# hx/path - path selectors
#
# Copyright (c) 2009-2010 MenTaLguY <mental@rydia.net>
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

module Hx
module Path

module Selector
  def prefix ; "" ; end
  def suffix ; "" ; end
  def regexp ; nil ; end
  def remaining_suffix(prefix_consumed) ; suffix ; end

  def accept?(path)
    raise NotImplementedError, "#{self.class}#accept? not implemented"
  end

  def |(other)
    Disjunction.new(self, other)
  end

  def &(other)
    Conjunction.new(self, other)
  end

  def ~()
    Negation.new(self)
  end
end

class All
  include Selector

  REGEXP = Regexp.new("^.*$")

  def regexp ; REGEXP ; end
  def accept?(path) ; true ; end
end

ALL = All.new

class Literal
  include Selector

  attr_reader :value
  alias prefix value

  def initialize(value)
    @value = value
    @regexp = nil
  end

  def remaining_suffix(prefix_consumed)
    @value[prefix_consumed..-1]
  end

  def regexp
    @regexp ||= Regexp.new("^#{Regexp.quote(@value)}$")
  end

  def accept?(path)
    @value == path
  end
end

def self.parse_pattern(pattern_string)
  tokens = []
  pattern_string.scan(/(\*\*?|[^*]+)/) do |token,|
    tokens << case token
              when "**"; :doublestar
              when "*"; :star
              else; token
              end
  end
  prefix = tokens.first
  if tokens.size == 1 and String === prefix
    Literal.new(prefix)
  else
    prefix = "" unless String === prefix
    suffix = tokens.last
    suffix = "" unless String === suffix
    regexp = Regexp.new("^#{tokens.map { |token|
      case token
      when :doublestar; '.*'
      when :star; '[^/]*'
      else; Regexp.quote(token)
      end
    }}$")
    Pattern.new(regexp, prefix, suffix)
  end
end

def self.literal(literal_string)
  Literal.new(literal_string)
end

class Pattern
  include Selector

  attr_reader :prefix
  attr_reader :suffix
  attr_reader :regexp

  def initialize(regexp, prefix, suffix)
    @regexp = regexp
    @prefix = prefix
    @suffix = suffix
  end

  def accept?(path)
    !!(@regexp.match(path))
  end
end

module Connective
  include Selector

  attr_reader :prefix
  attr_reader :suffix

  def initialize(*selectors)
    @selectors = selectors
    prefixes = selectors.map { |s| s.prefix }
    prefix_length = (prefixes.first || "").length
    prefixes.each_cons(2) do |a, b|
      prefix_length.downto(0) do |length|
        prefix_length = length
        break if a[0...length] == b[0...length]
      end
    end
    @prefix = prefixes.first[0...prefix_length]
    suffixes = selectors.map { |s| s.remaining_suffix(prefix_length) }
    suffix_length = (suffixes.first || "").length
    suffixes.each_cons(2) do |a, b|
      suffix_length.downto(0) do |length|
        suffix_length = length
        break if a[-length..-1] == b[-length..-1]
      end
    end
    @suffix = suffixes.first[-suffix_length..-1]
  end
end

class Conjunction
  include Connective

  def accept?(path)
    @selectors.all? { |s| s.accept? path }
  end
end

class Disjunction
  include Connective

  attr_reader :regexp

  def initialize(*selectors)
    super
    regexps = @selectors.map { |s| s.regexp }
    if regexps.all?
      @regexp = Regexp.union(*regexps)
    else
      @regexp = nil
    end
  end

  def accept?(path)
    if @regexp
      !!@regexp.match(path)
    else
      @selectors.any? { |s| s.accept? path }
    end
  end
end

class Negation
  include Selector

  def initialize(selector)
    @selector = selector
  end

  def accept?(path)
    not @selector.accept?(path)
  end
end

end
end