Replace switch orphan branch shell script with a Ruby program

bin/switch-content-orphan-branch

@@ -1,7 +0,0 @@
-#!/usr/bin/env nix-shell
-#! nix-shell -p findutils coreutils git fzf -i bash
-
-find ./content/ -mindepth 2 -iname 'index.adoc' -printf '%P\n' \
-    | xargs dirname \
-    | fzf --prompt "Choose orphan content branch " --filepath-word --info=hidden \
-    | xargs git switch --orphan

bin/switch-content-orphan-branch.rb

@@ -0,0 +1,54 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i ruby -p "ruby.withPackages (ps: with ps; [ rugged ])" coreutils fzf
+
+# frozen_string_literal: true
+
+require 'fileutils'
+require 'logger'
+require 'optparse'
+require 'rugged'
+
+CONTENT_DIRECTORY = 'content'
+
+options = {
+  prefix: 'posts/',
+  repo: './code-workspace'
+}
+logger = Logger.new($stdout)
+logger.level = Logger::WARN
+
+OptionParser.new do |opts|
+  opts.on('-p', '--prefix PREFIX',
+          <<~HELP
+            Sets the prefix corresponding to a subdirectory inside
+            the content directory.
+          HELP
+  ) do |prefix|
+    options[:prefix] = prefix
+  end
+
+  opts.on('--repo REPO', 'The repository location.') do |repo|
+    options[:repo] = repo
+  end
+
+  opts.on('-v', '--[no-]verbose', 'Make the program print results') do |v|
+    options[:verbose] = v
+  end
+end.parse!
+
+logger.level = Logger::INFO if options[:verbose]
+
+initial_path = File.expand_path(options[:prefix], CONTENT_DIRECTORY)
+files = Dir.new(initial_path)
+           .children
+           .select do |file|
+             path = File.expand_path(file, initial_path)
+             File.directory? path
+           end
+           .map { |file| File.join options[:prefix], file }
+           .sort
+selected_branch = `echo -e "#{files.join '\n'}" | fzf`.strip
+
+code_workspace = Rugged::Repository.discover(options[:repo])
+code_workspace.head=("refs/heads/#{selected_branch}")
+logger.info "Switched '#{options[:repo]}' to orphan branch '#{code_workspace}'"