    /*
    MIT License

    Copyright (c) 2019-2020 Andre Seidelt <superilu@yahoo.com>

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
    */

    /** @module ipx */

    /**
     * IPX definitions.
     * @property {*} DEFAULT_SOCKET default socket number for DOjS.
     * @property {*} BROADCAST broadcast address
     */
    IPX = {
    	MAX: 80,
    	DEFAULT_SOCKET: 0x2342,
    	DEBUG_SOCKET: 0x1234,
    	BROADCAST: [0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF],
    	HELLO: "_$HELLO="
    };

    /**
     * Convert a node address to a string.
     *
     * @param {IpxAddress} addr a node address.
     */
    function IpxAddressToString(addr) {
    	if (addr.length != 6) {
    		throw "Node address length does not match";
    	}

    	return addr[0].toString(16) + ":" +
    		addr[1].toString(16) + ":" +
    		addr[2].toString(16) + ":" +
    		addr[3].toString(16) + ":" +
    		addr[4].toString(16) + ":" +
    		addr[5].toString(16);
    }

    /**
     * Convert an address in hex-string notation back to an JS array.
     *
     * @param {*} addr a string of 6 hex numbers separated by ':'.
     * @returns {IpxAddress} An array of six numbers.
     */
    function IpxStringToAddress(addr) {
    	var parts = addr.split(":");
    	if (parts.length != 6) {
    		throw "Node address length does not match";
    	}

    	return [
    		parseInt(parts[0], 16),
    		parseInt(parts[1], 16),
    		parseInt(parts[2], 16),
    		parseInt(parts[3], 16),
    		parseInt(parts[4], 16),
    		parseInt(parts[5], 16)
    	];
    }

    /**
     * discover nodes on the network.
     *
     * @param {integer} num total number of nodes to search for (including the local node).
     * @param {IpxAddress[]} nodes an array to store the discovered nodes in.
     *
     * @returns {boolean} true if the wanted number of nodes was discovered, else false. The nodes array will contain the addresses of all found nodes.
     */
    function IpxFindNodes(num, nodes) {
    	var searchAddress = function (nodes, addr) {
    		var addrStr = IpxAddressToString(addr);
    		for (var i = 0; i < nodes.length; ++i) {
    			var str = IpxAddressToString(nodes[i]);
    			if (str === addrStr) {
    				return true;
    			}
    		}
    		return false;
    	};

    	if (nodes.length < num - 1) {
    		IpxSend(IPX.HELLO + MsecTime(), IPX.BROADCAST);

    		if (IpxCheckPacket()) {
    			var pck = IpxGetPacket();
    			if (pck.data.lastIndexOf(IPX.HELLO, 0) === 0) {
    				if (searchAddress(nodes, pck.source)) {
    					_Debug("Node " + JSON.stringify(pck.source) + " already known.");
    				} else {
    					nodes.push(pck.source);
    					_Debug("Node found " + JSON.stringify(pck.source));
    				}
    			}
    		}
    	} else {
    		return true;
    	}
    	return false;
    }

    /**
     * Send data to all nodes in array.
     *
     * @param {string} data the data to send
     * @param {IpxAddress[]} nodes the node addresses to send to.
     */
    function IpxAllNodes(data, nodes) {
    	for (var i = 0; i < nodes.length; i++) {
    		IpxSend(data, nodes[i]);
    	}
    }

    /**
     * @property {string} _ipxLogData remaining data to send to log viewer.
     */
    _ipxLogData = "";

    /**
     * @property {boolean} _ipxLogInit indicates if the IPX socket was already opened.
     */
    _ipxLogInit = false;

    /**
     * @property {IpxAddress[]} _ipxDebugNodes node list with the logviewer entry.
     */
    _ipxDebugNodes = [];

    /**
     * Send logmessages to logviewer using IPX networking.
     *
     * @param {string} str logmessage to send.
     */
    function IpxDebug(str) {
    	_ipxLogData += str;

    	if (!_ipxLogInit) {
    		// init
    		IpxSocketOpen(IPX.DEBUG_SOCKET);
    		_ipxLogInit = true;
    	}
    	if (_ipxLogInit && _ipxDebugNodes.length < 1) {
    		var success = IpxFindNodes(2, _ipxDebugNodes);
    	} else {
    		while (_ipxLogData.length > 0) {
    			var part = _ipxLogData.substring(0, IPX.MAX - 1);
    			_ipxLogData = _ipxLogData.slice(IPX.MAX);

    			IpxSend(part, _ipxDebugNodes[0]);
    		}
    	}
    }