View - a simple terminal image viewer

view.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'base64'

#
# View is a simple terminal image viewer
#
# NOTE: currently only iTerm is supported
#
# Instructions:
#   * Save this file as view.rb
#   * Make this file executable: 'chmod 755 view.rb'
#   * View image files: './view.rb <image1> <image2> <image3>'
class View
  def initialize(paths)
    @paths = paths
    validate_paths
    validate_terminal
  end

  def render
    @paths.each { |p| render_path(p) }
  end

  private

  def render_path(path)
    data = Base64.encode64(File.open(path, 'rb').read)
    puts "\033]1337;File=size=#{data.size};inline=1:#{data}\a\n\n"
  end

  def validate_paths
    usage('No image paths given') if @paths.empty?
    @paths.each do |path|
      unless File.exist?(path) && File.file?(path) && File.readable?(path)
        usage("Path '#{path}' does not appear to be a valid image path")
      end
    end
  end

  def validate_terminal
    usage('Please run this tool within iTerm') \
      if ENV['TERM_PROGRAM'] != 'iTerm.app'
  end

  def usage(error_msg = nil)
    puts "\n  #{error_msg}\n\n" if error_msg
    puts "Usage: #{$PROGRAM_NAME} </path/to/image/file1> <file2> <file3>"
    exit
  end
end

View.new(ARGV).render if $PROGRAM_NAME == __FILE__