module Neo4j
  module Core
    # Stolen from http://as.rubyonrails.org/classes/HashWithIndifferentAccess.html
    # We don't want to depend on active support
    class HashWithIndifferentAccess < Hash
      # Always returns true, so that <tt>Array#extract_options!</tt> finds members of this class.
      def extractable_options?
        true
      end

      def with_indifferent_access
        dup
      end

      def nested_under_indifferent_access
        self
      end

      def initialize(constructor = {})
        if constructor.is_a?(Hash)
          super()
          update(constructor)
        else
          super(constructor)
        end
      end

      def default(key = nil)
        if key.is_a?(Symbol) && include?(key = key.to_s)
          self[key]
        else
          super
        end
      end

      def self.new_from_hash_copying_default(hash)
        new(hash).tap do |new_hash|
          new_hash.default = hash.default
        end
      end

      alias_method :regular_writer, :[]= unless method_defined?(:regular_writer)
      alias_method :regular_update, :update unless method_defined?(:regular_update)

      # Assigns a new value to the hash:
      #
      #   hash = HashWithIndifferentAccess.new
      #   hash[:key] = "value"
      #
      def []=(key, value)
        regular_writer(convert_key(key), convert_value(value))
      end

      alias_method :store, :[]=

      # Updates the instantized hash with values from the second:
      #
      #   hash_1 = HashWithIndifferentAccess.new
      #   hash_1[:key] = "value"
      #
      #   hash_2 = HashWithIndifferentAccess.new
      #   hash_2[:key] = "New Value!"
      #
      #   hash_1.update(hash_2) # => {"key"=>"New Value!"}
      #
      def update(other_hash)
        if other_hash.is_a? HashWithIndifferentAccess
          super(other_hash)
        else
          other_hash.each_pair { |key, value| regular_writer(convert_key(key), convert_value(value)) }
          self
        end
      end

      alias_method :merge!, :update

      # Checks the hash for a key matching the argument passed in:
      #
      #   hash = HashWithIndifferentAccess.new
      #   hash["key"] = "value"
      #   hash.key? :key  # => true
      #   hash.key? "key" # => true
      #
      def key?(key)
        super(convert_key(key))
      end

      alias_method :include?, :key?
      alias_method :has_key?, :key?
      alias_method :member?, :key?

      # Fetches the value for the specified key, same as doing hash[key]
      def fetch(key, *extras)
        super(convert_key(key), *extras)
      end

      # Returns an array of the values at the specified indices:
      #
      #   hash = HashWithIndifferentAccess.new
      #   hash[:a] = "x"
      #   hash[:b] = "y"
      #   hash.values_at("a", "b") # => ["x", "y"]
      #
      def values_at(*indices)
        indices.collect { |key| self[convert_key(key)] }
      end

      # Returns an exact copy of the hash.
      def dup
        self.class.new(self).tap do |new_hash|
          new_hash.default = default
        end
      end

      # Merges the instantized and the specified hashes together, giving precedence to the values from the second hash.
      # Does not overwrite the existing hash.
      def merge(hash)
        dup.update(hash)
      end

      # Performs the opposite of merge, with the keys and values from the first hash taking precedence over the second.
      # This overloaded definition prevents returning a regular hash, if reverse_merge is called on a <tt>HashWithDifferentAccess</tt>.
      def reverse_merge(other_hash)
        super self.class.new_from_hash_copying_default(other_hash)
      end

      def reverse_merge!(other_hash)
        replace(reverse_merge(other_hash))
      end

      # Removes a specified key from the hash.
      def delete(key)
        super(convert_key(key))
      end

      def stringify_keys!
        self
      end

      def stringify_keys
        dup
      end
      #      undef :symbolize_keys!
      def symbolize_keys
        to_hash.symbolize_keys
      end

      def to_options!
        self
      end

      # Convert to a Hash with String keys.
      def to_hash
        Hash.new(default).merge!(self)
      end

      protected

      def convert_key(key)
        key.is_a?(Symbol) ? key.to_s : key
      end

      def convert_value(value)
        if value.is_a? Hash
          value # .nested_under_indifferent_access
        elsif value.is_a?(Array)
          value.dup.replace(value.map { |e| convert_value(e) })
        else
          value
        end
      end
    end
  end
end