From d7bc2a899d0a4b70ff9d980e0c05c729278b42f6 Mon Sep 17 00:00:00 2001
From: Nico Rikken <nico@nicorikken.eu>
Date: Sun, 20 Aug 2017 10:11:16 +0200
Subject: [PATCH] feat(asciidoctor): handle metadata

Adds metadata handling to the asciidoctor task. The asciidoctor task will now:
1. read asciidoctor attributes and add them as metadata
2. expose metadata to the asciidoctor process as attributes

Both processes are executed independently from each other.
---
 src/io/perun.clj             |  3 +-
 src/io/perun/asciidoctor.clj | 71 ++++++++++++++++++++++++++++++++++--
 2 files changed, 69 insertions(+), 5 deletions(-)

diff --git a/src/io/perun.clj b/src/io/perun.clj
index 0311681f..c0f6f2e7 100644
--- a/src/io/perun.clj
+++ b/src/io/perun.clj
@@ -459,7 +459,8 @@
                    :cmd-opts cmd-opts))))
 
 (def ^:private ^:deps asciidoctor-deps
-  '[[org.clojure/tools.namespace "0.3.0-alpha3"]
+  '[[clj-time "0.14.0"]
+    [org.clojure/tools.namespace "0.3.0-alpha3"]
     [org.asciidoctor/asciidoctorj "1.5.4"]])
 
 (def ^:private +asciidoctor-defaults+
diff --git a/src/io/perun/asciidoctor.clj b/src/io/perun/asciidoctor.clj
index 02c52529..c6b4ca91 100644
--- a/src/io/perun/asciidoctor.clj
+++ b/src/io/perun/asciidoctor.clj
@@ -1,16 +1,79 @@
 (ns io.perun.asciidoctor
   (:require [io.perun.core :as perun]
+            [clj-time.coerce :as tc]
+            [clj-time.format :as tf]
             [clojure.java.io :as io])
   (:import [org.asciidoctor Asciidoctor Asciidoctor$Factory]))
 
+(defn keywords->names
+  "Converts a map with keywords to a map with named keys. Only handles the top
+   level of any nested structure."
+  [m]
+  (reduce-kv #(assoc %1 (name %2) %3) {} m))
+
+(defn names->keywords
+  "Converts a map with named keys to a map with keywords. Only handles the top
+   level of any nested structure."
+  [m]
+  (reduce-kv #(assoc %1 (keyword %2) %3) {} m))
+
 (def container
   (Asciidoctor$Factory/create ""))
 
-(defn asciidoctor-to-html [file-content]
-  (.convert container file-content {}))
+(defn meta->attributes
+  "Takes the Perun meta and converts it to a collection of attributes, which can
+  be handed to the AsciidoctorJ process."
+  [meta]
+  (-> meta
+      keywords->names
+      (java.util.HashMap.)))
+
+(defn parse-date
+  "Tries to parse a date string into a DateTime object"
+  [date]
+  (when date
+    (if-let [parsed (tc/to-date date)]
+      parsed
+      (perun/report-info "asciidoctor" "failed to parse date %s" date))))
+
+(defn attributes->meta
+  "Add duplicate entries for the metadata keys gathered from the AsciidoctorJ
+  parsing using keys that adhere to the Perun specification of keys. The native
+  AsciidoctorJ keys are still available."
+  [attributes]
+  (let [meta (names->keywords (into {} attributes))]
+    (merge meta
+           {:author-email   (:email     meta)
+            :title          (:doctitle  meta)
+            :date-published (parse-date (:revdate meta))})))
+
+(defn protect-meta
+  "Strip keywords from metadata that are being used by Perun to properly
+  function."
+  [meta]
+  (dissoc meta
+          :canonical-url :extension :filename :full-path :parent-path :permalink
+          :short-filename :slug))
+
+(defn parse-file-metadata
+  "Processes the asciidoctor content and extracts all the attributes."
+  [adoc-content]
+  (->> (.readDocumentStructure container adoc-content {})
+       (.getHeader)
+       (.getAttributes)
+       attributes->meta
+       protect-meta))
+
+(defn asciidoctor-to-html [file-content attributes]
+  (let [options (if attributes
+                  {"attributes" attributes}
+                  {})]
+    (.convert container file-content options)))
 
 (defn process-asciidoctor [{:keys [entry]}]
   (perun/report-debug "asciidoctor" "processing asciidoctor" (:filename entry))
   (let [file-content (-> entry :full-path io/file slurp)
-        html         (asciidoctor-to-html file-content)]
-    (assoc entry :rendered html)))
+        attributes   (meta->attributes entry)
+        html         (asciidoctor-to-html file-content attributes)
+        meta         (parse-file-metadata file-content)]
+    (merge (assoc entry :rendered html) meta)))