""
    from .config import TIMEOUT, CHECK_SSL_VALIDITY, WGET_USER_AGENT
    timeout = timeout or TIMEOUT
    response = requests.get(
        url,
        headers={'User-Agent': WGET_USER_AGENT},
        verify=CHECK_SSL_VALIDITY,
        timeout=timeout,
    )

    content_type = response.headers.get('Content-Type', '')
    encoding = http_content_type_encoding(content_type) or html_body_declared_encoding(response.text)

    if encoding is not None:
        response.encoding = encoding

    return response.text


@enforce_types
def chrome_args(**options) -> List[str]:
    """helper to build up a chrome shell command with arguments"""

    from .config import CHROME_OPTIONS

    options = {**CHROME_OPTIONS, **options}

    cmd_args = [options['CHROME_BINARY']]

    if options['CHROME_HEADLESS']:
        cmd_args += ('--headless',)
    
    if not options['CHROME_SANDBOX']:
        # assume this means we are running inside a docker container
        # in docker, GPU support is limited, sandboxing is unecessary, 
        # and SHM is limited to 64MB by default (which is too low to be usable).
        cmd_args += (
            '--no-sandbox',
            '--disable-gpu',
            '--disable-dev-shm-usage',
            '--disable-software-rasterizer',
        )


    if not options['CHECK_SSL_VALIDITY']:
        cmd_args += ('--disable-web-security', '--ignore-certificate-errors')

    if options['CHROME_USER_AGENT']:
        cmd_args += ('--user-agent={}'.format(options['CHROME_USER_AGENT']),)

    if options['RESOLUTION']:
        cmd_args += ('--window-size={}'.format(options['RESOLUTION']),)

    if options['TIMEOUT']:
        cmd_args += ('--timeout={}'.format((options['TIMEOUT']) * 1000),)

    if options['CHROME_USER_DATA_DIR']:
        cmd_args.append('--user-data-dir={}'.format(options['CHROME_USER_DATA_DIR']))
    
    return cmd_args

def ansi_to_html(text):
    """
    Based on: https://stackoverflow.com/questions/19212665/python-converting-ansi-color-codes-to-html
    """
    from .config import COLOR_DICT

    TEMPLATE = '<span style="color: rgb{}"><br>'
    text = text.replace('[m', '</span>')

    def single_sub(match):
        argsdict = match.groupdict()
        if argsdict['arg_3'] is None:
            if argsdict['arg_2'] is None:
                _, color = 0, argsdict['arg_1']
            else:
                _, color = argsdict['arg_1'], argsdict['arg_2']
        else:
            _, color = argsdict['arg_3'], argsdict['arg_2']

        return TEMPLATE.format(COLOR_DICT[color][0])

    return COLOR_REGEX.sub(single_sub, text)


class AttributeDict(dict):
    """Helper to allow accessing dict values via Example.key or Example['key']"""

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        # Recursively convert nested dicts to AttributeDicts (optional):
        # for key, val in self.items():
        #     if isinstance(val, dict) and type(val) is not AttributeDict:
        #         self[key] = AttributeDict(val)

    def __getattr__(self, attr: str) -> Any:
        return dict.__getitem__(self, attr)

    def __setattr__(self, attr: str, value: Any) -> None:
        return dict.__setitem__(self, attr, value)


class ExtendedEncoder(pyjson.JSONEncoder):
    """
    Extended json serializer that supports serializing several model
    fields and objects
    """

    def default(self, obj):
        cls_name = obj.__class__.__name__

        if hasattr(obj, '_asdict'):
            return obj._asdict()

        elif isinstance(obj, bytes):
            return obj.decode()

        elif isinstance(obj, datetime):
            return obj.isoformat()

        elif isinstance(obj, Exception):
            return '{}: {}'.format(obj.__class__.__name__, obj)

        elif cls_name in ('dict_items', 'dict_keys', 'dict_values'):
            return tuple(obj)

        return pyjson.JSONEncoder.default(self, obj)