package db

import (
	"database/sql"
	"fmt"
	"gestion/models"

	"gorm.io/gorm"
)

func (d *Database) SetClientParrain(clientUsername, parrainUsername string) error {
	result := d.GDB.Model(&models.Client{}).
		Where("username = ? AND (parrain IS NULL OR parrain = '')", clientUsername).
		Update("parrain", parrainUsername)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return fmt.Errorf("client introuvable ou parrain déjà défini")
	}
	return nil
}

// SetClientParrainAndCredit assigne un parrain à un client et crédite le parrain
// dans une seule transaction, pour éviter un lien parrain enregistré sans le crédit associé.
func (d *Database) SetClientParrainAndCredit(clientUsername, parrainUsername string, creditAmount float64) error {
	return d.GDB.Transaction(func(tx *gorm.DB) error {
		result := tx.Model(&models.Client{}).
			Where("username = ? AND (parrain IS NULL OR parrain = '')", clientUsername).
			Update("parrain", parrainUsername)
		if result.Error != nil {
			return result.Error
		}
		if result.RowsAffected == 0 {
			return fmt.Errorf("client introuvable ou parrain déjà défini")
		}

		if creditAmount > 0 {
			result = tx.Model(&models.Client{}).Where("username = ?", parrainUsername).
				Updates(map[string]any{"referral_balance": gorm.Expr("referral_balance + ?", creditAmount)})
			if result.Error != nil {
				return result.Error
			}
			if result.RowsAffected == 0 {
				return fmt.Errorf("parrain non trouvé")
			}
		}
		return nil
	})
}

func (d *Database) GetClientParrain(clientUsername string) (string, error) {
	var parrain sql.NullString
	err := d.GDB.Table("clients").
		Select("parrain").
		Where("username = ?", clientUsername).
		Scan(&parrain).Error
	if err != nil {
		return "", err
	}
	return parrain.String, nil
}

func (d *Database) GetClientsByParrain(parrainUsername string) ([]models.Client, error) {
	var clients []models.Client
	err := d.GDB.
		Where("parrain = ?", parrainUsername).
		Find(&clients).Error
	return clients, err
}

func (d *Database) GetParrainStats() ([]map[string]any, error) {
	var rows []struct {
		Parrain         string  `gorm:"column:parrain"`
		FilleulCount    int     `gorm:"column:filleul_count"`
		ReferralBalance float64 `gorm:"column:referral_balance"`
	}

	err := d.GDB.Raw(`
		SELECT
			c.parrain,
			COUNT(c.username) AS filleul_count,
			p.referral_balance
		FROM clients c
		JOIN clients p ON p.username = c.parrain
		WHERE c.parrain IS NOT NULL AND c.parrain <> ''
		GROUP BY c.parrain, p.referral_balance
		ORDER BY filleul_count DESC
	`).Scan(&rows).Error
	if err != nil {
		return nil, err
	}

	result := make([]map[string]any, 0, len(rows))
	for _, r := range rows {
		result = append(result, map[string]any{
			"parrain":          r.Parrain,
			"filleul_count":    r.FilleulCount,
			"referral_balance": r.ReferralBalance,
		})
	}
	return result, nil
}