obsidian-callout.lua filter for Pandoc to convert Obsidian callout into pandoc fenced divs

obsidian-callout.lua

local stringify = (require "pandoc.utils").stringify

function BlockQuote (el)
    start = el.content[1]
    if (start.t == "Para" and start.content[1].t == "Str" and
        start.content[1].text:match("^%[!%w+%][-+]?$")) then
        _, _, ctype = start.content[1].text:find("%[!(%w+)%]")
        el.content:remove(1)
        start.content:remove(1)
        div = pandoc.Div(el.content, {class = "callout"})
        div.attributes["data-callout"] = ctype:lower()
        div.attributes["title"] = stringify(start.content):gsub("^ ", "")
        return div
    else
        return el
    end
end