module Scrivito

# @api public
# The Binary class represents the data stored in a binary attribute of an Obj
# or Widget
class Binary
  attr_reader :id, :transformation_definition

  def initialize(id, is_public, transformation_definition = nil, original = nil)
    @id = id
    @is_public = !!is_public
    @transformation_definition = transformation_definition
    @original = original
  end

  # @api public
  # Some Scrivito data is considered private, i.e. it is not currently intended
  # for the general public, for example content in a workspace that has not
  # been published yet.
  # @return [Boolean]
  def private?
    !@is_public
  end

  def public?
    @is_public
  end

  # @api public
  # The URL for accessing the binary data and downloading it using an HTTP GET request.
  #
  # @note URLs for private content have an expiration time in order to protect them.
  #   Therefore, the URL should be accessed immediately after it has been returned
  #   (i.e. within a couple of minutes). Accessing it after expiration causes an error.
  #
  # The URLs should not be used for long-term storage since they are no longer
  # accessible hours or days after they have been generated.
  # @return [String] the URL at which this content is available.
  def url
    find_url('get')
  end

  def url_from_cache
    blob_data = CmsBackend.instance
      .find_blob_data_from_cache(id, access_type, 'get', transformation_definition)
    if blob_data
      blob_data['url']
    end
  end

  # @api public
  # the filename of this binary data, for example "my_image.jpg"
  # @return [String] the filename of binary
  def filename
    File.basename(URI(url).path)
  end

  # @api public
  # the content type of this binary data, for example "image/jpeg"
  # @return [String] content type
  def content_type
    headers[:content_type]
  end

  # @api public
  # the length of this binary data, in bytes.
  # @return [Integer] number of bytes
  def content_length
    headers[:content_length].to_i
  end

  #
  # Returns a transformed {Scrivito::Binary}.
  #
  # @api beta
  #
  # Calling this method will not change the binary, but instead return a copy of it,
  # transformed using the +definition+.
  #
  # If the original binary has already been transformed, then the returned binary will be a
  # combination of the transformations. Thus the transformations can be chained (see examples).
  #
  # The transformed data is calculated "lazily", so calling {Scrivito::Binary#transform} will not
  # trigger any calculation. The calculation will be triggered only if data is accessed, for example
  # via {Scrivito::Binary#url}.
  #
  # @param [Hash] definition transformation definition
  #
  # @option definition [Fixnum,String] :width The width in pixels of the output image. Must be a
  #   positive integer.
  #
  #   If only this dimension is specified, the other dimension will be calculated automatically to
  #   preserve the aspect ratio of the input image.
  #
  #   If the +fit+ parameter is set to +:clip+, then the actual output one of width and height may
  #   be equal to or less than the dimensions you specify to prevent distortion.
  #
  #   If neither +width+ nor +height+ is given, the width and height of the input image
  #   will be used.
  #
  #   The maximum output image size width + height = 4096 pixels. The given width and height may be
  #   adjusted to accomodate this limit. The output image will never be larger than the source
  #   image, i.e. the given width and height may be adjusted to keep the output image from exceeding
  #   the dimensions of the input image.
  #
  #   When the given width and height are adjusted, the aspect ratio is preserved.
  #
  # @option definition [Fixnum,String] :height The height in pixels of the output image. Must be a
  #   positive integer.
  #
  #   If only this dimension is specified, the other dimension will be calculated automatically to
  #   preserve the aspect ratio of the input image.
  #
  #   If the +fit+ parameter is set to +:clip+, then the actual output one of width and height may
  #   be equal to or less than the dimensions you specify to prevent distortion.
  #
  #   If neither +width+ nor +height+ is given, the width and height of the input image
  #   will be used.
  #
  #   The maximum output image size width + height = 4096 pixels. The given width and height may be
  #   adjusted to accomodate this limit. The output image will never be larger than the source
  #   image, i.e. the given width and height may be adjusted to keep the output image from exceeding
  #   the dimensions of the input image.
  #
  #   When the given width and height are adjusted, the aspect ratio is preserved.
  #
  # @option definition [Symbol,String] :fit Controls how the tranformed image is fitted to the
  #   given width and heigth. Valid values are +:clip+ and +:crop+. The default value is +:clip+.
  #
  #   If set to +:clip+ it resizes the image to fit within the width and height boundaries without
  #   cropping or distorting the image. The resulting image is assured to match one of the
  #   constraining dimensions, while the other dimension is altered to maintain the same aspect
  #   ratio of the input image.
  #
  #   If set to +:crop+ it resizes the image to fill the given width and height and preserves the
  #   aspect ration by cropping any excess image data. The resulting image will match both the given
  #   width and height without distorting the image. The crop is done centered, i.e. the center of
  #   the image is preserved.
  #
  # @option definition [Fixnum,String] :quality Controls the output quality of lossy file formats.
  #   Applies when the format is +"jpg"+. Valid values are in the range from +0+ to +100+.
  #   The default value is +75+.
  #
  # @return [Scrivito::Binary] transformed binary
  #
  # @example Crop image to fit into 50 x 50 pixel square
  #   @obj.blob.transform(width: 50, height: 50, fit: :crop)
  #
  # @example Convert image to a low quality JPEG
  #   @obj.blob.transform(quality: 25)
  #
  # @example Combine the both transformations
  #   @obj.blob.transform(width: 50, height: 50, fit: :crop).transform(quality: 25)
  #
  def transform(definition)
    self.class.new(id, public?, (transformation_definition || {}).merge(definition), original)
  end

  #
  # Returns whether a binary is transformed.
  # @api beta
  #
  def transformed?
    !!transformation_definition
  end

  #
  # Returns the transformation original of a binary.
  #
  # @api beta
  #
  # If a binary is a result of a transformation, then its original binary is returned.
  # Otherwise +self+.
  #
  # @return [Scrivito::Binary] original binary
  #
  # @example
  #   @obj.blob.id # => "abc123"
  #   @obj.blob.original.id # => "abc123"
  #   @obj.blob.transform(width: 50).original.id # => "abc123"
  #   @obj.blob.transform(width: 50).transform(height: 50).original.id # => "abc123"
  #
  def original
    @original || self
  end

  private

  def public_content?
    !!@public_content
  end

  def headers
    CmsBackend.instance.find_blob_metadata(id, find_url('head'))
  end

  def find_url(verb)
    CmsBackend.instance.find_blob_data(id, access_type, verb, transformation_definition)['url']
  rescue ClientError => e
    case e.backend_code
    when 'binary.unprocessable.image.transform.source_too_large',
          'binary.unprocessable.image.transform.source_type_invalid'
      raise TransformationSourceError.new(e.message, e.backend_code)
    when 'binary.unprocessable.image.transform.invalid_config'
      raise TransformationDefinitionError.new(e.message, e.backend_code)
    else
      raise e
    end
  end

  def access_type
    public? ? 'public_access' : 'private_access'
  end
end

end