/// @file man.c
/// @brief Shows the available commands.
/// @copyright (c) 2014-2022 This file is distributed under the MIT License.
/// See LICENSE.md for details.

#include <fcntl.h>
#include <stdio.h>
#include <strerror.h>
#include <string.h>
#include <sys/dirent.h>
#include <sys/unistd.h>

int main(int argc, char *argv[])
{
    if (argc == 1)
    {
        int fd = open("/bin", O_RDONLY | O_DIRECTORY, 0);
        if (fd == -1)
        {
            printf("%s: cannot access '/bin': %s\n\n", argv[0], strerror(errno));
            return 1;
        }
        dirent_t dent;
        int per_line = 0;
        while (getdents(fd, &dent, sizeof(dirent_t)) == sizeof(dirent_t))
        {
            // Shows only regular files
            if (dent.d_type == DT_REG)
            {
                printf("%10s ", dent.d_name);
                if (++per_line == 6)
                {
                    per_line = 0;
                    putchar('\n');
                }
            }
        }
        putchar('\n');
        close(fd);
    }
    else if (argc == 2)
    {
        char filepath[PATH_MAX];
        strcpy(filepath, "/usr/share/man/");
        strcat(filepath, argv[1]);
        strcat(filepath, ".man");
        int fd = open(filepath, O_RDONLY, 42);
        if (fd < 0)
        {
            printf("%s: No manual entry for %s\n\n", argv[0], argv[1]);
        }
        else
        {
            // Prepare the buffer for reading the man file.
            char buffer[BUFSIZ];
            // Put on the standard output the characters.
            while (read(fd, buffer, BUFSIZ) > 0)
            {
                puts(buffer);
            }
            // Close the file descriptor.
            close(fd);
            // Terminate with a pair of newlines.
            putchar('\n');
            putchar('\n');
        }
    }
    return 0;
}