# frozen_string_literal: true

require "pg"

module Multiwoven::Integrations::Source
  module Redshift
    include Multiwoven::Integrations::Core
    class Client < SourceConnector
      def check_connection(connection_config)
        connection_config = connection_config.with_indifferent_access
        create_connection(connection_config)
        ConnectionStatus.new(
          status: ConnectionStatusType["succeeded"]
        ).to_multiwoven_message
      rescue PG::Error => e
        ConnectionStatus.new(
          status: ConnectionStatusType["failed"], message: e.message
        ).to_multiwoven_message
      end

      def discover(connection_config)
        connection_config = connection_config.with_indifferent_access
        query = "SELECT table_name, column_name, data_type, is_nullable
                 FROM information_schema.columns
                 WHERE table_schema = '#{connection_config[:schema]}' AND table_catalog = '#{connection_config[:database]}'
                 ORDER BY table_name, ordinal_position;"

        db = create_connection(connection_config)
        records = db.exec(query) do |result|
          result.map do |row|
            row
          end
        end
        catalog = Catalog.new(streams: create_streams(records))
        catalog.to_multiwoven_message
      rescue StandardError => e
        handle_exception(e, {
                           context: "REDSHIFT:DISCOVER:EXCEPTION",
                           type: "error"
                         })
      ensure
        db&.close
      end

      def read(sync_config)
        connection_config = sync_config.source.connection_specification
        connection_config = connection_config.with_indifferent_access
        query = sync_config.model.query
        query = batched_query(query, sync_config.limit, sync_config.offset) unless sync_config.limit.nil? && sync_config.offset.nil?

        db = create_connection(connection_config)

        query(db, query)
      rescue StandardError => e
        handle_exception(e, {
                           context: "REDSHIFT:READ:EXCEPTION",
                           type: "error",
                           sync_id: sync_config.sync_id,
                           sync_run_id: sync_config.sync_run_id
                         })
      ensure
        db&.close
      end

      private

      def query(connection, query)
        connection.exec(query) do |result|
          result.map do |row|
            RecordMessage.new(data: row, emitted_at: Time.now.to_i).to_multiwoven_message
          end
        end
      end

      def create_connection(connection_config)
        raise "Unsupported Auth type" unless connection_config[:credentials][:auth_type] == "username/password"

        PG.connect(
          host: connection_config[:host],
          dbname: connection_config[:database],
          user: connection_config[:credentials][:username],
          password: connection_config[:credentials][:password],
          port: connection_config[:port]
        )
      end

      def create_streams(records)
        group_by_table(records).map do |r|
          Multiwoven::Integrations::Protocol::Stream.new(name: r[:tablename], action: StreamAction["fetch"], json_schema: convert_to_json_schema(r[:columns]))
        end
      end

      def group_by_table(records)
        records.group_by { |entry| entry["table_name"] }.map do |table_name, columns|
          {
            tablename: table_name,
            columns: columns.map do |column|
              {
                column_name: column["column_name"],
                type: column["data_type"],
                optional: column["is_nullable"] == "YES"
              }
            end
          }
        end
      end
    end
  end
end