Subscription billing

# title: Subscription billing
# category: Vibescript Showcase
# difficulty: Showcase
# summary: Price a subscription invoice with typed plan enums and semantic money values.
# description: This example leans on enum-driven pricing and money arithmetic so billing code stays explicit about units and intent.
# tags: finance, money, enums, invoices
# featured: true
# feature_rank: 1
# vibe: 0.2

enum PlanTier
  Starter
  Growth
  Scale
end

def base_fee(plan: PlanTier) -> money
  if plan == PlanTier::Starter
    money("29.00 USD")
  elsif plan == PlanTier::Growth
    money("79.00 USD")
  else
    money("199.00 USD")
  end
end

def seat_fee_cents(plan: PlanTier) -> int
  if plan == PlanTier::Starter
    900
  elsif plan == PlanTier::Growth
    1900
  else
    2900
  end
end

def seats_total(plan: PlanTier, seats: int) -> money
  money_cents(seat_fee_cents(plan) * seats, "USD")
end

def invoice(plan: PlanTier, seats: int, discount: money) -> hash
  base = base_fee(plan)
  seats_fee = seats_total(plan, seats)
  subtotal = base + seats_fee
  total = subtotal - discount

  {
    plan: plan.name,
    base: base,
    seats: seats,
    seats_fee: seats_fee,
    discount: discount,
    total: total,
    currency: total.currency
  }
end

def run
  {
    growth: invoice(PlanTier::Growth, 4, money("10.00 USD")),
    scale: invoice(PlanTier::Scale, 12, money("0.00 USD"))
  }
end