/**
 * Billing/licensing boundary — STUB MODULE.
 *
 * This file defines the typed shape the settings UI (app/settings/billing) talks to.
 * Nothing here calls a real payment processor. Every exported function returns
 * hardcoded sample data or throws, and is marked with a TODO describing exactly
 * what a real integration would do.
 *
 * Do NOT wire a real Stripe (or other) publishable/secret key into this file.
 * When a processor is chosen:
 *   1. Add a c2-core router (e.g. `routers/billing.py`) that owns all server-side
 *      calls to the processor's API using a secret key from server env — never
 *      exposed to the frontend.
 *   2. Add a Stripe (or similar) webhook endpoint on c2-core that keeps an
 *      `organizations/{orgId}` Firestore doc in sync with subscription state
 *      (plan, status, current_period_end, seats, node_limit).
 *   3. Replace the bodies below with `c2api`-style `fetch` calls into that router.
 *      Checkout/portal functions should return a redirect URL from a real
 *      Checkout/Billing Portal session — the frontend's only job is
 *      `window.location.href = url`, it should never touch card data directly.
 */

export type PlanId = "free" | "pro" | "enterprise";
export type SubscriptionStatus = "trialing" | "active" | "past_due" | "canceled" | "none";
export type BillingInterval = "monthly" | "annual";

export interface PlanLimits {
  seats: number | "unlimited";
  nodes: number | "unlimited";
  retentionDays: number;
}

export interface PlanDefinition {
  id: PlanId;
  name: string;
  tagline: string;
  priceMonthlyUsd: number | null; // null = "contact us"
  priceAnnualUsd: number | null;
  limits: PlanLimits;
  features: string[];
  highlighted?: boolean;
}

export interface Subscription {
  planId: PlanId;
  status: SubscriptionStatus;
  interval: BillingInterval;
  currentPeriodEnd: string | null; // ISO date
  cancelAtPeriodEnd: boolean;
  trialEndsAt: string | null; // ISO date
  seatsUsed: number;
  nodesUsed: number;
}

export interface Invoice {
  id: string;
  date: string; // ISO date
  amountUsd: number;
  status: "paid" | "open" | "void" | "uncollectible";
  description: string;
  /** In a real integration, a short-lived link to the processor-hosted PDF/receipt. */
  hostedUrl: string | null;
}

export interface UsageSummary {
  seatsUsed: number;
  seatsLimit: number | "unlimited";
  nodesUsed: number;
  nodesLimit: number | "unlimited";
  periodStart: string;
  periodEnd: string;
}

// ---------------------------------------------------------------------------
// Plan catalog — this is real UI copy (safe to ship), just not wired to a
// live pricing table. In a real integration this would likely be fetched
// from the processor (Stripe Prices API) instead of hardcoded here so price
// changes don't require a frontend deploy.
// ---------------------------------------------------------------------------

export const PLANS: PlanDefinition[] = [
  {
    id: "free",
    name: "Community",
    tagline: "For a single node and a small crew keeping an eye on local traffic.",
    priceMonthlyUsd: 0,
    priceAnnualUsd: 0,
    limits: { seats: 3, nodes: 1, retentionDays: 7 },
    features: [
      "1 field node",
      "3 team seats",
      "Live incident map",
      "7-day call & incident history",
      "Discord voice relay",
    ],
  },
  {
    id: "pro",
    name: "Pro",
    tagline: "For agencies and serious hobbyist networks running multiple nodes.",
    priceMonthlyUsd: 79,
    priceAnnualUsd: 790,
    limits: { seats: 15, nodes: 10, retentionDays: 90 },
    features: [
      "Up to 10 field nodes",
      "15 team seats",
      "AI incident correlation & summaries",
      "90-day call & incident history",
      "Alert rules with Discord webhooks",
      "API key access",
    ],
    highlighted: true,
  },
  {
    id: "enterprise",
    name: "Enterprise",
    tagline: "For regional networks with custom retention, SSO, and support needs.",
    priceMonthlyUsd: null,
    priceAnnualUsd: null,
    limits: { seats: "unlimited", nodes: "unlimited", retentionDays: 365 },
    features: [
      "Unlimited field nodes",
      "Unlimited team seats",
      "1-year+ retention (custom)",
      "SSO / SAML",
      "Dedicated support & uptime SLA",
      "Custom data residency",
    ],
  },
];

export function getPlan(id: PlanId): PlanDefinition {
  return PLANS.find((p) => p.id === id) ?? PLANS[0];
}

// ---------------------------------------------------------------------------
// Sample account state — clearly a demo fixture, not a real customer record.
// TODO(billing): replace with `c2api.getSubscription()` once c2-core exposes
// GET /org/subscription backed by the processor + Firestore org doc.
// ---------------------------------------------------------------------------

const SAMPLE_SUBSCRIPTION: Subscription = {
  planId: "pro",
  status: "trialing",
  interval: "monthly",
  currentPeriodEnd: new Date(Date.now() + 1000 * 60 * 60 * 24 * 21).toISOString(),
  cancelAtPeriodEnd: false,
  trialEndsAt: new Date(Date.now() + 1000 * 60 * 60 * 24 * 7).toISOString(),
  seatsUsed: 4,
  nodesUsed: 2,
};

const SAMPLE_INVOICES: Invoice[] = [
  { id: "sample_inv_1003", date: "2026-07-16", amountUsd: 79, status: "paid", description: "Pro plan — monthly", hostedUrl: null },
  { id: "sample_inv_1002", date: "2026-06-16", amountUsd: 79, status: "paid", description: "Pro plan — monthly", hostedUrl: null },
  { id: "sample_inv_1001", date: "2026-05-16", amountUsd: 0,  status: "paid", description: "Community plan", hostedUrl: null },
];

/**
 * TODO(billing): replace with `c2api.getSubscription()` → GET /org/subscription.
 * Returns sample data so the settings UI has something real to render today.
 */
export async function getCurrentSubscription(): Promise<Subscription> {
  return SAMPLE_SUBSCRIPTION;
}

/**
 * TODO(billing): replace with `c2api.getUsageSummary()` → GET /org/usage,
 * computed server-side from `nodes` count + org member count.
 */
export async function getUsageSummary(): Promise<UsageSummary> {
  const sub = await getCurrentSubscription();
  const plan = getPlan(sub.planId);
  const now = new Date();
  const periodStart = new Date(now.getFullYear(), now.getMonth(), 1);
  const periodEnd = new Date(now.getFullYear(), now.getMonth() + 1, 0);
  return {
    seatsUsed: sub.seatsUsed,
    seatsLimit: plan.limits.seats,
    nodesUsed: sub.nodesUsed,
    nodesLimit: plan.limits.nodes,
    periodStart: periodStart.toISOString(),
    periodEnd: periodEnd.toISOString(),
  };
}

/**
 * TODO(billing): replace with `c2api.getInvoices()` → GET /org/invoices,
 * which on the backend would list Stripe Invoices for the org's customer id
 * and map them to this shape (hostedUrl = Stripe's `hosted_invoice_url`).
 */
export async function getInvoices(): Promise<Invoice[]> {
  return SAMPLE_INVOICES;
}

/**
 * TODO(billing): replace with `c2api.createCheckoutSession(planId, interval)`
 * → POST /org/billing/checkout-session, which creates a Stripe Checkout
 * Session server-side (secret key never leaves the server) and returns
 * `{ url }`. Frontend then does `window.location.href = url`.
 *
 * Throws here — there is no live checkout to redirect to.
 */
export async function createCheckoutSession(_planId: PlanId, _interval: BillingInterval): Promise<{ url: string }> {
  throw new Error(
    "Checkout is not wired to a payment processor yet. This is a demo build — " +
      "no card will be charged. See lib/billing.ts for the integration TODO."
  );
}

/**
 * TODO(billing): replace with `c2api.createBillingPortalSession()` →
 * POST /org/billing/portal-session, which creates a Stripe Billing Portal
 * session server-side and returns `{ url }` for redirect. The portal is
 * where a real integration would let customers update payment methods,
 * cancel, or download invoices — avoids building that UI ourselves.
 */
export async function createBillingPortalSession(): Promise<{ url: string }> {
  throw new Error(
    "Billing portal is not wired to a payment processor yet. See lib/billing.ts for the integration TODO."
  );
}

/**
 * TODO(billing): replace with `c2api.previewPlanChange(planId, interval)` →
 * GET /org/billing/preview?plan=…, which on the backend would call the
 * processor's upcoming-invoice/proration preview endpoint.
 * Returns a rough client-side estimate so the upgrade/downgrade UI has
 * something to show; not a real proration calculation.
 */
export async function previewPlanChange(planId: PlanId, interval: BillingInterval): Promise<{ dueTodayUsd: number; nextAmountUsd: number }> {
  const plan = getPlan(planId);
  const price = interval === "annual" ? plan.priceAnnualUsd : plan.priceMonthlyUsd;
  return { dueTodayUsd: price ?? 0, nextAmountUsd: price ?? 0 };
}