package service

import (
	"time"
	"wails-app/internal/dao"
	"wails-app/internal/global"
)

// CalculateFee is the shared parking-fee calculation used by vehicle exit
// flows and the digital-ticket live preview.
func CalculateFee(vehicle *dao.Vehicle, stayTime int64) float64 {
	if vehicle == nil || global.GVA_DB == nil {
		return 0
	}

	var feeConfig dao.FeeConfig
	if err := global.GVA_DB.Where("vehicle_type_id = ?", vehicle.VehicleTypeID).First(&feeConfig).Error; err != nil {
		return float64(stayTime) * 0.1
	}
	if feeConfig.UnitFee == 0 && feeConfig.StartFee == 0 && feeConfig.DailyMaxFee == 0 {
		return float64(stayTime) * 0.1
	}
	if feeConfig.UnitTime <= 0 {
		return feeConfig.StartFee
	}

	isVIP := false
	if vehicle.OwnerId != nil {
		var owner dao.Owner
		if err := global.GVA_DB.First(&owner, *vehicle.OwnerId).Error; err == nil {
			now := time.Now()
			isVIP = owner.IsVip && !owner.VipExpireTime.IsZero() && owner.VipExpireTime.After(now)
		}
	}
	if isVIP && feeConfig.IsVIPFree {
		return 0
	}
	if stayTime <= int64(feeConfig.StartTime) {
		return 0
	}

	extraTime := stayTime - int64(feeConfig.StartTime)
	extraUnits := extraTime / int64(feeConfig.UnitTime)
	if extraTime%int64(feeConfig.UnitTime) > 0 {
		extraUnits++
	}
	fee := feeConfig.StartFee + float64(extraUnits)*feeConfig.UnitFee
	if feeConfig.DailyMaxFee > 0 && fee > feeConfig.DailyMaxFee {
		fee = feeConfig.DailyMaxFee
	}
	if isVIP {
		fee *= feeConfig.VIPDiscount
	}
	return fee
}