const CONTINUE_BIT: u8 = 0x80;

pub struct LEB128;

impl LEB128 {
    pub fn write_leb128(buffer: &mut Vec<u8>, mut value: u64) -> usize {
        let mut size: usize = 0;
        loop {
            let mut byte: u8 = (value & (std::u8::MAX as u64)).try_into().unwrap();
            value >>= 7;
            if value != 0 {
                byte |= CONTINUE_BIT;
            }

            buffer.push(byte);
            size += 1;

            if value == 0 {
                return size;
            }
        }
    }

    pub fn read_leb128(buffer: &[u8]) -> (u32, usize) {
        let mut result: u32 = 0;
        let mut shift: usize = 0;
        let mut offset: usize = 0;
        loop {
            let byte: u8 = buffer[offset];
            result |= ((byte & (std::i8::MAX as u8)) as u32) << (shift as u32);
            offset += 1;
            if byte & CONTINUE_BIT == 0 || offset == 4 {
                return (result, offset);
            }
            shift += 7;
        }
    }
}