#include <u.h>
#include <libc.h>
#include <bio.h>

enum {
	HeaderSize = 10,
	MagicSize = 3,
	RecHdrSize = 10,	/* 6 for v2.2 */
	IdSize = 4,	/* 3 for v2.2 */
	LangSize = 3,
	MaxFields = 4,
	MaxStrings = 4,	/* arbitrary */
	MinPadding = 128,,	/* arbitrary */
	PadChunkSize = 1024,,	/* arbitrary */
};

typedef struct Header {
	char	magic[MagicSize+1];
	u8int	version;
	u8int	revision;
	u8int	flags;
	u32int	length;
} Header;

typedef struct Rechdr {
	char	id[IdSize+1];
	u32int	length;
	u16int	flags;
} Rechdr;

typedef struct Comment {
	char	language[LangSize+1];
	char	*description;	/* malloc'd */
	char	*comment;	/* malloc'd with description */
} Comment;

typedef struct Text {
	char	**strings;	/* nil terminated array of malloc'd utf strings */
} Text;

typedef struct Record {
	Rechdr;
	int	type;
	union {
		Comment	c;
		Text	t;
	};
} Record;

typedef struct Rectype {
	char *id;
	int	type;
} Rectype;

typedef void (*Recpacker)(uchar **, Record *);

typedef struct Recfields {
	int	type;
	Recpacker	pack;
	int	fields[MaxFields+1];
} Recfields;

typedef struct Enc {
	char	*str;
	int	len;
	char	sep[2];
} Enc;

enum {
	Hunsync	= 1<<7,
	Hext	= 1<<6,
	Hexp	= 1<<5,
	Hfoot	= 1<<4,
};

enum {
	Rcomment,
	Rtext,
	Runimplemented,
};

enum {
	Fend,

	Fenc,
	Flang,
	Fstring,	/* a single string */
	Fstrings,	/* a group of at least one separated strings */
};

enum {
	E8859,
	Eutf16le,
	Eutf16be,
	Eutf,

	Eend,
};

Enc enctab[];

/* dat.c */
int rectype(char *);
Recpacker recpacker(int);
Recfields *recfields(int);
int encnum(char *);

/* pack.c */
void gstr(uchar **, char *s, int);
void pstr(uchar **, char *s, int);
u8int g8(uchar **);
void p8(uchar **, u8int);
u16int g16(uchar **);
void p16(uchar **, u16int);
u32int g32(uchar **);
u32int gss32(uchar **);
void pss32(uchar **, u32int);
void gheader(uchar **, Header *);
void pheader(uchar **, Header *);
void grechdr(uchar **, Rechdr *, Header *);
void prechdr(uchar **, Rechdr *);
void precord(uchar **, Record *);
int gcomment(uchar **, Comment *, int);
void pcomment(uchar **, Record *);
int gtext(uchar **, Text *, int);
void ptext(uchar **, Record *r);

/* util.c */
void *emalloc(ulong);
void readrec(Biobuf *, void *, long, long, char *);

/* http://web.archive.org/web/20130114052304/http://id3.org/id3v2.4.0-structure
 * http://web.archive.org/web/20130114052304/http://id3.org/id3v2.4.0-frames
 * http://web.archive.org/web/20120831234820/http://www.id3.org/id3v2-00
 * http://gabriel.mp3-tech.org/mp3infotag.html
 */