//! # The outer container / structure

use nom::{
    bytes::complete::{tag, take},
    combinator::map_res,
    multi::length_data,
    number::complete::be_u32,
    IResult,
};

use crate::util::Buf;
#[derive(Debug)]
/// One chunk in the document container
pub struct Chunk<'a> {
    /// The tag of the chunk
    pub tag: &'a str,
    /// The content of the chunk
    pub buf: Buf<'a>,
}

/// A Signum! document container
#[derive(Debug)]
pub struct SDocContainer<'a> {
    /// The chunks in this container
    pub chunks: Vec<Chunk<'a>>,
}

fn take4(input: &[u8]) -> IResult<&[u8], &[u8]> {
    take(4usize)(input)
}

/// Parse a Signum! document
pub fn parse_sdoc0001_container(input: &[u8]) -> IResult<&[u8], SDocContainer> {
    let (input, _) = tag(b"sdoc")(input)?;
    let mut chunks = Vec::new();
    let mut input = input;
    while !input.is_empty() {
        let (rest, tag): (&[u8], &str) = map_res(take4, std::str::from_utf8)(input)?;
        let (rest, data) = length_data(be_u32)(rest)?;
        chunks.push(Chunk {
            tag,
            buf: Buf(data),
        });
        input = rest;
    }

    Ok((input, SDocContainer { chunks }))
}