/*
 * fileutil.c
 * 
 *  Alexander Occhipinti
 * Student ID: 29994705
 * Created: 3 Sep 2020
 * Last Modified: 4 Sep 2020
 * 
 * fileutil is a program which is a utility for files. It combines the functionality of cat cp and mv.
 * This program allows you to copy the contents of a given file to stdout or to a another file.
 * It also allows you to delete the original (i.e. mv) if you please.
 *  
*/

#include <unistd.h>
#include <sys/file.h>
#include <stdlib.h>
#include <string.h>
#include "fileutil.h"
#define FILE_BUF_SIZE 1024
#define DEFAULT_READ_PATH "logfile.txt"
#define NEW_FILE_PERMS 0664

/*
 * Prints a given string to stdout. Returns nothing.
*/
void to_stdout(char *string) {
    write(1, string, strlen(string));
}

/*
 * Prints a given string to stderr. Returns nothing.
*/
void to_stderr(char *string) {
    write(2, string, strlen(string));
}

/*
 * Prints the contents of a given file (provided a path) to stdout.
 * Returns nothing.
*/

int open_file(char *path, int flags){
        // Read the input file
    int fd;
    if ((fd = open(path, flags, NEW_FILE_PERMS)) <= 2){
        to_stderr(path);
        to_stderr(" could not be opened.\n");
        exit(1); // Exit if an error occurs
    }
    return fd;
}

void file_into_file(int source_fd, int dest_fd){
    int bytes_read;
    char buffer[FILE_BUF_SIZE];
    while ((bytes_read = read(source_fd, buffer, FILE_BUF_SIZE))) {
        write(dest_fd, buffer, bytes_read);
    }

}

void print_file(char *read_path) {
    int read_fd;
    read_fd = open_file(read_path, O_RDONLY);
    file_into_file(read_fd, 1);
    close(read_fd);
}

void copy_file(char *read_path, char *write_path, int overwrite) {
    int read_fd, write_fd;
    int write_flags = O_WRONLY | O_CREAT;
    if (overwrite) write_flags |= O_EXCL;

    read_fd = open_file(read_path, O_RDONLY);
    write_fd = open_file(write_path, write_flags);
    
    file_into_file(read_fd, write_fd);

    close(read_fd);
    close(write_fd);
}

char* get_filename(char *full_path){
    char* filename = strrchr(full_path, '/'); // Find the string after the last occurence of a '/'
    if (!filename) return full_path; // If there are no slashes, the whole path is already a filename
    return ++filename; // Return the filename without a leading slash

}

void copy_into_dir(char *file_path, char *dir_path){
    char* filename;
    char* new_path;
    size_t new_path_len;

    // filename = strrchr(dir_path, '/');
    filename = get_filename(file_path);
    // printf("%s\n", filename);
    new_path_len = strlen(dir_path) + strlen(filename) + 1;
    new_path = (char *) malloc(new_path_len);

    strcpy(new_path, dir_path);
    strcat(new_path, "/");
    strcat(new_path, filename);
    copy_file(file_path, new_path, 0);

    free(new_path);
}



int main(int argc, char *argv[]) {
    switch (argc){
        case 0:
            exit(1);
        case 1:
            print_file(DEFAULT_READ_PATH);
            break;
        case 2:
            print_file(argv[1]);
            break;
        case 3:
            to_stderr("Invalid number of arguments sepcified\n");
            exit(1);
            break;
        default:
            if (strcmp(argv[2], "-d") == 0){
                copy_into_dir(argv[1], argv[3]);
            } else {
                to_stderr("Invalid argument(s) sepcified\n");
                exit(1);
            }
    }
    return 0;
}