nairobi/app/models/tenant.rb

class Tenant < ApplicationRecord
  validates :schema,
    presence: true,
    uniqueness: true,
    exclusion: { in: ->(*) { excluded_subdomains }},
    format: { with: URI::DEFAULT_PARSER.regexp[:HOST] }
  validates :name, presence: true, uniqueness: true

  after_create :create_schema
  after_update :rename_schema
  after_destroy :destroy_schema

  def self.resolve_host(host)
    return nil unless Rails.application.config.multitenancy.present?
    return nil if host.blank? || host.match?(Resolv::AddressRegex)

    host_domain = allowed_domains.find { |domain| host == domain || host.ends_with?(".#{domain}") }
    host.delete_prefix("www.").sub(/\.?#{host_domain}\Z/, "").presence
  end

  def self.allowed_domains
    dev_domains = %w[localhost lvh.me example.com]
    dev_domains + [default_host]
  end

  def self.excluded_subdomains
    %w[mail public shared_extensions www]
  end

  def self.default_url_options
    ActionMailer::Base.default_url_options
  end

  def self.default_host
    default_url_options[:host]
  end

  def self.current_url_options
    default_url_options.merge(host: current_host)
  end

  def self.current_host
    host_for(current_schema)
  end

  def self.host_for(schema)
    if schema == "public"
      default_host
    elsif default_host == "localhost"
      "#{schema}.lvh.me"
    else
      "#{schema}.#{default_host}"
    end
  end

  def self.current_secrets
    if default?
      Rails.application.secrets
    else
      @secrets ||= {}
      @cached_rails_secrets ||= Rails.application.secrets

      if @cached_rails_secrets != Rails.application.secrets
        @secrets = {}
        @cached_rails_secrets = nil
      end

      @secrets[current_schema] ||= Rails.application.secrets.merge(
        Rails.application.secrets.dig(:tenants, current_schema.to_sym).to_h
      )
    end
  end

  def self.subfolder_path
    if default?
      ""
    else
      File.join("tenants", current_schema)
    end
  end

  def self.path_with_subfolder(filename_or_folder)
    File.join(subfolder_path, filename_or_folder).delete_prefix("/")
  end

  def self.default?
    current_schema == "public"
  end

  def self.current_schema
    Apartment::Tenant.current
  end

  def self.current
    find_by(schema: current_schema)
  end

  def self.switch(...)
    Apartment::Tenant.switch(...)
  end

  def self.run_on_each(&block)
    ["public"].union(Apartment.tenant_names).each do |schema|
      switch(schema, &block)
    end
  end

  def host
    self.class.host_for(schema)
  end

  private

    def create_schema
      Apartment::Tenant.create(schema)
    end

    def rename_schema
      if saved_change_to_schema?
        ActiveRecord::Base.connection.execute(
          "ALTER SCHEMA \"#{schema_before_last_save}\" RENAME TO \"#{schema}\";"
        )
      end
    end

    def destroy_schema
      Apartment::Tenant.drop(schema)
    end
end