chore: update

backend/gestion/db/db_referral.go

@@ -0,0 +1,62 @@
+package db
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+// GetClientReferralBalance retourne le solde parrainage d'un client.
+func (d *Database) GetClientReferralBalance(username string) (float64, error) {
+	var balance float64
+	err := d.QueryRow(
+		`SELECT referral_balance FROM clients WHERE username = $1`,
+		username,
+	).Scan(&balance)
+	if err == sql.ErrNoRows {
+		return 0, fmt.Errorf("client non trouvé")
+	}
+	return balance, err
+}
+
+// CreditClientReferral ajoute un montant au solde parrainage d'un client.
+func (d *Database) CreditClientReferral(username string, amount float64) error {
+	if amount <= 0 {
+		return fmt.Errorf("le montant doit être positif")
+	}
+	res, err := d.Exec(
+		`UPDATE clients SET referral_balance = referral_balance + $1 WHERE username = $2`,
+		amount, username,
+	)
+	if err != nil {
+		return err
+	}
+	n, _ := res.RowsAffected()
+	if n == 0 {
+		return fmt.Errorf("client non trouvé")
+	}
+	return nil
+}
+
+// UseClientReferralBalance déduit un montant du solde parrainage dans une transaction.
+// Retourne une erreur si le solde est insuffisant.
+func (d *Database) UseClientReferralBalance(tx *sql.Tx, username string, amount float64) error {
+	if amount <= 0 {
+		return nil
+	}
+	var balance float64
+	err := tx.QueryRow(
+		`SELECT referral_balance FROM clients WHERE username = $1 FOR UPDATE`,
+		username,
+	).Scan(&balance)
+	if err != nil {
+		return fmt.Errorf("client non trouvé")
+	}
+	if balance < amount {
+		return fmt.Errorf("solde parrainage insuffisant (disponible: %.2f€)", balance)
+	}
+	_, err = tx.Exec(
+		`UPDATE clients SET referral_balance = referral_balance - $1 WHERE username = $2`,
+		amount, username,
+	)
+	return err
+}