require "twitter_cldr"
require "bigdecimal"
require "plurimath"

module IsoDoc
  class PresentationXMLConvert < ::IsoDoc::Convert
    MATHML = { "m" => "http://www.w3.org/1998/Math/MathML" }.freeze

    def mathml(docxml)
      docxml.xpath("//m:math", MATHML).each { |f| mathml_linebreak(f) }
      locale = @lang.to_sym
      @numfmt = Plurimath::NumberFormatter
        .new(locale, localize_number: @localizenumber,
                     localizer_symbols: twitter_cldr_localiser_symbols)
      docxml.xpath("//m:math", MATHML).each do |f| # rubocop:disable Style/CombinableLoops
        mathml1(f, locale)
      end
    end

    # symbols is merged into
    # TwitterCldr::DataReaders::NumberDataReader.new(locale).symbols
    def localize_maths(node, locale)
      node.xpath(".//m:mn", MATHML).each do |x|
        x.children = @numfmt
          .localized_number(x.text, locale: locale,
                                    precision: num_precision(x.text))
      rescue ArgumentError
      end
    end

    def num_precision(num)
      precision = 0
      /\./.match?(num) and precision =
                             twitter_cldr_localiser_symbols[:precision] ||
                             num.sub(/^.*\./, "").size
      precision
    end

    def twitter_cldr_localiser_symbols
      {}
    end

    def asciimath_dup(node)
      @suppressasciimathdup || node.parent.at(ns("./asciimath")) and return
      math = node.to_xml.gsub(/ xmlns=["'][^"']+["']/, "")
        .gsub(%r{<[^:/>]+:}, "<").gsub(%r{</[^:/>]+:}, "</")
      ret = Plurimath::Math.parse(math, "mathml").to_asciimath
      node.next = "<asciimath>#{@c.encode(ret, :basic)}</asciimath>"
    rescue StandardError => e
      warn "Failure to convert MathML to AsciiMath\n#{node.parent.to_xml}\n#{e}"
    end

    def maths_just_numeral(node)
      mn = node.at(".//m:mn", MATHML).children
      if node.parent.name == "stem"
        node.parent.replace(mn)
      else
        node.replace(mn)
      end
    end

    def mathml1(node, locale)
      mathml_style_inherit(node)
      mathml_number(node, locale)
    end

    def mathml_linebreak(node)
      node.at(".//*/@linebreak") or return
      m = Plurimath::Math.parse(node.to_xml, :mathml)
        .to_mathml(split_on_linebreak: true)
      ret = Nokogiri::XML("<m>#{m}</m>").root
      ret.elements.each_with_index do |e, i|
        i.zero? or e.previous = "<br/>"
      end
      node.replace(<<~OUTPUT)
        <math-with-linebreak>#{ret.children}</math-with-linebreak><math-no-linebreak>#{node.to_xml}</math-no-linebreak>
      OUTPUT
    end

    def mathml_number(node, locale)
      justnumeral = numeric_mathml?(node)
      justnumeral or asciimath_dup(node)
      localize_maths(node, locale)
      justnumeral and maths_just_numeral(node)
    end

    def numeric_mathml?(node)
      m = {}
      node.traverse do |x|
        %w(mstyle mrow math text).include?(x.name) and next
        m[x.name] ||= 0
        m[x.name] += 1
      end
      m.keys.size == 1 && m["mn"] == 1
    end

    def mathml_style_inherit(node)
      node.at("./ancestor::xmlns:strong") or return
      node.children =
        "<mstyle mathvariant='bold'>#{node.children.to_xml}</mstyle>"
    end

    def mathml_number_to_number(node)
      (node.elements.size == 1 && node.elements.first.name == "mn") or return
      repl = node.at("./m:mn", MATHML).children
      if node.parent.name == "stem"
        node.parent.replace(repl)
      else
        node.replace(repl)
      end
    end
  end
end