require 'active_support/core_ext/array/extract_options'
class Array #:nodoc:
  include ActiveSupport::CoreExtensions::Array::ExtractOptions
end

class Array

  # Return all but the last  element
  # This will be [] for both an empty array and a length-1 array
  def most() self[0..-2] end

  # Return all but the first element.
  # This will be nil for an empty array and [] for a length-1 array
  def rest() self[1..-1] end

  # 'Un'-zip()s an array.  Returns an array of arrays: the first array has the
  # first element of each member, the second array has the second element of
  # each member, and so on.  Returns as many arrays as the first element in self
  # and inserts a nil where the member array wasn't long enough.
  #
  # foo, bar = foo.zip(bar).unzip should leave foo and bar with the same values
  # if foo and bar have the same length.
  #
  # Will fail on a not-array-of-arrays.
  def unzip()
    # An array of empty arrays, one for each vertical slot
    vslices = self[0].map{ Array.new }
    self.each do |hslice|
      # push the elements of each array onto its slice.
      vslices.zip(hslice).map{|vslice,h_el| vslice << h_el }
    end
    vslices
  end

  # Return a random element of this array.
  def random_element
    self[rand(self.length) - 1]
  end

  # convert an assoc (list of [key, val, [...]]'s) to a hash
  def to_openstruct
    mapped = {}
    each{ |key,value| mapped[key] = value.to_openstruct }
    OpenStruct.new(mapped)
  end

  # Return the elements of this array in a pretty-printed string,
  # inserting +final_string+ between the last two items.
  #
  #   >> [:one, :two, :three].quote_items_with "or"
  #   `one', `two', or `three'
  #
  def quote_items_with final_string = nil
    string_items = self.map { |item| "`" + item.to_s + "'" }
    case string_items.length
    when 0
      ""
    when 1
      string_items.first
    when 2
      if final_string then
        string_items.join(" #{final_string} ")
      else
        string_items.join(', ')
      end
    else
      string = string_items[0,string_items.length - 1].join ', '
      if final_string then
        string += ', ' + final_string + ' ' + string_items.last
      else
        string += ', ' + string_items.last
      end
      string
    end
  end

  def in_groups_of(number, fill_with = nil, &block)
    require 'enumerator'
    collection = dup
    collection << fill_with until collection.size.modulo(number).zero?
    collection.each_slice(number, &block)
  end

  # Returns a single hash containing the merge of all hashes in this
  # array.  This is useful when dealing with badly written YAML files.
  # Only merges hashes at depth zero, i.e. - this isn't recursive.
  def merge_hashes
    merged_hash = {}
    self.each do |element|
      merged_hash.merge!(element) if element.is_a?(Hash)
    end
    merged_hash
  end

  # Recurses through the elements of this Array collecting all String
  # or Symbol "terminal" nodes.
  def terminals &block
    terminals = []
    each do |element|
      if element.respond_to? :terminals then
        terminals += element.terminals
      else
        terminals << element
      end
    end
    terminals.map! {|terminal| yield terminal } if block
    terminals
  end

  # Dump the data in this array to the resource at the given +uri+.
  def dump uri
    IMW.open(uri, :mode => 'w').dump(self)
  end

end