import json
import requests
import urllib.parse as urlparse

DDG_BANGS = 'https://duckduckgo.com/bang.js'


def gen_bangs_json(bangs_file: str) -> None:
    """Generates a json file from the DDG bangs list

    Args:
        bangs_file: The str path to the new DDG bangs json file

    Returns:
        None

    """
    try:
        # Request full list from DDG
        r = requests.get(DDG_BANGS)
        r.raise_for_status()
    except requests.exceptions.HTTPError as err:
        raise SystemExit(err)

    # Convert to json
    data = json.loads(r.text)

    # Set up a json object (with better formatting) for all available bangs
    bangs_data = {}

    for row in data:
        bang_command = '!' + row['t']
        bangs_data[bang_command] = {
            'url': row['u'].replace('{{{s}}}', '{}'),
            'suggestion': bang_command + ' (' + row['s'] + ')'
        }

    json.dump(bangs_data, open(bangs_file, 'w'))
    print('* Finished creating ddg bangs json')


def resolve_bang(query: str, bangs_dict: dict) -> str:
    """Transform's a user's query to a bang search, if an operator is found

    Args:
        query: The search query
        bangs_dict: The dict of available bang operators, with corresponding
                    format string search URLs
                    (i.e. "!w": "https://en.wikipedia.org...?search={}")

    Returns:
        str: A formatted redirect for a bang search, or an empty str if there
             wasn't a match or didn't contain a bang operator

    """

    #if ! not in query simply return (speed up processing)
    if '!' not in query:
        return ''

    split_query = query.strip().split(' ')

    # look for operator in query if one is found, list operator should be of
    # length 1, operator should not be case-sensitive here to remove it later
    operator = [
        word
        for word in split_query
        if word.lower() in bangs_dict
    ]
    if len(operator) == 1:
        # get operator
        operator = operator[0]

        # removes operator from query
        split_query.remove(operator)

        # rebuild the query string
        bang_query = ' '.join(split_query).strip()

        # Check if operator is a key in bangs and get bang if exists
        bang = bangs_dict.get(operator.lower(), None)
        if bang:
            bang_url = bang['url']

            if bang_query:
                return bang_url.replace('{}', bang_query, 1)
            else:
                parsed_url = urlparse.urlparse(bang_url)
                return f'{parsed_url.scheme}://{parsed_url.netloc}'
    return ''