use std::io::{Read, Seek};

use anyhow::Result;

pub struct EbmlReader<T> {
    inner: T,
    position: usize,
}

impl<T: Read + Seek> EbmlReader<T> {
    pub fn new(inner: T) -> Self {
        Self { inner, position: 0 }
    }

    pub fn read_byte(&mut self) -> Result<u8> {
        let mut b = [0u8];
        self.inner.read_exact(&mut b)?;
        Ok(b[0])
    }
    pub fn read_vint(&mut self) -> Result<(u64, u64)> {
        let s = self.read_byte()? as u64;
        let len = s.leading_zeros() + 1;
        let mut value = s;
        value -= 1 << (8 - len);
        for _ in 0..(len - 1) {
            value <<= 8;
            value += self.read_byte()? as u64;
        }
        Ok((value, len.into()))
    }

    pub fn read_tag_id(&mut self) -> Result<u64> {
        let (value, len) = self.read_vint()?;
        Ok(value + (1 << (7 * len)))
    }

    pub fn read_tag(&mut self) -> Result<()> {
        let id = self.read_tag_id()?;

        Ok(())

    }
}