
/**
 * POP3 protocol - RFC1939 - https://www.ietf.org/rfc/rfc1939.txt
 *
 * Dependencies:
 * * poplib     - https://www.npmjs.com/package/poplib
 * * nodemailer - https://www.npmjs.com/package/nodemailer
 * * imap       - https://www.npmjs.com/package/imap
 * * mailparser - https://www.npmjs.com/package/mailparser
 */

module.exports = function(RED) {
    "use strict";
    var nodemailer = require("nodemailer");
    var Imap = require('imap');
    var POP3Client = require("poplib");
    var SimpleParser = require("mailparser").simpleParser;
    var util = require("util");

    if (parseInt(process.version.split("v")[1].split(".")[0]) < 8) {
        throw "Error : Requires nodejs version >= 8.";
    }

    try {
        var globalkeys = RED.settings.email || require(process.env.NODE_RED_HOME+"/../emailkeys.js");
    }
    catch(err) {
    }

    function EmailNode(n) {
        RED.nodes.createNode(this,n);
        this.topic = n.topic;
        this.name = n.name;
        this.outserver = n.server;
        this.outport = n.port;
        this.secure = n.secure;
        this.tls = true;
        var flag = false;
        if (this.credentials && this.credentials.hasOwnProperty("userid")) {
            this.userid = this.credentials.userid;
        } else {
            if (globalkeys) {
                this.userid = globalkeys.user;
                flag = true;
            }
        }
        if (this.credentials && this.credentials.hasOwnProperty("password")) {
            this.password = this.credentials.password;
        } else {
            if (globalkeys) {
                this.password = globalkeys.pass;
                flag = true;
            }
        }
        if (flag) {
            RED.nodes.addCredentials(n.id,{userid:this.userid, password:this.password, global:true});
        }
        if (n.tls === false) {
            this.tls = false;
        }
        var node = this;

        var smtpOptions = {
            host: node.outserver,
            port: node.outport,
            secure: node.secure,
            tls: {rejectUnauthorized: node.tls}
        }

        if (this.userid && this.password) {
            smtpOptions.auth = {
                user: node.userid,
                pass: node.password
            };
        }
        var smtpTransport = nodemailer.createTransport(smtpOptions);

        this.on("input", function(msg, send, done) {
            if (msg.hasOwnProperty("payload")) {
                send = send || function() { node.send.apply(node,arguments) };
                if (smtpTransport) {
                    node.status({fill:"blue",shape:"dot",text:"email.status.sending"});
                    if (msg.to && node.name && (msg.to !== node.name)) {
                        node.warn(RED._("node-red:common.errors.nooverride"));
                    }
                    var sendopts = { from: ((msg.from) ? msg.from : node.userid) };   // sender address
                    sendopts.to = node.name || msg.to; // comma separated list of addressees
                    if (node.name === "") {
                        sendopts.cc = msg.cc;
                        sendopts.bcc = msg.bcc;
                        sendopts.inReplyTo = msg.inReplyTo;
                        sendopts.replyTo = msg.replyTo;
                        sendopts.references = msg.references;
                    }
                    sendopts.subject = msg.topic || msg.title || "Message from Node-RED"; // subject line
                    if (msg.hasOwnProperty("envelope")) { sendopts.envelope = msg.envelope; }
                    if (Buffer.isBuffer(msg.payload)) { // if it's a buffer in the payload then auto create an attachment instead
                        if (!msg.filename) {
                            var fe = "bin";
                            if ((msg.payload[0] === 0xFF)&&(msg.payload[1] === 0xD8)) { fe = "jpg"; }
                            if ((msg.payload[0] === 0x47)&&(msg.payload[1] === 0x49)) { fe = "gif"; } //46
                            if ((msg.payload[0] === 0x42)&&(msg.payload[1] === 0x4D)) { fe = "bmp"; }
                            if ((msg.payload[0] === 0x89)&&(msg.payload[1] === 0x50)) { fe = "png"; } //4E
                            msg.filename = "attachment."+fe;
                        }
                        var fname = msg.filename.replace(/^.*[\\\/]/, '') || "file.bin";
                        sendopts.attachments = [ { content:msg.payload, filename:fname } ];
                        if (msg.hasOwnProperty("headers") && msg.headers.hasOwnProperty("content-type")) {
                            sendopts.attachments[0].contentType = msg.headers["content-type"];
                        }
                        // Create some body text..
                        sendopts.text = RED._("email.default-message",{filename:fname, description:(msg.description||"")});
                    }
                    else {
                        var payload = RED.util.ensureString(msg.payload);
                        sendopts.text = payload; // plaintext body
                        if (/<[a-z][\s\S]*>/i.test(payload)) { sendopts.html = payload; } // html body
                        if (msg.attachments) { sendopts.attachments = msg.attachments; } // add attachments
                    }
                    smtpTransport.sendMail(sendopts, function(error, info) {
                        if (error) {
                            node.error(error,msg);
                            node.status({fill:"red",shape:"ring",text:"email.status.sendfail",response:error.response,msg:{to:msg.to,topic:msg.topic,id:msg._msgid}});
                        } else {
                            node.log(RED._("email.status.messagesent",{response:info.response}));
                            node.status({text:"",response:info.response,msg:{to:msg.to,topic:msg.topic,id:msg._msgid}});
                            if (done) { done(); }
                        }
                    });
                }
                else { node.warn(RED._("email.errors.nosmtptransport")); }
            }
            else { node.warn(RED._("email.errors.nopayload")); }
        });
    }
    RED.nodes.registerType("e-mail",EmailNode,{
        credentials: {
            userid: {type:"text"},
            password: {type: "password"},
            global: { type:"boolean"}
        }
    });


    //
    // EmailInNode
    //
    // Setup the EmailInNode
    function EmailInNode(n) {
        var imap;

        RED.nodes.createNode(this,n);
        this.name = n.name;
        this.inputs = n.inputs;
        this.repeat = n.repeat * 1000 || 300000;
        if (this.repeat > 2147483647) {
            // setTimeout/Interval has a limit of 2**31-1 Milliseconds
            this.repeat = 2147483647;
            this.error(RED._("email.errors.refreshtoolarge"));
        }
        if (this.inputs === 1) { this.repeat = 0; }
        this.inserver = n.server || (globalkeys && globalkeys.server) || "imap.gmail.com";
        this.inport = n.port || (globalkeys && globalkeys.port) || "993";
        this.box = n.box || "INBOX";
        this.useSSL= n.useSSL;
        this.protocol = n.protocol || "IMAP";
        this.disposition = n.disposition || "None"; // "None", "Delete", "Read"
        this.criteria = n.criteria || "UNSEEN"; // "ALL", "ANSWERED", "FLAGGED", "SEEN", "UNANSWERED", "UNFLAGGED", "UNSEEN"

        var flag = false;

        if (this.credentials && this.credentials.hasOwnProperty("userid")) {
            this.userid = this.credentials.userid;
        } else {
            if (globalkeys) {
                this.userid = globalkeys.user;
                flag = true;
            } else {
                this.error(RED._("email.errors.nouserid"));
            }
        }
        if (this.credentials && this.credentials.hasOwnProperty("password")) {
            this.password = this.credentials.password;
        } else {
            if (globalkeys) {
                this.password = globalkeys.pass;
                flag = true;
            } else {
                this.error(RED._("email.errors.nopassword"));
            }
        }
        if (flag) {
            RED.nodes.addCredentials(n.id,{userid:this.userid, password:this.password, global:true});
        }

        var node = this;
        this.interval_id = null;

        // Process a new email message by building a Node-RED message to be passed onwards
        // in the message flow.  The parameter called `msg` is the template message we
        // start with while `mailMessage` is an object returned from `mailparser` that
        // will be used to populate the email.
        // DCJ NOTE: - heirachical multipart mime parsers seem to not exist - this one is barely functional.
        function processNewMessage(msg, mailMessage) {
            msg = RED.util.cloneMessage(msg); // Clone the message
            // Populate the msg fields from the content of the email message
            // that we have just parsed.
            msg.payload = mailMessage.text;
            msg.topic = mailMessage.subject;
            msg.date = mailMessage.date;
            msg.header = {};
            mailMessage.headers.forEach((v, k) => {msg.header[k] = v;});
            if (mailMessage.html) { msg.html = mailMessage.html; }
            if (mailMessage.to && mailMessage.to.length > 0) { msg.to = mailMessage.to; }
            if (mailMessage.cc && mailMessage.cc.length > 0) { msg.cc = mailMessage.cc; }
            if (mailMessage.bcc && mailMessage.bcc.length > 0) { msg.bcc = mailMessage.bcc; }
            if (mailMessage.from && mailMessage.from.value && mailMessage.from.value.length > 0) { msg.from = mailMessage.from.value[0].address; }
            if (mailMessage.attachments) { msg.attachments = mailMessage.attachments; }
            else { msg.attachments = []; }
            node.send(msg); // Propagate the message down the flow
        } // End of processNewMessage

        // Check the POP3 email mailbox for any new messages.  For any that are found,
        // retrieve each message, call processNewMessage to process it and then delete
        // the messages from the server.
        function checkPOP3(msg) {
            var currentMessage;
            var maxMessage;
            //node.log("Checking POP3 for new messages");

            // Form a new connection to our email server using POP3.
            var pop3Client = new POP3Client(
                node.inport, node.inserver,
                {enabletls: node.useSSL} // Should we use SSL to connect to our email server?
            );

            // If we have a next message to retrieve, ask to retrieve it otherwise issue a
            // quit request.
            function nextMessage() {
                if (currentMessage > maxMessage) {
                    pop3Client.quit();
                    setInputRepeatTimeout();
                    return;
                }
                pop3Client.retr(currentMessage);
                currentMessage++;
            } // End of nextMessage

            pop3Client.on("stat", function(status, data) {
                // Data contains:
                // {
                //   count: <Number of messages to be read>
                //   octect: <size of messages to be read>
                // }
                if (status) {
                    currentMessage = 1;
                    maxMessage = data.count;
                    nextMessage();
                } else {
                    node.log(util.format("stat error: %s %j", status, data));
                }
            });

            pop3Client.on("error", function(err) {
                setInputRepeatTimeout();
                node.log("error: " + JSON.stringify(err));
            });

            pop3Client.on("connect", function() {
                //node.log("We are now connected");
                pop3Client.login(node.userid, node.password);
            });

            pop3Client.on("login", function(status, rawData) {
                //node.log("login: " + status + ", " + rawData);
                if (status) {
                    pop3Client.stat();
                } else {
                    node.log(util.format("login error: %s %j", status, rawData));
                    pop3Client.quit();
                    setInputRepeatTimeout();
                }
            });

            pop3Client.on("retr", function(status, msgNumber, data, rawData) {
                // node.log(util.format("retr: status=%s, msgNumber=%d, data=%j", status, msgNumber, data));
                if (status) {

                    // We have now received a new email message.  Create an instance of a mail parser
                    // and pass in the email message.  The parser will signal when it has parsed the message.
                    SimpleParser(data, {}, function(err, parsed) {
                        //node.log(util.format("SimpleParser: on(end): %j", mailObject));
                        if (err) {
                            node.status({fill:"red", shape:"ring", text:"email.status.parseerror"});
                            node.error(RED._("email.errors.parsefail", {folder:node.box}), err);
                        }
                        else {
                            processNewMessage(msg, parsed);
                        }
                    });
                    pop3Client.dele(msgNumber);
                }
                else {
                    node.log(util.format("retr error: %s %j", status, rawData));
                    pop3Client.quit();
                    setInputRepeatTimeout();
                }
            });

            pop3Client.on("invalid-state", function(cmd) {
                node.log("Invalid state: " + cmd);
            });

            pop3Client.on("locked", function(cmd) {
                node.log("We were locked: " + cmd);
            });

            // When we have deleted the last processed message, we can move on to
            // processing the next message.
            pop3Client.on("dele", function(status, msgNumber) {
                nextMessage();
            });
        } // End of checkPOP3


        //
        // checkIMAP
        //
        // Check the email sever using the IMAP protocol for new messages.
        var s = false;
        var ss = false;
        function checkIMAP(msg) {
            //console.log("Checking IMAP for new messages");
            // We get back a 'ready' event once we have connected to imap
            s = true;
            imap.once("ready", function() {
                if (ss === true) { return; }
                ss = true;
                node.status({fill:"blue", shape:"dot", text:"email.status.fetching"});
                //console.log("> ready");
                // Open the inbox folder
                imap.openBox(node.box, // Mailbox name
                    false, // Open readonly?
                    function(err, box) {
                    //console.log("> Inbox err : %j", err);
                    //console.log("> Inbox open: %j", box);
                    if (err) {
                        s = false;
                        node.status({fill:"red", shape:"ring", text:"email.status.foldererror"});
                        node.error(RED._("email.errors.fetchfail", {folder:node.box}),err);
                        imap.end();
                        setInputRepeatTimeout();
                        return;
                    }
                    else {
                        var criteria = ((node.criteria === '_msg_')?
                                        (msg.criteria || ["UNSEEN"]):
                                        ([node.criteria]));
                        imap.search(criteria, function(err, results) {
                            if (err) {
                                node.status({fill:"red", shape:"ring", text:"email.status.foldererror"});
                                node.error(RED._("email.errors.fetchfail", {folder:node.box}),err);
                                imap.end();
                                s = false;
                                setInputRepeatTimeout();
                                return;
                            }
                            else {
                                //console.log("> search - err=%j, results=%j", err, results);
                                if (results.length === 0) {
                                    //console.log(" [X] - Nothing to fetch");
                                    node.status({results:0});
                                    imap.end();
                                    s = false;
                                    setInputRepeatTimeout();
                                    return;
                                }

                                var marks = false;
                                if (node.disposition === "Read") { marks = true; }
                                // We have the search results that contain the list of unseen messages and can now fetch those messages.
                                var fetch = imap.fetch(results, {
                                    bodies: '',
                                    struct: true,
                                    markSeen: marks
                                });

                                // For each fetched message returned ...
                                fetch.on('message', function(imapMessage, seqno) {
                                    //node.log(RED._("email.status.message",{number:seqno}));
                                    //console.log("> Fetch message - msg=%j, seqno=%d", imapMessage, seqno);
                                    imapMessage.on('body', function(stream, info) {
                                        //console.log("> message - body - stream=?, info=%j", info);
                                        SimpleParser(stream, {}, function(err, parsed) {
                                            if (err) {
                                                node.status({fill:"red", shape:"ring", text:"email.status.parseerror"});
                                                node.error(RED._("email.errors.parsefail", {folder:node.box}),err);
                                            }
                                            else {
                                                processNewMessage(msg, parsed);
                                            }
                                        });
                                    }); // End of msg->body
                                }); // End of fetch->message

                                // When we have fetched all the messages, we don't need the imap connection any more.
                                fetch.on('end', function() {
                                    node.status({results:results.length});
                                    var cleanup = function() {
                                        imap.end();
                                        s = false;
                                    };
                                    if (this.disposition === "Delete") {
                                        imap.addFlags(results, "\Deleted", cleanup);
                                    } else if (this.disposition === "Read") {
                                        imap.addFlags(results, "\Seen", cleanup);
                                    } else {
                                        cleanup();
                                    }
                                    setInputRepeatTimeout();
                                });

                                fetch.once('error', function(err) {
                                    console.log('Fetch error: ' + err);
                                    setInputRepeatTimeout();
                                });
                            }
                        }); // End of imap->search
                    }
                }); // End of imap->openInbox
            }); // End of imap->ready
            node.status({fill:"grey",shape:"dot",text:"node-red:common.status.connecting"});
            imap.connect();
        } // End of checkIMAP


        // Perform a check of the email inboxes using either POP3 or IMAP
        function checkEmail(msg) {
            if (node.protocol === "POP3") {
                checkPOP3(msg);
            } else if (node.protocol === "IMAP") {
                if (s === false) { checkIMAP(msg); }
            }
        }  // End of checkEmail

        if (node.protocol === "IMAP") {
            imap = new Imap({
                user: node.userid,
                password: node.password,
                host: node.inserver,
                port: node.inport,
                tls: node.useSSL,
                tlsOptions: { rejectUnauthorized: false },
                connTimeout: node.repeat,
                authTimeout: node.repeat
            });
            imap.on('error', function(err) {
                if (err.errno !== "ECONNRESET") {
                    node.log(err);
                    s = false;
                    node.status({fill:"red",shape:"ring",text:"email.status.connecterror"});
                }
                setInputRepeatTimeout();
            });
        }

        this.on("input", function(msg) {
            checkEmail(msg);
        });

        this.on("close", function() {
            if (this.interval_id != null) {
                clearTimeout(this.interval_id);
            }
            if (imap) { imap.destroy(); }
        });

        function setInputRepeatTimeout() {
            // Set the repetition timer as needed
            if (!isNaN(node.repeat) && node.repeat > 0) {
                node.interval_id = setTimeout( function() {
                    node.emit("input",{});
                }, node.repeat );
            }
            ss = false;
        }

        if (this.inputs !== 1) { node.emit("input",{}); }
    }

    RED.nodes.registerType("e-mail in",EmailInNode,{
        credentials: {
            userid: { type:"text" },
            password: { type: "password" },
            global: { type:"boolean" }
        }
    });
};
