DataSources: Implemented ID3 tag skipping for HTTPSDataSources.

include/data_sources.h

@@ -41,6 +41,8 @@ private:
 	WiFiClient* _stream = NULL;
 	HTTPClientWrapper* _http = NULL;
 	uint32_t _position;
+	String _url;
+	void _init(String url, uint32_t offset);
 public:
 	HTTPSDataSource(String url, uint32_t offset=0);
 	~HTTPSDataSource();
@@ -51,4 +53,6 @@ public:
 	size_t size();
 	void close();
 	bool usable();
+	int peek(int offset=0);
+	void skip_id3_tag();
 };

include/http_client_wrapper.h

@@ -34,4 +34,5 @@ public:
 	uint32_t getSize();
 	String readUntil(String sep);
 	String readLine();
+	int peek(int offset=0);
 };

src/data_sources.cpp

@@ -39,6 +39,12 @@ void SDDataSource::skip_id3_tag() {
 
 ////////////// HTTPSDataSource //////////////
 HTTPSDataSource::HTTPSDataSource(String url, uint32_t offset) {
+	_url = url;
+	_init(url, offset);
+}
+
+void HTTPSDataSource::_init(String url, uint32_t offset) {
+	_url = url;
 	_http = new HTTPClientWrapper();
 	if (!_http->get(url, offset)) return;
 	_position = 0;
@@ -52,6 +58,31 @@ bool HTTPSDataSource::usable() { return _http; }
 size_t HTTPSDataSource::read(uint8_t* buf, size_t len) { size_t result = _http->read(buf, len); _position += result; return result; }
 int HTTPSDataSource::read() { int b = _http->read(); if (b>=0) _position++; return b; }
 size_t HTTPSDataSource::position() { return _position; }
-void HTTPSDataSource::seek(size_t position) { return; /* TODO */ }
+void HTTPSDataSource::seek(size_t position) { _http->close(); delete _http; _init(_url, position); }
 size_t HTTPSDataSource::size() { return _http->getSize(); }
 void HTTPSDataSource::close() { _http->close(); }
+int HTTPSDataSource::peek(int offset) { return _http->peek(offset); }
+
+void HTTPSDataSource::skip_id3_tag() {
+	uint32_t offset = 0;
+	if (_http->peek(0)=='I' && _http->peek(1)=='D' && _http->peek(2)=='3') {
+		DEBUG("ID3 tag found\n");
+		// Skip ID3 tag marker
+		_http->read(); _http->read(); _http->read();
+		// Skip ID3 tag version
+		_http->read(); _http->read();
+		byte tags = _http->read();
+		bool footer_present = tags & 0x10;
+		DEBUG("ID3 footer found: %d\n", footer_present);
+		for (byte i=0; i<4; i++) {
+			offset <<= 7;
+			offset |= (0x7F & _http->read());
+		}
+		offset += 10;
+		if (footer_present) offset += 10;
+		DEBUG("ID3 tag length is %d bytes.\n", offset);
+		seek(offset);
+	} else {
+		DEBUG("No ID3 tag found\n");
+	}
+}

src/http_client_wrapper.cpp

@@ -211,3 +211,12 @@ String HTTPClientWrapper::readUntil(String sep) {
 String HTTPClientWrapper::readLine() {
 	return readUntil("\n\r");
 }
+
+int HTTPClientWrapper::peek(int offset) {
+	if (_buffer_position >= _buffer_length) _fill_buffer();
+
+	if (_buffer_position + offset < 0 || _buffer_position + offset >= _buffer_length) {
+		return -1;
+	}
+	return _buffer[_buffer_position + offset];
+}