error-handler.js

var STATUS_CODES = require('http').STATUS_CODES;
var sendJson = require('send-data/json');
var url = require('url');

function (req, res, opts) { 
    var clients = opts.clients;
    var config = opts.config;

    var errOpts = {
        // verbose is true in dev where it prints stacks
        // when verbose is false it wont print stacks
        verbose: config.get('playdoh-api.error.verbose') || false
    };
    
    return defaultErrorHandler;
    
   /*  

        type TypedError : {
            message: String,
            statusCode?: Number,
            type?: String,
            stack?: String,
            expected?: Boolean,
            messages?: Array<String>
        }

        defaultErrorHandler : (err?: TypedError)
    */
    function defaultErrorHandler(err) {
        var parsedUrl = url.parse(req.url);
        var statsdKey = 'playdoh-api.error-handler.' +
            parsedUrl.pathname;

        if (err) {
            if (typeof err.expected === 'string') {
                if (clients.statsd) {
                    clients.statsd.increment(statsdKey + '.expected');
                }
                sendExpectedError(req, res, err, errOpts);
            } else {
                clients.logger.error('unexpected error', err);
                if (clients.statsd) {
                    clients.statsd.increment(statsdKey + '.unexpected');
                }
                sendUnexpectedError(req, res, err, errOpts);
            }
        } else if (clients.statsd) {
            clients.statsd.increment(statsdKey + '.ok');
        }
    }
}

function sendExpectedError(req, res, err, opts) {
    var statusCode = err.statusCode || 500;
    var body = {
        message: err.message || STATUS_CODES[statusCode] ||
            STATUS_CODES[500]
    };

    if (typeof err.type === 'string') {
        body.type = err.type;
    }

    if (Array.isArray(err.messages)) {
        body.messages = err.messages;
    }

    if (opts.verbose) {
        body.stack = err.stack;
        body.expected = err.expected;
    }

    sendJson(req, res, {
        statusCode: statusCode,
        body: body
    });
}

function sendUnexpectedError(req, res, err, opts) {
    var statusCode = err.statusCode || 500;

    var body = {
        message: STATUS_CODES[statusCode] ||
            STATUS_CODES[500]
    };

    if (opts.verbose) {
        body.message = err.message || body.message;
        body.stack = err.stack;
        body.expected = err.expected;
    }

    sendJson(req, res, {
        statusCode: statusCode,
        body: body
    });
}