require 'active_record/tasks/database_tasks'
require 'shellwords'
require 'ipaddr'
require 'socket'

module ActiveRecord
  module Tasks

    class SQLServerDatabaseTasks

      DEFAULT_COLLATION = 'SQL_Latin1_General_CP1_CI_AS'

      delegate :connection, :establish_connection, :clear_active_connections!,
               to: ActiveRecord::Base

      def initialize(configuration)
        @configuration = configuration
      end

      def create(master_established = false)
        establish_master_connection unless master_established
        connection.create_database configuration['database'], configuration.merge('collation' => default_collation)
        establish_connection configuration
      rescue ActiveRecord::StatementInvalid => error
        if /database .* already exists/i === error.message
          raise DatabaseAlreadyExists
        else
          raise
        end
      end

      def drop
        establish_master_connection
        connection.drop_database configuration['database']
      end

      def charset
        connection.charset
      end

      def collation
        connection.collation
      end

      def purge
        clear_active_connections!
        drop
        create true
      end

      def structure_dump(filename, extra_flags)
        command = [
          "defncopy-ttds",
          "-S #{Shellwords.escape(configuration['host'])}",
          "-D #{Shellwords.escape(configuration['database'])}",
          "-U #{Shellwords.escape(configuration['username'])}",
          "-P #{Shellwords.escape(configuration['password'])}",
          "-o #{Shellwords.escape(filename)}",
        ]
        table_args = connection.tables.map { |t| Shellwords.escape(t) }
        command.concat(table_args)
        view_args = connection.views.map { |v| Shellwords.escape(v) }
        command.concat(view_args)
        raise 'Error dumping database' unless Kernel.system(command.join(' '))
        dump = File.read(filename)
        dump.gsub!(/^USE .*$\nGO\n/, '')                      # Strip db USE statements
        dump.gsub!(/^GO\n/, '')                               # Strip db GO statements
        dump.gsub!(/nvarchar\(8000\)/, 'nvarchar(4000)')      # Fix nvarchar(8000) column defs
        dump.gsub!(/nvarchar\(-1\)/, 'nvarchar(max)')         # Fix nvarchar(-1) column defs
        dump.gsub!(/text\(\d+\)/, 'text')                     # Fix text(16) column defs
        File.open(filename, "w") { |file| file.puts dump }
      end

      def structure_load(filename, extra_flags)
        connection.execute File.read(filename)
      end


      private

      def configuration
        @configuration
      end

      def default_collation
        configuration['collation'] || DEFAULT_COLLATION
      end

      def establish_master_connection
        establish_connection configuration.merge('database' => 'master')
      end

    end

    module DatabaseTasksSQLServer

      extend ActiveSupport::Concern

      module ClassMethods

        LOCAL_IPADDR = [
          IPAddr.new('192.168.0.0/16'),
          IPAddr.new('10.0.0.0/8'),
          IPAddr.new('172.16.0.0/12')
        ]

        private

        def local_database?(configuration)
          super || local_ipaddr?(configuration_host_ip(configuration))
        end

        def configuration_host_ip(configuration)
          return nil unless configuration['host']
          Socket::getaddrinfo(configuration['host'], 'echo', Socket::AF_INET)[0][3]
        end

        def local_ipaddr?(host_ip)
          return false unless host_ip
          LOCAL_IPADDR.any? { |ip| ip.include?(host_ip) }
        end

      end

    end

    DatabaseTasks.register_task %r{sqlserver}, SQLServerDatabaseTasks
    DatabaseTasks.send :include, DatabaseTasksSQLServer

  end
end