From ce002059a3d6e4a0066d41984c9931685615c952 Mon Sep 17 00:00:00 2001
From: alex <alex@slab.org>
Date: Sun, 6 Jun 2021 20:08:26 +0100
Subject: [PATCH] Pandoc - allow citeproc extension to be invoked, with
 bibliography. ref #8152

---
 docs/data/docs.json                   |  5 +++++
 markup/markup_config/config.go        |  3 +++
 markup/pandoc/convert.go              | 13 ++++++++++-
 markup/pandoc/pandoc_config/config.go | 32 +++++++++++++++++++++++++++
 4 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 markup/pandoc/pandoc_config/config.go

diff --git a/docs/data/docs.json b/docs/data/docs.json
index 5e27712e361..31746676e98 100644
--- a/docs/data/docs.json
+++ b/docs/data/docs.json
@@ -1585,6 +1585,11 @@
         "failureLevel": "fatal",
         "workingFolderCurrent": false,
         "preserveTOC": false
+      },
+      "pandoc": {
+        "mathjax": true,
+        "citeproc": false
+        "bibliography": "data/bibliography.json"
       }
     },
     "minify": {
diff --git a/markup/markup_config/config.go b/markup/markup_config/config.go
index a3562cd241f..428669cb28a 100644
--- a/markup/markup_config/config.go
+++ b/markup/markup_config/config.go
@@ -18,6 +18,7 @@ import (
 	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/docshelper"
 	"github.com/gohugoio/hugo/markup/asciidocext/asciidocext_config"
+	"github.com/gohugoio/hugo/markup/pandoc/pandoc_config"
 	"github.com/gohugoio/hugo/markup/blackfriday/blackfriday_config"
 	"github.com/gohugoio/hugo/markup/goldmark/goldmark_config"
 	"github.com/gohugoio/hugo/markup/highlight"
@@ -41,6 +42,7 @@ type Config struct {
 	BlackFriday blackfriday_config.Config
 
 	AsciidocExt asciidocext_config.Config
+	Pandoc pandoc_config.Config
 }
 
 func Decode(cfg config.Provider) (conf Config, err error) {
@@ -114,6 +116,7 @@ var Default = Config{
 	BlackFriday: blackfriday_config.Default,
 
 	AsciidocExt: asciidocext_config.Default,
+	Pandoc:      pandoc_config.Default,
 }
 
 func init() {
diff --git a/markup/pandoc/convert.go b/markup/pandoc/convert.go
index 1c25e41d2d6..874f7f5a16f 100644
--- a/markup/pandoc/convert.go
+++ b/markup/pandoc/convert.go
@@ -53,6 +53,7 @@ func (c *pandocConverter) Supports(feature identity.Identity) bool {
 
 // getPandocContent calls pandoc as an external helper to convert pandoc markdown to HTML.
 func (c *pandocConverter) getPandocContent(src []byte, ctx converter.DocumentContext) []byte {
+	cfg := c.cfg.MarkupConfig.Pandoc
 	logger := c.cfg.Logger
 	path := getPandocExecPath()
 	if path == "" {
@@ -60,7 +61,17 @@ func (c *pandocConverter) getPandocContent(src []byte, ctx converter.DocumentCon
 			"                 Leaving pandoc content unrendered.")
 		return src
 	}
-	args := []string{"--mathjax"}
+	args := []string{}
+
+	if cfg.Mathjax {
+		args = append(args, "--mathjax")
+	}
+
+	if cfg.Citeproc {
+		args = append(args, "--citeproc")
+		args = append(args, "--bibliography", cfg.Bibliography)
+	}
+
 	return internal.ExternallyRenderContent(c.cfg, ctx, src, path, args)
 }
 
diff --git a/markup/pandoc/pandoc_config/config.go b/markup/pandoc/pandoc_config/config.go
new file mode 100644
index 00000000000..47effbf3d15
--- /dev/null
+++ b/markup/pandoc/pandoc_config/config.go
@@ -0,0 +1,32 @@
+// Copyright 2021 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package pandoc_config holds pandoc related configuration.
+package pandoc_config
+
+var (
+	// Default holds Hugo's default pandoc configuration.
+	Default = Config{
+		Mathjax:              true,
+		Citeproc:             false,
+		Bibliography:         "data/bibliography.json",
+	}
+
+)
+
+// Config configures asciidoc.
+type Config struct {
+	Mathjax              bool
+	Citeproc             bool
+	Bibliography         string
+}