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
+}

internal/repository/postgresql/migrations/000001_init.down.sql

@@ -1,3 +1,4 @@
+drop table if exists alerter_state;
 drop table if exists alert;
 drop type alert_condition;
 drop table if exists instrument;

internal/repository/postgresql/migrations/000001_init.up.sql

@@ -34,3 +34,10 @@ insert into instrument (base_currency_id, quoted_currency_id) values
   ((select id from currency where symbol = 'BTC'), (select id from currency where symbol = 'USDT')),
   ((select id from currency where symbol = 'ETH'), (select id from currency where symbol = 'USDT')),
   ((select id from currency where symbol = 'SOL'), (select id from currency where symbol = 'USDT'));
+
+create table if not exists alerter_state (
+  last_alert_check timestamptz
+);
+
+-- single row; UPDATE always succeeds without upsert logic
+insert into alerter_state(last_alert_check) values (null);

internal/repository/repository.go

@@ -2,6 +2,7 @@ package repository
 
 import (
 	"context"
+	"time"
 
 	"gitea.computernetthings.ru/yash/crypto_alert_bot/internal/entities"
 	"github.com/shopspring/decimal"
@@ -22,4 +23,9 @@ type Storage interface {
 	DeleteAlert(ctx context.Context, id entities.AlertID) error
 	DisableAlert(ctx context.Context, id entities.AlertID) error
 	UpdateAlertPrice(ctx context.Context, id entities.AlertID, price decimal.Decimal) error
+
+	// GetLastAlertCheck returns the time of the last completed alert check.
+	// Returns zero time if no check has been recorded yet.
+	GetLastAlertCheck(ctx context.Context) (time.Time, error)
+	SetLastAlertCheck(ctx context.Context, t time.Time) error
 }