modify art page to display thumbnails

thumbnails are currently created using shell script and require
imagemagick installed on the server. i know it's stupid, but i think
that including thumbnails to repo is also stupid.

maybe later i replace this script with actual jekyll plugin, but for
this i'll need to familiarize myself with ruby.
but now i use following addition to the git hook on the server:

```
[ -f "$TMP_GIT_CLONE/art/thumbs.sh" ] && {
    dir="$PWD"
    cd "$TMP_GIT_CLONE/art/" && sh thumbs.sh && cd "$dir"
}
```

it happens after cloning to remote repo and before building with bundle.

overall, this is a bodge now, it recompiles all thumbnails every time
due to quirks in my current setup.

2 files changed, 21 insertions, 3 deletions

diff --git a/_includes/art-menu.html b/_includes/art-menu.html
index d74d9da..0d35b96 100644
--- a/_includes/art-menu.html
+++ b/_includes/art-menu.html
@@ -1,12 +1,12 @@
 <ul class="art-menu">
 {%- for page in site.pages -%}
-    {%- assign pagedir = page.dir | remove_first: "/" | split: "/" -%}
     {%- include pic-path.html -%}
+    {%- assign pagedir = page.dir | remove_first: "/" | split: "/" -%}
     {%- if pagedir.first == "art" and pagedir.size > 1 -%}
     <li class="art-category">
         <a class="link-mask" href="{{ page.url }}">{{ page.title }}</a>
         <div class="thumbnail">
-            <img src="{{ artpics.first }}">
+            <img src="{{ artthumbs.first }}">
         </div>
     </li>
     {% endif %}
diff --git a/_includes/pic-path.html b/_includes/pic-path.html
index fed2367..810f227 100644
--- a/_includes/pic-path.html
+++ b/_includes/pic-path.html
@@ -1,8 +1,26 @@
+{% comment %}
+    the purpose of this file is to provide arrays to use for art browsing
+{% endcomment %}
+
 {%- capture arts -%}
 {%- for file in site.static_files -%}
-    {%- if file.art and file.path contains page.title -%}
+    {%- if file.art and file.path contains page.title and file.thumbnail != true -%}
         {{ file.path }}
     {% endif %}
 {%- endfor -%}
 {%- endcapture -%}
 {% assign artpics = arts | split: " " %}
+
+{%- capture arts_thumbs -%}
+{%- for art in artpics -%}
+    {%- assign art_ext = art | split: "." | last -%}
+    {%- assign art_basepath = art | split: "." | first -%}
+    {%- assign art_name = art_basepath | split: "/" | last -%}
+    {%- assign art_thumbpath = art_basepath \
+        | remove: art_name | append: "thumbs/" \
+        | append: art_name | append: "_thumb." | append: art_ext \
+        | append: " " -%}
+    {{ art_thumbpath }}
+{%- endfor -%}
+{%- endcapture -%}
+{% assign artthumbs = arts_thumbs | split: " " %}