// File delimiters for appending metadata to a file. Should all

// include the string @META and META@, and should attempt to be a

// no-op in the language.

var delimiter = [

{

start: "###@META\n",

end: "\nMETA@###",

escape: function(s) { return s.replace(/###/g, '##\\u0023'); }

},

{

type: /\bjava(?:script)?\b/i,

start: "/**@META\n",

end: "\nMETA@**/",

escape: function(s) { return s.replace(/\*\//g, '*\\/'); }

},

{

type: /\bpython\b/i,

start: "'''@META\n",

end: "\nMETA@'''",

escape: function(s) { return s.replace(/'''/g, "''\\'"); }

}

];

function parseMetaString(buf) {

var j, d, limit, start, end, meta, enc, str = buf.toString('binary');

for (j = 0; j < delimiter.length; ++j) {

d = delimiter[j];

end = str.lastIndexOf(d.end);

if (end < 0) continue;

limit = str.lastIndexOf(d.start);

if (limit < 0) continue;

start = limit + d.start.length;

if (start >= end) continue;

if (str.substring(end + d.end.length).trim()) continue;

try {

// Redecode. Meta part is always encoded as utf8.

meta = JSON.parse(buf.toString('utf8', start, end));

// Data part is usually encoded as binary but can be overridden.

if (meta && meta.encoding && Buffer.isEncoding(meta.encoding)) {

enc = meta.encoding;

} else {

enc = 'binary';

}

return {

data: buf.toString(enc, 0, limit),

meta: meta

}

} catch (e) { }

}

return { data: str, meta: null };

}

function printMetaString(data, meta) {

if (meta == null &&

(data.lastIndexOf('META@') == -1 || data.lastIndexOf('@META') == -1) &&

/^[\0-\xff]*$/.test(data)) {

return new Buffer(data, 'binary');

}

var d = delimiter[0];

if (meta && meta.type) {

for (var j = 1; j < delimiter.length; ++j) {

if (delimiter[j].type.test(meta.type)) { d = delimiter[j]; break; }

}

}

var enc = 'binary';

if (meta && meta.encoding && Buffer.isEncoding(meta.encoding)) {

enc = meta.encoding;

} else if (!/^[\0-\xff]*$/.test(data)) {

// High characters default to utf8; otherwise binary/latin1.

if (!meta) { meta = {}; };

enc = meta.encoding = 'utf8';

}

return Buffer.concat([

new Buffer(data, enc),

new Buffer(d.start + d.escape(JSON.stringify(meta)) + d.end, 'utf8')

]);

}

exports.parseMetaString = parseMetaString;

exports.printMetaString = printMetaString;