Implement health check service and global exception handling

backend/src/common/filters/global-exception.filter.ts

@@ -0,0 +1,82 @@
+import {
+  ExceptionFilter,
+  Catch,
+  ArgumentsHost,
+  HttpException,
+  HttpStatus,
+  Logger,
+} from '@nestjs/common';
+import { Response } from 'express';
+
+interface ErrorResponse {
+  statusCode: number;
+  message: string;
+  timestamp: string;
+  path?: string;
+}
+
+/**
+ * Global exception filter som formaterar alla errors konsistent
+ * Returnerar tydliga, svenska felmeddelanden utan att läcka känslig info
+ */
+@Catch()
+export class GlobalExceptionFilter implements ExceptionFilter {
+  private readonly logger = new Logger(GlobalExceptionFilter.name);
+
+  catch(exception: any, host: ArgumentsHost) {
+    const ctx = host.switchToHttp();
+    const response = ctx.getResponse<Response>();
+    const request = ctx.getRequest();
+    const path = request.url;
+
+    let statusCode = HttpStatus.INTERNAL_SERVER_ERROR;
+    let message = 'Ett internt serverfel inträffade.';
+
+    // Hantera HTTP-exceptions (t.ex. NotFoundException)
+    if (exception instanceof HttpException) {
+      statusCode = exception.getStatus();
+      const exceptionResponse = exception.getResponse();
+
+      if (typeof exceptionResponse === 'object' && 'message' in exceptionResponse) {
+        message = (exceptionResponse as any).message || message;
+      } else if (typeof exceptionResponse === 'string') {
+        message = exceptionResponse;
+      }
+    } else if (exception instanceof Error) {
+      // Hantera vanliga Error-instanser
+      message = exception.message || message;
+      statusCode = HttpStatus.BAD_REQUEST;
+
+      // Log interna fel för debugging
+      this.logger.error(`Error: ${exception.message}`, exception.stack);
+    }
+
+    // Säkerställ att felmeddelanden är användarvänliga (på svenska)
+    if (message.includes('Unknown unit')) {
+      message = 'Okänd enhet. Kontrollera enheten och försök igen.';
+    } else if (message.includes('Cannot convert between incompatible unit types')) {
+      message = 'Kan inte konvertera mellan dessa enhetstyper.';
+    } else if (message.includes('Inventory item with id') && message.includes('not found')) {
+      message = 'Hemmavarorna hittades inte.';
+    } else if (message.includes('Product with id') && message.includes('not found')) {
+      message = 'Produkten hittades inte.';
+    } else if (message.includes('Recipe with id') && message.includes('not found')) {
+      message = 'Receptet hittades inte.';
+    } else if (message.includes('sourceProductId och targetProductId kan inte vara samma')) {
+      message = 'Du kan inte slå samman en produkt med sig själv.';
+    }
+
+    const errorResponse: ErrorResponse = {
+      statusCode,
+      message,
+      timestamp: new Date().toISOString(),
+      path,
+    };
+
+    this.logger.warn(
+      `${request.method} ${path} - Status: ${statusCode}, Message: ${message}`,
+    );
+
+    response.status(statusCode).json(errorResponse);
+  }
+}

backend/src/health/health.controller.ts

@@ -1,36 +1,41 @@
-import { Controller, Get } from '@nestjs/common';
-import { PrismaService } from '../prisma/prisma.service';
+import { Controller, Get, HttpCode, Res } from '@nestjs/common';
+import { Response } from 'express';
+import { HealthService } from './health.service';
 
 @Controller('health')
 export class HealthController {
-  constructor(private readonly prisma: PrismaService) {}
+  constructor(private readonly healthService: HealthService) {}
 
+  /**
+   * Övergripande hälsostatus för tjänsten
+   * Returnerar 200 om allt är bra, 503 om något är fel
+   */
   @Get()
-  getHealth() {
-    return {
-      status: 'ok',
-      service: 'recipe-api',
-      timestamp: new Date().toISOString(),
-    };
+  async getHealth(@Res() res: Response) {
+    const health = await this.healthService.getOverallHealth();
+    res.status(health.statusCode).json({
+      status: health.status,
+      service: health.service,
+      timestamp: health.timestamp,
+      uptime: health.uptime,
+      checks: health.checks,
+    });
   }
 
+  /**
+   * Databasspecific hälsokontroll
+   * Returnerar 200 om databasen är tillgänglig, 503 om inte
+   */
   @Get('db')
-  async getDatabaseHealth() {
-    try {
-      await this.prisma.$queryRaw`SELECT 1`;
+  async getDatabaseHealth(@Res() res: Response) {
+    const dbHealth = await this.healthService.getDatabaseHealth();
+    res.status(dbHealth.statusCode).json({
+      status: dbHealth.status,
+      database: dbHealth.database,
+      responseTime: `${dbHealth.responseTime}ms`,
+      timestamp: dbHealth.timestamp,
+      details: dbHealth.details,
+    });
+  }
+}
 
-      return {
-        status: 'ok',
-        database: 'connected',
-        timestamp: new Date().toISOString(),
-      };
-    } catch (error) {
-      return {
-        status: 'error',
-        database: 'not reachable',
-        message: error instanceof Error ? error.message : 'unknown error',
-        timestamp: new Date().toISOString(),
-      };
-    }
-  }
-}

backend/src/health/health.module.ts

@@ -1,7 +1,11 @@
 import { Module } from '@nestjs/common';
 import { HealthController } from './health.controller';
+import { HealthService } from './health.service';
+import { PrismaModule } from '../prisma/prisma.module';
 
 @Module({
+  imports: [PrismaModule],
   controllers: [HealthController],
+  providers: [HealthService],
 })
 export class HealthModule {}

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,
+      };
+    }
+  }
+}

backend/src/main.ts

@@ -1,11 +1,16 @@
 import { ValidationPipe } from '@nestjs/common';
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
+import { GlobalExceptionFilter } from './common/filters/global-exception.filter';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
 
   app.setGlobalPrefix('api');
+  
+  // Registrera global exception filter
+  app.useGlobalFilters(new GlobalExceptionFilter());
+  
   app.useGlobalPipes(
     new ValidationPipe({
       whitelist: true,

frontend/app/inventory/InventoryConsumptionHistory.tsx

@@ -1,6 +1,7 @@
 'use client';
 
 import { useState, useTransition } from 'react';
+import { parseErrorResponse } from '../../lib/error-handler';
 import type { InventoryConsumption } from '../../features/inventory/types';
 
 type Props = {
@@ -28,15 +29,16 @@ export default function InventoryConsumptionHistory({ id }: Props) {
         });
 
         if (!res.ok) {
-          const text = await res.text();
-          throw new Error(text || 'Kunde inte hämta historik.');
+          const errorMessage = await parseErrorResponse(res);
+          throw new Error(errorMessage);
         }
 
         const data: InventoryConsumption[] = await res.json();
         setHistory(data);
         setIsOpen(true);
       } catch (err) {
-        setError(err instanceof Error ? err.message : 'Okänt fel');
+        const message = err instanceof Error ? err.message : 'Ett okänt fel inträffade.';
+        setError(message);
       }
     });
   };

frontend/app/recipes/RecipePreview.tsx

@@ -2,6 +2,7 @@
 
 import { useState, useTransition } from 'react';
 import Link from 'next/link';
+import { parseErrorResponse } from '../../lib/error-handler';
 import type {
   Recipe,
   RecipeInventoryPreview,
@@ -74,14 +75,15 @@ export default function RecipePreview({ recipes }: Props) {
         });
 
         if (!res.ok) {
-          const text = await res.text();
-          throw new Error(text || 'Kunde inte hämta recept-preview.');
+          const errorMessage = await parseErrorResponse(res);
+          throw new Error(errorMessage);
         }
 
         const data: RecipeInventoryPreview = await res.json();
         setPreview(data);
       } catch (err) {
-        setError(err instanceof Error ? err.message : 'Okänt fel');
+        const message = err instanceof Error ? err.message : 'Ett okänt fel inträffade.';
+        setError(message);
       }
     });
   };

frontend/app/recipes/[id]/edit/page.tsx

@@ -3,6 +3,7 @@
 import { useState, useEffect } from 'react';
 import { useRouter, useParams } from 'next/navigation';
 import { fetchJson } from '../../../../lib/api';
+import { parseErrorResponse } from '../../../../lib/error-handler';
 import type { Product, Recipe } from '../../../../features/inventory/types';
 
 export default function EditRecipePage() {
@@ -99,12 +100,14 @@ export default function EditRecipePage() {
       });
 
       if (!response.ok) {
-        throw new Error('Kunde inte uppdatera receptet');
+        const errorMessage = await parseErrorResponse(response);
+        throw new Error(errorMessage);
       }
 
       router.push('/recipes');
     } catch (err) {
-      setError((err as Error).message);
+      const message = err instanceof Error ? err.message : 'Ett okänt fel inträffade. Försök igen.';
+      setError(message);
     } finally {
       setIsSaving(false);
     }

frontend/app/recipes/create/CreateRecipePage.tsx

@@ -3,6 +3,7 @@
 import { useState, useEffect } from 'react';
 import { useRouter } from 'next/navigation';
 import { fetchJson } from '../../../lib/api';
+import { parseErrorResponse } from '../../../lib/error-handler';
 import type { Product } from '../../../features/inventory/types';
 
 export default function CreateRecipePage() {
@@ -64,12 +65,14 @@ export default function CreateRecipePage() {
       });
 
       if (!response.ok) {
-        throw new Error('Kunde inte spara receptet');
+        const errorMessage = await parseErrorResponse(response);
+        throw new Error(errorMessage);
       }
 
       router.push('/recipes');
     } catch (err) {
-      setError((err as Error).message);
+      const message = err instanceof Error ? err.message : 'Ett okänt fel inträffade. Försök igen.';
+      setError(message);
     } finally {
       setIsLoading(false);
     }

frontend/lib/error-handler.ts

@@ -0,0 +1,69 @@
+/**
+ * Utility för att parse HTTP-responses och extrahera tydliga felmeddelanden
+ */
+export async function parseErrorResponse(response: Response): Promise<string> {
+  const status = response.status;
+  
+  try {
+    const data = await response.json();
+    
+    // Om backend skickade ett felmeddelande
+    if (data.message) {
+      return data.message;
+    }
+    if (data.error) {
+      return data.error;
+    }
+    if (data.details) {
+      return data.details;
+    }
+  } catch {
+    // Inte JSON, försök text
+    try {
+      const text = await response.text();
+      if (text && text.length < 200) {
+        return text;
+      }
+    } catch {
+      // Inget text-innehål
+    }
+  }
+
+  // Fallback baserat på HTTP-status
+  const defaultMessages: Record<number, string> = {
+    400: 'Ogiltiga data. Kontrollera dina inmatningar.',
+    401: 'Du är inte autentiserad. Logga in.',
+    403: 'Du har inte behörighet till detta.',
+    404: 'Resursen hittades inte.',
+    409: 'Konflikten med befintlig data.',
+    422: 'Valideringen misslyckades. Kontrollera dina inmatningar.',
+    500: 'Serverfel. Försök igen senare.',
+    503: 'Tjänsten är inte tillgänglig.',
+  };
+
+  return defaultMessages[status] || `Fel (${status}). Försök igen senare.`;
+}
+
+/**
+ * Hämta data från API med bra felhantering
+ */
+export async function fetchWithErrorHandling(
+  url: string,
+  options?: RequestInit,
+): Promise<any> {
+  try {
+    const response = await fetch(url, options);
+
+    if (!response.ok) {
+      const errorMessage = await parseErrorResponse(response);
+      throw new Error(errorMessage);
+    }
+
+    return await response.json();
+  } catch (err) {
+    if (err instanceof Error) {
+      throw err;
+    }
+    throw new Error('Ett okänt fel inträffade.');
+  }
+}