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servicelist.js
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servicelist.js
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/** servicelist.js
* Object that handles teletext services.
* This maintains a list of services.
*
* The methods that it should handle are:
* Add service
* Delete service
* Find service
* doLoad should find the relevant service, then let service find the page, then the page will load the
*/
var fs = require('fs');
var readline = require('readline');
require('./service.js'); // teletext service
// @todo: should server-side code be importing frontend files?
require('./public/page.js'); // Page to put in a service
// import logger
const LOG = require('./log.js');
ServiceList = function (callback) { // This callback is used to send a page
var data = {
S: 'BBCNEWS/BBC',
page: 100, // Page mpp
s: 0, // subpage 0
x: 0, // This signals that we should load the initial page (usually 100)
y: 0,
rowText: '',
};
var targetPage = new TextPage(data);
this.initialPage = 100;
this.services = [];
//this.callback=callback;
/** Finds the service with the required name.
* @return Index of service, or false;
*/
const findService = function (services, name) {
LOG.fn(
['servicelist', 'findService'],
`seeking ${name}`,
LOG.LOG_LEVEL_VERBOSE,
);
if (services.length === 0) {
// No services
return false;
}
for (var i = 0; i < services.length; i++) {
if (services[i].matchName(name))
return i;
}
return false; // Not found
};
/**
* doLoad loads a page.
* It loads the page into a service cache and then emits it to the client.
* On subsequent loads, the cache is sent.
* The cache also accepts updates from the client.
* When updated, the updates are emitted to all the clients that are looking at this page.
* The cache is written back to the disk periodically.
* A long interval is used to expire a cache entry. If it is not being used then remove it.
* A short interval is used to save the cache back to disk. This keeps the disk version up to date without saving after every single keystroke.
*/
this.doLoad = function (pageData) {
targetPage.blank();
var data = pageData; // copy needed here???
// For some reason, services does not get initialised in the contructor.
if (typeof this.services === 'undefined') {
this.services = [];
}
LOG.fn(
['servicelist', 'doLoad'],
`doing a load, pageData=${pageData}, data=${data}`,
LOG.LOG_LEVEL_VERBOSE,
);
// Find the filename that we want to load
if (data.x === 2000) {
data.p = 100;//initialPage;
data.x = 0;
}
var filename = data.S + data.p + '.ttix'; // This is the actual filename that we want to load
LOG.fn(
['servicelist', 'doLoad'],
`filename=${filename}, services.length=${this.services.length}`,
LOG.LOG_LEVEL_VERBOSE,
);
// Which service object do we want to send it to?
// Check if the page is already in cache
var found = findService(this.services, data.S);
if (found === false) {
LOG.fn(
['servicelist', 'doLoad'],
`Adding service, data.S=${data.S}`,
LOG.LOG_LEVEL_VERBOSE,
);
this.services.push(new Service(data.S)); // create the service
found = this.services.length - 1; // The index of the service we just created
}
// Now we have a service name. Does it contain our page?
var svc = this.services[found];
var page = svc.findPage(data.p);
LOG.fn(
['servicelist', 'doLoad'],
`Setting page to ${data.p}`,
LOG.LOG_LEVEL_VERBOSE,
);
targetPage.pageNumber = data.p;
if (page === false) {
LOG.fn(
['servicelist', 'doLoad'],
`Page not found ${data.p}`,
LOG.LOG_LEVEL_VERBOSE,
);
// What happens here? The page is loaded from disk into cache and added to the page list
var fail = false;
var instream;
instream = fs.createReadStream(filename);
instream.on('error', function () {
var data2 = {
x: -1 // Signal a 404 error
};
this.doLoad(data2);
});
// Make a new page object
targetPage = new TextPage(data);
LOG.fn(
['servicelist', 'doLoad'],
`Made a new page`,
LOG.LOG_LEVEL_VERBOSE,
);
rl = readline.createInterface({
input: instream,
terminal: false,
});
/** This procedure is called for each line itself until the whole page is read
* We take this opportunity to populate a page object.
*/
rl.on('line', function (line) {
if (line.indexOf('DE,') == 0) { // Detect a description row
var desc = line.substring(3);
//this.io.sockets.emit('description',desc); // Probably a huge mistake having this here !!!!!!! Move io back to top level/
LOG.fn(
['servicelist', 'doLoad', 'line'],
`Description=${desc}`,
LOG.LOG_LEVEL_VERBOSE,
);
targetPage.setDescription(desc);
} else if (line.indexOf('FL,') === 0) { // Detect a Fastext link
var ch;
var ix = 3;
data.fastext = [];
for (var link = 0; link < 4; link++) {
var flink = '';
for (ch = line.charAt(ix++); ch != ',';) {
flink = flink + ch;
ch = line.charAt(ix++);
}
data.fastext[link] = flink;
LOG.fn(
['servicelist', 'doLoad', 'line'],
`Link ${link}=${flink}`,
LOG.LOG_LEVEL_VERBOSE,
);
}
//this.io.sockets.emit('fastext',data);
LOG.fn(
['servicelist', 'doLoad', 'line'],
`fastext ${data}`,
LOG.LOG_LEVEL_VERBOSE,
);
return;
} else if (line.indexOf('OL,') === 0) { // Detect a teletext row
var p = 0;
var ix = 3;
var row = 0;
var ch;
ch = line.charAt(ix);
if (ch != ',') {
row = ch;
}
ix++;
ch = line.charAt(ix);
if (ch != ',') {
row = row + ch; // haha. Strange maths
ix++;
}
row = parseInt(row);
ix++; // Should be pointing to the first character now
} else {
// Not a row. Not interested
return;
}
data.y = row;
// @todo - Handle strings shorter than 40 characters
// Here is a line at a time
var result = '';
for (var i = 0; i < 40; i++) {
var ch = line.charAt(ix++);
if (ch === '\u001b') { // Prestel escape
ch = line.charAt(ix++).charCodeAt(0) - 0x40;// - 0x40;
ch = String.fromCharCode(ch);
}
data.k = ch;
data.x = i;
// io.sockets.emit('keystroke', data);
result += ch;
}
data.y = row;
data.rowText = result;
// this.io.sockets.emit('row',data);
targetPage.setRow(data.p, data.y, data.rowText);
targetPage.pageNumber = data.p; // having trouble setting this and making it stick
}.bind(this));
// Handler for the close event when this file is finished.
rl.on('close', function () {
callback(data, targetPage);
}.bind(this).bind(targetPage));
} else {
LOG.fn(
['servicelist', 'doLoad'],
`Setting page to ${data.p}`,
LOG.LOG_LEVEL_VERBOSE,
);
targetPage.pageNumber = data.p;
}
};
};