---@diagnostic disable: undefined-global
-- see https://pandoc.org/lua-filters.html
return {
    Link = function(link)
        -- set target="_blank" for outgoing links (open them in new tab)
        if string.match(link.target, "gzr.im") == nil then
            table.insert(link.attributes, { "target", "_blank" })
        end
        return link
    end,
    Pandoc = function(doc)
        local front = {}

        local toc = pandoc.structure.table_of_contents(doc)
        if doc.meta.toc and toc then
            table.insert(front, pandoc.RawBlock("html5", '<nav class="table-of-contents capital">'))
            table.insert(front, pandoc.RawBlock("html5", "<ol>"))
            -- insert jump to top
            table.insert(front, pandoc.Link("back to top", "#top"))
            -- create custom toc
            toc:walk({
                Link = function(e)
                    table.insert(front, pandoc.RawBlock("html5", "<li>"))
                    table.insert(front, e)
                    table.insert(front, pandoc.RawBlock("html5", "</li>"))
                end,
            })
            table.insert(front, pandoc.RawBlock("html5", "</ol>"))
            table.insert(front, pandoc.RawBlock("html5", "</nav>"))
        end

        -- insert date blocks
        if doc.meta.date then
            table.insert(front, pandoc.RawBlock("html5", '<span class="date">'))
            table.insert(front, doc.meta.date)
            table.insert(front, pandoc.RawBlock("html5", "</span>"))
        end

        -- prepend front stuffs
        for i = #front, 1, -1 do
            table.insert(doc.blocks, 1, front[i])
        end

        -- return finished ast
        return doc
    end,
}