# borrowed from http://github.com/wycats/merb-extlib/raw/master/lib/merb-extlib/mash.rb
# MIT-Licensed

# This class has dubious semantics and we only have it so that people can write
# params[:key] instead of params['key'].
module Grendel
  class Mash < Hash

    # @param constructor<Object>
    #   The default value for the mash. Defaults to an empty hash.
    #
    # @details [Alternatives]
    #   If constructor is a Hash, a new mash will be created based on the keys of
    #   the hash and no default value will be set.
    def initialize(constructor = {})
      if constructor.is_a?(Hash)
        super()
        update(constructor)
      else
        super(constructor)
      end
    end

    # @param key<Object> The default value for the mash. Defaults to nil.
    #
    # @details [Alternatives]
    #   If key is a Symbol and it is a key in the mash, then the default value will
    #   be set to the value matching the key.
    def default(key = nil)
      if key.is_a?(Symbol) && include?(key = key.to_s)
        self[key]
      else
        super
      end
    end

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

    # @param key<Object> The key to set.
    # @param value<Object>
    #   The value to set the key to.
    #
    # @see Mash#convert_key
    # @see Mash#convert_value
    def []=(key, value)
      regular_writer(convert_key(key), convert_value(value))
    end

    # @param other_hash<Hash>
    #   A hash to update values in the mash with. The keys and the values will be
    #   converted to Mash format.
    #
    # @return <Mash> The updated mash.
    def update(other_hash)
      other_hash.each_pair { |key, value| regular_writer(convert_key(key), convert_value(value)) }
      self
    end

    alias_method :merge!, :update

    # @param key<Object> The key to check for. This will be run through convert_key.
    #
    # @return <TrueClass, FalseClass> True if the key exists in the mash.
    def key?(key)
      super(convert_key(key))
    end

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

    # @param key<Object> The key to fetch. This will be run through convert_key.
    # @param *extras<Array> Default value.
    #
    # @return <Object> The value at key or the default value.
    def fetch(key, *extras)
      super(convert_key(key), *extras)
    end

    # @param *indices<Array>
    #   The keys to retrieve values for. These will be run through +convert_key+.
    #
    # @return <Array> The values at each of the provided keys
    def values_at(*indices)
      indices.collect {|key| self[convert_key(key)]}
    end

    # @return <Mash> A duplicate of this mash.
    def dup
      Mash.new(self)
    end

    # @param hash<Hash> The hash to merge with the mash.
    #
    # @return <Mash> A new mash with the hash values merged in.
    def merge(hash)
      self.dup.update(hash)
    end

    # @param key<Object>
    #   The key to delete from the mash.\
    def delete(key)
      super(convert_key(key))
    end

    # Used to provide the same interface as Hash.
    #
    # @return <Mash> This mash unchanged.
    def stringify_keys!; self end

    # @return <Hash> The mash as a Hash with string keys.
    def to_hash
      Hash.new(default).merge(self)
    end

    protected
    # @param key<Object> The key to convert.
    #
    # @param <Object>
    #   The converted key. If the key was a symbol, it will be converted to a
    #   string.
    #
    # @api private
    def convert_key(key)
      key.kind_of?(Symbol) ? key.to_s : key
    end

    # @param value<Object> The value to convert.
    #
    # @return <Object>
    #   The converted value. A Hash or an Array of hashes, will be converted to
    #   their Mash equivalents.
    #
    # @api private
    def convert_value(value)
      case value
      when Hash
        converted = Mash.new(value)
        converted.default = value.default
        converted
      when Array
        value.collect { |e| convert_value(e) }
      else
        value
      end
    end
  end
end