Ruby Metaprogramming for Infrastructure Documentation

# lib/infra_dsl/host.rb
module InfraDSL
  class Host
    attr_reader :name, :attributes

    def initialize(name, &block)
      @name = name
      @attributes = {}
      instance_eval(&block) if block_given?
    end

    # Metaprogramming: generate attribute methods dynamically
    %i[ip mac role vlan gateway dns].each do |attr|
      define_method(attr) do |value = nil|
        if value
          @attributes[attr] = value
        else
          @attributes[attr]
        end
      end
    end

    # Catch any undefined attributes
    def method_missing(method_name, *args, &block)
      if args.length == 1
        @attributes[method_name] = args.first
      elsif args.empty?
        @attributes[method_name]
      else
        super
      end
    end

    def respond_to_missing?(method_name, include_private = false)
      true
    end
  end
end

# lib/infra_dsl/infrastructure.rb
module InfraDSL
  class Infrastructure
    attr_reader :name, :hosts, :networks

    def initialize(name, &block)
      @name = name
      @hosts = {}
      @networks = {}
      instance_eval(&block) if block_given?
    end

    def host(name, &block)
      @hosts[name] = Host.new(name, &block)
    end

    def network(name, &block)
      @networks[name] = Network.new(name, &block)
    end

    # Generate outputs
    def to_asciidoc_attributes
      output = []
      @hosts.each do |name, host|
        host.attributes.each do |attr, value|
          output << "#{name}-#{attr}: #{value}"
        end
      end
      output.join("\n")
    end

    def to_ansible_inventory
      output = []
      @hosts.each do |name, host|
        line = "#{name} ansible_host=#{host.ip}"
        line += " ansible_user=#{host.attributes[:user]}" if host.attributes[:user]
        output << line
      end
      output.join("\n")
    end

    def to_d2
      # Generate D2 diagram source
      output = ["direction: right", ""]
      @hosts.each do |name, host|
        output << "#{name}: {"
        output << "  label: \"#{name}\\n#{host.ip}\""
        output << "  shape: rectangle"
        output << "}"
      end
      output.join("\n")
    end
  end
end

# lib/infra_dsl.rb
require_relative 'infra_dsl/host'
require_relative 'infra_dsl/network'
require_relative 'infra_dsl/infrastructure'

module InfraDSL
  def self.infrastructure(name, &block)
    Infrastructure.new(name, &block)
  end
end

# Make it available at top level
def infrastructure(name, &block)
  InfraDSL.infrastructure(name, &block)
end

# generators/asciidoc.rb
class AsciidocGenerator
  def initialize(infra)
    @infra = infra
  end

  def generate
    output = ["# Auto-generated from domus-infrastructure.rb",
              "# DO NOT EDIT - regenerate with: ruby generate.rb asciidoc",
              ""]

    @infra.hosts.each do |name, host|
      output << "# #{name}"
      host.attributes.each do |attr, value|
        key = "#{name.to_s.gsub('_', '-')}-#{attr.to_s.gsub('_', '-')}"
        val = value.is_a?(Array) ? value.join(', ') : value
        output << "#{key}: #{val}"
      end
      output << ""
    end

    output.join("\n")
  end

  def write(path)
    File.write(path, generate)
    puts "Generated: #{path}"
  end
end

# Usage:
# AsciidocGenerator.new(DOMUS).write("antora-attributes.yml")

# generators/d2.rb
class D2Generator
  def initialize(infra)
    @infra = infra
  end

  def generate_network_diagram
    output = ["# Auto-generated network diagram", "direction: right", ""]

    # Group hosts by role
    roles = @infra.hosts.values.group_by { |h| h.attributes[:role] }

    roles.each do |role, hosts|
      output << "#{role}: {"
      output << "  label: #{role.to_s.upcase}"
      output << "  style.fill: \"#e3f2fd\""
      output << ""

      hosts.each do |host|
        output << "  #{host.name}: {"
        output << "    label: \"#{host.name}\\n#{host.ip}\""
        output << "  }"
      end

      output << "}"
      output << ""
    end

    output.join("\n")
  end
end

# generators/ansible.rb
class AnsibleGenerator
  def initialize(infra)
    @infra = infra
  end

  def generate_ini
    output = ["# Auto-generated Ansible inventory", ""]

    # Group by role
    roles = @infra.hosts.values.group_by { |h| h.attributes[:role] }

    roles.each do |role, hosts|
      output << "[#{role}]"
      hosts.each do |host|
        line = "#{host.name} ansible_host=#{host.ip}"
        output << line
      end
      output << ""
    end

    output.join("\n")
  end

  def generate_yaml
    # YAML inventory format
    inventory = { 'all' => { 'children' => {} } }

    roles = @infra.hosts.values.group_by { |h| h.attributes[:role] }

    roles.each do |role, hosts|
      inventory['all']['children'][role.to_s] = {
        'hosts' => hosts.map { |h|
          [h.name.to_s, { 'ansible_host' => h.ip }]
        }.to_h
      }
    end

    require 'yaml'
    inventory.to_yaml
  end
end