/**
 * Unit tests for src/live/registry.ts — subscription registry.
 *
 * The registry is instantiated with a mocked authz client and a mocked
 * sendOutbound path. LiveConnection objects are synthetic stubs.
 *
 * Covers:
 *  - Subscribe to event:<uuid> with permitted user → `subscribed` reply,
 *    registry counts go up.
 *  - Subscribe with forbidden user → `error/forbidden` reply, no registry change.
 *  - Subscribe to `device:<imei>` → `error/unknown-topic`, no registry change.
 *  - Subscribe twice to the same topic → idempotent (single subscription,
 *    subscribed reply each call, gauge does not double-count).
 *  - Unsubscribe from a topic → `unsubscribed` reply, gauge decrements.
 *  - Unsubscribe from a topic not subscribed → `unsubscribed` reply (idempotent),
 *    gauge unchanged.
 *  - Connection close removes all subscriptions; gauge returns to pre-connection level.
 *  - connectionsForTopic returns the correct set.
 *  - topicsForConnection returns the correct set.
 */

import { describe, it, expect, vi, beforeEach } from 'vitest';
import type { Logger } from 'pino';
import type { Config } from '../src/config/load.js';
import type { Metrics } from '../src/core/types.js';
import { createSubscriptionRegistry } from '../src/live/registry.js';
import type { AuthzClient } from '../src/live/authz.js';
import type { LiveConnection } from '../src/live/server.js';
import WebSocket from 'ws';

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

function makeSilentLogger(): Logger {
  return {
    debug: vi.fn(), info: vi.fn(), warn: vi.fn(), error: vi.fn(),
    fatal: vi.fn(), trace: vi.fn(), child: vi.fn().mockReturnThis(),
    level: 'silent', silent: vi.fn(),
  } as unknown as Logger;
}

type TestMetrics = Metrics & {
  readonly incCalls: Array<{ name: string; labels?: Record<string, string> }>;
  readonly observeCalls: Array<{ name: string; value: number }>;
};

function makeMetrics(): TestMetrics {
  const incCalls: Array<{ name: string; labels?: Record<string, string> }> = [];
  const observeCalls: Array<{ name: string; value: number }> = [];
  return {
    incCalls,
    observeCalls,
    inc(name, labels) { incCalls.push({ name, labels }); },
    observe(name, value) { observeCalls.push({ name, value }); },
  };
}

function makeConfig(): Config {
  return {
    NODE_ENV: 'test',
    INSTANCE_ID: 'test-1',
    LOG_LEVEL: 'silent',
    REDIS_URL: 'redis://localhost:6379',
    POSTGRES_URL: 'postgres://localhost:5432/test',
    REDIS_TELEMETRY_STREAM: 'telemetry:t',
    REDIS_CONSUMER_GROUP: 'processor',
    REDIS_CONSUMER_NAME: 'test-consumer',
    METRICS_PORT: 0,
    BATCH_SIZE: 100,
    BATCH_BLOCK_MS: 500,
    WRITE_BATCH_SIZE: 50,
    DEVICE_STATE_LRU_CAP: 10_000,
    LIVE_WS_PORT: 8081,
    LIVE_WS_HOST: '0.0.0.0',
    LIVE_WS_PING_INTERVAL_MS: 30_000,
    LIVE_WS_DRAIN_TIMEOUT_MS: 5_000,
    LIVE_WS_BACKPRESSURE_THRESHOLD_BYTES: 1_048_576,
    DIRECTUS_BASE_URL: 'http://directus.test',
    DIRECTUS_AUTH_TIMEOUT_MS: 5_000,
    DIRECTUS_AUTHZ_TIMEOUT_MS: 5_000,
    LIVE_BROADCAST_GROUP_PREFIX: 'live-broadcast',
    LIVE_BROADCAST_BATCH_SIZE: 100,
    LIVE_BROADCAST_BATCH_BLOCK_MS: 1_000,
    LIVE_DEVICE_EVENT_REFRESH_MS: 30_000,
  };
}

const EVENT_ID = 'ada60b3d-b29f-4017-b702-cd6b700f9f6c';
const EVENT_TOPIC = `event:${EVENT_ID}`;

/**
 * Creates a synthetic LiveConnection stub that captures sent messages.
 */
function makeConn(id = 'conn-1'): LiveConnection & { sentMessages: unknown[] } {
  const sentMessages: unknown[] = [];
  const ws = {
    readyState: WebSocket.OPEN,
    bufferedAmount: 0,
    send: vi.fn((data: string) => { sentMessages.push(JSON.parse(data)); }),
    close: vi.fn(),
  } as unknown as WebSocket;

  return {
    id,
    ws,
    remoteAddr: '127.0.0.1',
    openedAt: new Date(),
    lastSeenAt: new Date(),
    user: {
      id: 'user-ada60b3d',
      email: 'test@example.com',
      role: null,
      first_name: 'Test',
      last_name: 'User',
    },
    cookieHeader: 'session=valid',
    sentMessages,
  };
}

function makeAllowedAuthzClient(): AuthzClient {
  return {
    canAccessEvent: vi.fn().mockResolvedValue({ allowed: true }),
  };
}

function makeForbiddenAuthzClient(): AuthzClient {
  return {
    canAccessEvent: vi.fn().mockResolvedValue({ allowed: false, reason: 'forbidden' }),
  };
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

describe('createSubscriptionRegistry', () => {
  let metrics: TestMetrics;

  beforeEach(() => {
    metrics = makeMetrics();
  });

  it('subscribe to a valid event topic with permitted user → subscribed reply and gauge increment', async () => {
    const conn = makeConn();
    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn, EVENT_TOPIC, 'corr-1');

    // Should have sent a `subscribed` message.
    expect(conn.sentMessages).toHaveLength(1);
    const msg = conn.sentMessages[0] as Record<string, unknown>;
    expect(msg['type']).toBe('subscribed');
    expect(msg['topic']).toBe(EVENT_TOPIC);
    expect(msg['id']).toBe('corr-1');
    expect(Array.isArray(msg['snapshot'])).toBe(true);

    // Gauge should have been updated.
    const subGaugeCalls = metrics.observeCalls.filter(
      (c) => c.name === 'processor_live_subscriptions',
    );
    expect(subGaugeCalls.length).toBeGreaterThanOrEqual(1);
    expect(subGaugeCalls[subGaugeCalls.length - 1]!.value).toBe(1);

    // Success counter.
    const successCalls = metrics.incCalls.filter(
      (c) => c.name === 'processor_live_subscribe_attempts_total' && c.labels?.['result'] === 'success',
    );
    expect(successCalls).toHaveLength(1);
  });

  it('subscribe with forbidden user → error/forbidden reply, no registry change', async () => {
    const conn = makeConn();
    const registry = createSubscriptionRegistry(
      makeForbiddenAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn, EVENT_TOPIC, 'corr-2');

    const msg = conn.sentMessages[0] as Record<string, unknown>;
    expect(msg['type']).toBe('error');
    expect(msg['code']).toBe('forbidden');
    expect(msg['topic']).toBe(EVENT_TOPIC);
    expect(msg['id']).toBe('corr-2');

    // Gauge should NOT have changed.
    const subGaugeCalls = metrics.observeCalls.filter(
      (c) => c.name === 'processor_live_subscriptions',
    );
    // May have been called with 0 for snapshot, but never with a positive value.
    const positiveGauge = subGaugeCalls.filter((c) => c.value > 0);
    expect(positiveGauge).toHaveLength(0);

    // connectionsForTopic should return empty.
    expect([...registry.connectionsForTopic(EVENT_TOPIC)]).toHaveLength(0);
  });

  it('subscribe to device:<imei> → error/unknown-topic, no registry change', async () => {
    const conn = makeConn();
    const authz = makeAllowedAuthzClient();
    const registry = createSubscriptionRegistry(
      authz, makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn, 'device:356307042441013', 'corr-3');

    const msg = conn.sentMessages[0] as Record<string, unknown>;
    expect(msg['type']).toBe('error');
    expect(msg['code']).toBe('unknown-topic');

    // Authz client should NOT have been called.
    expect(vi.mocked(authz.canAccessEvent)).not.toHaveBeenCalled();
  });

  it('subscribe twice to the same topic → idempotent (single subscription, subscribed each call)', async () => {
    const conn = makeConn();
    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn, EVENT_TOPIC);
    await registry.subscribe(conn, EVENT_TOPIC); // second call

    // Both calls send `subscribed`.
    expect(conn.sentMessages).toHaveLength(2);
    const msgs = conn.sentMessages as Array<Record<string, unknown>>;
    expect(msgs[0]!['type']).toBe('subscribed');
    expect(msgs[1]!['type']).toBe('subscribed');

    // Gauge should only count once.
    const finalGaugeCalls = metrics.observeCalls.filter(
      (c) => c.name === 'processor_live_subscriptions',
    );
    // Last value should be 1, not 2.
    expect(finalGaugeCalls[finalGaugeCalls.length - 1]!.value).toBe(1);

    // connectionsForTopic should have exactly one connection.
    expect([...registry.connectionsForTopic(EVENT_TOPIC)]).toHaveLength(1);
  });

  it('unsubscribe from a subscribed topic → unsubscribed reply and gauge decrement', async () => {
    const conn = makeConn();
    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn, EVENT_TOPIC);
    registry.unsubscribe(conn, EVENT_TOPIC, 'corr-4');

    const msgs = conn.sentMessages as Array<Record<string, unknown>>;
    expect(msgs[1]!['type']).toBe('unsubscribed');
    expect(msgs[1]!['topic']).toBe(EVENT_TOPIC);
    expect(msgs[1]!['id']).toBe('corr-4');

    // Gauge should be back at 0.
    const finalGaugeCalls = metrics.observeCalls.filter(
      (c) => c.name === 'processor_live_subscriptions',
    );
    expect(finalGaugeCalls[finalGaugeCalls.length - 1]!.value).toBe(0);
  });

  it('unsubscribe from a topic not subscribed to → unsubscribed reply (idempotent), gauge unchanged', async () => {
    const conn = makeConn();
    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    // Unsubscribe without ever subscribing.
    registry.unsubscribe(conn, EVENT_TOPIC, 'corr-5');

    const msg = conn.sentMessages[0] as Record<string, unknown>;
    expect(msg['type']).toBe('unsubscribed');

    // Gauge should still be 0 (not go negative).
    const finalGaugeCalls = metrics.observeCalls.filter(
      (c) => c.name === 'processor_live_subscriptions',
    );
    const values = finalGaugeCalls.map((c) => c.value);
    expect(values.every((v) => v >= 0)).toBe(true);
  });

  it('onConnectionClose removes all subscriptions; gauge returns to 0', async () => {
    const conn = makeConn();
    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn, EVENT_TOPIC);
    await registry.subscribe(conn, `event:f6114c7e-1e94-488a-93c3-41060fcb06bc`);

    registry.onConnectionClose(conn);

    // Gauge should be 0.
    const finalGaugeCalls = metrics.observeCalls.filter(
      (c) => c.name === 'processor_live_subscriptions',
    );
    expect(finalGaugeCalls[finalGaugeCalls.length - 1]!.value).toBe(0);

    // connectionsForTopic should be empty for both topics.
    expect([...registry.connectionsForTopic(EVENT_TOPIC)]).toHaveLength(0);
  });

  it('connectionsForTopic returns only connections subscribed to that topic', async () => {
    const conn1 = makeConn('conn-1');
    const conn2 = makeConn('conn-2');
    const otherTopic = 'event:f6114c7e-1e94-488a-93c3-41060fcb06bc';

    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn1, EVENT_TOPIC);
    await registry.subscribe(conn2, EVENT_TOPIC);
    await registry.subscribe(conn1, otherTopic);

    const connsForEvent = [...registry.connectionsForTopic(EVENT_TOPIC)];
    expect(connsForEvent).toHaveLength(2);
    expect(connsForEvent.map((c) => c.id).sort()).toEqual(['conn-1', 'conn-2'].sort());

    const connsForOther = [...registry.connectionsForTopic(otherTopic)];
    expect(connsForOther).toHaveLength(1);
    expect(connsForOther[0]!.id).toBe('conn-1');
  });

  it('stats() returns correct counts', async () => {
    const conn1 = makeConn('conn-1');
    const conn2 = makeConn('conn-2');
    const topic2 = 'event:f6114c7e-1e94-488a-93c3-41060fcb06bc';

    const registry = createSubscriptionRegistry(
      makeAllowedAuthzClient(), makeConfig(), makeSilentLogger(), metrics,
    );

    await registry.subscribe(conn1, EVENT_TOPIC);
    await registry.subscribe(conn2, EVENT_TOPIC);
    await registry.subscribe(conn1, topic2);

    const s = registry.stats();
    expect(s.subscriptions).toBe(3);
    expect(s.topics).toBe(2);
  });
});