/**
 * Simulated backend for UI tests.
 *
 * The end-to-end specs drive the real stack, which is the right way to prove
 * the system works. But some conditions are impractical to stage for real:
 * a 500 from the database, a fifteen-second response, a seat sold by someone
 * else in the half second between opening checkout and confirming, an agency
 * with a hundred thousand flights, a passenger whose name is 200 characters
 * long.
 *
 * These helpers intercept `/api/**` in the browser and answer it directly, so
 * a test can put the UI in any of those states deterministically, in
 * milliseconds, without touching the database.
 */
import { Page } from '@playwright/test';

// --- canned data -----------------------------------------------------------

export const TENANTS = [
  { slug: 'skyline', name: 'Skyline Travel' },
  { slug: 'globetrotter', name: 'Globetrotter Tours' },
];

export const SESSION = {
  user: {
    id: 'u-1',
    tenantId: 't-1',
    email: 'agent@skyline.test',
    fullName: 'Marcus Reid',
    role: 'agent',
    createdAt: '2026-01-01T00:00:00Z',
  },
  tenant: {
    id: 't-1',
    slug: 'skyline',
    name: 'Skyline Travel',
    status: 'active',
    createdAt: '2026-01-01T00:00:00Z',
  },
};

export const AIRPORTS = [
  { id: 'a-jfk', iataCode: 'JFK', name: 'John F. Kennedy International', city: 'New York', country: 'United States', timezone: 'America/New_York' },
  { id: 'a-lhr', iataCode: 'LHR', name: 'Heathrow', city: 'London', country: 'United Kingdom', timezone: 'Europe/London' },
];

export const AIRLINES = [{ id: 'al-aa', iataCode: 'AA', name: 'American Airlines' }];

export function makeFlight(overrides: Record<string, unknown> = {}) {
  return {
    id: 'f-1',
    flightNumber: 'AA100',
    airline: AIRLINES[0],
    origin: AIRPORTS[0],
    destination: AIRPORTS[1],
    departureTime: '2026-12-19T18:00:00Z',
    arrivalTime: '2026-12-20T01:00:00Z',
    durationMinutes: 420,
    aircraft: 'Boeing 787-9',
    cabinClass: 'economy',
    basePrice: 483.3,
    currency: 'USD',
    seatsTotal: 180,
    seatsAvailable: 165,
    status: 'scheduled',
    ...overrides,
  };
}

export function makeBooking(overrides: Record<string, unknown> = {}) {
  return {
    id: 'b-1',
    bookingReference: 'SIM001',
    flight: makeFlight(),
    passengers: [{ id: 'p-1', firstName: 'Dana', lastName: 'Whitfield' }],
    passengerCount: 1,
    totalAmount: 483.3,
    currency: 'USD',
    status: 'confirmed',
    contactEmail: 'ops@example.com',
    contactPhone: '',
    bookedBy: 'Marcus Reid',
    createdAt: '2026-09-12T13:10:00Z',
    ...overrides,
  };
}

export function makeDashboard(overrides: Record<string, unknown> = {}) {
  return {
    totalBookings: 6,
    confirmedBookings: 5,
    cancelledBookings: 1,
    totalRevenue: 7263.16,
    currency: 'USD',
    flightsInStock: 294,
    seatsSold: 12,
    recentBookings: [makeBooking()],
    topRoutes: [{ route: 'JFK to LHR', bookings: 3, revenue: 4000 }],
    ...overrides,
  };
}

export function page$<T>(items: T[], total = items.length, limit = 10, offset = 0) {
  return { items, total, limit, offset };
}

// --- scenario --------------------------------------------------------------

/**
 * How one endpoint should answer. A bare value is a 200 with that value as the
 * body; use `reply`, `fail` or `slow` for anything else.
 *
 * The envelope carries a symbol brand rather than being recognised by shape.
 * Domain objects here have a `status` field of their own -- a flight is
 * "scheduled", a booking is "confirmed" -- so duck-typing on `status` would
 * silently read a booking as an HTTP response.
 */
const ENVELOPE = Symbol('travelhub.reply');

export interface ReplyEnvelope {
  [ENVELOPE]: true;
  status: number;
  body: unknown;
  delayMs?: number;
}

export type Reply = ReplyEnvelope | unknown;

/** An explicit response: status, body and optional latency. */
export function reply(opts: { status?: number; body?: unknown; delayMs?: number }): ReplyEnvelope {
  return {
    [ENVELOPE]: true,
    status: opts.status ?? 200,
    body: opts.body ?? {},
    delayMs: opts.delayMs,
  };
}

/** An error response, in the shape the Go API uses. */
export function fail(status: number, error = 'simulated failure'): ReplyEnvelope {
  return reply({ status, body: { error } });
}

/** A successful but slow response, for asserting on loading states. */
export function slow(body: unknown, delayMs: number): ReplyEnvelope {
  return reply({ status: 200, body, delayMs });
}

export interface Scenario {
  /** Latency applied to every endpoint that does not set its own. */
  delayMs?: number;
  /** Abort every API call, as though the network were gone. */
  offline?: boolean;

  session?: Reply;
  tenants?: Reply;
  airports?: Reply;
  airlines?: Reply;
  flights?: Reply;
  flightById?: Reply;
  bookings?: Reply;
  bookingById?: Reply;
  createBooking?: Reply;
  cancelBooking?: Reply;
  dashboard?: Reply;
}

function normalise(value: Reply): { status: number; body: unknown; delayMs?: number } {
  if (value !== null && typeof value === 'object' && ENVELOPE in value) {
    const envelope = value as ReplyEnvelope;
    return { status: envelope.status, body: envelope.body, delayMs: envelope.delayMs };
  }
  return { status: 200, body: value };
}

const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));

/**
 * Installs the simulated API. Anything the scenario does not mention falls
 * back to a sensible, healthy default, so a test only spells out the one
 * condition it is about.
 */
export async function simulateApi(page: Page, scenario: Scenario = {}): Promise<void> {
  const defaults: Scenario = {
    session: SESSION,
    tenants: TENANTS,
    airports: AIRPORTS,
    airlines: AIRLINES,
    flights: page$([makeFlight()]),
    flightById: makeFlight(),
    bookings: page$([makeBooking()]),
    bookingById: makeBooking(),
    createBooking: reply({ status: 201, body: makeBooking() }),
    cancelBooking: makeBooking({ status: 'cancelled' }),
    dashboard: makeDashboard(),
  };

  const merged = { ...defaults, ...scenario };

  await page.route('**/api/**', async (route) => {
    if (scenario.offline) {
      await route.abort('internetdisconnected');
      return;
    }

    const request = route.request();
    const path = new URL(request.url()).pathname;
    const method = request.method();

    let answer: Reply;
    if (path === '/api/health') {
      answer = { status: 'ok' };
    } else if (path === '/api/tenants') {
      answer = merged.tenants;
    } else if (path === '/api/session') {
      answer = merged.session;
    } else if (path === '/api/airports') {
      answer = merged.airports;
    } else if (path === '/api/airlines') {
      answer = merged.airlines;
    } else if (path === '/api/dashboard') {
      answer = merged.dashboard;
    } else if (path === '/api/flights') {
      answer = merged.flights;
    } else if (path.startsWith('/api/flights/')) {
      answer = merged.flightById;
    } else if (path.endsWith('/cancel')) {
      answer = merged.cancelBooking;
    } else if (path === '/api/bookings') {
      answer = method === 'POST' ? merged.createBooking : merged.bookings;
    } else if (path.startsWith('/api/bookings/')) {
      answer = merged.bookingById;
    } else {
      answer = fail(404, 'not found');
    }

    const { status, body, delayMs } = normalise(answer);
    const wait = delayMs ?? merged.delayMs ?? 0;
    if (wait > 0) {
      await sleep(wait);
    }

    await route.fulfill({
      status,
      contentType: 'application/json',
      body: JSON.stringify(body),
    });
  });
}

/**
 * Puts credentials in localStorage before the app boots, so a simulated test
 * lands straight on the screen under test instead of signing in first.
 */
export async function primeCredentials(page: Page, tenant = 'skyline'): Promise<void> {
  await page.addInitScript(
    ([slug]) => {
      localStorage.setItem(
        'travelhub.credentials',
        JSON.stringify({ tenant: slug, basic: btoa('agent@skyline.test:demo1234') }),
      );
    },
    [tenant],
  );
}