picomap/firmware/include/dispatch.h

#pragma once
#include <cstdint>
#include <cstdio>
#include <functional>
#include <optional>
#include <span>
#include "wire.h"
#include "timer_queue.h"

struct responder {
    uint32_t message_id;
    std::function<void(std::span<const uint8_t>)> send;

    template <typename T>
    void respond(const T& msg) const {
        uint8_t buf[1024];
        span_writer out(buf, sizeof(buf));
        auto r = encode_response_into(out, message_id, msg);
        if (r) send({buf, *r});
    }
};

using handler_fn = void (*)(responder resp, std::span<const uint8_t> payload);

struct handler_entry {
    int8_t type_id;
    handler_fn handle;
};

template <typename Req, auto Fn>
void typed_handler(responder resp, std::span<const uint8_t> payload) {
    msgpack::parser p(payload.data(), static_cast<int>(payload.size()));
    Req req;
    auto tup = req.as_tuple();
    auto r = msgpack::unpack(p, tup);
    if (!r) {
        char err[64];
        snprintf(err, sizeof(err), "decode request ext_id=%d: msgpack error %d",
                 Req::ext_id, static_cast<int>(r.error()));
        resp.respond(DeviceError{1, err});
        return;
    }
    auto result = Fn(resp, req);
    if (result)
        resp.respond(*result);
}

void dispatch_init();
timer_handle dispatch_schedule_ms(uint32_t ms, std::function<void()> fn);
bool dispatch_cancel_timer(timer_handle h);
[[noreturn]] void dispatch_run(std::span<const handler_entry> handlers);