# = 半角変換フィルター
# thanks to masuidrive <masuidrive (at) masuidrive.jp>

ActiveSupport.on_load(:action_controller) do
  def self.hankaku_filter(options = {})
    before_action Jpmobile::HankakuFilter.new(options)
    after_action  Jpmobile::HankakuFilter.new(options)
  end
end

module Jpmobile
  class HankakuFilter
    cattr_accessor(:zen_to_han_table) do
      {
        'ガ' => 'ｶﾞ', 'ギ' => 'ｷﾞ', 'グ' => 'ｸﾞ', 'ゲ' => 'ｹﾞ', 'ゴ' => 'ｺﾞ',
        'ザ' => 'ｻﾞ', 'ジ' => 'ｼﾞ', 'ズ' => 'ｽﾞ', 'ゼ' => 'ｾﾞ', 'ゾ' => 'ｿﾞ',
        'ダ' => 'ﾀﾞ', 'ヂ' => 'ﾁﾞ', 'ヅ' => 'ﾂﾞ', 'デ' => 'ﾃﾞ', 'ド' => 'ﾄﾞ',
        'バ' => 'ﾊﾞ', 'ビ' => 'ﾋﾞ', 'ブ' => 'ﾌﾞ', 'ベ' => 'ﾍﾞ', 'ボ' => 'ﾎﾞ',
        'パ' => 'ﾊﾟ', 'ピ' => 'ﾋﾟ', 'プ' => 'ﾌﾟ', 'ペ' => 'ﾍﾟ', 'ポ' => 'ﾎﾟ',
        'ヴ' => 'ｳﾞ',
        'ア' => 'ｱ', 'イ' => 'ｲ', 'ウ' => 'ｳ', 'エ' => 'ｴ', 'オ' => 'ｵ',
        'カ' => 'ｶ', 'キ' => 'ｷ', 'ク' => 'ｸ', 'ケ' => 'ｹ', 'コ' => 'ｺ',
        'サ' => 'ｻ', 'シ' => 'ｼ', 'ス' => 'ｽ', 'セ' => 'ｾ', 'ソ' => 'ｿ',
        'タ' => 'ﾀ', 'チ' => 'ﾁ', 'ツ' => 'ﾂ', 'テ' => 'ﾃ', 'ト' => 'ﾄ',
        'ナ' => 'ﾅ', 'ニ' => 'ﾆ', 'ヌ' => 'ﾇ', 'ネ' => 'ﾈ', 'ノ' => 'ﾉ',
        'ハ' => 'ﾊ', 'ヒ' => 'ﾋ', 'フ' => 'ﾌ', 'ヘ' => 'ﾍ', 'ホ' => 'ﾎ',
        'マ' => 'ﾏ', 'ミ' => 'ﾐ', 'ム' => 'ﾑ', 'メ' => 'ﾒ', 'モ' => 'ﾓ',
        'ヤ' => 'ﾔ', 'ユ' => 'ﾕ', 'ヨ' => 'ﾖ',
        'ラ' => 'ﾗ', 'リ' => 'ﾘ', 'ル' => 'ﾙ', 'レ' => 'ﾚ', 'ロ' => 'ﾛ',
        'ワ' => 'ﾜ', 'ヲ' => 'ｦ', 'ン' => 'ﾝ',
        'ャ' => 'ｬ', 'ュ' => 'ｭ', 'ョ' => 'ｮ',
        'ァ' => 'ｧ', 'ィ' => 'ｨ', 'ゥ' => 'ｩ', 'ェ' => 'ｪ', 'ォ' => 'ｫ',
        'ッ' => 'ｯ',
        '゛' => 'ﾞ', '゜' => 'ﾟ', 'ー' => 'ｰ', '。' => '｡',
        '「' => '｢', '」' => '｣',
        '、' => '､', '・' => '･', '！' => '!', '？' => '?'
      }
    end

    class << self
      def hankaku_format(str)
        replace_chars(str, zen_to_han_table)
      end

      def zenkaku_format(str)
        replace_chars(str, han_to_zen_table)
      end

      private

      def replace_chars(str, table)
        @regexp_cache ||= {}
        str.gsub(@regexp_cache[table.object_id] ||= Regexp.union(table.keys), table)
      end

      def han_to_zen_table
        @han_to_zen_table ||= zen_to_han_table.invert
      end
    end

    def initialize(options = {})
      @options = {
        input: false,
      }.merge(options)

      @controller = nil
    end

    def before(controller)
      @controller = controller

      if apply_incoming?
        @controller.params = convert_parameters(@controller.params.dup)
      end
    end

    # 内部コードから外部コードに変換
    def after(controller)
      @controller = controller
      if apply_outgoing? && @controller.response.body.is_a?(String)
        @controller.response.body = to_external(@controller.response.body)
      end
    end

    private

    # 入出力フィルタの適用条件
    def apply_incoming?
      @controller.request.mobile?
    end

    def apply_outgoing?
      @controller.request.mobile? and
        [nil, 'text/html', 'application/xhtml+xml'].include?(@controller.response.content_type)
    end

    def to_internal(str)
      filter(:zenkaku, str)
    end

    def to_external(str)
      if @options[:input]
        encoding = (str =~ /^\s*<[^Hh>]*html/)
        nokogiri_klass =
          (str =~ /^\s*<[^Hh>]*html/) ? Nokogiri::HTML::Document : Nokogiri::HTML::DocumentFragment
        doc = if encoding
                nokogiri_klass.parse(str, nil, 'UTF-8')
              else
                nokogiri_klass.parse(str)
              end

        doc = convert_text_content(doc)

        html = doc.to_html.gsub("\xc2\xa0", '&nbsp;')
        html = html.gsub(/charset=[a-z0-9\-]+/i, "charset=#{default_charset}") if default_charset
        html
      else
        filter(:hankaku, str)
      end
    end

    def filter(method, str)
      str = str.dup

      # 一度UTF-8に変換
      before_encoding = str.encoding
      str.force_encoding('UTF-8')

      str = self.class.send("#{method}_format", str)

      # 元に戻す
      if before_encoding
        str.force_encoding(before_encoding)
      end

      str
    end

    # 再帰的に探す
    def convert_text_content(document)
      document.children.each do |element|
        if element.is_a?(Nokogiri::XML::Text)
          unless element.parent.node_name == 'textarea'
            # textarea 以外のテキストなら content を変換
            element.content = filter(:hankaku, element.content)
          end
        elsif (element.node_name == 'input') && %w[submit reset button].include?(element['type'])
          # テキスト以外でもボタンの value は変換
          element['value'] = filter(:hankaku, element['value'])
        elsif element.children.any?
          # 子要素があれば再帰的に変換
          element = convert_text_content(element)
        end
        element
      end

      document
    end

    def default_charset
      if @controller.request.mobile?
        @controller.request.mobile.default_charset
      end
    end

    def convert_parameters(params)
      params.each do |k, v|
        params[k] = if params[k].respond_to?(:each)
                      convert_parameters(params[k])
                    else
                      to_internal(v)
                    end
      end
    end
  end
end