Open PDF file with Preview.app at specified page

preview.rb

#!/usr/bin/env ruby
# Usage:
#   preview path/to/pdf:123 # to open path/to/pdf in Preview.app and jump to specified page

require "open3"
require "json"

OPEN_PAGE_SCRIPT = <<-JS
function run(argv) {
  var options = JSON.parse(argv[0]);
  var SystemEvents = Application("System Events");
  var Preview = Application("Preview");

  Preview.activate();
  delay(0.01);
  SystemEvents.keystroke("g", {using: ["command down", "option down"]});
  SystemEvents.keystroke(options.page.toString());
  SystemEvents.keyCode(36); // return
}
JS

def sh(*commands)
  out, err, status = Open3.capture3(*commands)
  unless status.success?
    $stderr.puts "command exited with #{status.to_i}"
    $stderr.puts err
    exit status.to_i
  end
  out
end

def osascript(source, arg = {})
  sh "/usr/bin/osascript", "-l", "JavaScript", "-e", source, arg.to_json
end

def open_page(page)
  osascript(OPEN_PAGE_SCRIPT, page: page)
end

files = ARGV

if files.empty?
  sh "open", "-a", "Preview"
  exit
end

files.each do |file|
  if file =~ /(.+):(\d+)\z/
    file, page = $1, $2.to_i
  end

  sh "open", "-a", "Preview", file

  if page
    open_page(page)
  end
end