import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
import { mkdtempSync, rmSync, existsSync } from 'node:fs';
import { join } from 'node:path';
import { tmpdir } from 'node:os';
import { initDatabaseAsync, closeDatabase } from '../db/index';
import { runMigrations } from '../db/migrate';
import { createHistoryEvent } from '../db/repositories/history-repository';
import { HealthService } from '../services/health';
import type { SchedulerState } from '../services/scheduler';

// ── Mock yt-dlp ──
vi.mock('../sources/yt-dlp', () => ({
  getYtDlpVersion: vi.fn(),
}));

// ── Mock statfs ──
vi.mock('node:fs/promises', async (importOriginal) => {
  const actual = await importOriginal<typeof import('node:fs/promises')>();
  return {
    ...actual,
    statfs: vi.fn(),
  };
});

import { getYtDlpVersion } from '../sources/yt-dlp';
import { statfs } from 'node:fs/promises';

const mockGetYtDlpVersion = vi.mocked(getYtDlpVersion);
const mockStatfs = vi.mocked(statfs);

// ── Test Helpers ──

let tmpDir: string;
let db: Awaited<ReturnType<typeof initDatabaseAsync>>;

async function setupDb(): Promise<void> {
  tmpDir = mkdtempSync(join(tmpdir(), 'tubearr-health-'));
  const dbPath = join(tmpDir, 'test.db');
  db = await initDatabaseAsync(dbPath);
  await runMigrations(dbPath);
}

function cleanup(): void {
  closeDatabase();
  try {
    if (tmpDir && existsSync(tmpDir)) {
      rmSync(tmpDir, { recursive: true, force: true });
    }
  } catch {
    // Windows cleanup best-effort
  }
}

function makeSchedulerState(overrides?: Partial<SchedulerState>): SchedulerState {
  return {
    running: true,
    channelCount: 3,
    channels: [],
    ...overrides,
  };
}

function makeStatfsResult(availableRatio: number, totalBlocks = 1000000) {
  // bsize=4096, total blocks = totalBlocks, available = totalBlocks * ratio
  const bsize = 4096;
  const bavail = Math.floor(totalBlocks * availableRatio);
  return {
    type: 0,
    bsize: BigInt(bsize),
    blocks: BigInt(totalBlocks),
    bfree: BigInt(bavail),
    bavail: BigInt(bavail),
    files: BigInt(0),
    ffree: BigInt(0),
  };
}

// ── Tests ──

describe('HealthService', () => {
  beforeEach(async () => {
    await setupDb();
    vi.clearAllMocks();
    // Default mocks
    mockGetYtDlpVersion.mockResolvedValue('2024.12.23');
    mockStatfs.mockResolvedValue(makeStatfsResult(0.5) as never); // 50% free
  });

  afterEach(() => {
    cleanup();
  });

  // ── Scheduler Component ──

  describe('scheduler component', () => {
    it('returns healthy with channel count when scheduler is running', async () => {
      const service = new HealthService(
        db,
        () => makeSchedulerState({ running: true, channelCount: 5 }),
        '/tmp/media'
      );

      const components = await service.getComponentHealth();
      const scheduler = components.find((c) => c.name === 'scheduler');

      expect(scheduler).toBeDefined();
      expect(scheduler!.status).toBe('healthy');
      expect(scheduler!.message).toBe('Running — 5 channel(s) monitored');
      expect(scheduler!.details).toEqual({ channelCount: 5 });
    });

    it('returns degraded when scheduler is disabled (null)', async () => {
      const service = new HealthService(db, () => null, '/tmp/media');

      const components = await service.getComponentHealth();
      const scheduler = components.find((c) => c.name === 'scheduler');

      expect(scheduler!.status).toBe('degraded');
      expect(scheduler!.message).toBe('Scheduler disabled');
    });

    it('returns unhealthy when scheduler is stopped', async () => {
      const service = new HealthService(
        db,
        () => makeSchedulerState({ running: false }),
        '/tmp/media'
      );

      const components = await service.getComponentHealth();
      const scheduler = components.find((c) => c.name === 'scheduler');

      expect(scheduler!.status).toBe('unhealthy');
      expect(scheduler!.message).toBe('Scheduler stopped');
    });
  });

  // ── yt-dlp Component ──

  describe('yt-dlp component', () => {
    it('returns healthy with version when yt-dlp is available', async () => {
      mockGetYtDlpVersion.mockResolvedValue('2024.12.23');

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const ytDlp = components.find((c) => c.name === 'ytDlp');

      expect(ytDlp!.status).toBe('healthy');
      expect(ytDlp!.message).toBe('yt-dlp 2024.12.23');
      expect(ytDlp!.details).toEqual({ version: '2024.12.23' });
    });

    it('returns unhealthy when yt-dlp is not available', async () => {
      mockGetYtDlpVersion.mockResolvedValue(null);

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const ytDlp = components.find((c) => c.name === 'ytDlp');

      expect(ytDlp!.status).toBe('unhealthy');
      expect(ytDlp!.message).toBe('yt-dlp not found');
    });
  });

  // ── Disk Space Component ──

  describe('disk space component', () => {
    it('returns healthy when >10% free', async () => {
      mockStatfs.mockResolvedValue(makeStatfsResult(0.5) as never); // 50% free

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const disk = components.find((c) => c.name === 'diskSpace');

      expect(disk!.status).toBe('healthy');
      expect(disk!.message).toMatch(/GB free of/);
      expect(disk!.message).toMatch(/50%/);
      expect(disk!.details).toHaveProperty('availableBytes');
      expect(disk!.details).toHaveProperty('totalBytes');
      expect(disk!.details).toHaveProperty('freePercent');
    });

    it('returns degraded when 5-10% free', async () => {
      mockStatfs.mockResolvedValue(makeStatfsResult(0.07) as never); // 7% free

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const disk = components.find((c) => c.name === 'diskSpace');

      expect(disk!.status).toBe('degraded');
    });

    it('returns unhealthy when <5% free', async () => {
      mockStatfs.mockResolvedValue(makeStatfsResult(0.03) as never); // 3% free

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const disk = components.find((c) => c.name === 'diskSpace');

      expect(disk!.status).toBe('unhealthy');
    });

    it('returns degraded on statfs error', async () => {
      mockStatfs.mockRejectedValue(new Error('ENOENT: no such file or directory'));

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const disk = components.find((c) => c.name === 'diskSpace');

      expect(disk!.status).toBe('degraded');
      expect(disk!.message).toMatch(/Disk check failed/);
      expect(disk!.message).toMatch(/ENOENT/);
    });
  });

  // ── Recent Errors Component ──

  describe('recent errors component', () => {
    it('returns healthy when no errors in 24h', async () => {
      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const errors = components.find((c) => c.name === 'recentErrors');

      expect(errors!.status).toBe('healthy');
      expect(errors!.message).toBe('0 error(s) in the last 24 hours');
    });

    it('returns degraded when 1-5 errors in 24h', async () => {
      // Insert 3 failed history events
      for (let i = 0; i < 3; i++) {
        await createHistoryEvent(db, {
          eventType: 'failed',
          status: 'failed',
          details: { error: `Test error ${i}` },
        });
      }

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const errors = components.find((c) => c.name === 'recentErrors');

      expect(errors!.status).toBe('degraded');
      expect(errors!.message).toBe('3 error(s) in the last 24 hours');
    });

    it('returns unhealthy when >5 errors in 24h', async () => {
      // Insert 7 failed events
      for (let i = 0; i < 7; i++) {
        await createHistoryEvent(db, {
          eventType: 'failed',
          status: 'failed',
          details: { error: `Test error ${i}` },
        });
      }

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const errors = components.find((c) => c.name === 'recentErrors');

      expect(errors!.status).toBe('unhealthy');
      expect(errors!.message).toBe('7 error(s) in the last 24 hours');
      expect(errors!.details).toEqual({ errorCount: 7 });
    });

    it('does not count non-failed events', async () => {
      // Insert a downloaded event — should not count
      await createHistoryEvent(db, {
        eventType: 'downloaded',
        status: 'success',
      });
      // Insert a failed event — should count
      await createHistoryEvent(db, {
        eventType: 'failed',
        status: 'failed',
      });

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();
      const errors = components.find((c) => c.name === 'recentErrors');

      expect(errors!.status).toBe('degraded');
      expect(errors!.message).toBe('1 error(s) in the last 24 hours');
    });
  });

  // ── Caching ──

  describe('caching', () => {
    it('caches yt-dlp version — second call does not invoke getYtDlpVersion', async () => {
      mockGetYtDlpVersion.mockResolvedValue('2024.12.23');

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      await service.getComponentHealth();
      await service.getComponentHealth();

      // getYtDlpVersion should only be called once due to caching
      expect(mockGetYtDlpVersion).toHaveBeenCalledTimes(1);
    });

    it('caches disk space — second call does not invoke statfs', async () => {
      mockStatfs.mockResolvedValue(makeStatfsResult(0.5) as never);

      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      await service.getComponentHealth();
      await service.getComponentHealth();

      // statfs should only be called once due to caching
      expect(mockStatfs).toHaveBeenCalledTimes(1);
    });
  });

  // ── Full Response Shape ──

  describe('full response', () => {
    it('returns all four components', async () => {
      const service = new HealthService(db, () => makeSchedulerState(), '/tmp/media');
      const components = await service.getComponentHealth();

      expect(components).toHaveLength(4);
      const names = components.map((c) => c.name);
      expect(names).toContain('scheduler');
      expect(names).toContain('ytDlp');
      expect(names).toContain('diskSpace');
      expect(names).toContain('recentErrors');
    });
  });
});