/**
 * Unit tests for src/core/publish.ts
 *
 * Covers:
 *  - jsonReplacer sentinel encoding (bigint, Buffer, Date, plain values)
 *  - serializePosition field shape
 *  - PublishOverflowError thrown when queue is full
 *  - publish() is non-blocking (returns before XADD completes)
 *  - connectRedis retry helper fails with a clear error on unreachable host
 */

import { describe, it, expect, vi } from 'vitest';
import type { Logger } from 'pino';
import type { Metrics, Position } from '../src/core/types.js';
import {
  jsonReplacer,
  serializePosition,
  createPublisher,
  PublishOverflowError,
  connectRedis,
} from '../src/core/publish.js';
import type { Config } from '../src/config/load.js';

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

function makePosition(overrides: Partial<Position> = {}): Position {
  return {
    device_id: 'TEST123456789',
    timestamp: new Date('2024-01-15T10:30:00.000Z'),
    latitude: 54.12345,
    longitude: 25.98765,
    altitude: 150,
    angle: 270,
    speed: 60,
    satellites: 8,
    priority: 1,
    attributes: {},
    ...overrides,
  };
}

function makeConfig(overrides: Partial<Config> = {}): Config {
  return {
    NODE_ENV: 'test',
    INSTANCE_ID: 'test-instance',
    LOG_LEVEL: 'silent',
    TELTONIKA_PORT: 5027,
    REDIS_URL: 'redis://localhost:6379',
    REDIS_TELEMETRY_STREAM: 'telemetry:teltonika',
    REDIS_STREAM_MAXLEN: 1_000_000,
    METRICS_PORT: 9090,
    PUBLISH_QUEUE_CAPACITY: 10_000,
    STRICT_DEVICE_AUTH: false,
    ...overrides,
  };
}

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

function makeMetrics(): Metrics {
  return {
    inc: vi.fn(),
    observe: vi.fn(),
  };
}

// Minimal ioredis stub used for queue tests
function makeHangingRedis(): {
  xadd: ReturnType<typeof vi.fn>;
  quit: ReturnType<typeof vi.fn>;
} {
  return {
    // Returns a promise that never resolves — simulates a hung Redis
    xadd: vi.fn(() => new Promise<string>(() => {})),
    quit: vi.fn().mockResolvedValue('OK'),
  };
}

// ---------------------------------------------------------------------------
// 1. jsonReplacer encoding
// ---------------------------------------------------------------------------

describe('jsonReplacer', () => {
  it('encodes bigint as { __bigint: "<digits>" }', () => {
    const result = jsonReplacer('x', BigInt('9007199254740993'));
    expect(result).toEqual({ __bigint: '9007199254740993' });
  });

  it('encodes zero bigint correctly', () => {
    expect(jsonReplacer('x', 0n)).toEqual({ __bigint: '0' });
  });

  it('encodes Buffer as { __buffer_b64: "<base64>" }', () => {
    const buf = Buffer.from([0xde, 0xad, 0xbe, 0xef]);
    const result = jsonReplacer('x', buf);
    expect(result).toEqual({ __buffer_b64: buf.toString('base64') });
  });

  it('encodes Buffer subarray view (zero-copy) correctly', () => {
    const backing = Buffer.from([0x00, 0x01, 0x02, 0x03, 0x04, 0x05]);
    const view = backing.subarray(2, 5); // [0x02, 0x03, 0x04]
    const result = jsonReplacer('x', view);
    expect(result).toEqual({ __buffer_b64: view.toString('base64') });
  });

  it('encodes Date as ISO string', () => {
    const d = new Date('2024-06-01T00:00:00.000Z');
    expect(jsonReplacer('x', d)).toBe('2024-06-01T00:00:00.000Z');
  });

  it('passes through plain numbers unchanged', () => {
    expect(jsonReplacer('x', 42)).toBe(42);
    expect(jsonReplacer('x', -3.14)).toBe(-3.14);
    expect(jsonReplacer('x', 0)).toBe(0);
  });

  it('passes through strings unchanged', () => {
    expect(jsonReplacer('x', 'hello')).toBe('hello');
  });

  it('passes through null unchanged', () => {
    expect(jsonReplacer('x', null)).toBeNull();
  });

  it('round-trips bigint + Buffer through JSON.parse with sentinel decoding', () => {
    const original = {
      big: BigInt('12345678901234567890'),
      buf: Buffer.from([0xca, 0xfe]),
      num: 99,
    };

    const json = JSON.stringify(original, jsonReplacer);
    const parsed = JSON.parse(json) as {
      big: { __bigint: string };
      buf: { __buffer_b64: string };
      num: number;
    };

    // Decode sentinels (simulating Processor-side decoder)
    expect(BigInt(parsed.big.__bigint)).toBe(BigInt('12345678901234567890'));
    expect(Buffer.from(parsed.buf.__buffer_b64, 'base64')).toEqual(
      Buffer.from([0xca, 0xfe]),
    );
    expect(parsed.num).toBe(99);
  });
});

// ---------------------------------------------------------------------------
// 2. serializePosition field shape
// ---------------------------------------------------------------------------

describe('serializePosition', () => {
  it('produces the expected top-level Redis fields', () => {
    const pos = makePosition();
    const fields = serializePosition(pos, '8');

    expect(fields).toHaveProperty('ts', '2024-01-15T10:30:00.000Z');
    expect(fields).toHaveProperty('device_id', 'TEST123456789');
    expect(fields).toHaveProperty('codec', '8');
    expect(fields).toHaveProperty('payload');
  });

  it('payload is valid JSON', () => {
    const pos = makePosition({ attributes: { speed_raw: 1234n, raw: Buffer.from([0xab]) } });
    const { payload } = serializePosition(pos, '8E');
    expect(() => JSON.parse(payload)).not.toThrow();
  });

  it('payload round-trips bigint and Buffer sentinels', () => {
    const original = makePosition({
      attributes: {
        big_io: BigInt('18446744073709551615'), // u64 max
        buf_io: Buffer.from([0xde, 0xad]),
        num_io: 255,
      },
    });

    const { payload } = serializePosition(original, '16');
    const parsed = JSON.parse(payload) as {
      attributes: Record<string, unknown>;
    };

    const big = parsed.attributes['big_io'] as { __bigint: string };
    const buf = parsed.attributes['buf_io'] as { __buffer_b64: string };
    const num = parsed.attributes['num_io'] as number;

    expect(BigInt(big.__bigint)).toBe(BigInt('18446744073709551615'));
    expect(Buffer.from(buf.__buffer_b64, 'base64')).toEqual(Buffer.from([0xde, 0xad]));
    expect(num).toBe(255);
  });

  it('codec label "8E" is preserved verbatim', () => {
    const fields = serializePosition(makePosition(), '8E');
    expect(fields['codec']).toBe('8E');
  });
});

// ---------------------------------------------------------------------------
// 3. Bounded queue overflow
// ---------------------------------------------------------------------------

describe('createPublisher — overflow', () => {
  it('throws PublishOverflowError when queue is at capacity', async () => {
    const redis = makeHangingRedis();
    // Capacity=3: worker picks up the 1st item (hangs on xadd), so the queue
    // drains to 0 after the first publish microtask. Subsequent publishes fill
    // it: 2nd→queue=1, 3rd→queue=2, 4th→queue=3 (full). 5th should overflow.
    const config = makeConfig({ PUBLISH_QUEUE_CAPACITY: 3 });

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const publisher = createPublisher(redis as any, config, makeSilentLogger(), makeMetrics());

    await publisher.publish(makePosition({ device_id: 'A' }), '8'); // worker takes A → queue=0
    await publisher.publish(makePosition({ device_id: 'B' }), '8'); // queue=1
    await publisher.publish(makePosition({ device_id: 'C' }), '8'); // queue=2
    await publisher.publish(makePosition({ device_id: 'D' }), '8'); // queue=3 = capacity

    // 5th publish should overflow
    await expect(publisher.publish(makePosition({ device_id: 'E' }), '8')).rejects.toBeInstanceOf(
      PublishOverflowError,
    );
  });

  it('increments the overflow metric on overflow', async () => {
    const redis = makeHangingRedis();
    // Capacity=1: worker picks up the 1st item immediately (queue→0).
    // 2nd item fills queue to capacity=1. 3rd overflows.
    const config = makeConfig({ PUBLISH_QUEUE_CAPACITY: 1 });
    const metrics = makeMetrics();

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const publisher = createPublisher(redis as any, config, makeSilentLogger(), metrics);

    await publisher.publish(makePosition({ device_id: 'A' }), '8'); // worker takes A
    await publisher.publish(makePosition({ device_id: 'B' }), '8'); // queue=1 = capacity
    await expect(publisher.publish(makePosition({ device_id: 'C' }), '8')).rejects.toBeInstanceOf(
      PublishOverflowError,
    );

    expect(metrics.inc).toHaveBeenCalledWith('teltonika_publish_overflow_total', { codec: '8' });
  });

  it('publish() resolves without waiting for XADD to complete (non-blocking guarantee)', async () => {
    // The hanging redis means XADD never completes. publish() must still return
    // promptly — it only enqueues, it does not await the XADD call itself.
    const redis = makeHangingRedis();
    const config = makeConfig({ PUBLISH_QUEUE_CAPACITY: 100 });

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const publisher = createPublisher(redis as any, config, makeSilentLogger(), makeMetrics());

    const start = Date.now();
    await publisher.publish(makePosition(), '8');
    const elapsed = Date.now() - start;

    // Should complete in well under 200ms regardless of Redis latency.
    // The worker may have already started (calling xadd which hangs), but
    // publish() itself returned before xadd resolved — that is the guarantee.
    expect(elapsed).toBeLessThan(200);
  });
});

// ---------------------------------------------------------------------------
// 4. connectRedis retry helper
// ---------------------------------------------------------------------------

describe('connectRedis', () => {
  it('calls process.exit(1) when Redis is unreachable after all retries', async () => {
    const exitSpy = vi.spyOn(process, 'exit').mockImplementation((_code) => {
      throw new Error('process.exit called');
    });

    const logger = makeSilentLogger();

    // Port 1 is almost certainly not listening
    await expect(
      connectRedis('redis://127.0.0.1:1', logger, 1),
    ).rejects.toThrow('process.exit called');

    expect(exitSpy).toHaveBeenCalledWith(1);

    exitSpy.mockRestore();
  });
}, 15_000);