/**
 * Datewise's checkout functions and their activation records, shared by Settings and the Today setup guide.
 *  - checkout guard  → a cart & checkout validation
 *  - delivery label  → a delivery customization
 *  - payment rules   → a payment customization
 * Functions are matched by extension handle, never by title, so one can't be mistaken for another.
 */
export const GUARD_HANDLE = "datewise-checkout-guard";
export const DELIVERY_LABEL_HANDLE = "datewise-delivery-label";
export const PAYMENT_RULES_HANDLE = "datewise-payment-rules";

export type AdminGraphql = { graphql: (q: string, o?: { variables?: Record<string, unknown> }) => Promise<Response> };

export async function gql<T>(admin: AdminGraphql, q: string, variables?: Record<string, unknown>) {
  const r = await admin.graphql(q, { variables });
  return ((await r.json()) as { data: T }).data;
}

type Fn = { id: string; handle: string };
type Activation = { id: string; enabled: boolean; shopifyFunction: { id: string } };

export async function findGuard(admin: AdminGraphql) {
  const d = await gql<{ shopifyFunctions: { nodes: Fn[] }; validations: { nodes: Activation[] } }>(admin, `#graphql
    query DatewiseGuard {
      shopifyFunctions(first: 50) { nodes { id handle } }
      validations(first: 25) { nodes { id enabled shopifyFunction { id } } }
    }`);
  const fn = d.shopifyFunctions.nodes.find((f) => f.handle === GUARD_HANDLE);
  const validation = fn ? d.validations.nodes.find((v) => v.shopifyFunction.id === fn.id) : undefined;
  return { fn, validation };
}

export type CustomizationKind = "delivery" | "payment";
export type CustomizationState = { deployed: boolean; enabled: boolean; id?: string };

/** Separate from findGuard: needs the delivery/payment customization scopes, which may not be granted yet. */
export async function findCustomizations(admin: AdminGraphql): Promise<Record<CustomizationKind, CustomizationState>> {
  const d = await gql<{
    shopifyFunctions: { nodes: Fn[] };
    deliveryCustomizations: { nodes: Activation[] };
    paymentCustomizations: { nodes: Activation[] };
  }>(admin, `#graphql
    query DatewiseCustomizations {
      shopifyFunctions(first: 50) { nodes { id handle } }
      deliveryCustomizations(first: 25) { nodes { id enabled shopifyFunction { id } } }
      paymentCustomizations(first: 25) { nodes { id enabled shopifyFunction { id } } }
    }`);
  const state = (handle: string, list: Activation[]): CustomizationState => {
    const fn = d.shopifyFunctions.nodes.find((f) => f.handle === handle);
    const act = fn ? list.find((c) => c.shopifyFunction.id === fn.id) : undefined;
    return { deployed: !!fn, enabled: !!act?.enabled, id: act?.id };
  };
  return {
    delivery: state(DELIVERY_LABEL_HANDLE, d.deliveryCustomizations.nodes),
    payment: state(PAYMENT_RULES_HANDLE, d.paymentCustomizations.nodes),
  };
}

const CUSTOMIZATION = {
  delivery: {
    handle: DELIVERY_LABEL_HANDLE,
    title: "Datewise: show chosen date and time",
    create: `#graphql
      mutation DeliveryLabelCreate($input: DeliveryCustomizationInput!) {
        deliveryCustomizationCreate(deliveryCustomization: $input) { deliveryCustomization { id } userErrors { message } }
      }`,
    update: `#graphql
      mutation DeliveryLabelUpdate($id: ID!, $input: DeliveryCustomizationInput!) {
        deliveryCustomizationUpdate(id: $id, deliveryCustomization: $input) { userErrors { message } }
      }`,
  },
  payment: {
    handle: PAYMENT_RULES_HANDLE,
    title: "Datewise: hide pay-in-person for shipping",
    create: `#graphql
      mutation PaymentRulesCreate($input: PaymentCustomizationInput!) {
        paymentCustomizationCreate(paymentCustomization: $input) { paymentCustomization { id } userErrors { message } }
      }`,
    update: `#graphql
      mutation PaymentRulesUpdate($id: ID!, $input: PaymentCustomizationInput!) {
        paymentCustomizationUpdate(id: $id, paymentCustomization: $input) { userErrors { message } }
      }`,
  },
} as const;

/** Turns a customization on or off, creating its activation record the first time. Returns an error message or null. */
export async function setCustomization(admin: AdminGraphql, kind: CustomizationKind, on: boolean): Promise<string | null> {
  const current = (await findCustomizations(admin))[kind];
  if (!current.deployed) return "This feature isn't deployed yet. Run `shopify app deploy`.";
  const c = CUSTOMIZATION[kind];
  type Res = Record<string, { userErrors: { message: string }[] }>;
  let res: Res;
  if (current.id) res = await gql<Res>(admin, c.update, { id: current.id, input: { enabled: on } });
  else if (on) res = await gql<Res>(admin, c.create, { input: { functionHandle: c.handle, title: c.title, enabled: true } });
  else return null;
  const errors = Object.values(res ?? {}).flatMap((x) => x?.userErrors ?? []);
  return errors.length ? errors.map((e) => e.message).join(" ") : null;
}