reorient

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

# reorient: extract and remove orientation tags from images while rotating

require "json"
require "open3"

ORIENTATION_MAP = {
  2 => %w[-flip horizontal],
  3 => %w[-rotate 180],
  4 => %w[-flip vertical],
  5 => %w[-transpose],
  6 => %w[-rotate 90],
  7 => %w[-transverse],
  8 => %w[-rotate 270],
}.freeze

def run!(*args)
  STDERR.puts "[+] #{args.join(" ")}" if ENV["VERBOSE"]
  output, status = Open3.capture2(*args)
  abort "[!] Fatal: Couldn't run #{args.first}" unless status.success?
  output
end

abort "Usage: reorient <file> [file ...]" if ARGV.empty?

json = run! "exiftool", "-Orientation", "-n", "-json", *ARGV

JSON.parse(json).tap do |d|
  d.each do |obj|
    filename = obj["SourceFile"]
    orientation = obj["Orientation"]

    case orientation
    when nil
      STDERR.puts "[!] #{filename} has no orientation information, skipping"
      next
    when 1
      next
    else
      orientation_flags = ORIENTATION_MAP[orientation]
      unless orientation_flags
        STDERR.puts "[!] Unknown orientation value (#{orientation}) for #{filename}"
        next
      end

      # TODO(ww): Might be worthwhile to check whether we're operating on a JPEG
      # here and use jpegtran instead.
      run! "convert", filename, "-quality", "100", *orientation_flags, filename
      run! "exiftool", "-Orientation=", "-overwrite_original", filename
    end
  end
end