require_relative 'sprite_animation_util'

module SpriteAnimation
  include SpriteAnimationUtil

  # Returns an image_tag inside a div, an populates the image
  # with data so it can be animated via javascript
  # Params:
  # +image_src+:: a sprite sheet source, just as you would pass to image_tag
  # +frame_count+:: a string representing the number of frames for the sheet
  # +params+:: a hash containing two optional parameters for the animation
  ##- +scale+:: a decimal number that will multiply the frame size. Default: 1
  ##- +orientation+:: a symbol representing the orientation of your sheet.
  ## Can be: :vertical or :horizontal. If not given, it will try to guess.
  def animate_sprite(image_src, frame_count, params = {})
    scale = params[:scale] || 1

    img_width, img_height = ImageSize.size(image_src).map { |d| d*scale }

    orientation = params[:orientation] ||
      guess_orientation(img_width, img_height)

    frame =
      send(orientation,*[img_width,img_height,frame_count])

    image = image_tag(image_url(image_src), class: "animated",
                      frameCount: frame_count, 
                      frameLength: frame[:length],
                      frameSide: frame[:margin],
                      style: frame[:style])

    content_tag(:div, image, 
                style: animated_div_style(frame[:width],frame[:height]))
  end 

  private

  def animated_div_style(frame_width, frame_height)
    "width: #{frame_width}px;
     height: #{frame_height}px;
     display: block;
     overflow: hidden"
  end

  def horizontal(img_width, img_height, frame_count)
    frame_width = img_width / frame_count.to_i
    frame_height = img_height
    {
      width: frame_width,
      height: frame_height,
      margin: "left",
      length: frame_width,
      style: "height: " + img_height.to_s + "px"
    }
  end

  def vertical(img_width, img_height, frame_count)
    frame_width = img_width
    frame_height = img_height / frame_count.to_i
    {
      width: frame_width,
      height: frame_height,
      margin: "top",
      length: frame_height,
      style: "width: " + img_width.to_s + "px"
    }
  end

  def guess_orientation(img_width, img_height)
    img_height > img_width ? :vertical : :horizontal
  end
end