candles based alerts

internal/repository/postgresql/alerter_state.go

@@ -0,0 +1,33 @@
+package postgresql
+
+import (
+	"context"
+	"fmt"
+	"time"
+)
+
+const getLastAlertCheckQuery = `select last_alert_check from alerter_state`
+
+// GetLastAlertCheck returns the persisted time of the last completed alert check.
+// Returns zero time if no check has been recorded yet (null in DB).
+func (p *Postgresql) GetLastAlertCheck(ctx context.Context) (time.Time, error) {
+	var t *time.Time
+	err := p.db.QueryRow(ctx, getLastAlertCheckQuery).Scan(&t)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("failed to exec getLastAlertCheckQuery: %w", err)
+	}
+	if t == nil {
+		return time.Time{}, nil
+	}
+	return *t, nil
+}
+
+const setLastAlertCheckQuery = `update alerter_state set last_alert_check = $1`
+
+func (p *Postgresql) SetLastAlertCheck(ctx context.Context, t time.Time) error {
+	_, err := p.db.Exec(ctx, setLastAlertCheckQuery, t)
+	if err != nil {
+		return fmt.Errorf("failed to exec setLastAlertCheckQuery: %w", err)
+	}
+	return nil
+}