Implement health check service and global exception handling

backend/src/health/health.service.ts

@@ -0,0 +1,116 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+
+export interface HealthStatus {
+  status: 'healthy' | 'degraded' | 'unhealthy';
+  service: string;
+  timestamp: string;
+  uptime: number;
+  checks: {
+    database: {
+      status: 'ok' | 'error';
+      responseTime: number;
+      details?: string;
+    };
+  };
+}
+
+@Injectable()
+export class HealthService {
+  private readonly startTime = Date.now();
+
+  constructor(private readonly prisma: PrismaService) {}
+
+  async getOverallHealth(): Promise<{
+    status: 'healthy' | 'degraded' | 'unhealthy';
+    statusCode: number;
+    service: string;
+    timestamp: string;
+    uptime: number;
+    checks: {
+      database: {
+        status: 'ok' | 'error';
+        responseTime: number;
+        details?: string;
+      };
+    };
+  }> {
+    const timestamp = new Date().toISOString();
+    const uptime = Date.now() - this.startTime;
+
+    // Testa databaskopplingen
+    const dbStart = Date.now();
+    let dbStatus: 'ok' | 'error' = 'ok';
+    let dbResponseTime = 0;
+    let dbDetails: string | undefined;
+
+    try {
+      await this.prisma.$queryRaw`SELECT 1`;
+      dbResponseTime = Date.now() - dbStart;
+    } catch (error) {
+      dbStatus = 'error';
+      dbResponseTime = Date.now() - dbStart;
+      dbDetails = error instanceof Error ? error.message : 'Unknown database error';
+    }
+
+    // Bestäm övergripande hälsa
+    let overallStatus: 'healthy' | 'degraded' | 'unhealthy' = 'healthy';
+    if (dbStatus === 'error') {
+      overallStatus = 'unhealthy';
+    }
+
+    const statusCode = overallStatus === 'unhealthy' ? 503 : 200;
+
+    return {
+      status: overallStatus,
+      statusCode,
+      service: 'recipe-api',
+      timestamp,
+      uptime,
+      checks: {
+        database: {
+          status: dbStatus,
+          responseTime: dbResponseTime,
+          details: dbDetails,
+        },
+      },
+    };
+  }
+
+  async getDatabaseHealth(): Promise<{
+    status: 'ok' | 'error';
+    database: string;
+    responseTime: number;
+    timestamp: string;
+    details?: string;
+    statusCode: number;
+  }> {
+    const timestamp = new Date().toISOString();
+    const startTime = Date.now();
+
+    try {
+      await this.prisma.$queryRaw`SELECT 1`;
+      const responseTime = Date.now() - startTime;
+
+      return {
+        status: 'ok',
+        database: 'connected',
+        responseTime,
+        timestamp,
+        statusCode: 200,
+      };
+    } catch (error) {
+      const responseTime = Date.now() - startTime;
+      const details = error instanceof Error ? error.message : 'Unknown database error';
+
+      return {
+        status: 'error',
+        database: 'not reachable',
+        responseTime,
+        timestamp,
+        details,
+        statusCode: 503,
+      };
+    }
+  }
+}