require 'uri'

module Pageflow
  class ZencoderAttachment
    cattr_accessor :default_options
    self.default_options = {
      path: '/:zencoder_asset_version/:host/:class/:id_partition/:filename',
      url: ':zencoder_protocol//:zencoder_host_alias:zencoder_path',
      hls_url: ':zencoder_protocol//:zencoder_hls_host_alias:zencoder_path',
      hls_origin_url: ':zencoder_protocol//:zencoder_hls_origin_host_alias:zencoder_path'
    }

    attr_reader :file_name_pattern, :instance, :options, :styles

    def initialize(instance, file_name_pattern, options = {})
      @instance = instance
      @file_name_pattern = file_name_pattern
      @options = options.reverse_merge(default_options)

      @styles = {}
    end

    def format
      options[:format]
    end

    def dir_name
      File.dirname(path)
    end

    def base_name_pattern
      File.basename(file_name_pattern)
    end

    def original_filename
      [file_name_pattern.gsub('{{number}}', '0'), options[:format]].compact * '.'
    end

    def path
      Paperclip::Interpolations.interpolate(options[:path], self, 'default')
    end

    def url(url_options = {})
      ensure_default_protocol(interpolate(url_pattern(url_options)),
                              url_options)
    end

    def url_relative_to(attachment)
      dir_path = File.dirname(URI.parse(attachment.url).path)

      unless URI.parse(url).path.start_with?(dir_path)
        raise("Could not generate relative url for #{url} based on #{attachment.url}.")
      end

      url.split("#{dir_path}/", 2).last
    end

    private

    def ensure_default_protocol(url, url_options)
      url =~ %r'^//' ? [url_options[:default_protocol], url].compact.join(':') : url
    end

    def url_pattern(url_options)
      base_url(url_options) + suffix(url_options)
    end

    def base_url(url_options)
      case (url_options[:host] || options[:host])
      when :hls
        options[:hls_url]
      when :hls_origin
        options[:hls_origin_url]
      else
        options[:url]
      end
    end

    def suffix(url_options)
      [
        options[:url_suffix],
        url_options[:unique_id] ? "?n=#{url_options[:unique_id]}" : nil
      ].compact.join
    end

    def interpolate(url)
      Paperclip::Interpolations.interpolate(url, self, 'default')
    end
  end
end