#include "trikke_transport.h"

static bool status_is_valid(trikke_transport_status_t status)
{
    return status >= TRIKKE_TRANSPORT_COMPLETE &&
           status <= TRIKKE_TRANSPORT_FATAL;
}

void trikke_transport_sender_init(trikke_transport_sender_t *sender)
{
    if (sender != NULL) {
        sender->pending = false;
        sender->begin_retry_count = 0;
    }
}

trikke_transport_status_t trikke_transport_sender_step(
    trikke_transport_sender_t *sender,
    const trikke_transport_t *transport,
    const uint8_t *packet,
    size_t packet_size)
{
    if (sender == NULL || transport == NULL || transport->begin == NULL ||
        transport->poll == NULL || packet == NULL || packet_size == 0) {
        return TRIKKE_TRANSPORT_FATAL;
    }

    const bool was_pending = sender->pending;
    const trikke_transport_status_t status = was_pending
        ? transport->poll(transport->context)
        : transport->begin(transport->context, packet, packet_size);
    if (!status_is_valid(status)) {
        sender->pending = was_pending;
        return TRIKKE_TRANSPORT_FATAL;
    }

    if (status == TRIKKE_TRANSPORT_PENDING) {
        sender->pending = true;
    } else if (status == TRIKKE_TRANSPORT_COMPLETE) {
        sender->pending = false;
    } else if (status == TRIKKE_TRANSPORT_RETRY) {
        if (was_pending) {
            // Once accepted, generic transport code cannot prove that retrying
            // the whole frame is duplicate-safe. Fail closed and keep ownership.
            sender->pending = true;
            return TRIKKE_TRANSPORT_FATAL;
        }
        ++sender->begin_retry_count;
        sender->pending = false;
    } else {
        sender->pending = was_pending;
    }
    return status;
}