// 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 <device_id.h>
#include <inet6.h>
#include <netifc.h>
#include <xefi.h>

#include <zircon/boot/netboot.h>
#include <tftp/tftp.h>

#define TFTP_BUF_SZ 2048
char tftp_session_scratch[TFTP_BUF_SZ];
char tftp_out_scratch[TFTP_BUF_SZ];

// item being downloaded
static nbfile* item;

// TFTP file state
typedef struct {
    nbfile* netboot_file_data;
    size_t file_size;
    unsigned int progress_reported;
} file_info_t;

// TFTP transport state
typedef struct {
    struct ip6_addr_t dest_addr;
    uint16_t dest_port;
} transport_info_t;

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;

static char advertise_nodename[64] = "";
static char advertise_data[256] = "nodename=zircon";

static void send_query_ack(const ip6_addr* addr, uint16_t port,
                           uint32_t cookie) {
    uint8_t buffer[256];
    nbmsg* msg = (void*)buffer;
    msg->magic = NB_MAGIC;
    msg->cookie = cookie;
    msg->cmd = NB_ACK;
    msg->arg = NB_VERSION_CURRENT;
    memcpy(msg->data, advertise_nodename, sizeof(advertise_nodename));
    udp6_send(buffer, sizeof(nbmsg) + strlen(advertise_nodename) + 1,
              addr, port, NB_SERVER_PORT);
}

static void advertise(void) {
    uint8_t buffer[sizeof(nbmsg) + sizeof(advertise_data)];
    nbmsg* msg = (void*)buffer;
    msg->magic = NB_MAGIC;
    msg->cookie = 0;
    msg->cmd = NB_ADVERTISE;
    msg->arg = NB_VERSION_CURRENT;
    size_t data_len = strlen(advertise_data) + 1;
    memcpy(msg->data, advertise_data, data_len);
    udp6_send(buffer, sizeof(nbmsg) + data_len, &ip6_ll_all_nodes,
              NB_ADVERT_PORT, NB_SERVER_PORT);
}

void netboot_recv(void* data, size_t len, const ip6_addr* saddr, uint16_t sport) {
    nbmsg* msg = data;
    nbmsg ack;
    int do_transmit = 1;

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

    // printf("netboot: MSG %08x %08x %08x %08x datalen %zu\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 (size_t 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, msg->arg);
        if (item) {
            item->offset = 0;
            ack.arg = msg->arg;
            size_t prefix_len = strlen(NB_FILENAME_PREFIX);
            const char* filename;
            if (!strncmp((char*)msg->data, NB_FILENAME_PREFIX, prefix_len)) {
                filename = &((const char*)msg->data)[prefix_len];
            } else {
                filename = (const char*)msg->data;
            }
            printf("netboot: Receive File '%s'...\n", filename);
        } else {
            printf("netboot: Rejected File '%s'...\n", (char*) msg->data);
            ack.cmd = NB_ERROR_BAD_FILE;
        }
        break;

    case NB_DATA:
    case NB_LAST_DATA:
        if (item == 0) {
            printf("netboot: > received chunk before NB_FILE\n");
            return;
        }
        if (msg->arg != item->offset) {
            // printf("netboot: < received chunk at offset %d but current offset is %zu\n", msg->arg, item->offset);
            ack.arg = item->offset;
            ack.cmd = NB_ACK;
        } else if ((item->offset + len) > item->size) {
            ack.cmd = NB_ERROR_TOO_LARGE;
            ack.arg = msg->arg;
        } else {
            memcpy(item->data + item->offset, msg->data, len);
            item->offset += len;
            ack.cmd = msg->cmd == NB_LAST_DATA ? NB_FILE_RECEIVED : NB_ACK;
            if (msg->cmd != NB_LAST_DATA) {
                do_transmit = 0;
            }
        }
        break;
    case NB_BOOT:
        nb_boot_now = 1;
        printf("netboot: Boot Kernel...\n");
        break;
    case NB_QUERY:
        // Send reply and return w/o getting the netboot state out of sync.
        send_query_ack(saddr, sport, msg->cookie);
        return;
    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;
    if (do_transmit) {
        // printf("netboot: MSG %08x %08x %08x %08x\n",
        //   ack.magic, ack.cookie, ack.cmd, ack.arg);

        udp6_send(&ack, sizeof(ack), saddr, sport, NB_SERVER_PORT);
    }
}

static tftp_status buffer_open(const char* filename, size_t size, void* cookie) {
    file_info_t* file_info = cookie;
    file_info->netboot_file_data = netboot_get_buffer(filename, size);
    if (file_info->netboot_file_data == NULL) {
        printf("netboot: unrecognized file %s - rejecting\n", filename);
        return TFTP_ERR_INVALID_ARGS;
    }
    file_info->netboot_file_data->offset = 0;
    const char* base_filename;
    size_t prefix_len = strlen(NB_FILENAME_PREFIX);
    if (!strncmp(filename, NB_FILENAME_PREFIX, prefix_len)) {
        base_filename = &filename[prefix_len];
    } else {
        base_filename = filename;
    }
    printf("Receiving %s [%lu bytes]... ", base_filename, (unsigned long)size);
    file_info->file_size = size;
    file_info->progress_reported = 0;
    return TFTP_NO_ERROR;
}

static tftp_status buffer_write(const void* data, size_t* len, off_t offset, void* cookie) {
    file_info_t* file_info = cookie;
    nbfile* nb_buf_info = file_info->netboot_file_data;
    if (offset > nb_buf_info->size || (offset + *len) > nb_buf_info->size) {
        printf("netboot: attempt to write past end of buffer\n");
        return TFTP_ERR_INVALID_ARGS;
    }
    memcpy(&nb_buf_info->data[offset], data, *len);
    nb_buf_info->offset = offset + *len;
    if (file_info->file_size >= 100) {
        unsigned int progress_pct = offset / (file_info->file_size / 100);
        if ((progress_pct > file_info->progress_reported) &&
            (progress_pct - file_info->progress_reported >= 5)) {
            printf("%u%%... ", progress_pct);
            file_info->progress_reported = progress_pct;
        }
    }
    return TFTP_NO_ERROR;
}

static void buffer_close(void* cookie) {
    file_info_t* file_info = cookie;
    file_info->netboot_file_data = NULL;
    printf("Done\n");
}

static tftp_status udp_send(void* data, size_t len, void* cookie) {
    transport_info_t* transport_info = cookie;
    int bytes_sent = udp6_send(data, len, &transport_info->dest_addr, transport_info->dest_port,
                               NB_TFTP_OUTGOING_PORT);
    return bytes_sent < 0 ? TFTP_ERR_IO : TFTP_NO_ERROR;
}

static int udp_timeout_set(uint32_t timeout_ms, void* cookie) {
    // TODO
    return 0;
}

static int strcmp8to16(const char* str8, const char16_t* str16) {
    while (*str8 != '\0' && *str8 == *str16) {
        str8++;
        str16++;
    }
    return *str8 - *str16;
}

void tftp_recv(void* data, size_t len, const ip6_addr* daddr, uint16_t dport,
               const ip6_addr* saddr, uint16_t sport) {
    static tftp_session* session = NULL;
    static file_info_t file_info = {.netboot_file_data = NULL};
    static transport_info_t transport_info = {};

    if (dport == NB_TFTP_INCOMING_PORT) {
        if (session != NULL) {
            printf("Aborting to service new connection\n");
        }
        // Start TFTP session
        int ret = tftp_init(&session, tftp_session_scratch, sizeof(tftp_session_scratch));
        if (ret != TFTP_NO_ERROR) {
            printf("netboot: failed to initiate tftp session\n");
            session = NULL;
            return;
        }

        // Override our window size on the Acer tablet
        if (!strcmp8to16("INSYDE Corp.", gSys->FirmwareVendor)) {
            uint16_t window_size = 8;
            tftp_set_options(session, NULL, NULL, &window_size);
        }

        // Initialize file interface
        tftp_file_interface file_ifc = {NULL, buffer_open, NULL, buffer_write, buffer_close};
        tftp_session_set_file_interface(session, &file_ifc);

        // Initialize transport interface
        memcpy(&transport_info.dest_addr, saddr, sizeof(struct ip6_addr_t));
        transport_info.dest_port = sport;
        tftp_transport_interface transport_ifc = {udp_send, NULL, udp_timeout_set};
        tftp_session_set_transport_interface(session, &transport_ifc);
    } else if (!session) {
        // Ignore anything sent to the outgoing port unless we've already established a connection
        return;
    }

    size_t outlen = sizeof(tftp_out_scratch);

    char err_msg[128];
    tftp_handler_opts handler_opts = {.inbuf = data,
                                      .inbuf_sz = len,
                                      .outbuf = tftp_out_scratch,
                                      .outbuf_sz = &outlen,
                                      .err_msg = err_msg,
                                      .err_msg_sz = sizeof(err_msg)};
    tftp_status status = tftp_handle_msg(session, &transport_info, &file_info, &handler_opts);
    if (status < 0) {
        printf("netboot: tftp protocol error: %s\n", err_msg);
        session = NULL;
    } else if (status == TFTP_TRANSFER_COMPLETED) {
        session = NULL;
    }
}

#define FAST_TICK 100
#define SLOW_TICK 1000

int netboot_init(const char* nodename) {
    if (netifc_open()) {
        printf("netboot: Failed to open network interface\n");
        return -1;
    }
    char buf[DEVICE_ID_MAX];
    if (!nodename || (nodename[0] == 0)) {
        device_id(eth_addr(), buf);
        nodename = buf;
    }
    if (nodename) {
        strncpy(advertise_nodename, nodename, sizeof(advertise_nodename) - 1);
        snprintf(advertise_data, sizeof(advertise_data),
                 "version=%s;nodename=%s", BOOTLOADER_VERSION, nodename);
    }
    return 0;
}

const char* netboot_nodename() {
    return advertise_nodename;
}

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();
}