//! An arbitrary well-formed `(type_id, tag, payload)` must survive a
//! frame encode → decode round trip byte-for-byte.

#![no_main]

use arbitrary::Arbitrary;
use donglora_protocol::{FrameDecoder, FrameResult, MAX_PAYLOAD_FIELD, MAX_WIRE_FRAME, encode_frame};
use libfuzzer_sys::fuzz_target;

#[derive(Debug, Arbitrary)]
struct Input<'a> {
    type_id: u8,
    tag: u16,
    payload: &'a [u8],
}

fuzz_target!(|input: Input| {
    if input.payload.len() > MAX_PAYLOAD_FIELD {
        return;
    }
    let mut wire = [0u8; MAX_WIRE_FRAME];
    let Ok(n) = encode_frame(input.type_id, input.tag, input.payload, &mut wire) else {
        return;
    };

    let mut decoder = FrameDecoder::new();
    let mut matched = false;
    decoder.feed(&wire[..n], |res| {
        if let FrameResult::Ok {
            type_id,
            tag,
            payload,
        } = res
        {
            assert_eq!(type_id, input.type_id);
            assert_eq!(tag, input.tag);
            assert_eq!(payload, input.payload);
            matched = true;
        } else {
            panic!("encode→decode produced a frame error: {:?}", res);
        }
    });
    assert!(matched, "encoded frame did not decode");
});