emiloberg/node-red-contrib-file-function

/**
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/

module.exports = function(RED) {
    "use strict";
    var util = require("util");
    var vm = require("vm");
    var fs = require("fs");

    function FunctionNode(n) {
        RED.nodes.createNode(this, n);

        this.filename = n.filename || "";
        this.loadedScript = '';
        this.loadedFilename = '';

        var node = this;
        
        // Read and file when node is initialized,
        // if user didn't check the "reload file every time"-checkbox, we'll be using
        // this when node is invoked.
        if (this.filename !== '') {
            node.loadedFilename = this.filename;
            fs.readFile(this.filename, {encoding: 'utf-8'}, function (err, fileContent) {
                if (err) {
                    if (err.code === 'ENOENT') {
                        node.warn('Could not find file "' + err.path + '". Hint: File path is relative to "' + process.env.PWD + '"');
                    } else {
                        node.warn(err);
                    }
                } else {
                    node.loadedScript = fileContent;
                }
            });
        }


        // On invocation
        this.on("input", function (msg) {
            var filename = msg.filename || this.filename;

            if (filename === '') {
                node.warn('No filename specified');
            } else if (n.reloadfile === false && filename === node.loadedFilename && node.loadedScript !== ''){ // Run script from "cache"
                runScript(node, msg, node.loadedScript);
            } else { // Read script from disk and run
                fs.readFile(filename, {encoding: 'utf-8'}, function (err, fileContent) {
                    if (err) {
                        if (err.code === 'ENOENT') {
                            node.warn('Could not find file "' + err.path + '". Hint: File path is relative to "' + process.env.PWD + '"');
                        } else {
                            node.warn(err);
                        }
                        msg.error = err;
                    } else {
                        node.loadedScript = fileContent;
                        node.loadedFilename = filename;
                        runScript(node, msg, fileContent);
                    }
                });
            }
        });
    }


    function runScript(node, msg, script) {
        var functionText = "var results = null; results = (function(msg){"+script+"\n})(msg);";

        var sandbox = {
            console:console,
            util:util,
            Buffer:Buffer,
            context: {
                global:RED.settings.functionGlobalContext || {}
            }
        };

        var context = vm.createContext(sandbox);
        var vmScript = vm.createScript(functionText);

        try {
            var start = process.hrtime();
            context.msg = msg;
            vmScript.runInContext(context);
            var results = context.results;
            if (results == null) {
                results = [];
            } else if (results.length == null) {
                results = [results];
            }

            if (msg.topic) {
                for (var m in results) {
                    if (results[m]) {
                        if (util.isArray(results[m])) {
                            for (var n=0; n < results[m].length; n++) {
                                results[m][n].topic = msg.topic;
                            }
                        } else {
                            results[m].topic = msg.topic;
                        }
                    }
                }
            }

            node.send(results);
            var duration = process.hrtime(start);
            if (process.env.NODE_RED_FUNCTION_TIME) {
                this.status({fill:"yellow",shape:"dot",text:""+Math.floor((duration[0]* 1e9 +  duration[1])/10000)/100});
            }

        } catch(err) {
            node.warn(err);
        }
    }

    RED.nodes.registerType("file function",FunctionNode);
    RED.library.register("functions");
};