class S3Service
  attr_reader :bucket, :key, :policy, :signature

  # based on https://github.com/iwasrobbed/Rails3-S3-Uploader-Plupload/blob/master/app/helpers/uploads_helper.rb
  def initialize(project_id)
    spec      = Gem::Specification.find_by_name("j_platform")
    @bucket   = S3_CONFIG[:BUCKET]
    @key      = S3_CONFIG[:KEY]
    secret    = S3_CONFIG[:SECRET]

    @policy = Base64.encode64(
      "{'expiration': '#{10.hours.from_now.utc.iso8601}',
        'conditions': [
          {'bucket': '#{@bucket}'},
          {'acl': 'public-read'},
          {'success_action_status': '201'},
          ['content-length-range', 0, #{100.megabytes}],
          ['starts-with', '$key', '#{project_id}/'],
          ['starts-with', '$Content-Type', ''],
          ['starts-with', '$name', ''],
          ['starts-with', '$filename', '']
        ]
      }").gsub(/\n|\r/, '')

    @signature = Base64.encode64(
                  OpenSSL::HMAC.digest(
                    OpenSSL::Digest::Digest.new('sha1'),
                    secret, @policy)).gsub("\n","")
  end
end