app2-api/helpers/controller.helper.js

'use strict';

const _ = require('lodash');
const httpStatus = require('http-status');

////////////////////////////////////////////////////////////////////////////////
// PRIVATE FUNCTIONS
////////////////////////////////////////////////////////////////////////////////

function buildErrorLog(err) {
    let errorLog;
    if (_.isUndefined(err)) {
        errorLog = 'Error not defined';
    } else if (!_.isUndefined(err.message)) {
        errorLog = err.message;
    } else if (!_.isUndefined(err.stack)) {
        errorLog = err.stack;
    } else {
        errorLog = JSON.stringify(err);
    }
    return errorLog;
}

function buildErrorResponse(nameController, nameMethod, error) {

    const errorDescription = buildErrorLog(error);

    const jsonResultFailed = {
        code: httpStatus.INTERNAL_SERVER_ERROR,
        message: 'Internal Server Error',
        description: `Internal Application Error in ${nameController}:${nameMethod}. ${errorDescription}`
    }
    return jsonResultFailed;
}

function getTotalCount(result) {

    const toType = function (obj) {
        return ({}).toString.call(obj).match(/\s([a-zA-Z]+)/)[1].toLowerCase()
    }    
    
    switch (toType(result)) {
        case 'boolean':
            return 1;
        case 'object':
            return 1;
        case 'array':
            return result.length;
        case 'null':
            return 0;
        default:
            return 0;
    }    
}

function setPaginationInfo(totalCount, res) {
    res.set({
        'X-Total-Count': totalCount,
    });
    
    const params = extractParamsFromRequest(null, res);
    console.log(params);
    if (params.paginate) {
        const 
            page = (params.paginate && params.paginate.page) ? params.paginate.page : null,
            limit = (params.paginate && params.paginate.limit) ? params.paginate.limit : null,
            count = (limit) ? Math.ceil(totalCount / limit) : null;
        
        if (params.paginate.hasNextPages(count)) {
            const nextPage = params.paginate.href();
            res.set('Link', nextPage + '; rel=next');
            res.set('Pagination-Next-Page', true);
        } else {
            res.set('Pagination-Next-Page', false);
        }
            
        res.set({
            'Pagination-Count': count,
            'Pagination-Page': page,
            'Pagination-Limit': limit,            
        });    
    }
}

////////////////////////////////////////////////////////////////////////////////
// PUBLIC FUNCTIONS
////////////////////////////////////////////////////////////////////////////////

function extractParamsFromRequest(req, res) {
    const result = {};

    result.params = (req && req.params) ? req.params : null;
    result.query = (req && req.query) ? req.params : null;

    if (res && res.locals) {
        Object.keys(res.locals).forEach(key => {
            result[key] = res.locals[key]
        })
    }

    return result;
}


function handleErrorResponse(controllerName, methodName, error, res) {   

    const jsonResultFailed = buildErrorResponse(controllerName, methodName, error);
    res.status(httpStatus.INTERNAL_SERVER_ERROR).send(jsonResultFailed);
}

function handleResultResponse(result, totalCount = null, params, res, statusCode = httpStatus.OK) {
    setPaginationInfo((totalCount) ? totalCount : getTotalCount(result), res);
    res.status(statusCode).send(result);
}


////////////////////////////////////////////////////////////////////////////////
// MODULE EXPORTS
////////////////////////////////////////////////////////////////////////////////

module.exports = {
    extractParamsFromRequest,
    handleErrorResponse,
    handleResultResponse,
    // for testing
    buildErrorLog,
    buildErrorResponse
};