#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <stdarg.h>
#include <time.h>

#include <getopt.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <search.h>
#include <errno.h>

#define PACKET_SIZE 8

#define LEN(x) (sizeof(x) / sizeof(x[0]))

typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
typedef unsigned long long ulonglong;

enum verbose_level {
    NONE,
    DEBUG,
    WARNING,
    ERROR
};

// in bootloader spam \n or anything? until some buffer is full

speed_t baud = 0;
char port[32] = {0};
int serial_fd = -1;
FILE *file = NULL;
const char *flush = "aaaaaaaaaaaaa\n";
int verbose = 0;

void help()
{
    puts("help");
    exit(EXIT_SUCCESS);
}

void die()
{
    if (file)
        fclose(file);
    if (serial_fd < 0)
        close(serial_fd);
    exit(EXIT_FAILURE);
}

int log_msg(int lvl, const char *fmt, ...)
{
    int ret = 0;
    va_list args;
    if (verbose >= lvl) {
        va_start(args, fmt);
        ret = vprintf(fmt, args);
        fflush(stdout);
        va_end(args);
    }
    return ret;
}

struct baud_pair {
    const char *b;
    speed_t c;
};

// Conversion table for baud rates
const struct baud_pair baud_rates[] = {
    {"1200",  B1200},
    {"2400",  B2400},
    {"4800",  B4800},
    {"9600",  B9600},
    {"19200", B19200},
};

int parse_argv(int argc, char *const argv[])
{
    struct option long_opts[] = {
        { "baud",    required_argument, 0, 'b'},
        { "verbose", no_argument,       0, 'v'},
        { "port",    required_argument, 0, 'p'},
        { "help",    no_argument,       0, 'h'},
        {      0,    0,                 0, 0  }
    };

    int long_index = 0;
    int c;

    while ((c = getopt_long(argc, argv, "b:p:h",
                            long_opts, &long_index)) != -1) {
        switch (c) {
        case 'b':
            for (int i = 0; i < LEN(baud_rates); i++) {
                if (!strcmp(baud_rates[i].b, optarg)) {
                    baud = baud_rates[i].c;
                    break;
                }
            }

            if (baud == 0) {
                fprintf(stderr, "Error: Invalid baud rate '%s'\n", optarg);
                exit(EXIT_FAILURE);
            }
            break;

        case 'v':
            verbose = 1;
            break;

        case 'p':
            strncpy(port, optarg, LEN(port));
            break;

        case 'h':
            help();
            break;

        case '?':
            help();
            break;

        default:
            break;
        }
    }

    if (argc <= optind) {
        fprintf(stderr, "Error: No file was provided to upload\n\n");
        help();
    }

    return optind;
}

int open_tty(const char *port)
{
    int fd = open(port, O_RDWR);

    if (fd < 0) {
        fprintf(stderr, "Error: Port '%s' could not be opened\n", port);
        exit(EXIT_FAILURE);
    }

    struct termios term;
    tcgetattr(fd, &term);

    cfmakeraw(&term);
    term.c_cc[VTIME] = 1;
    term.c_cc[VMIN] = 0;
    term.c_lflag &= ~OCRNL;
    cfsetspeed(&term, baud);

    tcsetattr(fd, TCSANOW, &term);

    return fd;
}

ssize_t read_line(int fd, uchar *buf, size_t len)
{
    int ret = 0;
    ssize_t bytes_read = 0;

    // The Serial port runs at ~9600 baud. This loop, as inefficient as it is,
    // won' t ever be a bottleneck
    for (int i = 0; bytes_read < len; i++) {
        ssize_t rd = read(fd, &buf[bytes_read], 1);
        if (rd < 0) {
            fprintf(stderr, "Error: read from port failed\n%s\n",
                    strerror(errno));
            die();
        }

        if (rd == 0)
            return -1;

        bytes_read += rd;
        if (buf[bytes_read - 1] == '\n')
            break;
    }

    buf[bytes_read] = 0;
    return bytes_read;
}

void flush_bootloader(int serial_fd)
{
    /* Clean up */
    // tcflush(serial_fd, TCIOFLUSH);
    /* Send empty line to get a ready prompt from bootloader */
    write(serial_fd, flush, strlen(flush));
    tcdrain(serial_fd);
}

/*
 * Get the bootloader in a ready state, cleaning up any previous errors
 */
void begin_command(int serial_fd)
{
    char buf[32];
    int timeout = 1;

    buf[0] = 0;

    while (timeout) {
        /* Comparing should stop after \n even if buf is undefined */
        while (strcmp("ready\r\n", buf) != 0) {
            if (read_line(serial_fd, buf, LEN(buf)) < 0) {
                timeout = 1;
                log_msg(DEBUG, "timeout\n%32s\n", buf);
                flush_bootloader(serial_fd);
                break;
            } else {
                timeout = 0;
            }
        }
    }
}

void send_packet(int index, uint address, int plen, const uchar *packet)
{
    char obuf[128];
    int len = sprintf(obuf, "W %04X %02X ", address, plen);

    for (int i = 0; i < plen; i++)
        len += sprintf(&obuf[len], "%02X", packet[i]);

    obuf[len++] = '\r';
    obuf[len++] = '\n';
    obuf[len] = '\0';

    int cmp = 1;
    char ibuf[128];
    char ebuf[128];

    for (int attempt = 1; cmp != 0; attempt++) {
        log_msg(DEBUG, "Sending packet %d, attempt %d\n", index, attempt);

        begin_command(serial_fd);
        write(serial_fd, obuf, len);

        if((read_line(serial_fd, ibuf, LEN(ibuf)) == -1)
           || (read_line(serial_fd, ebuf, LEN(ebuf)) == -1)) {
            continue;
        }

        log_msg(DEBUG, "sent: %s", obuf);
        log_msg(DEBUG, "recv: %s", ibuf);
        log_msg(DEBUG, "ebuf: %s", ebuf);

        cmp = strncmp(ibuf, obuf, LEN(ibuf));
        if (cmp != 0) {
            usleep(100);
        }
    }
}

int upload_file(FILE *file, int serial_fd)
{
    int file_size = 0;
    fseek(file, 0, SEEK_END);
    file_size = ftell(file);
    fseek(file, 0, SEEK_SET);

    int total = (file_size / PACKET_SIZE
                 + ((file_size % PACKET_SIZE) == 0 ? 0 : 1));

    printf("Sending %d bytes\n", file_size);
    printf("Progress: [ %3d%% ]", 0);
    fflush(stdout);

    uint address = 0x4000;
    uchar packet[PACKET_SIZE];

    for (int i = 1; !feof(file); i++) {
        size_t n = fread(packet, sizeof(uchar), LEN(packet), file);
        if (n > 0) {
            send_packet(i, address, n, packet);
            address += n;
        }
        printf("\rProgress: [ %3d%% ]", 100 * i / total);
        fflush(stdout);
    }
    return 0;
}

int main(int argc, char *argv[])
{
    int ind = parse_argv(argc, argv);
    serial_fd = open_tty(port);
    FILE *file = fopen(argv[ind], "r");

    if (!file) {
        fprintf(stderr, "Error: File '%s' could not be opened\n", argv[ind]);
        close(serial_fd);
        exit(EXIT_FAILURE);
    }

    tcflush(serial_fd, TCIOFLUSH);
    flush_bootloader(serial_fd);

    upload_file(file, serial_fd);
    puts("\ndone");

    fclose(file);
    close(serial_fd);

    exit(EXIT_SUCCESS);
}