[webtoons] Add a new extractor for webtoons.com (#761)

The webtoons extractor can extract episode and entire comic (all
episodes) from webtoons.com.

All the logic of the extractors should be trivial except for a couple
of kludges needed:

 - `ageGatePass' cookie is always set to avoid possible redirect and stop of
    extraction, especially in the comic extractor
 - The image URLs returned by the episode extractor could not be fetched
   directly and the `Referer:' HTTP header needs to be passed to fetch them

Close #593.

gallery_dl/extractor/__init__.py

@@ -115,6 +115,7 @@
     "vsco",
     "wallhaven",
     "warosu",
+    "webtoons",
     "weibo",
     "wikiart",
     "xhamster",

gallery_dl/extractor/webtoons.py

@@ -0,0 +1,138 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2020 Leonardo Taccari
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+"""Extract images from https://www.webtoons.com/"""
+
+from .common import Extractor, Message
+from .. import exception, text
+
+
+BASE_PATTERN = r"(?:https?://)?(?:www\.)?webtoons\.com/(?:en|fr)"
+
+
+class WebtoonsExtractor(Extractor):
+    category = "webtoons"
+    cookiedomain = "www.webtoons.com"
+
+    def __init__(self, match):
+        Extractor.__init__(self, match)
+        self.session.cookies.set("ageGatePass", "true",
+                                 domain=self.cookiedomain)
+
+
+class WebtoonsEpisodeExtractor(WebtoonsExtractor):
+    """Extractor for an episode on webtoons.com"""
+    subcategory = "episode"
+    directory_fmt = ("{category}", "{comic}")
+    filename_fmt = "{episode}-{num:>02}.{extension}"
+    archive_fmt = "{episode}_{num}"
+    pattern = (BASE_PATTERN + r"/([^/?&#]+)/([^/?&#]+)/(?:[^/?&#]+)"
+               r"/viewer(?:\?([^#]+))")
+    test = (
+        (("https://www.webtoons.com/en/comedy/safely-endangered"
+          "/ep-572-earth/viewer?title_no=352&episode_no=572"), {
+            "url": "11041d71a3f92728305c11a228e77cf0f7aa02ef",
+            "content": "4f7701a750368e377d65900e6e8f64a5f9cb9c86",
+            "count": 5,
+        }),
+    )
+
+    def __init__(self, match):
+        WebtoonsExtractor.__init__(self, match)
+        self.genre , self.comic, query = match.groups()
+        query = text.parse_query(query)
+        self.title_no = query.get("title_no")
+        if not self.title_no:
+            raise exception.NotFoundError("title_no")
+        self.episode = query.get("episode_no")
+        if not self.episode:
+            raise exception.NotFoundError("episode_no")
+        self.session.headers["Referer"] = self.url
+
+    def items(self):
+        page = self.request(self.url).text
+        data = self.get_job_metadata(page)
+        imgs = self.get_image_urls(page)
+        data["count"] = len(imgs)
+        yield Message.Version, 1
+        yield Message.Directory, data
+        for data["num"], url in enumerate(imgs, 1):
+            yield Message.Url, url, text.nameext_from_url(url, data)
+
+    def get_job_metadata(self, page):
+        """Collect metadata for extractor-job"""
+        title, pos = text.extract(
+            page, '<meta property="og:title" content="', '"')
+        descr, pos = text.extract(
+            page, '<meta property="og:description" content="', '"', pos)
+
+        return {
+            "genre": self.genre,
+            "comic": self.comic,
+            "title_no": self.title_no,
+            "episode": self.episode,
+            "title": text.unescape(title),
+            "description": text.unescape(descr),
+        }
+
+    @staticmethod
+    def get_image_urls(page):
+        """Extract and return a list of all image urls"""
+        return list(text.extract_iter(page, 'class="_images" data-url="', '"'))
+
+
+class WebtoonsComicExtractor(WebtoonsExtractor):
+    """Extractor for an entire comic on webtoons.com"""
+    subcategory = "comic"
+    pattern = (BASE_PATTERN + r"/([^/?&#]+)/([^/?&#]+)"
+               r"/list(?:\?([^#]+))")
+    test = (
+        (("https://www.webtoons.com/en/comedy/live-with-yourself/"
+          "list?title_no=919"), {
+            "range": "1-15",
+            "count": ">= 15",
+        }),
+    )
+
+    def __init__(self, match):
+        WebtoonsExtractor.__init__(self, match)
+        self.genre, self.comic, query = match.groups()
+        query = text.parse_query(query)
+        self.title_no = query.get("title_no")
+        if not self.title_no:
+            raise exception.NotFoundError("title_no")
+        self.page_no = int(query.get("page", 1))
+
+    def items(self):
+        data = {}
+        data["_extractor"] = WebtoonsEpisodeExtractor
+        while True:
+            page = self.request("https://www.webtoons.com/en/" +
+                                self.genre + "/" + self.comic + "/list?" +
+                                "title_no=" + self.title_no + "&"
+                                "page=" + str(self.page_no)).text
+            data["page"] = self.page_no
+
+            for url in self.get_episode_urls(page):
+                yield Message.Queue, url, data
+
+            if not self.has_next_page(page):
+                break
+
+            self.page_no += 1
+
+    def has_next_page(self, page):
+        return "/en/" + self.genre + "/" + self.comic + "/list?" + \
+               "title_no=" + self.title_no + \
+               "&page=" + str(self.page_no + 1) in page
+
+    @staticmethod
+    def get_episode_urls(page):
+        """Extract and return a list of all episode urls"""
+        return list(text.extract_iter(page, '<a href="',
+                    '" class="NPI=a:list', page.find('id="_listUl"')))

scripts/supportedsites.py

@@ -86,6 +86,7 @@
     "thebarchive"    : "The /b/ Archive",
     "vanillarock"    : "もえぴりあ",
     "vsco"           : "VSCO",
+    "webtoons"       : "Webtoon",
     "wikiart"        : "WikiArt.org",
     "worldthree"     : "World Three",
     "xhamster"       : "xHamster",