Add support for building self-contained presentations and for passing extra variables to pandoc

example/default.nix

@@ -6,6 +6,9 @@ with pkgs.lib;
   src = ./.;
   name = "example-presentation";
   # reveal version can be changed with revealJS
-  # 3.5.0 is used by default
+  # 3.7.0 is used by default
   revealVersion = "3.4.0";
+  extraPandocVariables = {
+    theme = "sky";
+  };
 }

mkPresentation.nix

@@ -4,31 +4,38 @@
   pkgs
 , src
 , name
-, revealVersion ? "3.5.0"
+, revealVersion ? "3.7.0"
+, selfContained ? false
   # extra dependencies
- ,extraBuildInputs ? []
-  # assets to include in the result packages, typically examples
- ,assets ? []
+, extraBuildInputs ? []
+, extraPandocVariables ? {}
 }:
+
+with pkgs;
+with pkgs.lib;
+
 let
   revealJS = fetchTarball "https://github.com/hakimel/reveal.js/archive/${revealVersion}.tar.gz";
+
+  extraVars = vars:
+    builtins.concatStringsSep "" (mapAttrsToList (name: value: "--variable " + name + "=" + value) vars);
 in
 
-pkgs.stdenv.mkDerivation rec {
+stdenv.mkDerivation rec {
   inherit name src;
 
   preferLocalBuild = true;
   allowSubstitutes = false;
 
   # dependencies declaration
-  buildInputs = with pkgs; [ pandoc ] ++ extraBuildInputs;
+  buildInputs = [ pandoc ] ++ extraBuildInputs;
 
   installPhase = ''
-    mkdir $out
     for presentation in $(find . -name "*\.md"); do
-      id=$(basename $presentation ".md")
-      pandoc -t revealjs -s -o $out/"$id".html "$id".md
+      id="$(basename "$presentation" ".md")"
+      path="$(dirname "$presentation")"
+      mkdir -p "$out/$path"
+      pandoc --to=revealjs --variable revealjs-url=${revealJS} ${extraVars extraPandocVariables} --resource-path="$src/$path" --standalone ${optionalString selfContained "--self-contained"} --out="$out/$path/$id.html" "$presentation"
     done
-    ln -s ${revealJS} $out/reveal.js
   '';
 }

readme.md

@@ -5,5 +5,9 @@ example slides are in example/presentation.md.
 Can be built by running:
 
 ```sh
-$ nix-build example
+$ nix-build --option build-use-sandbox false example
 ```
+
+NOTE that `--option build-use-sandbox false` is required when using a
+different theme than the default one and when `selfContained` is enabled
+because Pandoc needs network access.