Function calculateBillingProjection

apps/sim/lib/billing/core/usage.ts:774–815

* Calculate billing projection based on current usage

(userId: string)

 * Calculate billing projection based on current usage
 */
async function calculateBillingProjection(userId: string): Promise<BillingData> {
  try {
    const usageData = await getUserUsageData(userId)

    if (!usageData.billingPeriodStart || !usageData.billingPeriodEnd) {
      return {
        currentPeriodCost: usageData.currentUsage,
        projectedCost: usageData.currentUsage,
        limit: usageData.limit,
        billingPeriodStart: null,
        billingPeriodEnd: null,
        daysRemaining: 0,
      }
    }

    const now = new Date()
    const periodStart = new Date(usageData.billingPeriodStart)
    const periodEnd = new Date(usageData.billingPeriodEnd)

    const totalDays = Math.ceil(
      (periodEnd.getTime() - periodStart.getTime()) / (1000 * 60 * 60 * 24)
    )
    const daysElapsed = Math.ceil((now.getTime() - periodStart.getTime()) / (1000 * 60 * 60 * 24))
    const daysRemaining = Math.max(0, totalDays - daysElapsed)

    // Project cost based on daily usage rate
    const dailyRate = daysElapsed > 0 ? usageData.currentUsage / daysElapsed : 0
    const projectedCost = dailyRate * totalDays

    return {
      currentPeriodCost: usageData.currentUsage,
      projectedCost: Math.min(projectedCost, usageData.limit), // Cap at limit
      limit: usageData.limit,
      billingPeriodStart: usageData.billingPeriodStart,
      billingPeriodEnd: usageData.billingPeriodEnd,
      daysRemaining,
    }
  } catch (error) {
    logger.error('Failed to calculate billing projection', { userId, error })
    throw error
  }
}

/**
 * Send usage threshold notification when crossing from <80% to ≥80%.