# encoding: utf-8
#
# This file is part of the brauser gem. Copyright (C) 2013 and above Shogun <shogun@cowtech.it>.
# Licensed under the MIT license, which can be found at http://www.opensource.org/licenses/mit-license.php.
#

module Brauser
  # A class which hold a definition of a browser, a platform or a language
  # This class represents a detection of the current user browser.
  #
  # @attribute tag
  #   @return [String|Symbol] An identifier for this definition.
  # @attribute label
  #   @return [String] A human readable label for this definition.
  # @attribute primary
  #   @return [String|Symbol|Proc] The primary matcher of this definition. Used to match browser engine, platform name and language.
  # @attribute secondary
  #   @return [String|Symbol|Proc] The secondary matcher of this definition. Used to match browser version.
  class Definition
    attr_accessor :tag, :label, :primary, :secondary

    # Creates a new definition.
    #
    # @param tag [String|Symbol] An identifier for this definition.
    # @param label [String] A human readable label for this definition.
    # @param primary [String|Symbol|Proc] The primary matcher of this definition.
    # @param secondary [String|Symbol|Proc] The secondary matcher of this definition.
    def initialize(tag = nil, label = nil, primary = nil, secondary = nil)
      self.tag = tag if tag
      self.label = label if label
      self.primary = primary if primary
      self.secondary = secondary if secondary
    end

    # Performs a match of this definition.
    #
    # @param type [Symbol] The matcher to perform. Can be `:primary` (default) or `:secondary`.
    # @param args [Array] Arguments to pass to the matcher. The first is the definition itself.
    # @return [Object|NilClass] A match if matcher succeeded, `nil` otherwise.
    def match(type, *args)
      begin
        matcher = send(type || :primary)
      rescue NoMethodError
        nil
      end

      perform_match(matcher, args[1], args)
    end

    private

    # Recognizes a browser disambiguating against another.
    #
    # @param agent [String] The agent to match.
    # @param positive_matcher [Regexp] The expression to match.
    # @param negative_matcher [Regexp] The expression NOT to match.
    # @return [Boolean] `true` if matching succeeded, `false otherwise`.
    def self.disambiguate_browser(agent, positive_matcher, negative_matcher)
      agent =~ positive_matcher && agent !~ negative_matcher
    end

    # Performs a match against a target.
    #
    # @param matcher [Object] The matcher to run, can be a `Regexp`, a `Proc` or a string.
    # @param target [String] The string to match.
    # @param args [Array] Arguments to pass to the matcher. The first is definition itself.
    # @return [Object|NilClass] A match if matcher succeeded, `nil` otherwise.
    def perform_match(matcher, target, args)
      if matcher.is_a?(::Regexp)
        matcher.match(target)
      elsif matcher.respond_to?(:call)
        matcher.call(*args)
      elsif target == matcher
        target
      else
        nil
      end
    end
  end
end