# include <stdio.h>
# include <stdint.h>
# include <stdlib.h>
# include <unistd.h>
# include <string.h>
# include <errno.h>
# include <sys/types.h>
# include <sys/stat.h>
# include <fcntl.h>
# include <arpa/inet.h>
# include <getopt.h>

struct fpv
{
        uint32_t        		len;
        uint8_t         		type;
        uint32_t        		ms;
        uint8_t         		pad[8];
} __attribute__((packed));


static const char short_options[] = "s:e:";
static const struct option long_options[] =
{
        { "start",	required_argument,  	NULL, 's' },
        { "end",   	required_argument,  	NULL, 'e' },
        { 0, 		0, 			NULL,  0  }
};

static int opt_s = 0;
static int opt_e = -1;

size_t in(int fd, uint8_t *data, size_t len)
{
        int res = 0;

        while (len > 0) {
                size_t n = read(fd, data, len);
                if (n > 0) {
                        len -= n;
                        data += n;
                        res  += n;
                } else {
                        if (n < 0) {
                                if (errno != EAGAIN) {
                                        printf("read: %s\n", strerror(errno));
                                } else {
                                        continue;
                                }
                        }
                        break;
                }
        }
        return res;
}

int main(int argc, char *argv[])
{
        struct fpv fpv;
        static uint8_t data[8 * 1024 * 1024];
        int i;

        for (;;) {
                int c;

                if ((c = getopt_long_only(argc, argv, short_options, long_options, &i)) == -1) {
                        break;
                }

                switch (c) {
                case 's':
                        opt_s = atoi(optarg);
                        break;

                case 'e':
                        opt_e = atoi(optarg);
                        break;

                case 0:
                        break;

                default:
                        return 1;
                }
        }

        if ((argc - optind) < 1) {
                return 1;
        }

        for (i = 0; (optind + i) < argc; i++) {
                int fd = open(argv[optind + i], O_RDONLY);

                fprintf(stderr, "%s\n", argv[optind + i]);
                if (fd >= 0) {
                        while (1) {
                                if (in(fd, (uint8_t*)&fpv, sizeof(fpv)) < 0) {
                                        break;
                                }

                                if (in(fd, data, fpv.len) < 0) {
                                        break;
                                }

                                if (opt_e > 0 && fpv.ms >= opt_e) {
                                        break;
                                }

                                if (fpv.ms >= opt_s) {
                                        fpv.ms -= opt_s;
                                        write(fileno(stdout), &fpv, sizeof(fpv));
                                        write(fileno(stdout), data, fpv.len);
                                }
                        }
                        close(fd);
                }
        }
        return 0;
}