/*
Copyright 2018 Intel Corporation

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.
*/

var MemoryStream = require('MemoryStream');
var lme_id = 0;
var lme_port_offset = 0; // Debug: Set this to "-100" to bind to 16892 & 16893 and IN_ADDRANY. This is for LMS debugging.


var APF_DISCONNECT = 1;
var APF_SERVICE_REQUEST = 5;
var APF_SERVICE_ACCEPT = 6;
var APF_USERAUTH_REQUEST = 50;
var APF_USERAUTH_FAILURE = 51;
var APF_USERAUTH_SUCCESS = 52;
var APF_GLOBAL_REQUEST = 80;
var APF_REQUEST_SUCCESS = 81;
var APF_REQUEST_FAILURE = 82;
var APF_CHANNEL_OPEN = 90;
var APF_CHANNEL_OPEN_CONFIRMATION = 91;
var APF_CHANNEL_OPEN_FAILURE = 92;
var APF_CHANNEL_WINDOW_ADJUST = 93;
var APF_CHANNEL_DATA = 94;
var APF_CHANNEL_CLOSE = 97;
var APF_PROTOCOLVERSION = 192;


function lme_object() {
    this.ourId = ++lme_id;
    this.amtId = -1;
    this.LME_CHANNEL_STATUS = 'LME_CS_FREE';
    this.txWindow = 0;
    this.rxWindow = 0;
    this.localPort = 0;
    this.errorCount = 0;
}

function stream_bufferedWrite() {
    var emitterUtils = require('events').inherits(this);
    this.buffer = [];
    this._readCheckImmediate = undefined;
    
    // Writable Events
    emitterUtils.createEvent('close');
    emitterUtils.createEvent('drain');
    emitterUtils.createEvent('error');
    emitterUtils.createEvent('finish');
    emitterUtils.createEvent('pipe');
    emitterUtils.createEvent('unpipe');
    
    // Readable Events
    emitterUtils.createEvent('readable');
    this.isEmpty = function () {
        return (this.buffer.length == 0);
    };
    this.isWaiting = function () {
        return (this._readCheckImmediate == undefined);
    };
    this.write = function (chunk) {
        for (var args in arguments) { if (typeof (arguments[args]) == 'function') { this.once('drain', arguments[args]); break; } }
        var tmp = Buffer.alloc(chunk.length);
        chunk.copy(tmp);
        this.buffer.push({ offset: 0, data: tmp });
        this.emit('readable');
        return (this.buffer.length == 0 ? true : false);
    };
    this.read = function () {
        var size = arguments.length == 0 ? undefined : arguments[0];
        var bytesRead = 0;
        var list = [];
        while ((size == undefined || bytesRead < size) && this.buffer.length > 0) {
            var len = this.buffer[0].data.length - this.buffer[0].offset;
            var offset = this.buffer[0].offset;
            
            if (len > (size - bytesRead)) {
                // Only reading a subset
                list.push(this.buffer[0].data.slice(offset, offset + size - bytesRead));
                this.buffer[0].offset += (size - bytesRead);
                bytesRead += (size - bytesRead);
            } else {
                // Reading the entire thing
                list.push(this.buffer[0].data.slice(offset));
                bytesRead += len;
                this.buffer.shift();
            }
        }
        this._readCheckImmediate = setImmediate(function (buffered) {
            buffered._readCheckImmediate = undefined;
            if (buffered.buffer.length == 0) {
                buffered.emit('drain'); // Drained
            } else {
                buffered.emit('readable'); // Not drained
            }
        }, this);
        return (Buffer.concat(list));
    };
}


function lme_heci(options) {
    var emitterUtils = require('events').inherits(this);
    emitterUtils.createEvent('error');
    emitterUtils.createEvent('connect');
    
    if (options.debug == true) { lme_port_offset = -100; } // LMS debug mode

    var heci = require('heci');
    this.INITIAL_RXWINDOW_SIZE = 4096;
    
    this._LME = heci.create();
    this._LME.LMS = this;
    this._LME.on('error', function (e) { this.LMS.emit('error', e); });
    this._LME.on('connect', function () {
        this.LMS.emit('connect');
        this.on('data', function (chunk) {
            // this = HECI
            var cmd = chunk.readUInt8(0);
            
            switch (cmd) {
                default:
                    //console.log('Received ' + chunk.length + ' bytes of data for LMS');
                    //console.log('Command = ' + cmd);
                    break;
                case APF_SERVICE_REQUEST:
                    var nameLen = chunk.readUInt32BE(1);
                    var name = chunk.slice(5, nameLen + 5);
                    //console.log("Service Request for: " + name);
                    if (name == 'pfwd@amt.intel.com' || name == 'auth@amt.intel.com') {
                        var outBuffer = Buffer.alloc(5 + nameLen);
                        outBuffer.writeUInt8(6, 0);
                        outBuffer.writeUInt32BE(nameLen, 1);
                        outBuffer.write(name.toString(), 5);
                        this.write(outBuffer);
                        //console.log('Answering APF_SERVICE_REQUEST');
                    } else {
                        //console.log('UNKNOWN APF_SERVICE_REQUEST');
                    }
                    break;
                case APF_GLOBAL_REQUEST:
                    var nameLen = chunk.readUInt32BE(1);
                    var name = chunk.slice(5, nameLen + 5).toString();
                    
                    switch (name) {
                        case 'tcpip-forward':
                            var len = chunk.readUInt32BE(nameLen + 6);
                            var port = chunk.readUInt32BE(nameLen + 10 + len);
                            //console.log("[" + chunk.length + "/" + len + "] APF_GLOBAL_REQUEST for: " + name + " on port " + port);
                            if (this[name] == undefined) {
                                this[name] = {};
                            }
                            this[name][port] = require('net').createServer();
                            this[name][port].HECI = this;
                            if (lme_port_offset == 0) {
                                this[name][port].listen({ port: port, host: '127.0.0.1' }); // Normal mode
                            } else {
                                this[name][port].listen({ port: (port + lme_port_offset) }); // Debug mode
                            }
                            this[name][port].on('connection', function (socket) {
                                //console.log('New [' + socket.remoteFamily + '] TCP Connection on: ' + socket.remoteAddress + ' :' + socket.localPort);
                                this.HECI.LMS.bindDuplexStream(socket, socket.remoteFamily, socket.localPort - lme_port_offset);
                            });
                            var outBuffer = Buffer.alloc(5);
                            outBuffer.writeUInt8(81, 0);
                            outBuffer.writeUInt32BE(port, 1);
                            this.write(outBuffer);
                            break;
                        case 'cancel-tcpip-forward':
                            break;
                        case 'udp-send-to@amt.intel.com':
                            break;
                        default:
                            //console.log("Unknown APF_GLOBAL_REQUEST for: " + name);
                            break;
                    }
                    break;
                case APF_CHANNEL_OPEN_CONFIRMATION:
                    var rChannel = chunk.readUInt32BE(1);
                    var sChannel = chunk.readUInt32BE(5);
                    var wSize = chunk.readUInt32BE(9);
                    //console.log('rChannel/' + rChannel + ', sChannel/' + sChannel + ', wSize/' + wSize);
                    if (this.sockets[rChannel] != undefined) {
                        this.sockets[rChannel].lme.amtId = sChannel;
                        this.sockets[rChannel].lme.rxWindow = wSize;
                        this.sockets[rChannel].lme.txWindow = wSize;
                        this.sockets[rChannel].lme.LME_CHANNEL_STATUS = 'LME_CS_CONNECTED';
                        //console.log('LME_CS_CONNECTED');
                        this.sockets[rChannel].bufferedStream = new stream_bufferedWrite();
                        this.sockets[rChannel].bufferedStream.socket = this.sockets[rChannel];
                        this.sockets[rChannel].bufferedStream.on('readable', function () {
                            if (this.socket.lme.txWindow > 0) {
                                var buffer = this.read(this.socket.lme.txWindow);
                                var packet = Buffer.alloc(9 + buffer.length);
                                packet.writeUInt8(APF_CHANNEL_DATA, 0);
                                packet.writeUInt32BE(this.socket.lme.amtId, 1);
                                packet.writeUInt32BE(buffer.length, 5);
                                buffer.copy(packet, 9);
                                this.socket.lme.txWindow -= buffer.length;
                                this.socket.HECI.write(packet);
                            }
                        });
                        this.sockets[rChannel].bufferedStream.on('drain', function () {
                            this.socket.resume();
                        });
                        this.sockets[rChannel].on('data', function (chunk) {
                            if (!this.bufferedStream.write(chunk)) { this.pause(); }
                        });
                        this.sockets[rChannel].on('end', function () {
                            var outBuffer = Buffer.alloc(5);
                            outBuffer.writeUInt8(APF_CHANNEL_CLOSE, 0);
                            outBuffer.writeUInt32BE(this.lme.amtId, 1);
                            this.HECI.write(outBuffer);
                        });
                        this.sockets[rChannel].resume();
                    }
                    
                    break;
                case APF_PROTOCOLVERSION:
                    var major = chunk.readUInt32BE(1);
                    var minor = chunk.readUInt32BE(5);
                    var reason = chunk.readUInt32BE(9);
                    var outBuffer = Buffer.alloc(93);
                    outBuffer.writeUInt8(192, 0);
                    outBuffer.writeUInt32BE(1, 1);
                    outBuffer.writeUInt32BE(0, 5);
                    outBuffer.writeUInt32BE(reason, 9);
                    //console.log('Answering PROTOCOL_VERSION');
                    this.write(outBuffer);
                    break;
                case APF_CHANNEL_WINDOW_ADJUST:
                    var rChannelId = chunk.readUInt32BE(1);
                    var bytesToAdd = chunk.readUInt32BE(5);
                    if (this.sockets[rChannelId] != undefined) {
                        this.sockets[rChannelId].lme.txWindow += bytesToAdd;
                        if (!this.sockets[rChannelId].bufferedStream.isEmpty() && this.sockets[rChannelId].bufferedStream.isWaiting()) {
                            this.sockets[rChannelId].bufferedStream.emit('readable');
                        }
                    } else {
                        //console.log('Unknown Recipient ID/' + rChannelId + ' for APF_CHANNEL_WINDOW_ADJUST');
                    }
                    break;
                case APF_CHANNEL_DATA:
                    var rChannelId = chunk.readUInt32BE(1);
                    var dataLen = chunk.readUInt32BE(5);
                    var data = chunk.slice(9, 9 + dataLen);
                    if (this.sockets[rChannelId] != undefined) {
                        this.sockets[rChannelId].pendingBytes.push(data.length);
                        this.sockets[rChannelId].write(data, function () {
                            var written = this.pendingBytes.shift();
                            var outBuffer = Buffer.alloc(9);
                            outBuffer.writeUInt8(APF_CHANNEL_WINDOW_ADJUST, 0);
                            outBuffer.writeUInt32BE(this.lme.amtId, 1);
                            outBuffer.writeUInt32BE(written, 5);
                            this.HECI.write(outBuffer);
                        });
                    } else {
                        //console.log('Unknown Recipient ID/' + rChannelId + ' for APF_CHANNEL_DATA');
                    }
                    break;
                case APF_CHANNEL_CLOSE:
                    var rChannelId = chunk.readUInt32BE(1);
                    if (this.sockets[rChannelId] != undefined) {
                        this.sockets[rChannelId].end();
                        var amtId = this.sockets[rChannelId].lme.amtId;
                        var buffer = Buffer.alloc(5);
                        delete this.sockets[rChannelId];
                        
                        buffer.writeUInt8(APF_CHANNEL_CLOSE, 0);
                        buffer.writeUInt32BE(amtId, 1);
                        this.write(buffer);
                    } else {
                        //console.log('Unknown Recipient ID/' + rChannelId + ' for APF_CHANNEL_CLOSE');
                    }
                    break;
            }
        });
    });
    
    this.bindDuplexStream = function (duplexStream, remoteFamily, localPort) {
        var socket = duplexStream;
        //console.log('New [' + remoteFamily + '] Virtual Connection/' + socket.localPort);
        socket.pendingBytes = [];
        socket.HECI = this._LME;
        socket.LMS = this;
        socket.lme = new lme_object();
        socket.lme.Socket = socket;
        var buffer = new MemoryStream();
        buffer.writeUInt8(0x5A);
        buffer.writeUInt32BE(15);
        buffer.write('forwarded-tcpip');
        buffer.writeUInt32BE(socket.lme.ourId);
        buffer.writeUInt32BE(this.INITIAL_RXWINDOW_SIZE);
        buffer.writeUInt32BE(0xFFFFFFFF);
        for (var i = 0; i < 2; ++i) {
            if (remoteFamily == 'IPv6') {
                buffer.writeUInt32BE(3);
                buffer.write('::1');
            } else {
                buffer.writeUInt32BE(9);
                buffer.write('127.0.0.1');
            }
            buffer.writeUInt32BE(localPort);
        }
        this._LME.write(buffer.buffer);
        if (this._LME.sockets == undefined) { this._LME.sockets = {}; }
        this._LME.sockets[socket.lme.ourId] = socket;
        socket.pause();
    };
    
    this._LME.connect(heci.GUIDS.LME, { noPipeline: 0 });
}

module.exports = lme_heci;