require "uuidtools"
require "asciimath"
require "htmlentities"
require "nokogiri"
require "plane1converter"

module Html2Doc
  @xsltemplate =
    Nokogiri::XSLT(File.read(File.join(File.dirname(__FILE__), "mml2omml.xsl"),
                             encoding: "utf-8"))

  def self.asciimath_to_mathml1(x)
    AsciiMath::MathMLBuilder.new(:msword => true).append_expression(
      AsciiMath.parse(HTMLEntities.new.decode(x)).ast).to_s.
        gsub(/<math>/, "<math xmlns='http://www.w3.org/1998/Math/MathML'>")
  end

  def self.asciimath_to_mathml(doc, delims)
    return doc if delims.nil? || delims.size < 2
    m = doc.split(/(#{Regexp.escape(delims[0])}|#{Regexp.escape(delims[1])})/)
    m.each_slice(4).map.with_index do |(*a), i|
      i % 500 == 0 && m.size > 1000 && i > 0 and
        warn "MathML #{i} of #{(m.size / 4).floor}"
      a[2].nil? || a[2] = asciimath_to_mathml1(a[2])
      a.size > 1 ? a[0] + a[2] : a[0]
    end.join
  end

  def self.unwrap_accents(doc)
    doc.xpath("//*[@accent = 'true']").each do |x|
      x.elements.length > 1 or next
      x.elements[1].name == "mrow" and
        x.elements[1].replace(x.elements[1].children)
    end
    doc
  end

  # random fixes to MathML input that OOXML needs to render properly
  def self.ooxml_cleanup(m, docnamespaces)
    m = unwrap_accents(mathml_preserve_space(
      mathml_insert_rows(m, docnamespaces), docnamespaces))
    m.add_namespace(nil, "http://www.w3.org/1998/Math/MathML")
    m
  end

  def self.mathml_insert_rows(m, docnamespaces)
    m.xpath(%w(msup msub msubsup munder mover munderover).
            map { |m| ".//xmlns:#{m}" }.join(" | "), docnamespaces).each do |x|
      next unless x.next_element && x.next_element != "mrow"
      x.next_element.wrap("<mrow/>")
    end
    m
  end

  def self.mathml_preserve_space(m, docnamespaces)
    m.xpath(".//xmlns:mtext", docnamespaces).each do |x|
      x.children = x.children.to_xml.gsub(/^\s/, "&#xA0;").gsub(/\s$/, "&#xA0;")
    end
    m
  end

  def self.unitalic(m)
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:scr)]/xmlns:sty[@m:val = 'p']]").each do |x|
      x.wrap("<span style='font-style:normal;'></span>")
    end
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:scr)]/xmlns:sty[@m:val = 'bi']]").each do |x|
      x.wrap("<span class='nostem' style='font-weight:bold;'><em></em></span>")
    end
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:scr)]/xmlns:sty[@m:val = 'i']]").each do |x|
      x.wrap("<span class='nostem'><em></em></span>")
    end
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:scr)]/xmlns:sty[@m:val = 'b']]").each do |x|
      x.wrap("<span style='font-style:normal;font-weight:bold;'></span>")
    end
    m.xpath(".//xmlns:r[xmlns:rPr/xmlns:scr[@m:val = 'monospace']]").each do |x|
      toPlane1(x, :monospace)
    end
    m.xpath(".//xmlns:r[xmlns:rPr/xmlns:scr[@m:val = 'double-struck']]").each do |x|
      toPlane1(x, :doublestruck)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:sty) or xmlns:sty/@m:val = 'p']/xmlns:scr[@m:val = 'script']]").each do |x|
      toPlane1(x, :script)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[xmlns:sty/@m:val = 'b']/xmlns:scr[@m:val = 'script']]").each do |x|
      toPlane1(x, :scriptbold)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:sty) or xmlns:sty/@m:val = 'p']/xmlns:scr[@m:val = 'fraktur']]").each do |x|
      toPlane1(x, :fraktur)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[xmlns:sty/@m:val = 'b']/xmlns:scr[@m:val = 'fraktur']]").each do |x|
      toPlane1(x, :frakturbold)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[not(xmlns:sty) or xmlns:sty/@m:val = 'p']/xmlns:scr[@m:val = 'sans-serif']]").each do |x|
      toPlane1(x, :sans)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[xmlns:sty/@m:val = 'b']/xmlns:scr[@m:val = 'sans-serif']]").each do |x|
      toPlane1(x, :sansbold)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[xmlns:sty/@m:val = 'i']/xmlns:scr[@m:val = 'sans-serif']]").each do |x|
      toPlane1(x, :sansitalic)
    end
    m.xpath(".//xmlns:r[xmlns:rPr[xmlns:sty/@m:val = 'bi']/xmlns:scr[@m:val = 'sans-serif']]").each do |x|
      toPlane1(x, :sansbolditalic)
    end
    m
  end

  def self.toPlane1(x, font)
    x.traverse do |n|
      next unless n.text?
      n.replace(Plane1Converter.conv(HTMLEntities.new.decode(n.text), font))
    end
    x
  end

  def self.mathml_to_ooml(docxml)
    docnamespaces = docxml.collect_namespaces
    m = docxml.xpath("//*[local-name() = 'math']")
    m.each_with_index do |x, i|
      i % 100 == 0 && m.size > 500 && i > 0 and
        warn "Math OOXML #{i} of #{m.size}"
      element = ooxml_cleanup(x, docnamespaces)
      doc = Nokogiri::XML::Document::new()
      doc.root = element
      ooxml = (unitalic(esc_space(@xsltemplate.transform(doc)))).to_s.
        gsub(/<\?[^>]+>\s*/, "").
        gsub(/ xmlns(:[^=]+)?="[^"]+"/, "").
        gsub(%r{<(/)?(?!span)(?!em)([a-z])}, "<\\1m:\\2")
      ooxml = uncenter(x, ooxml)
      x.swap(ooxml)
    end
  end

  # escape space as &#x32;; we are removing any spaces generated by 
  # XML indentation
  def self.esc_space(xml)
    xml.traverse do |n|
      next unless n.text?
      n = n.text.gsub(/ /, "&#x32;")
    end
    xml
  end

  # if oomml has no siblings, by default it is centered; override this with
  # left/right if parent is so tagged
  def self.uncenter(m, ooxml)
    if m.next == nil && m.previous == nil
      alignnode = m.at(".//ancestor::*[@style][local-name() = 'p' or "\
                       "local-name() = 'div' or local-name() = 'td']/@style")
      return ooxml unless alignnode
      if alignnode.text.include? ("text-align:left")
        ooxml = "<m:oMathPara><m:oMathParaPr><m:jc "\
          "m:val='left'/></m:oMathParaPr>#{ooxml}</m:oMathPara>"
      elsif alignnode.text.include? ("text-align:right")
        ooxml = "<m:oMathPara><m:oMathParaPr><m:jc "\
          "m:val='right'/></m:oMathParaPr>#{ooxml}</m:oMathPara>"
      end
    end
    ooxml
  end
end