import { type FastifyInstance } from 'fastify';
import { getRawClient } from '../../db/index';
import type { HealthResponse, ComponentHealth } from '../../types/api';

const serverStartTime = Date.now();

/**
 * Health route plugin.
 * 
 * Registers:
 *   GET /ping         — unauthenticated liveness probe (Docker health checks)
 *   GET /api/v1/health — authenticated component health status
 */
export async function healthRoutes(fastify: FastifyInstance): Promise<void> {
  // Unauthenticated liveness probe
  fastify.get('/ping', async (_request, _reply) => {
    return { status: 'ok' };
  });

  // robots.txt — disallow all crawlers (private media manager)
  fastify.get('/robots.txt', async (_request, reply) => {
    return reply
      .type('text/plain')
      .send('User-agent: *\nDisallow: /\n');
  });

  // Authenticated component health
  fastify.get('/api/v1/health', async (_request, _reply) => {
    const components: ComponentHealth[] = [];

    // Database health check
    const dbHealth = await checkDatabaseHealth();
    components.push(dbHealth);

    // Server health (always healthy if we're responding)
    components.push({
      name: 'server',
      status: 'healthy',
      message: 'Fastify server is running',
    });

    // Health service components (scheduler, yt-dlp, disk space, recent errors)
    if (fastify.healthService) {
      const serviceComponents = await fastify.healthService.getComponentHealth();
      components.push(...serviceComponents);
    }

    // Overall status: degraded if any component is degraded, unhealthy if any is unhealthy
    let overallStatus: HealthResponse['status'] = 'healthy';
    if (components.some((c) => c.status === 'unhealthy')) {
      overallStatus = 'unhealthy';
    } else if (components.some((c) => c.status === 'degraded')) {
      overallStatus = 'degraded';
    }

    const uptimeSeconds = Math.floor((Date.now() - serverStartTime) / 1000);

    const response: HealthResponse = {
      status: overallStatus,
      components,
      uptime: uptimeSeconds,
    };

    return response;
  });
}

/**
 * Check database connectivity by running a simple query.
 */
async function checkDatabaseHealth(): Promise<ComponentHealth> {
  const start = Date.now();
  try {
    const client = getRawClient();
    await client.execute('SELECT 1');
    const elapsed = Date.now() - start;

    return {
      name: 'database',
      status: 'healthy',
      message: 'SQLite connection is active',
      responseTime: elapsed,
    };
  } catch (err) {
    const elapsed = Date.now() - start;
    return {
      name: 'database',
      status: 'unhealthy',
      message: err instanceof Error ? err.message : 'Database check failed',
      responseTime: elapsed,
    };
  }
}