module Goldberg
  module Migration 

    def self.included(base)
      base.class_eval do
        
        def self.prefix
          if not @prefix
            if self.pg_conn?
              self.create_goldberg_schema
              @prefix = 'goldberg.'
            else
              @prefix = 'goldberg_'
            end
          end
          @prefix
        end
        
        def self.pg_conn?
          ActiveRecord::Base.connection.class.to_s == 
            'ActiveRecord::ConnectionAdapters::PostgreSQLAdapter'
        end
        
        def self.goldberg_schema_exists?
          if self.pg_conn?
            count = ActiveRecord::Base.connection.select_value <<-END
SELECT COUNT(*) FROM pg_namespace WHERE nspname = 'goldberg'
END
            count.to_i > 0
          else
            false
          end
        end
        
        def self.create_goldberg_schema
          if self.pg_conn? and not self.goldberg_schema_exists?
            ActiveRecord::Base.connection.execute <<-END
CREATE SCHEMA goldberg
END
          end
        end
        
        def self.drop_goldberg_schema
          if self.pg_conn? and self.goldberg_schema_exists?
            ActiveRecord::Base.connection.execute <<-END
DROP SCHEMA goldberg
END
          end
        end
        
      end  # class_eval
    end  # self.included
    

    def self.load_bootstrap
      self.goldberg_classes.each do |klass|
        self.load_for_class klass, "#{File.dirname(__FILE__)}/../../db"
      end
    end

    def self.dump_bootstrap
      # Before dumping a bootstrap configuration, copy the existing
      # bootstrap to tst/fixtures (unless already exists)
      fixtures_path = "#{File.dirname(__FILE__)}/../../test/fixtures"
      unless File.exists?(fixtures_path)
        Dir.mkdir(fixtures_path)
        Dir["#{File.dirname(__FILE__)}/../../db/*.yml"].each do |fixture|
          FileUtils.cp(fixture, fixtures_path)
        end
      end
      self.goldberg_classes.each do |klass|
        self.dump_for_class klass, "#{File.dirname(__FILE__)}/../../db"
      end
    end

    def self.goldberg_classes
      return [ Goldberg::Permission, Goldberg::SiteController, 
               Goldberg::ContentPage, Goldberg::ControllerAction,
               Goldberg::MenuItem, Goldberg::Role,
               Goldberg::RolesPermission, Goldberg::SystemSettings,
               Goldberg::User ]
    end
    
    def self.dump_for_class(klass, dest)
      filename = "#{dest}/#{klass.to_s.sub(/^Goldberg::/, '')}.yml"
      records = klass.find(:all).collect do |record|
        record.attributes
      end
      File.open(filename, 'w') do |out|  
        YAML.dump(records, out)
      end
    end
    
    def self.load_for_class(klass, src)
      filename = "#{src}/#{klass.to_s.sub(/^Goldberg::/, '')}.yml"
      File.open(filename) do |src|
        records = YAML::load(src)
        records.each do |src_rec|
          attrs = (src_rec.respond_to?(:attributes) ? src_rec.attributes :
                   src_rec)
          record = klass.new(attrs)
          record.id = attrs['id']
          record.save!
        end
      end
      # Reset table sequence if applicable (i.e. PostgreSQL)
      if klass.connection.respond_to?(:reset_pk_sequence!)
        klass.connection.reset_pk_sequence!(klass.table_name)
      end
    end
    
  end
end