1 files changed, 144 insertions, 0 deletions
diff --git a/src/server/YoutubeFallback.hx b/src/server/YoutubeFallback.hx
new file mode 100644
index 0000000..34ea8a9
--- /dev/null
+++ b/src/server/YoutubeFallback.hx
@@ -0,0 +1,144 @@
+package server;
+
+import haxe.Json;
+import js.lib.Function;
+import js.lib.Object;
+import js.lib.Promise;
+import js.node.Https.Https;
+import js.node.Https.HttpsRequestOptions;
+import js.node.url.URLSearchParams;
+import utils.YoutubeUtils;
+
+using Lambda;
+
+class YoutubeFallback {
+	static function httpsGet(
+		url:String,
+		?options:HttpsRequestOptions,
+		?callback:(status:Int, data:String) -> Void
+	):Void {
+		final request = Https.get(url, options, res -> {
+			var data = "";
+			res.on("data", chunk -> data += chunk.toString());
+			res.on("end", () -> callback(res.statusCode, data));
+		});
+		request.on("error", err -> {
+			trace(url);
+			trace("request error: ", err);
+		});
+	}
+
+	public static function resolvePlayerResponse(watchHtml:String):String {
+		if (watchHtml == null) return "";
+		final resReg = ~/ytInitialPlayerResponse = (.*)}}};/;
+		var matches = resReg.match(watchHtml);
+		return matches ? resReg.matched(1) + "}}}" : "";
+	}
+
+	public static function resoleM3U8Link(watchHtml:String):Null<String> {
+		if (watchHtml == null) return null;
+		final hlsReg = ~/hlsManifestUrl":"(.*\/file\/index\.m3u8)/;
+		return hlsReg.match(watchHtml) ? hlsReg.matched(1) : null;
+	}
+
+	public static function buildDecoder(watchHtml:String, callback:(decoder:(cipher:String) -> String) -> Void):Void {
+		if (watchHtml == null) return callback(null);
+
+		final jsFileUrlReg = ~/\/s\/player\/[A-Za-z0-9]+\/[A-Za-z0-9_.]+\/[A-Za-z0-9_]+\/base\.js/;
+		if (!jsFileUrlReg.match(watchHtml)) return callback(null);
+
+		final url = "https://www.youtube.com" + jsFileUrlReg.matched(0);
+		httpsGet(url, {}, (status, jsFileContent) -> {
+			final funcReg = ~/function.*\.split\(""\).*\.join\(""\)}/;
+			if (!funcReg.match(jsFileContent)) return callback(null);
+
+			final decodeFunction = funcReg.matched(0);
+			final varNameReg = ~/\.split\(""\);([a-zA-Z0-9]+)\./i;
+			if (!varNameReg.match(decodeFunction)) return callback(null);
+
+			final varStartIndex = jsFileContent.indexOf("var " + varNameReg.matched(1) + "={");
+			if (varStartIndex < 0) return callback(null);
+
+			final varEndIndex = jsFileContent.indexOf("}};", varStartIndex);
+			if (varEndIndex < 0) return callback(null);
+
+			final varDeclares = jsFileContent.substring(varStartIndex, varEndIndex + 3);
+			if (varDeclares.length == 0) return callback(null);
+
+			callback(signatureCipher -> {
+				final params = new URLSearchParams(signatureCipher);
+				final obj = Object.fromEntries(params);
+				final signature = obj.s;
+				final signatureParam = obj.sp ?? "signature";
+				final url = obj.url;
+				final decodedSignature = new Function('
+					"use strict";
+					$varDeclares
+					return ($decodeFunction)("$signature");
+				').call(null);
+				return '$url&$signatureParam=${untyped encodeURIComponent(decodedSignature)}';
+			});
+		});
+	}
+
+	public static function getInfo(url:String, callback:(info:Null<YouTubeVideoInfo>) -> Void):Void {
+		final videoId = YoutubeUtils.extractVideoId(url);
+		if (videoId.length == 0) {
+			trace("youtube videoId is not found");
+			return callback(null);
+		}
+
+		final url = 'https://www.youtube.com/watch?v=$videoId';
+		httpsGet(url, {}, (status, data) -> {
+			if (status != 200 || data.length == 0) {
+				trace("Cannot get youtube video response");
+				return callback(null);
+			}
+
+			final ytInitialPlayerResponse = resolvePlayerResponse(data);
+			final parsedResponse = Json.parse(ytInitialPlayerResponse);
+			final streamingData:YouTubeVideoInfo = parsedResponse.streamingData ?? cast {};
+			streamingData.formats ??= [];
+			streamingData.adaptiveFormats ??= [];
+			var formats:Array<YoutubeVideoFormat> = streamingData.formats.concat(streamingData.adaptiveFormats);
+
+			final promises:Array<Promise<Any>> = [];
+
+			final isEncryptedVideo = formats.exists(it -> it.signatureCipher != null);
+			if (isEncryptedVideo) {
+				final promise = new Promise((resolve, reject) -> {
+					buildDecoder(data, decoder -> {
+						if (decoder != null) {
+							formats = formats.map(item -> {
+								if (item.url != null || item.signatureCipher == null) return item;
+
+								item.url = decoder(item.signatureCipher);
+								item.signatureCipher = null;
+								return item;
+							});
+						}
+						resolve(null);
+					});
+				});
+				promises.push(promise);
+			}
+
+			Promise.all(promises).then(_ -> {
+				final result:YouTubeVideoInfo = {
+					videoDetails: parsedResponse.videoDetails ?? cast {},
+					formats: formats.filter(format -> format.url != null)
+				};
+				if (result.videoDetails.isLiveContent) {
+					final m3u8Link = resoleM3U8Link(data);
+					try {
+						result.liveData = {
+							manifestUrl: m3u8Link,
+							// data: m3u8Parser.getResult()
+						};
+					}
+				}
+				callback(result);
+			});
+		});
+	}
+}