function html.picofmt(post_tbl)
  local email = post_tbl.Email
  if email and (email == "nofo" or email:match("^nofo ") or email:match(" nofo$") or email:match(" nofo ")) then
    local s = html.striphtml(post_tbl.Comment)
      :gsub("[\1-\8\11-\31\127]", "")
      :gsub("^\n+", "")
      :gsub("%s+$", "")
      :gsub("\n", "<br />")
    return s
  end

  local function handle_refs(number, append)
    number = tonumber(number)
    local ref_post_tbl = pico.post.tbl(post_tbl.Board, number, true)

    if ref_post_tbl then
      return ("<a href='/%s/%d#%d'>\2\2%d</a>%s"):format(
        ref_post_tbl.Board, ref_post_tbl.Parent or number, number, number, append)
    else
      return ("<s><a>\2\2%d</a></s>%s"):format(number, append)
    end
  end

  local function handle_xbrefs(board, number, append)
    if number == "" then
      return ("<a href='/%s/'>\2\2\2/%s/</a>%s"):format(board, board, append)
    else
      number = tonumber(number)
    end

    local ref_post_tbl = pico.post.tbl(board, number, true)

    if ref_post_tbl then
      return ("<a href='/%s/%d#%d'>\2\2\2/%s/%d</a>%s"):format(
        board, ref_post_tbl.Parent or number, number, board, number, append)
    else
      return ("<s><a>\2\2\2/%s/%d</a></s>%s"):format(board, number, append)
    end
  end

  local function handle_url(prev, url)
    local balance_tbl = {
      ["("] = ")",
      ["\1"] = "\2",
      ["{"] = "}",
      ["["] = "]",
      ["\3"] = "\3",
      ["\4"] = "\4",
    }
    local balance = balance_tbl[prev]
    local append = ""
    if balance then
      local first, second = (prev .. url):match("^(%b" .. prev .. balance .. ")(.-)$")
      if first then
        url = first:sub(2, -2)
        append = balance .. second
      end
    else
      local last = url:match("[!,%.:;%?]$")
      if last then
        url = url:sub(1, -2)
        append = last
      end
    end
    return ("%s<a href='%s'>%s</a>%s"):format(prev, url, url, append)
  end

  local blocks = {}
  local iblocks = {}

  local function handle_code(b, c, t, e)
    return function(block)
      b[#b + 1] = t .. block .. e
      return c
    end
  end

  local function insert_escaped(t)
    return function()
      if #t > 0 then
        return table.remove(t, 1)
      end
      return ""
    end
  end

  local punct = "!\4#%$%%&\3%(%)%*%+,%-%./:;\1=\2%?@%[\\%]%^_`{|}~"

  local s = ("\n" .. post_tbl.Comment .. "\n")
    :gsub("[\1-\8\11-\31\127]", "")

    :gsub("&", "&amp;")
    :gsub("<", "\1")
    :gsub(">", "\2")
    :gsub("'", "\3")
    :gsub("\"", "\4")

    :gsub("```\n*(.-)\n*```", handle_code(blocks, "\5", "<code>", "</code>"))
    :gsub("([^\n])\5", "%1\n\5")
    :gsub("\5([^\n])", "\5\n%1")
    :gsub("`([^\n]-)`", handle_code(iblocks, "\6", "<span class='code'>", "</span>"))

    :gsub("\2\2\2/([%l%d]+)/(%d-)([%s" .. punct .. "])", handle_xbrefs)
    :gsub("\2\2(%d+)([%s" .. punct .. "])", handle_refs)

    :gsub("\3\3\3([^\n]-)\3\3\3", "<b>%1</b>")
    :gsub("\3\3([^\n]-)\3\3", "<i>%1</i>")
    :gsub("~~([^\n]-)~~", "<s>%1</s>")
    :gsub("__([^\n]-)__", "<u>%1</u>")
    :gsub("==([^\n]-)==", "<span class='redtext'>%1</span>")
    :gsub("%*%*([^\n]-)%*%*", "<span class='spoiler'>%1</span>")
    :gsub("%(%(%([^\n]-%)%)%)", "<span class='kiketext'>%1</span>")
    :gsub("\n(\2[^\n]*)", "\n<span class='greentext'>%1</span>")
    :gsub("\n(\1[^\n]*)", "\n<span class='pinktext'>%1</span>")

    :gsub("(.)(https?://[%w" .. punct .. "]+)", handle_url)

    :gsub("\6", insert_escaped(iblocks))
    :gsub("\5", insert_escaped(blocks))

    :gsub("\4", "&quot;")
    :gsub("\3", "&#39;")
    :gsub("\2", "&gt;")
    :gsub("\1", "&lt;")

    :gsub("^\n+", "")
    :gsub("%s+$", "")
    :gsub("\n", "<br />")

  return s
end