Add support for requesting Markdown from the server

ChangeLog.md

@@ -4,8 +4,11 @@
 
 **Released: WiP**
 
-- Add a configuration option to allow for "traditional quit".
+- Added a configuration option to allow for "traditional quit".
   ([#148](https://github.com/davep/hike/pull/148))
+- Added support for requesting a Markdown version of a URL before deciding
+  it can't be handled in Hike.
+  ([#150](https://github.com/davep/hike/pull/150))
 
 ## v1.2.1
 

src/hike/data/__init__.py

@@ -11,13 +11,19 @@
     update_configuration,
 )
 from .history import load_history, save_history
-from .location_types import is_editable, looks_urllike, maybe_markdown
+from .location_types import (
+    can_be_negotiated_to_markdown,
+    is_editable,
+    looks_urllike,
+    maybe_markdown,
+)
 
 ##############################################################################
 # Exports.
 __all__ = [
     "Bookmark",
     "Bookmarks",
+    "can_be_negotiated_to_markdown",
     "Configuration",
     "is_editable",
     "load_bookmarks",

src/hike/data/location_types.py

@@ -7,13 +7,14 @@
 
 ##############################################################################
 # httpx imports.
-from httpx import URL
+from httpx import URL, AsyncClient, HTTPStatusError, RequestError
 
 ##############################################################################
 from typing_extensions import TypeIs
 
 ##############################################################################
 # Local imports.
+from .. import USER_AGENT
 from ..types import HikeLocation
 from .config import load_configuration
 
@@ -50,6 +51,45 @@ def _(location: URL) -> bool:
     return maybe_markdown(location.path)
 
 
+##############################################################################
+async def can_be_negotiated_to_markdown(location: HikeLocation) -> bool:
+    """Can the given location be negotiated to Markdown?
+
+    Args:
+        location: The location to test.
+
+    Returns:
+        `True` if the location can be negotiated to Markdown, `False` if
+        not.
+    """
+    if isinstance(location, Path):
+        return False
+    async with AsyncClient() as client:
+        try:
+            response = await client.head(
+                location,
+                follow_redirects=True,
+                headers={
+                    "user-agent": USER_AGENT,
+                    "Accept": ",".join(
+                        load_configuration().markdown_content_types + ["*/*;q=0.1"]
+                    ),
+                },
+            )
+        except RequestError:
+            return False
+    try:
+        response.raise_for_status()
+    except HTTPStatusError:
+        return False
+    if content_type := response.headers.get("content-type"):
+        return any(
+            content_type.startswith(accepted_type)
+            for accepted_type in load_configuration().markdown_content_types
+        )
+    return False
+
+
 ##############################################################################
 def looks_urllike(candidate: str) -> bool:
     """Does the given value look like a URL?

src/hike/screens/main.py

@@ -54,6 +54,7 @@
     ToggleNavigation,
 )
 from ..data import (
+    can_be_negotiated_to_markdown,
     load_bookmarks,
     load_command_history,
     load_configuration,
@@ -246,13 +247,15 @@ def _copy_text_to_clipbaord(self, message: CopyToClipboard) -> None:
         self.notify("Copied")
 
     @on(OpenLocation)
-    def _open_markdown(self, message: OpenLocation) -> None:
+    async def _open_markdown(self, message: OpenLocation) -> None:
         """Open a file for viewing.
 
         Args:
             message: The message requesting the file be opened.
         """
-        if maybe_markdown(message.to_open):
+        if maybe_markdown(message.to_open) or await can_be_negotiated_to_markdown(
+            message.to_open
+        ):
             self.query_one(Viewer).location = message.to_open
             if load_configuration().focus_viewer_on_load:
                 self.query_one(Viewer).focus()

src/hike/widgets/viewer.py

@@ -366,7 +366,12 @@ async def _load_from_url(self, location: URL, remember: bool) -> None:
                 response = await client.get(
                     location,
                     follow_redirects=True,
-                    headers={"user-agent": USER_AGENT},
+                    headers={
+                        "user-agent": USER_AGENT,
+                        "Accept": ",".join(
+                            load_configuration().markdown_content_types + ["*/*;q=0.1"]
+                        ),
+                    },
                 )
         except RequestError as error:
             self.notify(str(error), title="Request error", severity="error", timeout=8)