module Scrivito

# @api public
# The Binary class represents the data stored in a binary attribute of an {Scrivito::BasicObj Obj}
# or a {Scrivito::BasicWidget Widget}.
class Binary
  attr_reader :id, :transformation_definition, :obj_id

  def self.assert_valid_options(options)
    options.each_pair do |key, value|
      raise ArgumentError, "#{key} cannot be blank" if value.blank?
    end
  end

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

  #
  # @api public
  #
  # Uploads a local file to the CMS.
  #
  # @param file_or_path [File, String] the file to be uploaded or the path of the file to be uploaded.
  # @param options [Hash]
  # @option options [String] filename the desired filename. Defaults to the name of the given file.
  # @option options [String] content_type the desired content type. By default, the content type is
  #   calculated based on the extension of the filename.
  #
  # @return [Scrivito::FutureBinary] the returned object should be inserted into the binary field
  #   of an {Scrivito::BasicObj Obj} or {Scrivito::BasicWidget Widget}.
  #
  # @raise ArgumentError if given +filename+ or +content_type+ is blank.
  #
  # @example Upload a single file
  #   @obj.update(blob: Scrivito::Binary.upload("./kitten.jpg"))
  #
  #   # Is equivalent to
  #   @obj.update(blob: File.new("./kitten.jpg"))
  #
  # @example Upload a file with a different +filename+ and +content_type+
  #   @obj.update(blob: Scrivito::Binary.upload("./rick_astley",
  #     filename: "ufo_landing.m4v", content_type: "video/mp4"))
  #
  def self.upload(file_or_path, options = {})
    assert_valid_options(options)
    FutureBinary.new(options.reverse_merge(
      filename: File.basename(file_or_path),
      file_to_upload: file_or_path.is_a?(File) ? file_or_path : File.new(file_or_path)
    ))
  end

  #
  # @api public
  #
  # Create a copy of this {Scrivito::Binary Binary} with a different filename and/or content type.
  #
  # @param options [Hash]
  # @option options [String] filename the desired filename. Defaults to the +filename+ of the
  #   original binary.
  # @option options [String] content_type the desired content type. By default, the content type is
  #   calculated based on the extension of the filename.
  #
  # @return [Scrivito::FutureBinary] the returned object should be inserted into the binary field
  #   of an {Scrivito::BasicObj Obj} or {Scrivito::BasicWidget Widget}.
  #
  # @raise ArgumentError if given +filename+ or +content_type+ is blank.
  #
  # @example Change +filename+ and +content_type+ of an existing binary. Binary content remains the same.
  #   @obj.update(blob: @obj.blob.copy(filename: "cute_kitten.jpg", content_type: "video/mp4"))
  #
  def copy(options = {})
    self.class.assert_valid_options(options)
    FutureBinary.new(options.reverse_merge(filename: self.filename, id_to_copy: id))
  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 The URL is calculated on demand, i.e. if the URL has not been cached yet,
  #   this method calls the Scrivito API to retrieve the URL.
  #   If you want to link to a Binary, consider using {Scrivito::ControllerHelper#scrivito_url}
  #   instead. This is generally much faster,
  #   as it performs the Scrivito API call asynchronously.
  #
  # @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
    blob_data = CmsBackend.find_blob_data(id, access_type, 'get',
      transformation_definition: transformation_definition)
    blob_data['url']
  rescue ClientError => e
    case e.backend_code
    when /\Abinary\.unprocessable\.image\.transform\.source\./
      raise TransformationSourceError.new(e.message, e.backend_code)
    when 'binary.unprocessable.image.transform.config.invalid'
      raise TransformationDefinitionError.new(e.message, e.backend_code)
    else
      raise e
    end
  end

  def url_from_cache
    blob_data = CmsBackend.find_blob_data_from_cache(id, access_type, 'get',
      transformation_definition: 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 the 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
  #
  # @raise [Scrivito::ScrivitoError] If the binary is the result of a transformation.
  def content_type
    raise_field_not_available('Content type') if transformed?
    meta_data[:content_type]
  end

  # @api public
  # The length of this binary data, in bytes.
  # @return [Integer] number of bytes
  #
  # @raise [Scrivito::ScrivitoError] If the binary is the result of a transformation.
  def content_length
    raise_field_not_available('Content length') if transformed?
    meta_data[:content_length]
  end

  #
  # Use this method to transform images, i.e. to scale down large images or to generate thumbnails of images.
  # Only applicable if this {Scrivito::Binary} is an image.
  #
  # @api public
  #
  # This method does not change the binary. Instead, it returns a copy of it,
  # transformed using the +definition+.
  #
  # If the original binary has already been transformed, 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} does not
  # trigger any calculation. The calculation is triggered only when data is accessed, for example
  # via {Scrivito::Binary#url}.
  #
  # Note that transforming images is slow and therefore should not be carried out inside a
  # request. The {ScrivitoHelper#scrivito_image_tag #scrivito_image_tag} and
  # {Scrivito::ControllerHelper#scrivito_path #scrivito_path} helpers transform images
  # asynchronously and don't place additional load onto requests.
  #
  # @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 has been specified, the other dimension is calculated automatically to
  #   preserve the aspect ratio of the input image.
  #
  #   If the +fit+ parameter is set to +:resize+, then either the actual output width or the output
  #   height may be less than the amount you specified to prevent distortion.
  #
  #   If neither +width+ nor +height+ is given, the width and height of the input image
  #   is used.
  #
  #   The maximum size of the output image is defined as width + height = 4096 pixels. The given
  #   width and height may be adjusted to accommodate this limit. The output image will never be
  #   larger than the source image, i.e. the given width and height may be adjusted to prevent the
  #   dimensions of the output image from exceeding those of the input image.
  #
  #   If 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 has been specified, the other dimension is calculated automatically to
  #   preserve the aspect ratio of the input image.
  #
  #   If the +fit+ parameter is set to +:resize+, then either the actual output width or the output
  #   height may be less than the amount you specified to prevent distortion.
  #
  #   If neither +width+ nor +height+ is given, the width and height of the input image
  #   is used.
  #
  #   The maximum size of the output image is defined as width + height = 4096 pixels. The given
  #   width and height may be adjusted to accommodate this limit. The output image will never be
  #   larger than the source image, i.e. the given width and height may be adjusted to prevent the
  #   dimensions of the output image from exceeding those of the input image.
  #
  #   If the given width and height are adjusted, the aspect ratio is preserved.
  #
  # @option definition [Symbol,String] :fit Controls how the transformed image is fitted to the
  #   given width and height. Valid values are +:resize:+ and +:crop+. The default value is
  #   +:resize+.
  #
  #   If set to +:resize+, the image is resized so as 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+, the image is resized so as to fill the given width and height, preserving
  #   the aspect ratio by cropping any excess image data. The resulting image will match both the given
  #   width and height without distorting the image. Cropping is done centered by default,
  #   i.e. the center of the image is preserved. The area to preserve can be configured using
  #   the +crop+ parameter.
  #
  # @option definition [Fixnum,String] :quality Controls the output quality of lossy file formats.
  #   Applies if the format is +"jpg"+. Valid values are in the range from +0+ to +100+.
  #   The default value is +75+.
  #
  # @option definition [Symbol, String] :crop Controls the area to preserve when cropping and
  #   is only applicable if +fit+ is set to +crop+. Valid values are +center+, +top+, +left+,
  #   +right+, and +bottom+.
  #
  #   For example, setting +crop+ to +left+ means that the left part
  #   of the image will be preserved when cropping, i.e. if necessary, cropping cuts away the
  #   right side of the image
  #
  # @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 two transformations.
  #   @obj.blob.transform(width: 50, height: 50, fit: :crop).transform(quality: 25)
  #
  # @see Scrivito::Configuration
  # @see ScrivitoHelper#scrivito_image_tag
  #
  def transform(definition)
    self.class.new(id, public?,
      transformation_definition: (transformation_definition || {}).merge(definition),
      original: original,
      obj_id: obj_id)
  end

  #
  # Returns whether a binary has been transformed.
  # @api public
  #
  def transformed?
    !!transformation_definition
  end

  #
  # Returns the original version of a transformed binary.
  #
  # @api public
  #
  # If a binary is the result of a transformation, the original version of the binary is returned.
  # Otherwise +self+.
  #
  # @return [Scrivito::Binary] original binary
  def original
    @original || self
  end

  # @api public
  #
  # Returns the meta data for the given binary.
  #
  # @return [Scrivito::MetaDataCollection] meta data collection
  #
  # @see Scrivito::MetaDataCollection List of available meta data attributes.
  #
  # @example Accessing meta data
  #   @obj.blob.meta_data['width'] # => 150
  #   @obj.blob.meta_data['content_type'] # => 'image/jpeg'
  #
  # @raise [Scrivito::ScrivitoError] If the binary is the result of a transformation.
  def meta_data
    raise_field_not_available('Meta data') if transformed?

    @meta_data ||= begin
      deserialized_meta_data = deserialize_meta_data(CmsBackend.find_binary_meta_data(id))
      MetaDataCollection.new(deserialized_meta_data)
    end
  end

  private

  def raise_field_not_available(field_name)
    raise ScrivitoError, "#{field_name} is not available for transformed images"
  end

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

  def deserialize_meta_data(raw_meta_data)
    deserialized_meta_data = {}
    raw_meta_data.each_pair do |key, (type, value)|
      deserialized_meta_data[key] = case type
                                    when 'date' then DateConversion.deserialize_from_backend(value)
                                    when 'number' then value.to_i
                                    else value
                                    end
    end
    deserialized_meta_data
  end
end

end