export type BillingPlanId = "starter" | "basic" | "pro" | "ultimate";
export type PaidBillingPlanId = Exclude<BillingPlanId, "starter">;

export type BillingPlanDefinition = {
  id: BillingPlanId;
  name: string;
  price: string;
  period: string;
  monthlyImageLimit: number | null;
};

export const BILLING_PLAN_DEFINITIONS: BillingPlanDefinition[] = [
  {
    id: "starter",
    name: "Starter",
    price: "¥0",
    period: "/month",
    monthlyImageLimit: 200,
  },
  {
    id: "basic",
    name: "Basic",
    price: "¥69",
    period: "/month",
    monthlyImageLimit: 1200,
  },
  {
    id: "pro",
    name: "Pro",
    price: "¥199",
    period: "/month",
    monthlyImageLimit: 6000,
  },
  {
    id: "ultimate",
    name: "Ultimate",
    price: "¥599",
    period: "/month",
    monthlyImageLimit: null,
  },
];

const PAID_PLAN_IDS: PaidBillingPlanId[] = ["basic", "pro", "ultimate"];

const STRIPE_PRICE_ENV: Record<PaidBillingPlanId, string> = {
  basic: "STRIPE_PRICE_ID_BASIC",
  pro: "STRIPE_PRICE_ID_PRO",
  ultimate: "STRIPE_PRICE_ID_ULTIMATE",
};

export function isBillingPlanId(value: string): value is BillingPlanId {
  return BILLING_PLAN_DEFINITIONS.some((plan) => plan.id === value);
}

export function isPaidBillingPlanId(value: string): value is PaidBillingPlanId {
  return PAID_PLAN_IDS.includes(value as PaidBillingPlanId);
}

export function getBillingPlanById(planId: BillingPlanId) {
  return BILLING_PLAN_DEFINITIONS.find((plan) => plan.id === planId) || null;
}

export function getPaidPlanById(planId: PaidBillingPlanId) {
  return BILLING_PLAN_DEFINITIONS.find((plan) => plan.id === planId) || null;
}

export function getMonthlyImageLimitByPlanId(planId: BillingPlanId) {
  return getBillingPlanById(planId)?.monthlyImageLimit ?? null;
}

export function getStripePriceIdForPlan(planId: PaidBillingPlanId) {
  const envName = STRIPE_PRICE_ENV[planId];
  const value = process.env[envName];
  return value && value.trim().length > 0 ? value.trim() : null;
}

export function getCheckoutEnabledPlans() {
  return PAID_PLAN_IDS.reduce<Record<PaidBillingPlanId, boolean>>((acc, planId) => {
    acc[planId] = Boolean(getStripePriceIdForPlan(planId));
    return acc;
  }, {
    basic: false,
    pro: false,
    ultimate: false,
  });
}