API Response

import { applyDecorators, Type } from "@nestjs/common";
import {
  ApiOkResponse,
  ApiCreatedResponse,
  ApiBadRequestResponse,
  ApiUnauthorizedResponse,
  ApiForbiddenResponse,
  ApiNotFoundResponse,
  ApiInternalServerErrorResponse,
  getSchemaPath,
  ApiExtraModels,
} from "@nestjs/swagger";

// Standard error response DTO
class ErrorResponseDto {
  statusCode: number;
  message: string | string[];
  error: string;
}

/**
 * Decorator for paginated list responses.
 * 
 * Usage:
 * @ApiPaginatedResponse(UserDto)
 * @Get()
 * findAll() {}
 */
export function ApiPaginatedResponse<TModel extends Type<unknown>>(
  model: TModel
) {
  return applyDecorators(
    ApiExtraModels(model),
    ApiOkResponse({
      description: "Paginated list response",
      schema: {
        allOf: [
          {
            properties: {
              data: {
                type: "array",
                items: { $ref: getSchemaPath(model) },
              },
              meta: {
                type: "object",
                properties: {
                  total: { type: "number" },
                  page: { type: "number" },
                  limit: { type: "number" },
                  totalPages: { type: "number" },
                  hasNext: { type: "boolean" },
                  hasPrev: { type: "boolean" },
                },
              },
            },
          },
        ],
      },
    })
  );
}

/**
 * Standard success response wrapper.
 */
export function ApiSuccessResponse<TModel extends Type<unknown>>(
  model: TModel,
  description = "Successful response"
) {
  return applyDecorators(
    ApiExtraModels(model),
    ApiOkResponse({
      description,
      schema: {
        properties: {
          success: { type: "boolean", example: true },
          data: { $ref: getSchemaPath(model) },
        },
      },
    })
  );
}

/**
 * Standard created response wrapper.
 */
export function ApiCreatedSuccessResponse<TModel extends Type<unknown>>(
  model: TModel,
  description = "Resource created successfully"
) {
  return applyDecorators(
    ApiExtraModels(model),
    ApiCreatedResponse({
      description,
      schema: {
        properties: {
          success: { type: "boolean", example: true },
          data: { $ref: getSchemaPath(model) },
        },
      },
    })
  );
}

/**
 * Apply common error responses to controller methods.
 */
export function ApiCommonErrors() {
  return applyDecorators(
    ApiBadRequestResponse({
      description: "Bad Request - Invalid input",
      type: ErrorResponseDto,
    }),
    ApiUnauthorizedResponse({
      description: "Unauthorized - Authentication required",
      type: ErrorResponseDto,
    }),
    ApiForbiddenResponse({
      description: "Forbidden - Insufficient permissions",
      type: ErrorResponseDto,
    }),
    ApiNotFoundResponse({
      description: "Not Found - Resource does not exist",
      type: ErrorResponseDto,
    }),
    ApiInternalServerErrorResponse({
      description: "Internal Server Error",
      type: ErrorResponseDto,
    })
  );
}

/**
 * Combine success and error responses.
 */
export function ApiStandardResponse<TModel extends Type<unknown>>(
  model: TModel,
  description = "Successful response"
) {
  return applyDecorators(
    ApiSuccessResponse(model, description),
    ApiCommonErrors()
  );
}