Resolve relative href urls in a html elements.

Most docs will use relative urls to link across their pages,
without resolving them ourselves the links remain unusable in discord's
markdown and break out of codeblocks on mobile.

1 files changed, 13 insertions, 3 deletions

diff --git a/bot/cogs/doc.py b/bot/cogs/doc.py
index 204cffb37..51fb2cb82 100644
--- a/bot/cogs/doc.py
+++ b/bot/cogs/doc.py
@@ -7,6 +7,7 @@ from collections import OrderedDict
 from contextlib import suppress
 from types import SimpleNamespace
 from typing import Any, Callable, Optional, Tuple
+from urllib.parse import urljoin
 
 import discord
 from bs4 import BeautifulSoup
@@ -98,6 +99,10 @@ def async_cache(max_size: int = 128, arg_offset: int = 0) -> Callable:
 class DocMarkdownConverter(MarkdownConverter):
     """Subclass markdownify's MarkdownCoverter to provide custom conversion methods."""
 
+    def __init__(self, *, page_url: str, **options):
+        super().__init__(**options)
+        self.page_url = page_url
+
     def convert_code(self, el: PageElement, text: str) -> str:
         """Undo `markdownify`s underscore escaping."""
         return f"`{text}`".replace('\\', '')
@@ -107,10 +112,15 @@ class DocMarkdownConverter(MarkdownConverter):
         code = ''.join(el.strings)
         return f"```py\n{code}```"
 
+    def convert_a(self, el: PageElement, text: str) -> str:
+        """Resolve relative URLs to `self.page_url`."""
+        el["href"] = urljoin(self.page_url, el["href"])
+        return super().convert_a(el, text)
+
 
-def markdownify(html: str) -> DocMarkdownConverter:
+def markdownify(html: str, *, url: str = "") -> DocMarkdownConverter:
     """Create a DocMarkdownConverter object from the input html."""
-    return DocMarkdownConverter(bullets='•').convert(html)
+    return DocMarkdownConverter(bullets='•', page_url=url).convert(html)
 
 
 class InventoryURL(commands.Converter):
@@ -293,7 +303,7 @@ class Doc(commands.Cog):
 
         signatures = scraped_html[0]
         permalink = self.inventories[symbol]
-        description = markdownify(scraped_html[1])
+        description = markdownify(scraped_html[1], url=permalink)
 
         # Truncate the description of the embed to the last occurrence
         # of a double newline (interpreted as a paragraph) before index 1000.