# encoding: utf-8
require 'mongo'

module CarrierWave
  module Storage

    ##
    # The GridFS store uses MongoDB's GridStore file storage system to store files
    #
    # There are two ways of configuring the GridFS connection. Either you create a
    # connection or you reuse an existing connection.
    #
    # Creating a connection looks something like this:
    # 
    #     CarrierWave.configure do |config|
    #       config.storage = :grid_fs
    #       config.grid_fs_host = "your-host.com"
    #       config.grid_fs_port = "27017"
    #       config.grid_fs_database = "your_dbs_app_name"
    #       config.grid_fs_username = "user"
    #       config.grid_fs_password = "verysecret"
    #       config.grid_fs_access_url = "/images"
    #     end
    #
    #   In the above example your documents url will look like:
    #   
    #      http://your-app.com/images/:document-identifier-here
    #
    # When you already have a Mongo connection object (for example through Mongoid)
    # you can also reuse this connection:
    #
    #     CarrierWave.configure do |config|
    #       config.storage = :grid_fs
    #       config.grid_fs_connection = Mongoid.database
    #       config.grid_fs_access_url = "/images"
    #     end
    #
    class GridFS < Abstract

      class File

        def initialize(uploader, path)
          @path = path
          @uploader = uploader
        end

        def path
          nil
        end

        def url
          unless @uploader.grid_fs_access_url
            nil
          else
            [@uploader.grid_fs_access_url, @path].join("/")
          end
        end

        def read
          grid.open(@path, 'r').data
        end

        def write(file)
          grid.open(@uploader.store_path, 'w', :content_type => file.content_type) do |f| 
            f.write(file.read)
          end
        end

        def delete
          grid.delete(@path)
        end

        def content_type
          grid.open(@path, 'r').content_type
        end
        
        def file_length
          grid.open(@path, 'r').file_length
        end

      protected

        def database
          @connection ||= @uploader.grid_fs_connection || begin
            host = @uploader.grid_fs_host
            port = @uploader.grid_fs_port
            database = @uploader.grid_fs_database
            username = @uploader.grid_fs_username
            password = @uploader.grid_fs_password
            db = Mongo::Connection.new(host, port).db(database)
            db.authenticate(username, password) if username && password
            db
          end
        end
        
        def grid
          @grid ||= Mongo::GridFileSystem.new(database)
        end

      end

      ##
      # Store the file in MongoDB's GridFS GridStore
      #
      # === Parameters
      #
      # [file (CarrierWave::SanitizedFile)] the file to store
      #
      # === Returns
      #
      # [CarrierWave::SanitizedFile] a sanitized file
      #
      def store!(file)
        stored = CarrierWave::Storage::GridFS::File.new(uploader, uploader.store_path)
        stored.write(file)
        stored
      end

      ##
      # Retrieve the file from MongoDB's GridFS GridStore
      #
      # === Parameters
      #
      # [identifier (String)] the filename of the file
      #
      # === Returns
      #
      # [CarrierWave::Storage::GridFS::File] a sanitized file
      #
      def retrieve!(identifier)
        CarrierWave::Storage::GridFS::File.new(uploader, uploader.store_path(identifier))
      end

    end # File
  end # Storage
end # CarrierWave