package billing

import (
	"context"

	"github.com/youruser/base/model"

	"gorm.io/gorm"
)

// QuotaService handles quota freeze/settle/unfreeze operations
type QuotaService struct{}

func NewQuotaService() *QuotaService {
	return &QuotaService{}
}

// CheckAndFreeze checks if user has sufficient balance and freezes the estimated cost.
// Returns nil if successful, error if insufficient balance.
// If apiKeyId > 0, it's a user-provided key — skip billing.
func (s *QuotaService) CheckAndFreeze(ctx context.Context, db *gorm.DB, userId int64, estimatedCost float64, apiKeyId int64) error {
	// User-provided keys skip billing
	if apiKeyId > 0 {
		return nil
	}

	// Ensure quota record exists
	_, err := model.AIUserQuotaEnsure(ctx, db, userId)
	if err != nil {
		return err
	}

	return model.AIUserQuotaFreeze(ctx, db, userId, estimatedCost)
}

// Settle finalizes billing: releases frozen amount, deducts actual cost, refunds difference.
func (s *QuotaService) Settle(ctx context.Context, db *gorm.DB, userId int64, frozenAmount, actualCost float64, apiKeyId int64) error {
	if apiKeyId > 0 {
		return nil
	}
	return model.AIUserQuotaSettle(ctx, db, userId, frozenAmount, actualCost)
}

// Unfreeze releases frozen amount back to balance (used on error).
func (s *QuotaService) Unfreeze(ctx context.Context, db *gorm.DB, userId int64, amount float64, apiKeyId int64) error {
	if apiKeyId > 0 {
		return nil
	}
	return model.AIUserQuotaUnfreeze(ctx, db, userId, amount)
}