zhdk/madek

module DBHelper

  class << self

    def reload! 
      load Rails.root.join(__FILE__)
    end

    def module_path # for convenient reloading
      Rails.root.join(__FILE__)
    end

    ###########################################################################
    # database adapter specific
    ###########################################################################

    def file_extension
      "pgsql.gz"
    end

    def base_file_name
      date_string = DateTime.now.to_s.gsub(":","-")
      migration_version =  ActiveRecord::Migrator.current_version
      "db_dump_#{date_string}_#{migration_version}"
    end

    def dump_file_path opts={}
      dir = opts[:dir] || (Rails.root.join "tmp")
      "#{dir}/#{base_file_name}.#{opts[:extension] || file_extension}"
    end

    def set_pg_env config
      ENV['PGHOST']     = config['host']          if config['host']
      ENV['PGPORT']     = config['port'].to_s     if config['port']
      ENV['PGPASSWORD'] = config['password'].to_s if config['password']
      ENV['PGUSER']     = config['username'].to_s if config['username']
      ENV['PGDATABASE'] = config['database'].to_s if config['database']
    end


    ###########################################################################
    # dump and restore data only 
    ###########################################################################
  
    def dump_data options= {}
      options = options.symbolize_keys
      path = options[:path] || dump_file_path(options.merge({extension: 'pgsql'}))
      set_pg_env (options[:config] || 
                  Rails.configuration.database_configuration[Rails.env])
      cmd = "pg_dump -x -T schema_migrations -E utf-8 -a --no-acl -f #{path}"
      system cmd
      raise "#{cmd} failed" unless $?.exitstatus == 0
      {path: path, return_value: $?}
    end

    def dump options= {}
      options = options.symbolize_keys
      path = options[:path] || dump_file_path(options.merge({extension: 'pgbin'}))
      set_pg_env (options[:config] || 
                  Rails.configuration.database_configuration[Rails.env])
      cmd = "pg_dump -x -E utf-8 -F c -f #{path}"
      system cmd
      raise "#{cmd} failed" unless $?.exitstatus == 0
      {path: path, return_value: $?}
    end


    def load_data path, options = {} 
      config = options[:config] || Rails.configuration.database_configuration[Rails.env]
      set_pg_env config 
      cond_unzip_pipe = case path.to_s
                   when /\.gz$/
                     "| gunzip"
                   else
                     ""
                   end
      cmd = "cat #{path} #{cond_unzip_pipe} | psql -q #{config['database'].to_s}"
      system cmd
      raise "#{cmd} failed" unless $?.exitstatus == 0
      $?
    end

    def truncate_tables
      ActiveRecord::Base.connection.tap do |connection|
        connection.tables.reject{|tn|tn=="schema_migrations"}.join(', ').tap do |tables|
          connection.execute " TRUNCATE TABLE #{tables} CASCADE; "
        end
      end
    end

  end
end