base = File.dirname(__FILE__)
require File.join(base, 'libxml_loader')
require File.join(base, 's33r_exception')

module S33r
  # Represents a ListBucketResult
  # (see http://docs.amazonwebservices.com/AmazonS3/2006-03-01/)
  class BucketListing < Hash
    # Name of the bucket this listing is for.
    attr_reader :name
    
    attr_reader :delimiter, :prefix, :marker, :max_keys, :is_truncated, :common_prefixes, :contents

    # +bucket_listing_xml+ is a ListBucketResult document, as returned from a GET on a bucket.
    # +bucket+ is a Bucket instance; any objects in the listing are assigned to this bucket.
    def initialize(bucket_listing_xml)
      @common_prefixes = []
      set_listing_xml(bucket_listing_xml)
    end

    # Convert a ListBucketResult XML document into an object representation.
    def set_listing_xml(bucket_listing_xml)
      begin
        parse_listing(bucket_listing_xml)
      rescue
        message = "Cannot create bucket listing from supplied XML"
        message += " (was nil)" if bucket_listing_xml.nil?
        raise S3Exception::InvalidBucketListing, message
      end
    end

    # Parse raw XML ListBucketResponse from S3 into object instances.
    # The S3Objects are skeletons, and are not automatically populated 
    # from S3 (their @value attributes are nil). To load the data into 
    # an object, grab it from the listing and call the fetch method to 
    # pull the data down from S3.
    # 
    #-- TODO: common_prefixes
    def parse_listing(bucket_listing_xml)
      bucket_listing_xml = S33r.remove_namespace(bucket_listing_xml)
      doc = XML.get_xml_doc(bucket_listing_xml)

      prop_setter = lambda do |prop, path|
        node = doc.find("//ListBucketResult/#{path}").to_a.first
        self.send("#{prop}=", node.content) if node
      end

      # metadata
      prop_setter.call(:name, 'Name')
      prop_setter.call(:delimiter, 'Delimiter')
      prop_setter.call(:prefix, 'Prefix')
      prop_setter.call(:marker, 'Marker')
      prop_setter.call(:max_keys, 'MaxKeys')
      prop_setter.call(:is_truncated, 'IsTruncated')

      # contents
      doc.find('//Contents').to_a.each do |node|
        obj = S3Object.from_xml_node(node)
        # Add to the contents for the bucket
        self[obj.key] = obj
      end
    end

    # Setters which perform some type casts and normalisation.
    private
    def name=(val); @name = string_prop_normalise(val); end
    def prefix=(val); @prefix = string_prop_normalise(val); end
    def delimiter=(val); @delimiter = string_prop_normalise(val); end
    def marker=(val); @marker = string_prop_normalise(val); end
    def max_keys=(val); @max_keys = val.to_i; end
    def is_truncated=(val); @is_truncated = ('true' == val || true == val || 'True' == val); end

    # normalise string properties:
    # if value for XML element is nil, set property to empty string
    def string_prop_normalise(val)
      val = '' if val.nil?
      val
    end

  end
end