#![no_main]
use clawhdf5_format::btree_v2::{BTreeV2Header, collect_btree_v2_records};
use libfuzzer_sys::fuzz_target;

fuzz_target!(|data: &[u8]| {
    for &offset_size in &[4u8, 8] {
        for &length_size in &[4u8, 8] {
            if let Ok(header) = BTreeV2Header::parse(data, 0, offset_size, length_size) {
                let _ = collect_btree_v2_records(data, &header, offset_size, length_size);
            }
        }
    }

    // Parsing a header requires a valid checksum, which random input almost
    // never has, so the traversal behind it went unfuzzed — and that is where
    // a node listing itself as its own child overflowed the stack. Take the
    // header fields straight from the input instead and walk the rest.
    let Some((fields, file)) = data.split_first_chunk::<20>() else {
        return;
    };
    let header = BTreeV2Header {
        tree_type: fields[0],
        node_size: u32::from_le_bytes([fields[1], fields[2], fields[3], fields[4]]),
        record_size: u16::from_le_bytes([fields[5], fields[6]]),
        depth: u16::from_le_bytes([fields[7], fields[8]]),
        root_node_address: u64::from(u32::from_le_bytes([
            fields[9], fields[10], fields[11], fields[12],
        ])),
        num_records_in_root: u16::from_le_bytes([fields[13], fields[14]]),
        total_records: u64::from(u32::from_le_bytes([
            fields[15], fields[16], fields[17], fields[18],
        ])),
    };
    let offset_size = if fields[19] & 1 == 0 { 4 } else { 8 };
    let _ = collect_btree_v2_records(file, &header, offset_size, 8);
});