# frozen_string_literal: true

module Aws
  module Record
    class TableMigration
      # @!attribute [rw] client
      #   @return [Aws::DynamoDB::Client] the
      #     {http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html Aws::DynamoDB::Client}
      #     class used by this table migration instance.
      attr_accessor :client

      # @param [Aws::Record] model a model class that includes {Aws::Record}.
      # @param [Hash] opts
      # @option opts [Aws::DynamoDB::Client] :client Allows you to inject your
      #  own
      #  {http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html Aws::DynamoDB::Client}
      #  class. If this option is not included, a client will be constructed for
      #  you with default parameters.
      def initialize(model, opts = {})
        _assert_model_valid(model)
        @model = model
        @client = opts[:client] || model.dynamodb_client || Aws::DynamoDB::Client.new
        @client.config.user_agent_frameworks << 'aws-record'
      end

      # This method calls
      # {http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html#create_table-instance_method
      # Aws::DynamoDB::Client#create_table}, populating the attribute definitions and
      # key schema based on your model class, as well as passing through other
      # parameters as provided by you.
      #
      # @example Creating a table with a global secondary index named +:gsi+
      #   migration.create!(
      #     provisioned_throughput: {
      #       read_capacity_units: 5,
      #       write_capacity_units: 2
      #     },
      #     global_secondary_index_throughput: {
      #       gsi: {
      #         read_capacity_units: 3,
      #         write_capacity_units: 1
      #       }
      #     }
      #   )
      #
      # @param [Hash] opts options to pass on to the client call to
      #  +#create_table+. See the documentation above in the AWS SDK for Ruby
      #  V2.
      # @option opts [Hash] :billing_mode Accepts values 'PAY_PER_REQUEST' or
      #  'PROVISIONED'. If :provisioned_throughput option is specified, this
      #  option is not required, as 'PROVISIONED' is assumed. If
      #  :provisioned_throughput is not specified, this option is required
      #  and must be set to 'PAY_PER_REQUEST'.
      # @option opts [Hash] :provisioned_throughput Unless :billing_mode is
      #  set to 'PAY_PER_REQUEST', this is a required argument, in which
      #  you must specify the +:read_capacity_units+ and
      #  +:write_capacity_units+ of your new table.
      # @option opts [Hash] :global_secondary_index_throughput This argument is
      #  required if you define any global secondary indexes, unless
      #  :billing_mode is set to 'PAY_PER_REQUEST'. It should map your
      #  global secondary index names to their provisioned throughput, similar
      #  to how you define the provisioned throughput for the table in general.
      def create!(opts)
        gsit = opts.delete(:global_secondary_index_throughput)
        _validate_billing(opts)

        create_opts = opts.merge(
          table_name: @model.table_name,
          attribute_definitions: _attribute_definitions,
          key_schema: _key_schema
        )
        if (lsis = @model.local_secondary_indexes_for_migration)
          create_opts[:local_secondary_indexes] = lsis
          _append_to_attribute_definitions(lsis, create_opts)
        end
        if (gsis = @model.global_secondary_indexes_for_migration)
          unless gsit || opts[:billing_mode] == 'PAY_PER_REQUEST'
            raise ArgumentError, 'If you define global secondary indexes, you must also define'\
                                 ' :global_secondary_index_throughput on table creation,'\
                                 " unless :billing_mode is set to 'PAY_PER_REQUEST'."
          end
          gsis_opts = if opts[:billing_mode] == 'PAY_PER_REQUEST'
                        gsis
                      else
                        _add_throughput_to_gsis(gsis, gsit)
                      end
          create_opts[:global_secondary_indexes] = gsis_opts
          _append_to_attribute_definitions(gsis, create_opts)
        end
        @client.create_table(create_opts)
      end

      # This method calls
      # {http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html#update_table-instance_method
      # Aws::DynamoDB::Client#update_table} using the parameters that you provide.
      #
      # @param [Hash] opts options to pass on to the client call to
      #  +#update_table+. See the documentation above in the AWS SDK for Ruby
      #  V2.
      # @raise [Aws::Record::Errors::TableDoesNotExist] if the table does not
      #  currently exist in Amazon DynamoDB.
      def update!(opts)
        update_opts = opts.merge(
          table_name: @model.table_name
        )
        @client.update_table(update_opts)
      rescue DynamoDB::Errors::ResourceNotFoundException
        raise Errors::TableDoesNotExist
      end

      # This method calls
      # {http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html#delete_table-instance_method
      # Aws::DynamoDB::Client#delete_table} using the table name of your model.
      #
      # @raise [Aws::Record::Errors::TableDoesNotExist] if the table did not
      #  exist in Amazon DynamoDB at the time of calling.
      def delete!
        @client.delete_table(table_name: @model.table_name)
      rescue DynamoDB::Errors::ResourceNotFoundException
        raise Errors::TableDoesNotExist
      end

      # This method waits on the table specified in the model to exist and be
      # marked as ACTIVE in Amazon DynamoDB. Note that this method can run for
      # several minutes if the table does not exist, and is not created within
      # the wait period.
      def wait_until_available
        @client.wait_until(:table_exists, table_name: @model.table_name)
      end

      private

      def _assert_model_valid(model)
        _assert_required_include(model)
        model.model_valid?
      end

      def _assert_required_include(model)
        unless model.include?(::Aws::Record)
          raise Errors::InvalidModel, 'Table models must include Aws::Record'
        end
      end

      def _validate_billing(opts)
        valid_modes = %w[PAY_PER_REQUEST PROVISIONED]
        if opts.key?(:billing_mode)
          unless valid_modes.include?(opts[:billing_mode])
            raise ArgumentError, ":billing_mode option must be one of #{valid_modes.join(', ')}"\
                                 " current value is: #{opts[:billing_mode]}"
          end
        end
        if opts.key?(:provisioned_throughput)
          if opts[:billing_mode] == 'PAY_PER_REQUEST'
            raise ArgumentError, 'when :provisioned_throughput option is specified, :billing_mode'\
                                 " must either be unspecified or have a value of 'PROVISIONED'"
          end
        else
          if opts[:billing_mode] != 'PAY_PER_REQUEST'
            raise ArgumentError, 'when :provisioned_throughput option is not specified,'\
                                 " :billing_mode must be set to 'PAY_PER_REQUEST'"
          end
        end
      end

      def _attribute_definitions
        _keys.map do |_type, attr|
          {
            attribute_name: attr.database_name,
            attribute_type: attr.dynamodb_type
          }
        end
      end

      def _append_to_attribute_definitions(secondary_indexes, create_opts)
        attributes = @model.attributes
        attr_def = create_opts[:attribute_definitions]
        secondary_indexes.each do |si|
          si[:key_schema].each do |key_schema|
            exists = attr_def.find do |a|
              a[:attribute_name] == key_schema[:attribute_name]
            end
            unless exists
              attr = attributes.attribute_for(
                attributes.db_to_attribute_name(key_schema[:attribute_name])
              )
              attr_def << {
                attribute_name: attr.database_name,
                attribute_type: attr.dynamodb_type
              }
            end
          end
        end
        create_opts[:attribute_definitions] = attr_def
      end

      def _add_throughput_to_gsis(global_secondary_indexes, gsi_throughput)
        missing_throughput = []
        ret = global_secondary_indexes.map do |params|
          name = params[:index_name]
          throughput = gsi_throughput[name]
          missing_throughput << name unless throughput
          params.merge(provisioned_throughput: throughput)
        end
        unless missing_throughput.empty?
          raise ArgumentError, 'Missing provisioned throughput for the following global secondary'\
                               " indexes: #{missing_throughput.join(', ')}. GSIs:"\
                               " #{global_secondary_indexes} and defined throughput:"\
                               " #{gsi_throughput}"
        end
        ret
      end

      def _key_schema
        _keys.map do |type, attr|
          {
            attribute_name: attr.database_name,
            key_type: type == :hash ? 'HASH' : 'RANGE'
          }
        end
      end

      def _keys
        @model.keys.each_with_object({}) do |(type, name), acc|
          acc[type] = @model.attributes.attribute_for(name)
          acc
        end
      end
    end
  end
end