handler.py

"""Manage Handlers and map subdomains and domain names to Handlers."""

from collections import defaultdict
import tldextract

from handlers.article_handler import ArticleHandler
from handlers.business_times_handler import BusinesstimesHandler
from handlers.cna_lifestyle_handler import CNAlifestyleHandler
from handlers.ricemedia_handler import RicemediaHandler
from handlers.straits_times_handler import STHandler
from handlers.tnp_handler import TNPHandler
from handlers.today_online_handler import TodayonlineHandler
from handlers.yahoo_handler import YahooHandler


class HandlerManager:
    """
    Manage Handlers and map subdomains and domain names to Handlers.
    """
    handlers = {
        "businesstimes.com.sg": defaultdict(
            lambda: BusinesstimesHandler
        ),
        "channelnewsasia.com": defaultdict(
            lambda: ArticleHandler,  # Default Handler for all subdomains (unless specify)
                                     # for channelnewsasia.com
            cnalifestyle=CNAlifestyleHandler
        ),
        "mothership.sg": defaultdict(
            lambda: ArticleHandler
        ),
        "ricemedia.co": defaultdict(
            lambda: RicemediaHandler
        ),
        "straitstimes.com": defaultdict(
            lambda: STHandler
        ),
        "tnp.sg": defaultdict(
            lambda: TNPHandler
        ),
        "todayonline.com": defaultdict(
            lambda: TodayonlineHandler
        ),
        "yahoo.com": defaultdict(
            lambda: YahooHandler
        ),
        "zula.sg": defaultdict(
            lambda: ArticleHandler
        )
    }

    @classmethod
    def extract_hostname(cls, url):
        """Extract subdomain and domain name from URL."""
        url_extract = tldextract.extract(url)
        domains = {
            "subdomain": url_extract.subdomain,
            "domain_name": url_extract.domain + "." + url_extract.suffix
        }
        return domains

    @classmethod
    def has_handler(cls, url):
        """Check if a submission URL has an appropriate Handler."""
        domains = cls.extract_hostname(url)
        return domains["domain_name"] in cls.handlers

    @classmethod
    def get_handler(cls, url):
        """
        Return the Handler corresponding to a subdomain and domain name.
        Will return the default domain Handler if subdomain Handler do not exist.
        Raise ValueError if no domain Handler exists.
        """
        if not cls.has_handler(url):
            raise ValueError("Domain name {} has no Handler".format(url))
        domains = cls.extract_hostname(url)
        return cls.handlers[domains["domain_name"]][domains["subdomain"]]