require 'tmpdir'

module CloudCrowd

  # The AssetStore provides a common API for storing files and returning URLs 
  # that can access them. In production this will be S3 but in development 
  # it may be the filesystem.
  #
  # You shouldn't need to use the AssetStore directly -- Action's +download+
  # and +save+ methods use it behind the scenes.
  class AssetStore
    include FileUtils
    
    # Creating an AssetStore will determine wether to save private or public
    # files on S3, depending on the value of <tt>use_s3_authentication</tt> in 
    # <tt>config.yml</tt>.
    def initialize
      @use_auth = CloudCrowd.config[:use_s3_authentication]
      mkdir_p temp_storage_path unless File.exists? temp_storage_path
    end
    
    # Get the path to CloudCrowd's temporary local storage. All actions run
    # in subdirectories of this.
    def temp_storage_path
      "#{Dir.tmpdir}/cloud_crowd_tmp"
    end
    
    # Copy a finished file from our local storage to S3. Save it publicly unless
    # we're configured to use S3 authentication.
    def save(local_path, save_path)
      ensure_s3_connection
      permission = @use_auth ? 'private' : 'public-read'
      @bucket.put(save_path, File.open(local_path), {}, permission)
    end
    
    # Cleanup all S3 files for a job that's been completed and retrieved.
    def cleanup_job(job)
      ensure_s3_connection
      @bucket.delete_folder("#{job.action}/job_#{job.id}")
    end
    
    # Return the S3 public URL for a finshed file. Authenticated links expire
    # after one day by default.
    def url(save_path)
      @use_auth ? @s3.interface.get_link(@bucket, save_path) :
                  @bucket.key(save_path).public_link
    end
    
    private
    
    # Unused for the moment. Think about using the filesystem instead of S3
    # in development.
    def save_to_filesystem(local_path, save_path)
      save_path = File.join("/tmp/cloud_crowd_storage", save_path)
      save_dir = File.dirname(save_path)
      mkdir_p save_dir unless File.exists? save_dir
      cp(local_path, save_path)
    end
    
    # Workers, through the course of many WorkUnits, keep around an AssetStore.
    # Ensure we have a persistent S3 connection after first use.
    def ensure_s3_connection
      unless @s3 && @bucket
        params = {:port => 80, :protocol => 'http'}
        @s3 = RightAws::S3.new(CloudCrowd.config[:aws_access_key], CloudCrowd.config[:aws_secret_key], params)
        @bucket = @s3.bucket(CloudCrowd.config[:s3_bucket], true)
      end
    end
  
  end

end