import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
import { getScenarioRuntime, RudderClient } from '../../src/client/RudderClient.js';
import { createFakeTokenStore } from '../helpers/FakeTokenStore.js';
import { createFakeGateway, type FakeGateway } from '../helpers/fakeGateway.js';
import { stubDeterministicUuid } from '../helpers/memoryPlanStore.js';
import { plan } from '../helpers/plan.js';
import type { StoreOfferEffect } from '../../src/index.js';
import type { PlanRun, ScenarioRunFailedEvent } from '../../src/scenario/engine/types.js';

function makeClient(): RudderClient {
  return new RudderClient({
    baseUrl: 'https://api.test.rudder.build',
    projectKey: 'test-project',
    tokenStore: createFakeTokenStore(),
    runtime: { planStateStore: null },
  });
}

/**
 * An offer whose `onPurchase` continuation lives server-side (boundary node):
 * the client doesn't hold the post-purchase DAG — it must call back so the
 * server can validate the transaction and decide what happens next.
 *
 * `onDecline`, by contrast, is a plain local edge handled entirely on-device.
 */
function offerWithBoundary() {
  return plan('offer_flow')
    .runId('offer_flow-run')
    .node('offer', 'store', { storeSlug: 'starter', message: 'Buy the starter pack!' })
    .node('consolation', 'notification', { message: 'Maybe next time!' })
    .edge('offer', 'onDecline', 'consolation')
    .boundary('offer', 'onPurchase') // server owns what comes after a purchase
    .build();
}

/** What the server returns from the callback — a fresh plan = a new run. */
function rewardContinuation() {
  return plan('reward_flow')
    .runId('reward_flow-run')
    .node('reward', 'notification', { message: 'Reward granted: 500 gems!' })
    .build();
}

describe('E2E: boundary nodes (server-side continuation)', () => {
  let gateway: FakeGateway;
  let client: RudderClient;

  beforeEach(() => {
    stubDeterministicUuid();
    gateway = createFakeGateway({
      stores: [{
        slug: 'starter',
        name: 'Starter',
        offers: [{ id: 'pack_1', name: 'Starter Pack' }],
      }],
    });
    gateway.install();
    client = makeClient();
  });

  afterEach(() => vi.unstubAllGlobals());

  it('purchase crosses the boundary → callback fires and continues the scenario', async () => {
    gateway.onEvent('player_login', offerWithBoundary());
    gateway.onCallback('offer', 'onPurchase', rewardContinuation());

    const messages: string[] = [];
    const completed: PlanRun[] = [];
    let offer: StoreOfferEffect | undefined;
    const runtime = await getScenarioRuntime(client);
    client.effects.onStoreOffer((effect) => { offer = effect; });
    client.effects.onNotification((effect) => { messages.push(effect.message); });
    runtime.onRunCompleted = (r) => completed.push(r);

    const token = (await client.auth.loginWithDevice()).accessToken;
    await vi.waitFor(() => expect(offer).toBeDefined());

    await offer!.buy(offer!.offers[0]);

    // The callback hit the gateway with the boundary's source node/handle + token.
    const callback = gateway.recorded.find((r) => r.path === '/sdk/v1/scenarios/callback');
    expect(callback?.body).toEqual({ scenarioId: 'offer_flow', nodeId: 'offer', handle: 'onPurchase', runId: 'offer_flow-run' });
    expect(callback?.authToken).toBe(token);

    // The server-supplied continuation ran (as a new run), not the local edge.
    expect(messages).toEqual(['Reward granted: 500 gems!']);
    expect(messages).not.toContain('Maybe next time!');

    // The original run finished; the continuation ('reward_flow') is now active.
    expect(completed.map((r) => r.scenarioId)).toContain('offer_flow');
    expect(runtime.activeRuns.map((r) => r.scenarioId)).toEqual(['reward_flow']);
  });

  it('decline stays local → no callback, local edge is followed', async () => {
    gateway.onEvent('player_login', offerWithBoundary());

    const messages: string[] = [];
    let offer: StoreOfferEffect | undefined;
    client.effects.onStoreOffer((effect) => { offer = effect; });
    client.effects.onNotification((effect) => { messages.push(effect.message); });

    await client.auth.loginWithDevice();
    await vi.waitFor(() => expect(offer).toBeDefined());
    await offer!.dismiss();

    expect(gateway.recorded.some((r) => r.path === '/sdk/v1/scenarios/callback')).toBe(false);
    expect(messages).toEqual(['Maybe next time!']);
  });

  it('a boundary takes precedence over a local edge on the SAME handle', async () => {
    // `offer` has BOTH a boundary AND a local edge on onPurchase.
    const conflicting = plan('offer_flow')
      .runId('offer_flow-conflict')
      .node('offer', 'store', { storeSlug: 'starter', message: 'Buy!' })
      .node('local_next', 'notification', { message: 'LOCAL branch' })
      .edge('offer', 'onPurchase', 'local_next')
      .boundary('offer', 'onPurchase')
      .build();
    gateway.onEvent('player_login', conflicting);
    gateway.onCallback('offer', 'onPurchase', rewardContinuation());

    const messages: string[] = [];
    let offer: StoreOfferEffect | undefined;
    client.effects.onStoreOffer((effect) => { offer = effect; });
    client.effects.onNotification((effect) => { messages.push(effect.message); });

    await client.auth.loginWithDevice();
    await vi.waitFor(() => expect(offer).toBeDefined());
    await offer!.buy(offer!.offers[0]);

    // Only the server continuation ran; the local edge was suppressed.
    expect(messages).toEqual(['Reward granted: 500 gems!']);
    expect(messages).not.toContain('LOCAL branch');
  });

  it('a failing callback does not fail or crash the run', async () => {
    gateway.onEvent('player_login', offerWithBoundary());
    gateway.onCallbackError('offer', 'onPurchase', 500);

    const failures: ScenarioRunFailedEvent[] = [];
    const completed: PlanRun[] = [];
    let offer: StoreOfferEffect | undefined;
    const runtime = await getScenarioRuntime(client);
    client.effects.onStoreOffer((effect) => { offer = effect; });
    runtime.onRunFailed = (e) => failures.push(e);
    runtime.onRunCompleted = (r) => completed.push(r);

    await client.auth.loginWithDevice();
    await vi.waitFor(() => expect(offer).toBeDefined());

    // Must not throw despite the 500 from the callback endpoint.
    await expect(offer!.buy(offer!.offers[0])).resolves.toMatchObject({ success: true });

    expect(failures).toHaveLength(0);                    // 500 is transient — no terminal failure
    // The run stays pending because the boundary call failed transiently.
    // On reconnection the consumer can retry the purchase completion.
    expect(runtime.isRunning).toBe(true);
  });
});