// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stdio.h>
#include <string.h>

#include <inet6.h>
#include <netboot.h>
#include <netifc.h>

static uint32_t last_cookie = 0;
static uint32_t last_cmd = 0;
static uint32_t last_arg = 0;
static uint32_t last_ack_cmd = 0;
static uint32_t last_ack_arg = 0;

static int nb_boot_now = 0;
static int nb_active = 0;

// item being downloaded
static nbfile* item;

void udp6_recv(void* data, size_t len,
               const ip6_addr* daddr, uint16_t dport,
               const ip6_addr* saddr, uint16_t sport) {
    nbmsg* msg = data;
    nbmsg ack;

    if (dport != NB_SERVER_PORT)
        return;

    if (len < sizeof(nbmsg))
        return;
    len -= sizeof(nbmsg);

    //printf("netboot: MSG %08x %08x %08x %08x datalen %d\n",
    //	msg->magic, msg->cookie, msg->cmd, msg->arg, len);

    if ((last_cookie == msg->cookie) &&
        (last_cmd == msg->cmd) && (last_arg = msg->arg)) {
        // host must have missed the ack. resend
        ack.magic = NB_MAGIC;
        ack.cookie = last_cookie;
        ack.cmd = last_ack_cmd;
        ack.arg = last_ack_arg;
        goto transmit;
    }

    ack.cmd = NB_ACK;
    ack.arg = 0;

    switch (msg->cmd) {
    case NB_COMMAND:
        if (len == 0)
            return;
        msg->data[len - 1] = 0;
        break;
    case NB_SEND_FILE:
        if (len == 0)
            return;
        msg->data[len - 1] = 0;
        for (int i = 0; i < (len - 1); i++) {
            if ((msg->data[i] < ' ') || (msg->data[i] > 127)) {
                msg->data[i] = '.';
            }
        }
        item = netboot_get_buffer((const char*) msg->data);
        if (item) {
            item->offset = 0;
            printf("netboot: Receive File '%s'...\n", (char*) msg->data);
        } else {
            printf("netboot: Rejected File '%s'...\n", (char*) msg->data);
            ack.cmd = NB_ERROR_BAD_FILE;
        }
        break;
    case NB_DATA:
        if (item == 0)
            return;
        if (msg->arg != item->offset)
            return;
        ack.arg = msg->arg;
        if ((item->offset + len) > item->size) {
            ack.cmd = NB_ERROR_TOO_LARGE;
        } else {
            memcpy(item->data + item->offset, msg->data, len);
            item->offset += len;
            ack.cmd = NB_ACK;
        }
        break;
    case NB_BOOT:
        nb_boot_now = 1;
        printf("netboot: Boot Kernel...\n");
        break;
    default:
        ack.cmd = NB_ERROR_BAD_CMD;
        ack.arg = 0;
    }

    last_cookie = msg->cookie;
    last_cmd = msg->cmd;
    last_arg = msg->arg;
    last_ack_cmd = ack.cmd;
    last_ack_arg = ack.arg;

    ack.cookie = msg->cookie;
    ack.magic = NB_MAGIC;
transmit:
    nb_active = 1;
    udp6_send(&ack, sizeof(ack), saddr, sport, NB_SERVER_PORT);
}

static char advertise_data[] =
    "version\00.1\0"
    "serialno\0unknown\0"
    "board\0unknown\0";

static void advertise(void) {
    uint8_t buffer[256];
    nbmsg* msg = (void*)buffer;
    msg->magic = NB_MAGIC;
    msg->cookie = 0;
    msg->cmd = NB_ADVERTISE;
    msg->arg = 0;
    memcpy(msg->data, advertise_data, sizeof(advertise_data));
    udp6_send(buffer, sizeof(nbmsg) + sizeof(advertise_data),
              &ip6_ll_all_nodes, NB_ADVERT_PORT, NB_SERVER_PORT);
}

#define FAST_TICK 100
#define SLOW_TICK 1000

int netboot_init(void) {
    if (netifc_open()) {
        printf("netboot: Failed to open network interface\n");
        return -1;
    }
    return 0;
}

static int nb_fastcount = 0;
static int nb_online = 0;

int netboot_poll(void) {
    if (netifc_active()) {
        if (nb_online == 0) {
            printf("netboot: interface online\n");
            nb_online = 1;
            nb_fastcount = 20;
            netifc_set_timer(FAST_TICK);
            advertise();
        }
    } else {
        if (nb_online == 1) {
            printf("netboot: interface offline\n");
            nb_online = 0;
        }
        return 0;
    }
    if (netifc_timer_expired()) {
        if (nb_fastcount) {
            nb_fastcount--;
            netifc_set_timer(FAST_TICK);
        } else {
            netifc_set_timer(SLOW_TICK);
        }
        if (nb_active) {
            // don't advertise if we're in a transfer
            nb_active = 0;
        } else {
            advertise();
        }
    }

    netifc_poll();

    if (nb_boot_now) {
        nb_boot_now = 0;
        return 1;
    } else {
        return 0;
    }
}

void netboot_close(void) {
    netifc_close();
}