Editing Module:Cats

local p = {}

-- Utility to add a value to a table if not empty
local function addIfValid(tbl, val)
    if val and val ~= "" then
        table.insert(tbl, val)
    end
end

-- Parse a "*"-style hierarchy string into a flat list of all nodes
local function parseTaxonomyFlat(taxonomy)
    local flat = {}
    for stars, label in taxonomy:gmatch("(%*+)([^%*]+)") do
        label = mw.text.trim(label)
        addIfValid(flat, label)
    end
    return flat
end

-- Main function: generate categories from fields + taxonomy
function p.addCats(frame)
    local categories = {}

    -- 1. Collect from fields
    for k, v in pairs(frame.args) do
        if k:match("^has.*Type$") or k:match("^hasCategory$") or k:match("^hasClass$") then
            for item in mw.text.gsplit(v, ",", true) do
                addIfValid(categories, mw.text.trim(item))
            end
        end
    end

    -- 2. Collect from taxonomy (hasTaxonomy)
    local taxonomy_str = frame.args.hasTaxonomy or ""
    if taxonomy_str ~= "" then
        local nodes = parseTaxonomyFlat(taxonomy_str)
        for _, node in ipairs(nodes) do
            addIfValid(categories, node)
        end
    end

    -- 3. Deduplicate
    local seen = {}
    local output = {}
    for _, cat in ipairs(categories) do
        if not seen[cat] then
            seen[cat] = true
            table.insert(output, "[[Category:" .. cat .. "]]")
        end
    end

    return table.concat(output, "\n")
end

return p