# frozen_string_literal: true

module ImageUtils
  PNG_REGEXP = %r{\Aimage/(?:png|apng|vnd\.mozilla\.apng)\z}
  JPEG_REGEXP = %r{\Aimage/(?:jpeg|jpg|pjpeg)\z}
  ICO_REGEXP = %r{\Aimage/(?:x-icon|vnd\.microsoft\.icon)\z}
  BMP_REGEXP = %r{\Aimage/(?:bmp|x-bmp|x-ms-bmp)\z}

  UnsupportedFormat = Class.new(StandardError)

  module_function

  def load_vips(data, content_type: nil, autorot: false)
    content_type ||= Marcel::MimeType.for(data)

    image =
      case content_type
      when PNG_REGEXP
        Vips::Image.pngload_buffer(data)
      when JPEG_REGEXP
        Vips::Image.jpegload_buffer(data)
      when ICO_REGEXP
        LoadIco.call(data)
      when BMP_REGEXP
        LoadBmp.call(data)
      else
        raise UnsupportedFormat, content_type.to_s
      end

    autorot ? image.autorot : image
  end

  def blank?(image)
    stats = image.stats

    min = (0...image.bands).map { |i| stats.getpoint(0, i)[0] }
    max = (0...image.bands).map { |i| stats.getpoint(1, i)[0] }

    return true if min.all?(255) && max.all?(255)
    return true if min.all?(0) && max.all?(0)

    false
  end

  def error?(image)
    image = image.crop(0, 0, image.width / 4, 2)

    row1, row2 = image.to_a

    row1[3..] == row2[..-4] && row1.each_cons(2).none? { |a, b| a == b }
  end
end