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

#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <limits.h> // necesar pentru PATH_MAX

#define SECTOR_SIZE 4096

void scrieFisier(char *map_addr, int length);
void recursive(int f, int length, int offset, int PageSize);

int main(int argc, char **argv)
{
    if (argc < 2)
    {
        printf("Introdu numele fisierului.\n");
        exit(1);
    }

    for (int i = 1; i < argc; i++)
        if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0)
        {
            system("rev -h");
            exit(1);
        }
    for (int i = 1; i < argc; i++)
        if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--version") == 0)
        {
            printf("1.0.0\n");
            exit(1);
        }

    for (int i = 1; i < argc; i++)
    {
        int f = open(argv[i], O_RDONLY);

        if (f == -1)
        {
            perror("A aparut o eroare cand am incercat sa deschide fisierul");
            continue;
        }

        long PageSize = sysconf(_SC_PAGE_SIZE);
        struct stat sb;

        if (PageSize == -1)
        {
            perror("Eroare la sysconf");
            exit(1);
        }

        if (fstat(f, &sb) == -1)
        {
            perror("Eroare la fstat");
            exit(2);
        }

        recursive(f, sb.st_size, 0, PageSize);
    }
}

void reverse(char *sir)
{
    int lg = strlen(sir) - 1;
    for (int i = 0; i <= lg / 2; i++)
    {
        char aux = sir[i];
        sir[i] = sir[lg - i];
        sir[lg - i] = aux;
    }
}

void scrieFisier(char *map_addr, int length)
{
    char aux[SECTOR_SIZE] = {0};
    for (int i = 0; i < length; i++)
        if (map_addr[i] != '\n')
        {
            int lg = strlen(aux);
            aux[lg] = map_addr[i];
            aux[lg + 1] = '\0';
        }
        else
        {
            reverse(aux);
            printf("%s\n", aux);
            aux[0] = '\0';
        }

    if (strlen(aux) > 0)
    {
        reverse(aux);
        printf("%s\n", aux);
        aux[0] = '\0';
    }
}

void recursive(int f, int length, int offset, int PageSize)
{
    int ok = 0;
    char *map_addr;
    if (length > PageSize)
    {
        map_addr = mmap(NULL, PageSize, PROT_READ, MAP_PRIVATE, f, offset);
        scrieFisier(map_addr, PageSize);
        recursive(f, length - PageSize, offset + PageSize, PageSize);
        if (munmap(map_addr, PageSize) == -1)
        {
            perror("Erroare la munmap.");
            exit(4);
        }
        return;
    }
    map_addr = mmap(NULL, length, PROT_READ, MAP_PRIVATE, f, offset);
    scrieFisier(map_addr, length);
    if (munmap(map_addr, length) == -1)
    {
        perror("Erroare la munmap.");
        exit(4);
    }
}