Editing Module:Update history navbox

local p = {}

local months = {
    'January', 'February', 'March', 'April', 'May', 'June',
    'July', 'August', 'September', 'October', 'November', 'December'
}


function p.render()
    local index = mw.title.new('Update history'):getContent() or ''
    local region = index:match('<!%-%- bconomy:begin version%-index %-%->(.-)<!%-%- bconomy:end version%-index %-%->')
    if not region then
        return '[[Update history|Browse the chronological index]]'
    end

    local root = mw.html.create('table'):addClass('bc-navbox-table bc-navbox-years')
    local year, month, monthTable, list
    for y, m, link in region:gmatch('| data%-sort%-value="(%d%d%d%d)%-(%d%d)%-%d%d"[^\n]*\n| (%[%[[^\n]+%]%])\n') do
        if year ~= y then
            year, month = y, nil
            local row = root:tag('tr')
            row:tag('th'):attr('scope', 'row'):addClass('bc-navbox-year'):wikitext(y)
            monthTable = row:tag('td'):addClass('bc-navbox-year-body')
                :tag('table'):addClass('bc-navbox-months')
        end
        if month ~= m then
            month = m
            local monthRow = monthTable:tag('tr')
            monthRow:tag('th'):attr('scope', 'row'):wikitext(months[tonumber(m)] or m)
            list = monthRow:tag('td'):tag('ul'):addClass('bc-release-links')
        end
        local target, label = link:match('^%[%[([^|%]]+)|?([^%]]*)%]%]$')
        if target then
            label = (label ~= '' and label or target):gsub('^V(%d)', 'v%1')
            list:tag('li'):wikitext('[[' .. target .. '|' .. label .. ']]')
        end
    end
    if not year then
        return '[[Update history|Browse the chronological index]]'
    end
    return tostring(root)
end

return p