function has_class(el, class)
  if el.attr == nil then
    return nil
  end
  for i,v in ipairs(el.attr.classes) do
    if v == class then
      return true
    end
  end
  return false
end

function get_block_with_class(el, class)
  return find_node(el, function(el)
    return has_class(el, class)
  end)
end

function get_image(el)
  return find_node(el, function (v)
    return v.t == "Image"
  end)
end

function attribute(el, name, default)
  for k,v in pairs(el.attr.attributes) do
    if k == name then
      return v
    end
  end
  return default
end

function replace_node(blocks, predicate, replacement)
  for i, el in pairs(blocks) do
    if predicate(el) then      
      table.remove(blocks, i)
      if type(replacement) == "function" then
        replacement = replacement(el)
      end
      table.insert(blocks, i, replacement)
      return el
    end
  end
  return nil
end

local bibname = ''

return {
  {
    Meta = function(meta)
      for _i, v in ipairs(meta.bibliography) do
        if bibname ~= '' then
          bibname = bibname .. ','
        end
        bibname = bibname .. pandoc.utils.stringify(v)
      end
      
    end,
    Pandoc = function(doc)
      if not quarto.doc.is_format("latex") then
        return doc
      end

      -- add bibliography to the right place
      -- local bibname = "sample-base"
      local bibliography = pandoc.RawBlock(
        "latex", 
        "\\bibliographystyle{ACM-Reference-Format}\n\\bibliography{" .. bibname .. "}")
      replace_node(doc.blocks, function(el)
        return el.t == "Header" and pandoc.utils.stringify(el.content) == "References"
      end, bibliography)

      -- fix appendix compilation
      local appendix = pandoc.RawBlock("latex", "\\appendix")
      replace_node(doc.blocks, function(el)
        return el.t == "Header" and pandoc.utils.stringify(el.content) == "Appendix"
      end, appendix)

      -- fix acknowledgments
      replace_node(doc.blocks, function(el)
        return el.t == "Div" and has_class(el, "acks")
      end, function(el)
        local text = pandoc.write(pandoc.Pandoc(el.content), "latex")
        local node = pandoc.RawBlock(
          "latex", "\\begin{acks}\n" .. text .. "\n\\end{acks}")
        return node        
      end)

      return doc
    end
  }
}