metadata.rb in ezid-client-0.5.0

- old
+ new

@@ -1,18 +1,18 @@
 require "delegate"
-require_relative "metadata_elements"
+require "singleton"
 
 module Ezid
   #
   # EZID metadata collection for an identifier
   #
+  # @note Although this API is not private, its direct use is discouraged.
+  #   Instead use the metadata element accessors through Ezid::Identifier.
   # @api public
   #
   class Metadata < SimpleDelegator
 
-    include MetadataElements
-
     # EZID metadata field/value separator
     ANVL_SEPARATOR = ": "
 
     ELEMENT_VALUE_SEPARATOR = " | "
 
@@ -23,11 +23,11 @@
     # Characters to escape in element names on output to EZID
     # @see http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
     ESCAPE_NAMES_RE = /[%:\r\n]/
 
     # Character sequence to unescape from EZID
-    # http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
+    # @see http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
     UNESCAPE_RE = /%\h\h/
 
     # A comment line
     COMMENT_RE = /^#.*(\r?\n)?/ 
 
@@ -35,10 +35,103 @@
     LINE_CONTINUATION_RE = /\r?\n\s+/
 
     # A line ending
     LINE_ENDING_RE = /\r?\n/
     
+    # A metadata element
+    Element = Struct.new(:name, :writer)
+    
+    # Metadata profiles
+    PROFILES = {
+      "dc"       => %w( creator title publisher date type ).freeze,
+      "datacite" => %w( creator title publisher publicationyear resourcetype ).freeze,
+      "erc"      => %w( who what when ).freeze,
+      "crossref" => [].freeze
+      }.freeze
+
+    # EZID reserved metadata elements that have time values
+    # @see http://ezid.cdlib.org/doc/apidoc.html#internal-metadata
+    RESERVED_TIME_ELEMENTS = %w( _created _updated )
+
+    # EZID reserved metadata elements that are read-only
+    # @see http://ezid.cdlib.org/doc/apidoc.html#internal-metadata
+    RESERVED_READONLY_ELEMENTS = %w( _owner _ownergroup _shadows _shadowedby _datacenter _created _updated )
+
+    # EZID reserved metadata elements that may be set by clients
+    # @see http://ezid.cdlib.org/doc/apidoc.html#internal-metadata
+    RESERVED_READWRITE_ELEMENTS = %w( _coowners _target _profile _status _export _crossref )
+
+    # All EZID reserved metadata elements
+    # @see http://ezid.cdlib.org/doc/apidoc.html#internal-metadata
+    RESERVED_ELEMENTS = RESERVED_READONLY_ELEMENTS + RESERVED_READWRITE_ELEMENTS
+
+    # Metadata element registry
+    class ElementRegistry < SimpleDelegator
+      include Singleton
+
+      def initialize
+        super(Hash.new)
+      end
+
+      def readers
+        keys
+      end
+
+      def writers
+        keys.select { |k| self[k].writer }.map(&:to_s).map { |k| k.concat("=") }.map(&:to_sym)
+      end
+    end
+
+    def self.initialize!
+      register_elements
+      define_element_accessors
+    end
+
+    def self.elements
+      ElementRegistry.instance
+    end
+
+    def self.register_elements
+      register_profile_elements
+      register_reserved_elements
+      elements.freeze
+    end
+
+    def self.define_element_accessors
+      elements.each do |accessor, element|
+        define_method(accessor) { reader(element.name) }
+      
+        if element.writer
+          define_method("#{accessor}=") { |value| writer(element.name, value) }
+        end
+      end
+    end
+
+    def self.register_element(accessor, element, opts={})
+      writer = opts.fetch(:writer, true)
+      elements[accessor] = Element.new(element, writer).freeze
+    end
+
+    def self.register_profile_elements
+      PROFILES.each do |profile, profile_elements|
+        profile_elements.each do |element|
+          register_element("#{profile}_#{element}".to_sym, "#{profile}.#{element}")
+        end
+        register_element(profile.to_sym, profile) unless profile == "dc"
+      end
+    end
+
+    def self.register_reserved_elements
+      RESERVED_ELEMENTS.each do |element|
+        accessor = ((element == "_crossref") ? element : element.sub("_", "")).to_sym
+        register_element(accessor, element, writer: RESERVED_READWRITE_ELEMENTS.include?(element))
+      end
+    end
+
+    private_class_method :register_element, :register_elements, :register_reserved_elements, 
+                         :register_profile_elements, :define_element_accessors
+
     def initialize(data={})
       super(coerce(data))
     end
 
     # Output metadata in EZID ANVL format
@@ -54,61 +147,76 @@
       to_anvl
     end
 
     private
 
-    # Coerce data into a Hash of elements
-    def coerce(data)
-      data.to_h
-    rescue NoMethodError
-      coerce_string(data)
-    end
+      def reader(element)
+        value = self[element]
+        if RESERVED_TIME_ELEMENTS.include?(element)
+          time = value.to_i
+          value = (time == 0) ? nil : Time.at(time).utc
+        end
+        value
+      end
 
-    # Escape elements hash keys and values
-    def escape_elements(hsh)
-      hsh.each_with_object({}) do |(n, v), memo|
-        memo[escape_name(n)] = escape_value(v)
+      def writer(element, value)
+        self[element] = value
       end
-    end
 
-    # Escape an element name
-    def escape_name(n)
-      escape(ESCAPE_NAMES_RE, n)
-    end
+      # Coerce data into a Hash of elements
+      def coerce(data)
+        data.to_h
+      rescue NoMethodError
+        coerce_string(data)
+      end
 
-    # Escape an element value
-    def escape_value(v)
-      escape(ESCAPE_VALUES_RE, v)
-    end
+      # Escape elements hash keys and values
+      def escape_elements(hsh)
+        hsh.each_with_object({}) do |(n, v), memo|
+          memo[escape_name(n)] = escape_value(v)
+        end
+      end
 
-    # Escape string for sending to EZID host
-    # @see http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
-    # @param re [Regexp] the regular expression to match for escaping
-    # @param s [String] the string to escape
-    # @return [String] the escaped string
-    def escape(re, s)
-      s.gsub(re) { |m| URI.encode_www_form_component(m.force_encoding(Encoding::UTF_8)) }
-    end
+      # Escape an element name
+      def escape_name(n)
+        escape(ESCAPE_NAMES_RE, n)
+      end
 
-    # Unescape value from EZID host (or other source)
-    # @see http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
-    # @param value [String] the value to unescape
-    # @return [String] the unescaped value
-    def unescape(value)
-      value.gsub(UNESCAPE_RE) { |m| URI.decode_www_form_component(m) }
-    end
-    
-    # Coerce a string of metadata (e.g., from EZID host) into a Hash
-    # @note EZID host does not send comments or line continuations.
-    # @param data [String] the string to coerce
-    # @return [Hash] the hash of coerced data
-    def coerce_string(data)
-      data.gsub!(COMMENT_RE, "")
-      data.gsub!(LINE_CONTINUATION_RE, " ")
-      data.split(LINE_ENDING_RE).each_with_object({}) do |line, memo|
-        element, value = line.split(ANVL_SEPARATOR, 2)
-        memo[unescape(element.strip)] = unescape(value.strip)
+      # Escape an element value
+      def escape_value(v)
+        escape(ESCAPE_VALUES_RE, v)
       end
-    end
 
+      # Escape string for sending to EZID host
+      # @see http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
+      # @param re [Regexp] the regular expression to match for escaping
+      # @param s [String] the string to escape
+      # @return [String] the escaped string
+      def escape(re, s)
+        s.gsub(re) { |m| URI.encode_www_form_component(m.force_encoding(Encoding::UTF_8)) }
+      end
+
+      # Unescape value from EZID host (or other source)
+      # @see http://ezid.cdlib.org/doc/apidoc.html#request-response-bodies
+      # @param value [String] the value to unescape
+      # @return [String] the unescaped value
+      def unescape(value)
+        value.gsub(UNESCAPE_RE) { |m| URI.decode_www_form_component(m) }
+      end
+      
+      # Coerce a string of metadata (e.g., from EZID host) into a Hash
+      # @note EZID host does not send comments or line continuations.
+      # @param data [String] the string to coerce
+      # @return [Hash] the hash of coerced data
+      def coerce_string(data)
+        data.gsub!(COMMENT_RE, "")
+        data.gsub!(LINE_CONTINUATION_RE, " ")
+        data.split(LINE_ENDING_RE).each_with_object({}) do |line, memo|
+          element, value = line.split(ANVL_SEPARATOR, 2)
+          memo[unescape(element.strip)] = unescape(value.strip)
+        end
+      end
+
   end
 end
+
+Ezid::Metadata.initialize!