From ffdeca66eaf215573027faae55ee1e3538736a63 Mon Sep 17 00:00:00 2001
From: Aliaksei Sapach <dreamsonic@tut.by>
Date: Thu, 23 Apr 2015 22:37:23 +0300
Subject: [PATCH] check if download is complete an notify tracker

---
 index.js              | 19 +++++++++++++++++++
 lib/peer-discovery.js | 11 ++++++++++-
 package.json          |  1 +
 test/storage.js       |  7 +++++++
 test/tracker.js       |  7 +++++--
 5 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/index.js b/index.js
index 7a6f3e3..650519d 100644
--- a/index.js
+++ b/index.js
@@ -11,6 +11,7 @@ var path = require('path');
 var fs = require('fs');
 var os = require('os');
 var eos = require('end-of-stream');
+var debounce = require('lodash.debounce');
 
 var peerDiscovery = require('./lib/peer-discovery');
 var blocklist = require('ip-set');
@@ -32,6 +33,8 @@ var BAD_PIECE_STRIKES_DURATION = 120000; // 2 minutes
 var RECHOKE_INTERVAL = 10000;
 var RECHOKE_OPTIMISTIC_DURATION = 2;
 
+var COMPLETE_DEBOUNCE_DELAY = 250;
+
 var TMP = fs.existsSync('/tmp') ? '/tmp' : os.tmpDir();
 
 var noop = function() {};
@@ -719,6 +722,22 @@ var torrentStream = function(link, opts, cb) {
 		discovery.updatePort(engine.port);
 	};
 
+	// check if download is complete
+	engine.on('verify', debounce(function checkComplete () {
+		var bits = engine.torrent.pieces.length;
+		var bytes = bits / 8 | 0;
+		var rem = bits % 8;
+		var buffer = engine.bitfield.buffer;
+		for (var i = 0; i < bytes; i++) {
+			if (buffer[i] !== 255) return; // every byte must be full of ones
+		}
+		var mask = 256 - Math.pow(2, 8 - rem); // the last byte may be not full
+		if (rem === 0 || buffer[bytes] === mask) {
+			discovery.complete();
+			engine.emit('complete');
+		}
+	}, COMPLETE_DEBOUNCE_DELAY));
+
 	return engine;
 };
 
diff --git a/lib/peer-discovery.js b/lib/peer-discovery.js
index 00caad9..a5ad611 100644
--- a/lib/peer-discovery.js
+++ b/lib/peer-discovery.js
@@ -51,7 +51,11 @@ module.exports = function(torrent, opts) {
 		tr.on('peer', onpeer);
 		tr.on('error', function() { /* noop */ });
 
-		tr.start();
+		if (discovery.amSeeder) {
+			tr.complete();
+		} else {
+			tr.start();
+		}
 		return tr;
 	};
 
@@ -78,6 +82,11 @@ module.exports = function(torrent, opts) {
 		if (torrent) discovery.tracker = createTracker(torrent);
 	};
 
+	discovery.complete = function () {
+		discovery.amSeeder = true;
+		if (discovery.tracker) discovery.tracker.complete();
+	};
+
 	discovery.stop = function() {
 		if (discovery.tracker) discovery.tracker.stop();
 		if (discovery.dht) discovery.dht.destroy();
diff --git a/package.json b/package.json
index 129a0dd..2125cc6 100644
--- a/package.json
+++ b/package.json
@@ -16,6 +16,7 @@
     "hat": "0.0.3",
     "ip": "^0.3.0",
     "ip-set": "^1.0.0",
+    "lodash.debounce": "^3.0.3",
     "magnet-uri": "^2.0.1",
     "mkdirp": "^0.3.5",
     "parse-torrent": "^4.0.0",
diff --git a/test/storage.js b/test/storage.js
index 75ee2dd..d2b6d2f 100644
--- a/test/storage.js
+++ b/test/storage.js
@@ -19,6 +19,13 @@ test('fixture can verify the torrent', function(t) {
 	});
 });
 
+test('fixture should report `complete`', function(t) {
+	t.plan(1);
+	fixture.once('complete', function() {
+		t.ok(true, 'should be complete');
+	});
+});
+
 test('fixture can read the file contents', function(t) {
 	t.equal(fixture.files.length, 1, 'should have one file');
 	var file = fixture.files[0];
diff --git a/test/tracker.js b/test/tracker.js
index d3d79fa..5072958 100644
--- a/test/tracker.js
+++ b/test/tracker.js
@@ -16,7 +16,7 @@ server.on('error', function() {
 });
 
 test('seed should connect to the tracker', function(t) {
-	t.plan(3);
+	t.plan(4);
 
 	server.once('listening', function() {
 		t.ok(true, 'tracker should be listening');
@@ -28,7 +28,10 @@ test('seed should connect to the tracker', function(t) {
 		fixture.once('ready', t.ok.bind(t, true, 'should be ready'));
 	});
 	server.once('start', function(addr) {
-		t.equal(addr, '127.0.0.1:6882');
+		t.equal(addr, '127.0.0.1:6882', 'should report `start`');
+	});
+	server.once('complete', function(addr) {
+		t.equal(addr, '127.0.0.1:6882', 'should report `complete`');
 	});
 	server.listen(12345);
 });