require_relative 'dom'

module OLD
  class RoffBuilder
    include DOM
    attr_accessor :title, :section, :date, :source, :manual,
      :hr_width, :name
    def initialize(elem)
      @elem = elem
    end

    def build()
      notable_tags =["p", "hr", "blockquote", "div/blockquote",
                     "br", "table"]
      query = notable_tags.join('|')
      paragraphs = xpath(@elem, query).map do |node|
        html2roff(node)
      end
      body = paragraphs.join("")
      <<-"EOS"
.TH "#{@title}" #{@section} "#{@date.strftime("%Y-%m-%d")}" "#{@source}" "#{@manual}"
.SH NAME
#{@name}

#{body}
EOS
    end

    def span2roff(e, child)
      child
    end

    def is_section_title?(string)
      # regard as a section title when:
      # * inner text ends width ':'
      #   like "Description:", "Item #:" ...
      # * inner text contains characteristic words
      title_patterns = [
        /^Item #:$/i,
        /^Special Containment Procedures:$/i,
        /^Object class:$/i,
        /^Status/i,
        /^Description:$/i,
        /^[a-zA-Z ]*Log/i,
        /^Addendum/i,
        /^Appendix/i,
        /^Notes [0-9]+/i,
        /^Document.*[0-9]+/i
      ]
      title_patterns.any? {|pattern| string =~ pattern }
    end

    def table2roff(table)
      rows = xpath("table, tr")
      column = xpath(rows.first, "td").length
      separater = "^"
      content = rows.map { |tr|
        row = xpath(tr, "td").map { |td|
          elem2roff(td, false) + separater
        }.join("")
      }.join("\n")
      <<EOS
  .TS
  tab(#{separater});
  #{"l " * column }.
  #{content}
  .TE
EOS
    end

    def elem2roff(e, context)
      ch_context = context
      ch_context[:depth] = context[:depth] + 1
      ch_context[:order] = -1
      children = children(e).map do |ch|
        ch_context[:order] += 1
        html2roff(ch, ch_context)
      end

      depth = context[:depth]
      order = context[:order]

      case tag_name(e)
      when "strong"
        child = children.join("")
        if depth <= 2 and is_section_title?(child) then
          "\n.SH \"#{child.gsub(/:[ ]*$/, "") }\"\n"
        elsif depth <= 2 and order == 0 then
          "\n.SS \"#{child.gsub(/:[ ]*$/, "") }\"\n"
        else
          "\\fB#{child}\\fR"
        end
      when "br"
        "\n.PP\n"
      when "hr"
        "\n.ce 1\n\\l'#{@hr_width / 4 * 3}'\n.ce 0\n"
      when "blockquote"
        ".RS\n" + children.join("") + "\n.RE\n"
      when "p"
        "\n.br\n#{children.join("").gsub(/^ /, "")}\n.br\n"
      when "span"
        child = children.join("")
        span2roff(e, child)
      when "table"
        table2roff(e)
      else
        children.join("")
      end
    end

    def html2roff(e, context = {:depth => 0, :order => 0})
      if is_text?(e)
        return text(e) + (text(e)[-1] == '.' ? " ": "")
      else
        elem2roff(e, context)
      end
    end
  end
end