//! `CobsDecoder::feed` must never panic or yield an oversized payload
//! when fed arbitrary bytes in arbitrary chunks.
//!
//! The input is split into chunks driven by a leading length-prefix
//! stream so the fuzzer can exercise boundary handling.

#![no_main]

use donglora_protocol::MAX_PAYLOAD;
use donglora_protocol::framing::CobsDecoder;
use libfuzzer_sys::fuzz_target;

fuzz_target!(|data: &[u8]| {
    let mut decoder = CobsDecoder::new();
    let mut cursor = 0;

    // Use the first byte (if any) as a pseudo-chunk-schedule: low nibble
    // picks a split size 1..=16, high nibble is skipped. Subsequent
    // leading bytes drive subsequent splits.
    let mut sched_idx = 0;
    while cursor < data.len() {
        let split = if sched_idx < data.len() {
            ((data[sched_idx] & 0x0F) as usize) + 1
        } else {
            16
        };
        sched_idx = sched_idx.saturating_add(1);
        let end = (cursor + split).min(data.len());
        decoder.feed(&data[cursor..end], |cmd| {
            if let donglora_protocol::Command::Transmit { payload, .. } = cmd {
                assert!(payload.len() <= MAX_PAYLOAD);
            }
        });
        cursor = end;
    }
});