Editing Module:Gallery

-- This module implements {{gallery}} by wrapping the <gallery> core extension tag.

local p = {}

local templatestyles = 'Module:Gallery/styles.css'
local yesno = require('Module:Yesno')
local plaintextModule = require('Module:Plain text')

local function plaintext(text)
	-- stips out external links without labels,
	-- and then passes to the Plain_text module to clean the rest
    return plaintextModule.main({ args = {
    	text:gsub("([^%[])%[([^%[%]%s]+)%]", '%1')
    	, encode = "no" } })
end

local function trim(s)
	return mw.ustring.gsub(mw.ustring.gsub(s or '', '%s', ' '), '^%s*(.-)%s*$', '%1')
end

local tracking, preview

local function isImage(file)
    local file = trim(file):lower() -- Case insensitive check

    -- Check if it starts with "File:", "Image:", or "Media:"
    local prefix = file:match("^(%a+):")
    if prefix and (prefix == "file" or prefix == "image" or prefix == "media") then
        return true
    end
    
    local valid_extensions = {
        "apng", "djvu", "flac", "gif", "jfi", "jfif", "jif", "jpe", "jpeg", "jpg",
        "m1a", "m1v", "m2a", "m2v", "mid", "mp1", "mp2", "mp3", "mpa", "mpe", "mpeg", "mpg",
        "mpv", "oga", "ogg", "ogv", "opus", "pdf", "png", "stl", "svg", "svgz", "tif", "tiff",
        "wav", "wave", "webm", "webp", "xcf"
    }
    
    -- Extract file extension, of 3 or 4 characters only
    local ext = file:match("%.(%w%w%w%w?)$")
    
    -- Check if the extension is in the valid list
    if ext then
        for _, valid_ext in ipairs(valid_extensions) do
            if ext == valid_ext then
            	table.insert(tracking, '[[Category:Pages using gallery without a media namespace prefix]]')
                return true
            end
        end
    end
    return false
end

local function checkarg(k,v)
	if k and type(k) == 'string' then
		if k == 'align' or k == 'state' or k == 'style' or k == 'title' or
			k == 'width' or k == 'height' or k == 'whitebg' or
			k == 'mode' or k == 'footer' or k == 'perrow' or k == 'noborder' or
			k:match('^alt%d+$') or k:match('^class%d+$') or k:match('^%d+$') then
			-- valid
		elseif k == 'captionstyle' then
			if not v:match('^text%-align%s*:%s*center[;%s]*$') then
				table.insert(tracking, '[[Category:Pages using gallery with the captionstyle parameter]]')
			end
		else
			-- invalid
			local vlen = mw.ustring.len(k)
			k = mw.ustring.sub(k, 1, (vlen < 25) and vlen or 25)
			k = mw.ustring.gsub(k, '[^%w%-_ ]', '?')
			table.insert(tracking, '[[Category:Pages using gallery with unknown parameters|' .. k .. ']]')
			table.insert(preview, '"' .. k .. '"')
		end
	end
end

function p.gallery(frame)
	-- If called via #invoke, use the args passed into the invoking template.
	-- Otherwise, for testing purposes, assume args are being passed directly in.
	local origArgs = (type(frame.getParent) == 'function') and frame:getParent().args or frame

    -- ParserFunctions considers the empty string to be false, so to preserve the previous
    -- behavior of {{gallery}}, change any empty arguments to nil, so Lua will consider
    -- them false too.
    local args = {}
    tracking, preview = {}, {}
    for k, v in pairs(origArgs) do
    	if v ~= '' then
    		args[k] = v
    		checkarg(k,v)
    	end
	end
	
	if (args.mode or '') == 'packed' and (args.align or '') == '' then
		args.align = 'center'
	end

	if (args.align or '') == 'centre' then
		args.align = 'center'
	end

	local tbl = mw.html.create('div')
	tbl:addClass('mod-gallery')

	if args.state then
		tbl
			:addClass('mod-gallery-collapsible')
			:addClass('collapsible')
			:addClass(args.state)
	end
	
	if args.style then
		tbl:cssText(args.style)
	else
		tbl:addClass('mod-gallery-default')
	end
	
	if args.align then
		tbl:addClass('mod-gallery-' .. args.align:lower())
	end

	if args.title then
		tbl:tag('div')
			:addClass('title')
				:tag('div')
					:wikitext(args.title)
	end
	
	local gargs = {}
	gargs['class'] = 'nochecker' .. (args.noborder and '' or ' bordered-images')
	gargs['widths'] = tonumber(args.width) or 180
	gargs['heights'] = tonumber(args.height) or 180
	gargs['style'] = args.captionstyle
	gargs['perrow'] = args.perrow
	gargs['mode'] = args.mode
	if yesno(args.whitebg or 'yes') then
		gargs['class'] = gargs['class'] .. ' whitebg'
	end
	
	local virtualgallery = {}
	local gallery = {}
	
	local imageCount = 0

	local zwsp = string.char(0xE2, 0x80, 0x8B) -- U+200B Zero Width Space
	local zwnj = string.char(0xE2, 0x80, 0x8C) -- U+200C Zero Width Non-Joiner
	
	-- create a coding to identify classes
	-- using unicode non-printing characters
	-- this is a workaround until we get the class arg in the <gallery> tag
	-- https://phabricator.wikimedia.org/T344784
 
	local skininvert    = zwsp .. zwsp .. zwsp;
	local bgtransparent = zwsp .. zwsp .. zwnj;
	
	for i = 1, #args do
	    local currentfield = trim(args[i]) or ''
	
	    if currentfield == '' then
	        -- Skip empty fields
	    elseif isImage(currentfield) then
	        imageCount = imageCount + 1
	        virtualgallery[imageCount] = { currentfield }
	    elseif imageCount > 0 and virtualgallery[imageCount][2] == nil then
	    	-- In case of multiple captions, use the first and ignore the laters
	        virtualgallery[imageCount][2] = currentfield
	    end
	end
	
	local altCount = 0;
	
	-- Run through virtualgallery and builds gallery
	for n = 1, #virtualgallery do
	    local img = virtualgallery[n][1]
	    local caption = virtualgallery[n][2] or ''
	    local alt = trim(args['alt' .. n] or '')
	    local class = trim(args['class' .. n] or '')
	    
	    -- we count alt text only before any modification
	    if alt ~= '' then
	    	altCount = altCount + 1
	    else
	    	-- if alt is empty, we use the caption as a alt text.
	    	-- It is necessary because we add classes codes in the next step,
	    	-- we do not want to let the alt empty with just the non-printing characters.
	    	alt = (caption ~= '') and plaintext(caption) or ''
	    end

	    -- we attach the non-printing code to the end of the alt text
	    if mw.ustring.find(class, 'skin%-invert') then -- this matches both skin-invert and skin-invert-image
	    	alt = alt .. skininvert
	    end
	    
	    -- as it is possible to combine multiple classes, we use find instead of ==
	    if mw.ustring.find(class, 'bg%-transparent') then
	    	alt = alt .. bgtransparent
	    end
	    
	    -- Some space between the arguments and the pipe to prevent unexpected behaviors.
	    -- for example: in some cases the parser interpret the pipe as part of urls
	    table.insert(gallery, img .. 
	    	(alt ~= '' and (' |alt=' .. alt) or '') ..
	    	(caption ~= '' and (' |' .. caption) or ''))
	end
	
	-- For tracking and verifying during migration to the new algorimth.
	-- It can be removed once everything is verified
	if math.ceil(#args / 2) > imageCount then
		if altCount > 0 then
			table.insert(tracking, '[[Category:Pages using gallery with potential alt text mismatch]]')
		--else
		--	table.insert(tracking, '[[Category:Pages using gallery with extra empty fields]]')
		end
	end
	
	tbl:tag('div')
		:addClass('main')
		:tag('div')
			:wikitext(
				frame:extensionTag{ name = 'gallery', content = '\n' .. table.concat(gallery,'\n'), args = gargs}
				)

	if args.footer then
		tbl:tag('div')
			:addClass('footer')
				:tag('div')
					:wikitext(args.footer)
	end

	local trackstr = (#tracking > 0) and table.concat(tracking, '') or ''
	if #preview > 0 then
		trackstr = require('Module:If preview')._warning({
			'Unknown parameters ' .. table.concat(preview, '; ') .. '.'
		}) .. trackstr
	end
	
	return frame:extensionTag{ name = 'templatestyles', args = { src = templatestyles} } .. tostring(tbl) .. trackstr
end

return p