var events = require('events'),
	util = require('util'),
	libxml = require('libxmljs'); // npm install libxmljs

function DumpReader() {
	events.EventEmitter.call(this);
	this.makeParser();
}

util.inherits(DumpReader, events.EventEmitter);

/**
 * @param {Stream} stream input stream to read XML from
 */
DumpReader.prototype.makeParser = function() {

	var self = this;
	var complete = false;

	var stack = [{}],
		workspace = {},
		buffer = '';

	function flip(arr) {
		var obj = {};
		arr.forEach(function(val) {
			obj[val] = true;
		});
		return obj;
	}
	var textNodes = flip(['id', 'text', 'title', 'minor', 'comment', 'username', 'timestamp']),
		boolNodes = flip(['minor', 'redirect']),
		ignoreNodes = flip(['mediawiki', 'siteinfo', 'upload', 'thread']);

	var parser = new libxml.SaxPushParser();
	this.parser = parser;
	parser.on('startElementNS', function(elem, attrs, prefix, uri, namespaces) {
		//console.warn( 'elem: ' + elem );
		if (elem in ignoreNodes) {
			// ...
		} else if (elem == 'page') {
			//console.warn( 'starting page' );
			stack = [];
			workspace = {};
		} else if (elem == 'revision') {
			stack.push(workspace);
			workspace = {
				page: workspace
			};
		} else if (elem in textNodes || elem in boolNodes) {
			buffer = '';
		} else {
			stack.push(workspace);
			workspace = {};
		}
	});

	parser.on( 'endElementNS', function(elem, prefix, uri) {
		// ping something!
		if (elem == 'mediawiki') {
			self.complete = true;
			//stream.pause();
			self.emit('end', {});
		} else if (elem == 'page') {
			self.emit('page', workspace);
			workspace = stack.pop();
		} else if (elem == 'revision') {
			self.emit('revision', workspace);
			workspace = stack.pop();
		} else if (elem in textNodes) {
			workspace[elem] = buffer;
		} else if (elem in boolNodes) {
			workspace[elem] = true;
		} else {
			var current = workspace;
			workspace = stack.pop();
			workspace[elem] = current;
		}
	});

	parser.on( 'characters', function(chars) {
		buffer += chars;
	});
	parser.on( 'cdata', function(cdata) {
		buffer += cdata;
	});
	parser.on( 'endDocument', function() {
		// This doesn't seem to run...?
		self.complete = true;
		//stream.pause();
		self.emit('end', {});
	});
	parser.on( 'error', function(err) {
		self.emit('error', err);
		// Should we.... stop reading now or what?
	});

};

DumpReader.prototype.push = function( chunk ) {
	//console.log( 'dr read' + chunk );
	this.parser.push( chunk );
};


module.exports.DumpReader = DumpReader;

if (module === require.main) {
	var reader = new DumpReader();
	reader.on('end', function() {
		console.log('done!');
		process.exit();
	});
	reader.on('error', function(err) {
		console.log('error!', err);
		process.exit(1);
	});
	reader.on('page', function(page) {
		console.log('page', page);
	});
	reader.on('revision', function(revision) {
		revision.text = revision.text.substr(0, 40);
		console.log('revision', revision);
	});
	console.log('Reading!');
	process.stdin.setEncoding('utf8');

	process.stdin.on('data', reader.push.bind(reader) );
	process.stdin.resume();
}