module ActiveRecord
  module Tasks # :nodoc:
    class MySQLDatabaseTasks # :nodoc:
      ACCESS_DENIED_ERROR = 1045

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

      def initialize(configuration)
        @configuration = configuration
      end

      def create
        establish_connection configuration_without_database
        connection.create_database configuration["database"], creation_options
        establish_connection configuration
      rescue ActiveRecord::StatementInvalid => error
        if error.message.include?("database exists")
          raise DatabaseAlreadyExists
        else
          raise
        end
      rescue error_class => error
        if error.respond_to?(:errno) && error.errno == ACCESS_DENIED_ERROR
          $stdout.print error.message
          establish_connection root_configuration_without_database
          connection.create_database configuration["database"], creation_options
          if configuration["username"] != "root"
            connection.execute grant_statement.gsub(/\s+/, " ").strip
          end
          establish_connection configuration
        else
          $stderr.puts error.inspect
          $stderr.puts "Couldn't create database for #{configuration.inspect}, #{creation_options.inspect}"
          $stderr.puts "(If you set the charset manually, make sure you have a matching collation)" if configuration["encoding"]
        end
      end

      def drop
        establish_connection configuration
        connection.drop_database configuration["database"]
      end

      def purge
        establish_connection configuration
        connection.recreate_database configuration["database"], creation_options
      end

      def charset
        connection.charset
      end

      def collation
        connection.collation
      end

      def structure_dump(filename, extra_flags)
        args = prepare_command_options
        args.concat(["--result-file", "#{filename}"])
        args.concat(["--no-data"])
        args.concat(["--routines"])
        args.concat(["--skip-comments"])
        args.concat(["#{configuration['database']}"])
        args.unshift(*extra_flags) if extra_flags

        run_cmd("mysqldump", args, "dumping")
      end

      def structure_load(filename, extra_flags)
        args = prepare_command_options
        args.concat(["--execute", %{SET FOREIGN_KEY_CHECKS = 0; SOURCE #{filename}; SET FOREIGN_KEY_CHECKS = 1}])
        args.concat(["--database", "#{configuration['database']}"])
        args.unshift(*extra_flags) if extra_flags

        run_cmd("mysql", args, "loading")
      end

      private

        def configuration
          @configuration
        end

        def configuration_without_database
          configuration.merge("database" => nil)
        end

        def creation_options
          Hash.new.tap do |options|
            options[:charset]     = configuration["encoding"]   if configuration.include? "encoding"
            options[:collation]   = configuration["collation"]  if configuration.include? "collation"
          end
        end

        def error_class
          if configuration["adapter"].include?("jdbc")
            require "active_record/railties/jdbcmysql_error"
            ArJdbcMySQL::Error
          elsif defined?(Mysql2)
            Mysql2::Error
          else
            StandardError
          end
        end

        def grant_statement
          <<-SQL
GRANT ALL PRIVILEGES ON `#{configuration['database']}`.*
  TO '#{configuration['username']}'@'localhost'
IDENTIFIED BY '#{configuration['password']}' WITH GRANT OPTION;
          SQL
        end

        def root_configuration_without_database
          configuration_without_database.merge(
            "username" => "root",
            "password" => root_password
          )
        end

        def root_password
          $stdout.print "Please provide the root password for your MySQL installation\n>"
          $stdin.gets.strip
        end

        def prepare_command_options
          args = {
            "host"      => "--host",
            "port"      => "--port",
            "socket"    => "--socket",
            "username"  => "--user",
            "password"  => "--password",
            "encoding"  => "--default-character-set",
            "sslca"     => "--ssl-ca",
            "sslcert"   => "--ssl-cert",
            "sslcapath" => "--ssl-capath",
            "sslcipher" => "--ssl-cipher",
            "sslkey"    => "--ssl-key"
          }.map { |opt, arg| "#{arg}=#{configuration[opt]}" if configuration[opt] }.compact

          args
        end

        def run_cmd(cmd, args, action)
          fail run_cmd_error(cmd, args, action) unless Kernel.system(cmd, *args)
        end

        def run_cmd_error(cmd, args, action)
          msg = "failed to execute: `#{cmd}`\n"
          msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
          msg
        end
    end
  end
end
