=begin

= myrds.rb

*Copyright*::    (C) 2013 by Novu, LLC
*Author(s)*::    Tamara Temple <tamara.temple@novu.com>
*Since*::        2013-05-01
*License*::      MIT
*Version*::      0.0.1

== Description

Restore an RDS database snapshot

=end

require 'methadone'
require 'fog'

module NewBackup

  class MyRds

    include Methadone::CLILogging

    # Initialize the class with options
    def initialize(options={})
      debug "#{self.class}##{__method__}:#{File.basename(__FILE__)}:#{__LINE__}: Options: #{options}"
      @options = options
    end


    # Maximum number of tries to wait for database servers to be ready
    MAX_TRIES = 3

    # Restore a snapshot of the target database yielding the database to the block
    def restore(&block)
      connect do |connection|
        get_rds(connection) do |rds_server|
          retrieve_snapshot(rds_server) do |snapshot|
            restore_db(connection,snapshot) do |db|
              yield db
            end
          end
        end
      end
    end

    # Establishes a connection to AWS RDS and yeilds a block on the connection
    def connect(&block)
      raise "no block given in #{self.class}#connect" unless block_given?
      aws = @options[:aws]
      debug "AWS Options: #{aws}"
      fog_options = {
        :aws_access_key_id 	=> aws[:access_key],
        :aws_secret_access_key 	=> aws[:secret_key],
        :region 		=> aws[:rds_region]}

      Fog.timeout = @options[:fog][:timeout]
      yield Fog::AWS::RDS.new(fog_options)
    end

    # Get the RDS server
    def get_rds(connection)
      debug "#{self.class}##{__method__}:#{File.basename(__FILE__)}:#{__LINE__}: rds instance_id: #{@options[:rds][:instance_id]}\nConnection servers: #{connection.servers}"
      rds_server = connection.servers.get(@options[:rds][:instance_id])
      raise "No RDS server!" if rds_server.nil?
      yield rds_server
    end


    # Retrieve a snapshot 
    def retrieve_snapshot(rds_server, &block)
      begin
        rds_server.snapshots.new(:id => snap_name).save
        new_snapshot = rds_server.snapshots.get(snap_name)
        1.upto(MAX_TRIES) do |i|
          debug "#{self.class}##{__method__}:#{File.basename(__FILE__)}:#{__LINE__}: waiting for new snapshot, try ##{i}"
          new_snapshot.wait_for { ready? }
        end
        
        yield new_snapshot
      ensure
        unless @options[:debug]
          new_snapshot.destroy unless new_snapshot.nil?
        end
      end
      
    end

    # Restore the snapshot to a database
    def restore_db(connection, snapshot, &block)
      begin
        connection.
          restore_db_instance_from_db_snapshot(snapshot.id,
                                               backup_server_id,
                                               {"DBSubnetGroupName" => @options[:rds][:subnet_group],
                                                 "DBInstanceClass" => @options[:rds][:instance_type]}
                                               )
        backup_server = connection.servers.get(backup_server_id)
        1.upto(MAX_TRIES) do |i|
          debug "#{self.class}##{__method__}:#{File.basename(__FILE__)}:#{__LINE__}: waiting for backup server, try ##{i}"
          backup_server.wait_for { ready? }
        end

        
        yield MySqlCmds.new(backup_server.endpoint['Address'],
                            @options[:mysql][:username],
                            @options[:mysql][:password],
                            @options[:mysql][:database],
                            @options[:mysql][:obfuscate_script])
                              

      ensure
        unless @options[:debug]
          backup_server.destroy unless backup_server.nil?
        end
      end
      
    end



    # Return the snapshot name
    def snap_name
      "s3-dump-snap-#{@options[:timestamp]}".tap do |t|
      debug "#{self.class}##{__method__}:#{File.basename(__FILE__)}:#{__LINE__}: Snap Name: #{t}"
      end
    end

    # Return the backup server id
    def backup_server_id
      "#{@options[:rds][:instance_id]}-s3-dump-server-#{@options[:timestamp]}".tap do |t|
        debug "#{self.class}##{__method__}:#{File.basename(__FILE__)}:#{__LINE__}: Backup Server ID: #{t}"
      end
    end



  end


end