-- Module to display an icon with a tooltip such as "Edit this at Wikidata".
-- Icon is linked to the Wikidata entry for the article where this is placed.
-- This message is only displayed if a local_parameter is not supplied
-- i.e. when called from a template, it can be coded not to display the message.
-- The qid of a Wikidata entry can optionally be supplied for testing outside the article.
-- Usage:
-- {{#invoke:EditAtWikidata|showMessage|local_parameter}}
-- {{#invoke:EditAtWikidata|showMessage|qid=<ArticleID>|local_parameter}}

local p = {}

local i18n =
{
	["message"] = "Edit this at Wikidata"
}

local function trimToNil(text)
	-- Return trimmed non-empty text, or nil.
	if type(text) == 'string' then
		return text:match('(%S.-)%s*$')
	end
end

function p._showMessage(args)
	local local_parm = trimToNil(args[1])
	if local_parm then return "" end
	-- Parameter qid=x specifies the Wikidata ID for the article.
	-- This is not normally used except for testing outside the article.
	local qid = trimToNil(args.qid) or mw.wikibase.getEntityIdForCurrentPage()
	if qid and mw.wikibase.entityExists(qid) then
		-- Parameter pid=x uses x as an anchor in the link to the Wikidata entry.
		local anchor = trimToNil(args.pid)
		-- Parameter nbsp replaces the leading space with &nbsp;
		local space = trimToNil(args.nbsp) and "&nbsp;" or " "
		return
			space ..
			"[[File:OOjs UI icon edit-ltr-progressive.svg|frameless|text-top|10px" ..
			"|alt=" .. i18n.message ..
			"|link=https://www.wikidata.org/key/" .. qid ..
			(anchor and ("#" .. anchor) or "") ..
			"|class=noprint" ..
			"|" .. i18n.message ..
			"]]"
	end
	return ""
end

function p.showMessage(frame)
	return p._showMessage(frame.args)
end

return p