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TiddlyWiki5/js/FileRetriever.js
2011-11-30 11:41:26 +00:00

76 lines
2.5 KiB
JavaScript

/*
FileRetriever can asynchronously retrieve files from HTTP URLs or the local file system. It incorporates
throttling so that we don't get error EMFILE "Too many open files".
*/
var fs = require("fs"),
path = require("path"),
url = require("url"),
util = require("util"),
http = require("http"),
https = require("https"),
utils = require("./Utils.js");
var FileRetriever = exports;
var fileRequestQueue = utils.queue(function(task,callback) {
fs.readFile(task.filepath,"utf8", function(err,data) {
callback(err,data);
console.error("Retrieved " + task.filepath);
});
},10);
var httpRequestQueue = utils.queue(function(task,callback) {
var opts = url.parse(task.url);
var httpLib = opts.protocol === "http:" ? http : https;
var request = httpLib.get(opts,function(res) {
if(res.statusCode != 200) {
var err = new Error("HTTP error");
err.code = res.statusCode.toString();
callback(err);
} else {
var data = [];
res.on("data", function(chunk) {
data.push(chunk)
});
res.on("end", function() {
callback(null,data.join(""));
console.error("Retrieved " + task.url);
});
}
});
request.addListener("error", function(err) {
callback(err);
});
request.end();
},4);
// Retrieve a file given a filepath specifier and a context path. If the filepath isn't an absolute
// filepath or an absolute URL, then it is interpreted relative to the context path, which can also be
// a filepath or a URL. On completion, the callback function is called as callback(err,data). It
// returns an object:
// path: full path used to reach the file
// basename: the basename of the file (used as the default tiddler title)
// extname: the extension of the file
FileRetriever.retrieveFile = function(filepath,contextPath,callback) {
var httpRegExp = /^(https?:\/\/)/gi,
result = {},
filepathIsHttp = httpRegExp.test(filepath),
contextPathIsHttp = httpRegExp.test(contextPath);
if(contextPathIsHttp || filepathIsHttp) {
// If we've got a full HTTP URI then we're good to go
result.path = url.resolve(contextPath,filepath);
var parsedPath = url.parse(result.path);
result.extname = path.extname(parsedPath.pathname);
result.basename = path.basename(parsedPath.extname);
httpRequestQueue.push({url: result.path},callback);
} else {
// It's a file requested in a file context
result.path = path.resolve(path.dirname(contextPath),filepath);
result.extname = path.extname(result.path);
result.basename = path.basename(result.path,result.extname);
fileRequestQueue.push({filepath: result.path},callback);
}
return result;
}