Add generate-themes-doc.fish

* Generates `docs/Themes.md` that can be used
  for preview available themes

README.md

@@ -61,7 +61,7 @@ List installed packages.
 
 #### `omf theme` _`<theme>`_
 
-Apply a theme. To list available themes type `omf theme`.
+Apply a theme. To list available themes type `omf theme`. You can also [preview available Themes](./docs/Themes.md) before installing.
 
 #### `omf remove` _`<name>`_
 

tools/generate-themes-doc.fish

+#!/usr/bin/env fish
+
+set -l project_dir (status -f|xargs dirname|xargs dirname)
+set -l theme_doc "$project_dir/docs/Themes.md"
+set temp_theme_contents (mktemp /tmp/fish.Themes.Content.XXXXX.md)
+set temp_theme_toc (mktemp /tmp/fish.Themes.TOC.XXXXX.md)
+
+function __write_theme_readme -a name raw_content readme
+  set -l escaped_raw_content (echo $raw_content | sed -r s"#[\/]#\\\/#gi")
+  curl -s "$raw_content/$readme" | \
+    sed -r 's/^#(.*)$/###\1/gi' | \
+    sed -r 's/^=+$//gi' | \
+    sed -r 's/^!\[(.*)\]\(([^h][^t][^t].*)\)$/![\1]('$escaped_raw_content'\/\2)/gi' \
+    >> $temp_theme_contents
+  echo "" >> $temp_theme_contents
+  echo "" >> $temp_theme_contents
+end
+
+function __find_readme -a raw_content
+  for readme in "README.md" "readme.md"
+    if curl -Ifs "$raw_content/$readme" > /dev/null
+      echo $readme
+      break
+    end
+  end
+end
+
+echo "Generating Themes documentation ..."
+echo "# Available themes" > $temp_theme_toc
+
+for theme in (command find $project_dir/db/themes/ -type f|sort)
+  set -l name (echo $theme|xargs basename)
+  set -l url (cat $theme)
+  set -l raw_content (echo $url|sed -r 's#https://github.com/([-.a-z0-9]+)/([-.a-z0-9]+)#https://raw.githubusercontent.com/\1/\2/master#gi')
+  set -l readme (__find_readme $raw_content)
+
+  echo "- [$name](#$name)" >> $temp_theme_toc
+  echo "# $name" >> $temp_theme_contents
+  if [ $readme ]
+    echo "Fetching readme for $name"
+    __write_theme_readme $name $raw_content $readme
+  else
+    echo "FAILED: No readme for $name" 1>&2
+    echo "See $url for details" >> $temp_theme_contents
+  end
+end
+
+echo "" >> $temp_theme_toc
+cat $temp_theme_contents >> $temp_theme_toc
+rm $theme_doc
+cat $temp_theme_toc >> $theme_doc
+echo "All done: $theme_doc"
+
+rm $temp_theme_contents
+rm $temp_theme_toc