#include "net.h"
#include "pico/unique_id.h"
#include "pico/time.h"
#include "eth.h"
#include "arp.h"
#include "ipv4.h"
#include "udp.h"
#include "igmp.h"
#include "parse_buffer.h"
#include "prepend_buffer.h"
#include "w6300.h"
#include "debug_log.h"

static constexpr ipv4::ip4_addr IP_BROADCAST_SUBNET = {169, 254, 255, 255};
static constexpr uint16_t PICOMAP_PORT = __builtin_bswap16(28781);

static net_state state;
static w6300::socket_id raw_socket{0};
static net_handler msg_handler;
static frame_cb_list frame_callbacks;

void net_send_raw(std::span<const uint8_t> data) {
    dlog_if_slow("net_send_raw", 1000, [&]{
        auto result = w6300::send(raw_socket, data);
        if (!result)
            dlogf("w6300 send failed: %zu bytes, err %d",
                  data.size(), static_cast<int>(result.error()));
    });
}

static void handle_udp(std::span<const uint8_t> frame, span_writer& tx) {
    parse_buffer pb(frame);
    auto* eth_hdr = pb.consume<eth::header>();
    auto* ip = pb.consume<ipv4::header>();
    if (!ip) return;

    size_t options_len = ip->header_len() - sizeof(ipv4::header);
    if (options_len > 0 && !pb.skip(options_len)) return;

    auto* uhdr = pb.consume<udp::header>();
    if (!uhdr) return;
    if (uhdr->dst_port != PICOMAP_PORT) return;
    if (!msg_handler) return;

    size_t udp_len = __builtin_bswap16(uhdr->length);
    if (udp_len < sizeof(udp::header)) return;
    size_t payload_len = udp_len - sizeof(udp::header);
    if (pb.remaining_size() < payload_len) return;

    eth::mac_addr dst_mac = eth_hdr->src;
    ipv4::ip4_addr dst_ip = ip->src;
    uint16_t dst_port = uhdr->src_port;

    msg_handler(pb.remaining().subspan(0, payload_len),
        [dst_mac, dst_ip, dst_port](std::span<const uint8_t> resp_data) {
            prepend_buffer<4096> buf;
            buf.append_copy(resp_data);
            udp::prepend(buf, dst_mac, state.mac, state.ip, dst_ip,
                         PICOMAP_PORT, dst_port, resp_data.size());
            net_send_raw(buf.span());
        });
}

static bool mac_match(const eth::mac_addr& dst) {
    return dst == state.mac || dst == eth::MAC_BROADCAST || igmp::is_member_mac(dst);
}

static void process_frame(std::span<const uint8_t> frame, span_writer& tx) {
    if (frame.size() < sizeof(eth::header)) return;
    auto& eth_hdr = *reinterpret_cast<const eth::header*>(frame.data());

    if (!mac_match(eth_hdr.dst)) return;

    frame_callbacks.for_each([&](frame_cb_list::node* n) {
        if (n->value(frame))
            frame_callbacks.remove(n);
    });

    switch (eth_hdr.ethertype) {
    case eth::ETH_ARP:
        arp::handle(frame, tx, state.mac, state.ip, net_send_raw);
        break;
    case eth::ETH_IPV4:
        ipv4::handle(frame, tx, state.mac, state.ip, IP_BROADCAST_SUBNET, net_send_raw, handle_udp);
        break;
    }
}

bool net_init() {
    w6300::init_spi();
    w6300::reset();
    w6300::init();
    if (!w6300::check()) return false;

    pico_unique_board_id_t uid;
    pico_get_unique_board_id(&uid);
    state.mac[0] = (uid.id[0] & 0xFC) | 0x02;
    state.mac[1] = uid.id[1];
    state.mac[2] = uid.id[2];
    state.mac[3] = uid.id[3];
    state.mac[4] = uid.id[4];
    state.mac[5] = uid.id[5];

    state.ip[0] = 169;
    state.ip[1] = 254;
    state.ip[2] = state.mac[4];
    state.ip[3] = state.mac[5];

    w6300::open_socket(raw_socket, w6300::protocol::macraw, w6300::sock_flag::none);
    w6300::set_interrupt_mask(w6300::ik_sock_0);

    igmp::join(igmp::PICOMAP_DISCOVERY_GROUP, state.mac, state.ip, net_send_raw);

    return true;
}

const net_state& net_get_state() {
    return state;
}

void net_set_handler(net_handler handler) {
    msg_handler = std::move(handler);
}

frame_cb_handle net_add_frame_callback(net_frame_callback cb) {
    auto h = frame_callbacks.insert(std::move(cb));
    if (!h) dlog("frame callback alloc failed");
    return h;
}

void net_remove_frame_callback(frame_cb_handle h) {
    frame_callbacks.remove(h);
}

void net_poll(std::span<uint8_t> tx) {
    if (!w6300::irq_pending) return;
    w6300::irq_pending = false;
    w6300::clear_interrupt(w6300::ik_int_all);
    static uint8_t rx_buf[1518];
    int budget = 10;
    while (budget-- > 0 && w6300::get_socket_recv_buf(raw_socket) > 0) {
        auto result = w6300::recv(raw_socket, std::span{rx_buf});
        if (!result) break;
        span_writer tx_writer(tx);
        process_frame({rx_buf, *result}, tx_writer);
    }
}