Fix authors in RSS feed by using site.data.authors instead of pages

The jekyll-feed plugin doesn't know about our custom pages, but it
does support `site.data.authors` as a map. So, let's use that as
our "source of truth" instead.

Then, as secondary effect, generate author pages automatically
with a plugin from that data.

_data/authors.yml

@@ -0,0 +1,2 @@
+alice: Alice Fitzgerald
+jlind: James Lind

_includes/opengraph.html

@@ -53,7 +53,7 @@
 {% if page.layout == "post" and page.date and page.author %}
 <meta property="og:type" content="article">
 <meta property="article:published_time" content="{{ page.date | date_to_xmlschema }}">
-<meta name="author" content="{% include author-text.html author=page.author %}">
+<meta name="author" content="{{ site.data.authors[include.author] | default: include.author | escape }}">
 {% endif %}
 
 {% endcapture -%}

_layouts/post.html

@@ -11,8 +11,8 @@ <h1>{{ page.title | escape }}</h1>
 		<p class="post-meta byline">Posted on <a href="{{ page.url | relative_url }}" rel="bookmark"><time itemprop="pubdate" datetime="{{ page.date | date_to_xmlschema }}">{{ page.date | date: date_format }}</time></a>{% if page.author %} by <span class="vcard"><span class="fn n" rel="author">
         {%- assign author_page = site.pages | where: "layout", "posts-author" | where: "author", page.author | first -%}
         {%- if author_page -%}
-	        <a href="{{ author_page.url | relative_url }}">{{ author_page.title | escape }}</a>
-        {%- else -%}{{ page.author | escape }}
+	        <a href="{{ author_page.url | relative_url }}">{{ site.data.authors[page.author] | default: page.author | escape }}</a>
+        {%- else -%}{{ site.data.authors[page.author] | default: page.author | escape}}
 	    {%- endif -%}</span></span>{% endif %}</p>
 	</header>
 	{{ content }}

_layouts/posts-tag.html

@@ -12,7 +12,7 @@ <h1>Tag: {{ page.title | escape }}</h1>
 	{%- for post in posts -%}
 	<div class="post-row">
 		<h2><a href="{{ post.url | relative_url }}">{{ post.title | escape }}</a></h2>
-		<p class="post-meta">Posted on <time datetime="{{ post.date | date_to_xmlschema }}">{{ post.date | date: date_format }}</time>{% if post.author %} by {% include author-text.html author=post.author %}{% endif %}</p>
+		<p class="post-meta">Posted on <time datetime="{{ post.date | date_to_xmlschema }}">{{ post.date | date: date_format }}</time>{% if post.author %} by {{ site.data.authors[include.author] | default: include.author | escape }}{% endif %}</p>
 		<div class="post">
 			{{- post.excerpt -}}
 			{%- if post.excerpt != post.content %}

_layouts/posts-year.html

@@ -12,7 +12,7 @@ <h1>Archive: {{ page.date | date: '%Y' }}</h1>
 	{%- for post in posts -%}
 	<div class="post-row">
 		<h2><a href="{{ post.url | relative_url }}">{{ post.title | escape }}</a></h2>
-		<p class="post-meta">Posted on <time datetime="{{ post.date | date_to_xmlschema }}">{{ post.date | date: date_format }}</time>{% if post.author %} by {% include author-text.html author=post.author %}{% endif %}</p>
+		<p class="post-meta">Posted on <time datetime="{{ post.date | date_to_xmlschema }}">{{ post.date | date: date_format }}</time>{% if post.author %} by {{ site.data.authors[include.author] | default: include.author | escape }}{% endif %}</p>
 		<div class="post">
 			{{- post.excerpt -}}
 			{%- if post.excerpt != post.content %}

_layouts/posts.html

@@ -13,7 +13,7 @@ <h1>{{ page.title }}</h1>
 	{% for post in posts -%}
 	<div class="post-row">
 		<h2><a href="{{ post.url | relative_url }}">{{ post.title | escape }}</a></h2>
-		<p class="post-meta">Posted on <time datetime="{{ post.date | date_to_xmlschema }}">{{ post.date | date: date_format }}</time>{% if post.author %} by {% include author-text.html author=post.author %}{% endif %}</p>
+		<p class="post-meta">Posted on <time datetime="{{ post.date | date_to_xmlschema }}">{{ post.date | date: date_format }}</time>{% if post.author %} by {{ site.data.authors[include.author] | default: include.author | escape }}{% endif %}</p>
 		<div class="post">
 			{{- post.excerpt -}}
 			{%- if post.excerpt != post.content %}

lib/jekyll-theme-amethyst.rb

@@ -37,3 +37,37 @@ def file_version_query(input, *filenames)
 end
 
 Liquid::Template.register_filter(Jekyll::AmethystFilters)
+
+module AmethystPlugin
+
+	class AuthorPageWithoutAFile < Jekyll::PageWithoutAFile
+		def template
+			# The template of the permalink, can be customized e.g. to "/blog/author/:author/"
+			# for sites with both API docs and a blog.
+			site.config["amethyst"]["author_permalink"] || "/author/:author"
+		end
+
+		def url_placeholders
+			super.merge({
+				"author" => data["author"]
+			})
+		end
+	end
+
+	class AuthorPageGenerator < Jekyll::Generator
+		safe true
+
+		def generate(site)
+			site.data["authors"].each do |slug, name|
+				site.pages << AuthorPageWithoutAFile.new(site, site.source, 'author', "#{slug}.html").tap do |page|
+					page.data.merge!(
+						"layout" => "posts-author",
+						"title" => name,
+						"author" => slug
+					)
+				end
+			end
+		end
+	end
+
+end