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
}