package main

import (
	// External
	werr "git.gibonuddevalla.se/go/wrappederror"

	// Standard
	"database/sql"
	"time"
)

// nodataLoop  checks if datapoint last_value is larger than the nodata_problem_seconds period and
// marks them as problems. They are then notified.
func nodataLoop() {
	var ids []int
	var err error

	// TODO - should be configurable
	ticker := time.NewTicker(time.Second * 5)
	for {
		<-ticker.C
		ids, err = nodataDatapointIDs()
		if err != nil {
			err = werr.Wrap(err).Log()
			logger.Error("nodata", "error", err)
			continue
		}

		if len(ids) == 0 {
			continue
		}

		logger.Info("nodata", "problem_ids", ids)
	}
}

func nodataDatapointIDs() (ids []int, err error) {
	ids = []int{}

	var rows *sql.Rows
	rows, err = service.Db.Conn.Query(`
		UPDATE datapoint
		SET
			nodata_is_problem = true
		FROM (
			SELECT
				id
			FROM
				datapoint
			WHERE
				NOT nodata_is_problem AND
				extract(EPOCH from (NOW() - last_value))::int > nodata_problem_seconds
			) AS subquery
		WHERE
			datapoint.id = subquery.id
		RETURNING
			datapoint.id

	`)
	if err != nil {
		err = werr.Wrap(err)
		return
	}
	defer rows.Close()

	var id int
	for rows.Next() {
		if err = rows.Scan(&id); err != nil {
			err = werr.Wrap(err)
			return
		}
		ids = append(ids, id)
	}
	return
}