install-gist.rb

#!/usr/bin/env ruby
# install_gist.rb — installs a gist by ID into a directory
#
# Fetches the gist, downloads its file(s), and registers them in .gist-ids
#
# Setup:
#   1. Install gh CLI: https://cli.github.com
#   2. Run: gh auth login
#
# Usage:
#   ruby install_gist.rb <gist_id> [directory]   # defaults to current dir

require "open3"
require "json"

# ── args ──────────────────────────────────────────────────────────────────────

gist_id = ARGV[0]
dir     = ARGV[1] || "."

unless gist_id
  abort "Usage: ruby install_gist.rb <gist_id> [directory]"
end

mapping_file = File.join(dir, ".gist-ids")

# ── checks ────────────────────────────────────────────────────────────────────

unless system("which gh > /dev/null 2>&1")
  abort "❌  gh CLI not found. Install it: https://cli.github.com"
end

Dir.mkdir(dir) unless Dir.exist?(dir)

# ── fetch gist metadata ───────────────────────────────────────────────────────

puts "🔍  Fetching gist #{gist_id}..."

stdout, stderr, status = Open3.capture3("gh", "api", "/gists/#{gist_id}")

unless status.success?
  abort "❌  Could not fetch gist: #{stderr.strip}"
end

gist = JSON.parse(stdout.force_encoding("UTF-8"))
files = gist["files"]

if files.nil? || files.empty?
  abort "❌  Gist has no files"
end

# ── load existing mappings ────────────────────────────────────────────────────

existing = {}
if File.exist?(mapping_file)
  File.foreach(mapping_file, encoding: "UTF-8") do |line|
    line.strip!
    next if line.empty? || line.start_with?("#")
    fname, gid = line.split("=", 2).map(&:strip)
    existing[fname] = gid if fname && gid
  end
end

# ── install each file ─────────────────────────────────────────────────────────

puts ""
installed = 0
skipped   = 0

files.each do |filename, meta|
  filepath = File.join(dir, filename)

  if existing[filename]
    if existing[filename] == gist_id
      puts "⏭   '#{filename}' already registered — skipping"
    else
      puts "⚠️   '#{filename}' already registered with a different gist ID — skipping"
    end
    skipped += 1
    next
  end

  # content is already in the metadata response, unless the file is too big
  print "↓  Downloading '#{filename}'... "
  content = meta["content"]

  if meta["truncated"] || content.nil?
    content, content_stderr, content_status = Open3.capture3(
      "gh", "gist", "view", gist_id, "--filename", filename, "--raw"
    )

    unless content_status.success?
      puts "❌  failed"
      $stderr.puts "    #{content_stderr.strip}"
      next
    end
  end

  File.write(filepath, content.force_encoding("UTF-8"), mode: "w:UTF-8")
  puts "✅"

  # register in .gist-ids
  File.open(mapping_file, "a") { |f| f.puts "#{filename}=#{gist_id}" }
  existing[filename] = gist_id
  installed += 1
end

# ── summary ───────────────────────────────────────────────────────────────────

puts ""
puts "─────────────────────────────"
puts "✅  Installed : #{installed}"
puts "⏭   Skipped  : #{skipped}" if skipped > 0
puts ""
puts "📄  .gist-ids updated: #{File.realpath(mapping_file)}" if installed > 0