1 files changed, 53 insertions, 0 deletions
diff --git a/tag.cpp b/tag.cpp
new file mode 100644
index 0000000..833735a
--- /dev/null
+++ b/tag.cpp
@@ -0,0 +1,53 @@
+#include "tag.h"
+
+#include <id3tag.h>
+
+#include <cstdlib>
+#include <stdexcept>
+
+void ID3Tag::tag_add_string(struct id3_tag *id3tag, const char *type, const char *id) {
+	struct id3_frame *frame = id3_tag_findframe(id3tag, id, 0);
+
+	if(frame == NULL) {
+		return;
+	}
+
+	if(frame->nfields != 2) {
+		throw std::runtime_error("unexpected nfields value");
+	}
+
+	const union id3_field *field = id3_frame_field(frame, 1);
+	unsigned int nstrings = id3_field_getnstrings(field);
+
+	for(unsigned int i = 0; i < nstrings; i++) {
+		const id3_ucs4_t *ucs4 = id3_field_getstrings(field, i);
+
+		if(ucs4 == NULL) {
+			throw std::runtime_error("ucs4 is NULL");
+		}
+
+		id3_utf8_t *utf8 = id3_ucs4_utf8duplicate(ucs4);
+		fields[type] = (char*)utf8;
+		free(utf8);
+	}
+}
+
+ID3Tag::ID3Tag(const std::string filename) {
+	struct id3_file *file = id3_file_open(filename.c_str(), ID3_FILE_MODE_READONLY);
+
+	if(file == NULL) {
+		throw std::runtime_error("failed to open file for reading");
+	}
+
+	struct id3_tag *id3tag = id3_file_tag(file);
+
+	if(id3tag == NULL) {
+		throw std::runtime_error("tag is NULL");
+	}
+
+	tag_add_string(id3tag, "artist", ID3_FRAME_ARTIST);
+	tag_add_string(id3tag, "title", ID3_FRAME_TITLE);
+	tag_add_string(id3tag, "album", ID3_FRAME_ALBUM);
+
+	id3_file_close(file);
+}