From 8d29728abfcc2e4207afb3fd8606feff17c15cec Mon Sep 17 00:00:00 2001
From: Matt Sturgeon <matt@sturgeon.me.uk>
Date: Mon, 11 Nov 2024 17:49:40 +0000
Subject: [PATCH] docs: specify `site-url`

Fixes 404 page's relative links and styling being relative to `/`.

Cherry-picked:
- a92339d83bdc47f6d42998a5ac96020f9dd7c2d6
- cdbda982f04bd021cfa8d549896410c5caf84fdf
---
 docs/mdbook/book.toml   | 3 +++
 docs/mdbook/default.nix | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/docs/mdbook/book.toml b/docs/mdbook/book.toml
index 59e8c630..4024b309 100644
--- a/docs/mdbook/book.toml
+++ b/docs/mdbook/book.toml
@@ -5,6 +5,9 @@ multilingual = false
 src = "."
 title = "nixvim docs"
 
+[output.html]
+site-url = "@SITE_URL@"
+
 [output.html.fold]
 enable = true
 level = 0
diff --git a/docs/mdbook/default.nix b/docs/mdbook/default.nix
index 1e8d8821..28d70b91 100644
--- a/docs/mdbook/default.nix
+++ b/docs/mdbook/default.nix
@@ -6,6 +6,8 @@
   nixosOptionsDoc,
   transformOptions,
   hmOptions,
+  # The root directory of the site
+  baseHref ? "/",
 }:
 with lib;
 let
@@ -238,6 +240,10 @@ let
     # Using pkgs.writeShellScript helps to avoid the "bash: argument list too long" error
     bash -e ${pkgs.writeShellScript "copy_docs" docs.commands}
 
+    # Patch book.toml
+    substituteInPlace ./book.toml \
+      --replace-fail "@SITE_URL@" "${baseHref}"
+
     # Prepare SUMMARY.md for mdBook
     # Using pkgs.writeText helps to avoid the same error as above
     substituteInPlace ./SUMMARY.md \