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// http://id3.org/id3v2.3.0
use std::convert::TryFrom;
use std::io::{self, Read};
use std::iter;
use std::num::TryFromIntError;
use crate::encoding::{from_latin_1, from_ucs_2_bom};
use crate::error::IntoIOError;
use crate::util::read_big_endian;
fn parse_id3v2_header(bytes: &[u8]) -> Option<(u16, u8, usize)> {
if bytes.len() == 10 &&
bytes[0] == b'I' &&
bytes[1] == b'D' &&
bytes[2] == b'3' &&
bytes[3] != 0xff &&
bytes[4] != 0xff &&
bytes[6..10].iter().all(|b| (b & 0x80) == 0) {
Some((
read_big_endian(&bytes[3..5], 8) as u16,
bytes[5],
read_big_endian(&bytes[6..10], 7)
))
} else {
None
}
}
#[derive(Debug)]
pub struct ID3v2 {
header_size: usize,
pub frames: Vec<RawFrame>,
}
#[derive(Debug)]
pub struct RawFrame {
id: String,
flags: u16,
body: Vec<u8>,
}
#[derive(Debug)]
pub enum Frame {
TIT2(String),
TYER(String),
TPE1(String),
TALB(String),
TRCK(String),
}
struct ArrayIter2<T> {
arr: [T; 2],
cursor: u8,
}
impl<T> ArrayIter2<T> {
fn new(arr: [T; 2]) -> Self {
Self { arr, cursor: 0 }
}
}
impl<T: Clone> Iterator for ArrayIter2<T> {
type Item = T;
fn next(&mut self) -> Option<T> {
if (self.cursor as usize) < self.arr.len() {
let i = self.cursor;
self.cursor += 1;
Some(self.arr[i as usize].clone())
} else {
None
}
}
}
impl RawFrame {
fn parse(data: &[u8]) -> Result<Option<(Self, usize)>, String> {
if data.len() < 10 {
return Err(String::from("Frame buffer too short"));
}
if data[0..4].iter().all(|&b| b == 0) {
return Ok(None)
}
if !data[0..4].iter().all(|&b| (b'A' <= b && b <= b'Z') || (b'0' <= b && b <= b'9')) {
return Err(format!("Invalid frame type {:?}", &data[0..4]));
}
let id = String::from_utf8(data[0..4].to_vec()).unwrap();
let size = read_big_endian(&data[4..8], 8);
let flags = read_big_endian(&data[8..10], 8) as u16;
let body = data[10..10+size].to_vec();
Ok(Some((RawFrame { id, flags, body }, 10 + size)))
}
fn interpret_encoded_string(&self) -> io::Result<String> {
match self.body.get(0).ok_or("String field too small".ioerr())? {
0 => { // Latin-1
let mut i = self.body.len();
while i > 0 && self.body[i-1] == 0 { i -= 1; }
from_latin_1(&self.body[1..i]).ok_or("Invalid Latin-1 string field".ioerr())
}
1 => { // UCS-2
let mut i = self.body.len();
while i > 1 && self.body[i-2] == 0 && self.body[i-1] == 0 { i -= 2; }
from_ucs_2_bom(&self.body[1..i]).ok_or("Invalid UCS-2 string field".ioerr())
}
enc => {
Err(format!("Unknown string encoding {}", enc).ioerr())
}
}
}
fn encode_string(s: &str) -> io::Result<Vec<u8>> {
let as_latin1 = || iter::once(Ok(0))
.chain(s.chars().map(|c| u8::try_from(u32::from(c))))
.collect::<Result<Vec<u8>, _>>();
let as_ucs2 = || {
let nibbles = s.chars()
.map(|c| u16::try_from(u32::from(c)))
.collect::<Result<Vec<u16>, _>>()?;
Ok(iter::once(1)
.chain(nibbles.iter().flat_map(|&n| ArrayIter2::new([(n >> 8) as u8, n as u8])))
.collect::<Vec<u8>>())
};
as_latin1()
.or_else(|_| as_ucs2())
.map_err(|e: TryFromIntError| e.ioerr())
}
pub fn interpret(&self) -> io::Result<Option<Frame>> {
let type_t = |typ: fn(String) -> Frame| self.interpret_encoded_string().map(typ).map(Some);
if self.id == "TIT2" { type_t(Frame::TIT2) }
else if self.id == "TYER" { type_t(Frame::TYER) }
else if self.id == "TPE1" { type_t(Frame::TPE1) }
else if self.id == "TALB" { type_t(Frame::TALB) }
else if self.id == "TRCK" { type_t(Frame::TRCK) }
else {
Ok(None)
}
}
pub fn map_string<F: Fn(String) -> String>(self, f: F) -> io::Result<Option<Self>> {
let type_t = |id: &str, body: String| -> io::Result<Self> {
Ok(Self {
id: id.to_string(),
flags: 0,
body: Self::encode_string(&body)?,
})
};
match self.interpret()? {
Some(Frame::TIT2(s)) => Ok(Some(type_t("TIT2", f(s))?)),
Some(Frame::TYER(s)) => Ok(Some(type_t("TYER", f(s))?)),
Some(Frame::TPE1(s)) => Ok(Some(type_t("TPE1", f(s))?)),
Some(Frame::TALB(s)) => Ok(Some(type_t("TALB", f(s))?)),
Some(Frame::TRCK(s)) => Ok(Some(type_t("TRCK", f(s))?)),
None => Ok(Some(self)),
}
}
}
impl ID3v2 {
pub fn from_stream<R: Read>(stream: &mut R) -> io::Result<Self> {
let mut header = [0u8; 10];
stream.read_exact(&mut header)?;
let (id3version, flags, header_size) = parse_id3v2_header(&header).ok_or("Invalid ID3 header".ioerr())?;
if id3version != 0x0300 {
return Err(format!("ID3 header version {}.{} not supported", id3version / 256, id3version % 256).ioerr())
}
if flags != 0 {
return Err(format!("No ID3 header flags supported ({:x})", flags).ioerr());
}
let body = {
let mut body = Vec::new();
body.resize(header_size, 0u8);
stream.read_exact(&mut body)?;
body
};
let mut frames = Vec::new();
let mut cursor = 0;
while cursor < body.len() {
match RawFrame::parse(&body[cursor..]).map_err(|e| e.ioerr())? {
Some((frame, consumed)) => {
frames.push(frame);
cursor += consumed;
}
None => {
break;
}
}
}
Ok(ID3v2 { frames, header_size })
}
}
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