[FR] Offer a way to add link using new ipv6 convention

Definely something with Pandoc which HTML escape the characters when parsing the link

echo '[test](http://[fd04::123]:8080)' | pandoc -f markdown -t native                            
[ Para
    [ Link
        ( "" , [] , [] )
        [ Str "test" ]
        ( "http://%5Bfd04::123%5D:8080" , "" )
    ]
]

They do escape at reading time with usual URI escaping
https://github.com/jgm/pandoc/blob/e4ac26d255ad8748c01301b3319975de39a8f43f/src/Text/Pandoc/URI.hs#L29-L32

Note that JS function also does it

> encodeURI('http://[fd04::123]:8080')
'http://%5Bfd04::123%5D:8080'

So I think those URL are quite specific, right ?

It seems it requires a specific handling for ipv6 following recent RFC3986
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURI#encoding_for_rfc3986

So it definitely need an update to Pandoc to follow ipv6 compliance if possible.

but you could also for now do that yourself using Lua filter

-- ipv6.lua
Link = function(l)
    if l.classes:includes("ipv6") then
    	_, i = l.classes:find("ipv6")
        l.classes:remove(i)
        l.target = l.target:gsub("%%5B", "[")
        l.target = l.target:gsub("%%5D", "]")
    end
    return l
end 

❯ echo '[test](http://\[fd04::123\]:8080){.ipv6}' | pandoc -f markdown -t native --lua-filter=ipv6.lua
[ Para
    [ Link
        ( "" , [] , [] )
        [ Str "test" ]
        ( "http://[fd04::123]:8080" , "" )
    ]
]

❯ echo '[test](http://\[fd04::123\]:8080){.ipv6}' | pandoc -f markdown -t html --lua-filter=ipv6.lua  
<p><a href="http://[fd04::123]:8080">test</a></p>

Hope it helps

Originally posted by @cderv in https://github.com/quarto-dev/quarto-cli/discussions/9229#discussioncomment-8953991