class TitreIdentiteWatermarkJob < ApplicationJob
  MAX_IMAGE_SIZE = 1500
  SCALE = 0.9
  WATERMARK = Rails.root.join("app/assets/images/#{WATERMARK_FILE}")

  def perform(blob)
    blob.open do |file|
      watermark = resize_watermark(file)
      processed = watermark_image(file, watermark)

      blob.metadata[:watermark] = true
      blob.upload(processed)
      blob.save
    end
  end

  private

  def watermark_image(file, watermark)
    ImageProcessing::MiniMagick
      .source(file)
      .convert("png")
      .resize_to_limit(MAX_IMAGE_SIZE, MAX_IMAGE_SIZE)
      .composite(watermark, mode: "over", gravity: "center")
      .call
  end

  def resize_watermark(file)
    metadata = image_metadata(file)

    width = [metadata[:width], MAX_IMAGE_SIZE].min * SCALE
    height = [metadata[:height], MAX_IMAGE_SIZE].min * SCALE
    diagonal = Math.sqrt(height**2 + width**2)
    angle = Math.asin(height / diagonal) * 180 / Math::PI

    ImageProcessing::MiniMagick
      .source(WATERMARK)
      .resize_to_limit(diagonal, diagonal / 2)
      .rotate(-angle, background: :transparent)
      .call
  end

  def image_metadata(file)
    read_image(file) do |image|
      if rotated_image?(image)
        { width: image.height, height: image.width }
      else
        { width: image.width, height: image.height }
      end
    end
  end

  def read_image(file)
    require "mini_magick"
    image = MiniMagick::Image.new(file.path)

    if image.valid?
      yield image
    else
      logger.info "Skipping image analysis because ImageMagick doesn't support the file"
      {}
    end
  end

  def rotated_image?(image)
    ['RightTop', 'LeftBottom'].include?(image["%[orientation]"])
  end
end