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libs/api/shared/presenters/src/lib/filters/domain-error.filter.ts

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+import {
+  ArgumentsHost,
+  Catch,
+  ExceptionFilter,
+  HttpStatus,
+  Logger,
+} from '@nestjs/common';
+import { GqlContextType } from '@nestjs/graphql';
+import { DomainError, DomainErrorCode } from '@task-stream/api/shared/domain';
+import { Response } from 'express';
+import { GraphQLError } from 'graphql';
+
+const HTTP_STATUS: Record<DomainErrorCode, HttpStatus> = {
+  NOT_FOUND: HttpStatus.NOT_FOUND,
+  FORBIDDEN: HttpStatus.FORBIDDEN,
+  VALIDATION: HttpStatus.BAD_REQUEST,
+  CONFLICT: HttpStatus.CONFLICT,
+  BUSINESS_RULE: HttpStatus.UNPROCESSABLE_ENTITY,
+};
+
+/** Translates domain errors into GraphQL errors (extensions.code) or HTTP responses. */
+@Catch(DomainError)
+export class DomainErrorFilter implements ExceptionFilter {
+  private readonly logger = new Logger(DomainErrorFilter.name);
+
+  catch(error: DomainError, host: ArgumentsHost): unknown {
+    this.logger.debug(`${error.name}: ${error.message}`);
+    if (host.getType<GqlContextType>() === 'graphql') {
+      return new GraphQLError(error.message, {
+        extensions: { code: error.code },
+      });
+    }
+    const response = host.switchToHttp().getResponse<Response>();
+    return response.status(HTTP_STATUS[error.code]).json({
+      statusCode: HTTP_STATUS[error.code],
+      code: error.code,
+      message: error.message,
+    });
+  }
+}