Module:Library work multi-author

local p = {}

local function formatList(items)
    local count = #items
    if count == 0 then
        return ""			-- returns nothing if empty
    elseif count == 1 then
        return items[1]		-- just return the string input if alone
    elseif count == 2 then
        return items[1] .. " and " .. items[2]		-- returns "string1, string2, ... and last_string"
    else
        local last = table.remove(items)
        return table.concat(items, ", ") .. " and " .. last
    end
end

-- Helper function to split comma-separated string
local function splitString(input)
    local items = {}
    if not input or input == "" then
        return items
    end
    
    -- Split by comma and trim whitespace from each item
    for item in string.gmatch(input, "([^,]+)") do
        item = string.gsub(item, "^%s*(.-)%s*$", "%1")  -- Trim whitespace
        if item ~= "" then
            table.insert(items, item)
        end
    end
    
    return items
end

-- Just prints "a,b,c, ... and z"

function p.main(frame)
    local args = frame:getParent().args
    local inputString = args[1] or ""
    
    local items = splitString(inputString)
    return formatList(items)
end

-- Prints with links if exists "a,[[b]],[[c]], ... and z"

function p.link(frame)
    local args = frame:getParent().args
    local inputString = args[1] or ""
    
    local items = splitString(inputString)
    local linkedItems = {}
    
    for _, value in ipairs(items) do
        local title = mw.title.new(value)		-- creates object for page
        if title and title.exists then			-- checks if page exists
            table.insert(linkedItems, "[[" .. value .. "]]")	-- adds with wikilink format
        else
            table.insert(linkedItems, value)				-- adds without wikilink format
        end
    end
    
    return formatList(linkedItems)
end

-- Returns categories if exists "[[Category:Library works by a]]"
--								"[[Category:Library works by b]]"
function p.cat(frame)
    local args = frame:getParent().args
    local inputString = args[1] or ""
    
    if inputString == "" then
        return ""
    end
    
    local items = splitString(inputString)
    local result = {}
    
    for _, item in ipairs(items) do
        local category = "Category:Library works by " .. item
        local conditional = "{{#ifexist:" .. category .. "|[[Category:Library works by " .. item .. "]]}}"
        table.insert(result, conditional)
    end
    
    return table.concat(result, "\n")
end


return p