more refactors

internal/db/delete.go

@@ -0,0 +1,58 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/pkg/errors"
+	"github.com/uptrace/bun"
+)
+
+type deleter[T any] struct {
+	q *bun.DeleteQuery
+}
+
+type systemType interface {
+	isSystem() bool
+}
+
+func DeleteItem[T any](tx bun.Tx) *deleter[T] {
+	return &deleter[T]{
+		tx.NewDelete().
+			Model((*T)(nil)),
+	}
+}
+
+func (d *deleter[T]) Where(query string, args ...any) *deleter[T] {
+	d.q = d.q.Where(query, args...)
+	return d
+}
+
+func (d *deleter[T]) Delete(ctx context.Context) error {
+	_, err := d.q.Exec(ctx)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil
+		}
+	}
+	return errors.Wrap(err, "bun.DeleteQuery.Exec")
+}
+
+func DeleteByID[T any](tx bun.Tx, id int) *deleter[T] {
+	return DeleteItem[T](tx).Where("id = ?", id)
+}
+
+func DeleteWithProtection[T systemType](ctx context.Context, tx bun.Tx, id int) error {
+	deleter := DeleteByID[T](tx, id)
+	item, err := GetByID[T](tx, id).GetFirst(ctx)
+	if err != nil {
+		return errors.Wrap(err, "GetByID")
+	}
+	if item == nil {
+		return errors.New("record not found")
+	}
+	if (*item).isSystem() {
+		return errors.New("record is system protected")
+	}
+	return deleter.Delete(ctx)
+}