JSON to Zod Schema — Ruby source

# JSON -> Zod schema inference — Ruby port of the json-to-zod tool: parse
# with the stdlib json (Ruby hashes preserve insertion order) and run the
# recursive InferZod walk from jsonToZod.ts / go.go. Mixed-type arrays render
# z.union([every element]); one shared type renders z.array(T).
require "json"

module JsonToZod
  module_function

  # Reduce an arbitrary string to a usable JS identifier ("9lives" -> "_lives").
  def sanitize_var_name(name)
    cleaned = name.gsub(/[^A-Za-z0-9_$]/, "")
    cleaned = cleaned.gsub(/\A[0-9]+/) { |digits| "_" * digits.length }
    cleaned.empty? ? "schema" : cleaned
  end

  def infer_zod(value, indent = 2)
    case value
    when nil then "z.null()"
    when true, false then "z.boolean()"       # `when` uses ===, so 1 is not "true"
    when Numeric then "z.number()"
    when String then "z.string()"
    when Array
      return "z.array(z.unknown())" if value.empty?

      types = value.map { |e| infer_zod(e, indent + 2) }
      inner =
        if types.uniq.one?
          types.first
        else                                  # union of EVERY element
          padded = types.join(",\n").split("\n").map { |l| l.empty? ? l : (" " * (indent + 2)) + l }.join("\n")
          "z.union([\n#{padded}\n])"          # close unpadded: pad("", indent) is ""
        end
      "z.array(#{inner})"
    when Hash                                 # fields in insertion order
      return "z.object({})" if value.empty?

      fields = value.map { |k, v| "#{' ' * (indent + 2)}#{k}: #{infer_zod(v, indent + 2)}," }
      "z.object({\n#{fields.join("\n")}\n#{' ' * indent}})"
    else "z.unknown()"                        # unreachable for valid JSON
    end
  end

  # Never raises — parse failures are returned as {ok: false, error:}, the
  # same Result shape the TS lib and the Go twin use.
  def convert(json_string, root_name = "Root")
    value = JSON.parse(json_string)
    { ok: true, code: "const #{sanitize_var_name(root_name)} = #{infer_zod(value)};",
      error: nil }
  rescue JSON::ParserError => e
    { ok: false, code: "", error: e.message }
  end
end

# {"name": "Ada", "admin": true, "meta": {"roles": ["admin", 1]}}
puts JsonToZod.convert(
  '{"name": "Ada", "admin": true, "meta": {"roles": ["admin", 1]}}', "User"
)[:code]