// Shopify App Pricing: the shop's plan comes from the Partner API's activeSubscription query, not from the
// Admin API (currentAppInstallation) or billing webhooks, which App Pricing doesn't use.
// https://shopify.dev/docs/apps/launch/billing/shopify-app-pricing/redirect-plan-selection-page

const PARTNER_API_VERSION = "2026-07";

const QUERY = `query OfferlystActiveSubscription($appId: ID!, $shopId: ID!) {
  activeSubscription(appId: $appId, shopId: $shopId) { cancelAtEndOfCycle items { handle } currentBillingCycle { endTime } pendingUpdate { items { handle } } }
}`;

export interface ActiveSubscription {
  /** plan handles of the subscription's items, e.g. ["growth"] */
  handles: string[];
  /** a scheduled change (e.g. a downgrade from a yearly plan): its plan handles and when it applies */
  pendingHandles: string[];
  changesAt: string | null;
  /** the subscription was cancelled (app uninstalled, or cancelled in the admin) and only runs out its paid period */
  cancelled: boolean;
}

// Only confirmed subscriptions are cached, briefly: a merchant who just approved a plan is checked at once,
// and a cancellation is picked up when the entry expires.
const CACHE_MS = 5 * 60 * 1000;
const cache = new Map<string, { at: number; sub: ActiveSubscription }>();

export function partnerApiConfigured() {
  return !!(process.env.SHOPIFY_PARTNER_ORG_ID && process.env.SHOPIFY_PARTNER_API_ACCESS_TOKEN && process.env.SHOPIFY_APP_GID);
}

/** Returns the shop's active subscription, or null when it has none. Throws when the Partner API fails,
 *  so callers never treat an outage or throttling as "no plan". */
export async function fetchActiveSubscription(shopGid: string, { fresh = false } = {}): Promise<ActiveSubscription | null> {
  const hit = cache.get(shopGid);
  if (!fresh && hit && Date.now() - hit.at < CACHE_MS) return hit.sub;

  const res = await fetch(`https://partners.shopify.com/${process.env.SHOPIFY_PARTNER_ORG_ID}/api/${PARTNER_API_VERSION}/graphql.json`, {
    method: "POST",
    headers: { "Content-Type": "application/json", "X-Shopify-Access-Token": process.env.SHOPIFY_PARTNER_API_ACCESS_TOKEN || "" },
    body: JSON.stringify({ query: QUERY, variables: { appId: process.env.SHOPIFY_APP_GID, shopId: shopGid } }),
  });
  const json = (await res.json().catch(() => ({}))) as {
    data?: {
      activeSubscription: {
        cancelAtEndOfCycle: boolean;
        items: { handle: string | null }[];
        currentBillingCycle: { endTime: string } | null;
        pendingUpdate: { items: { handle: string | null }[] } | null;
      } | null;
    };
    errors?: unknown;
  };
  if (!res.ok || json.errors || !json.data) {
    throw new Error(`Partner API request failed: ${JSON.stringify(json.errors ?? res.status)}`);
  }
  const active = json.data.activeSubscription;
  if (!active) {
    cache.delete(shopGid);
    return null;
  }
  const handlesOf = (items: { handle: string | null }[] = []) => items.map((i) => i.handle || "").filter(Boolean);
  const pendingHandles = handlesOf(active.pendingUpdate?.items);
  const sub = {
    handles: handlesOf(active.items),
    pendingHandles,
    changesAt: pendingHandles.length || active.cancelAtEndOfCycle ? active.currentBillingCycle?.endTime || null : null,
    cancelled: !!active.cancelAtEndOfCycle,
  };
  cache.set(shopGid, { at: Date.now(), sub });
  return sub;
}