#include <iostream>
#include <string.h>
#include <dirent.h>
#include <unistd.h>
#include <stdio.h>
#include <vector>
#include <errno.h>

using namespace std;

//Returns the file name separated from it's extension
string get_filename(string full_file_name) {
  string filename;

  int dotPos = full_file_name.find_last_of(".");
  if (dotPos > 0) {
    if (full_file_name == "." && full_file_name == "..") { //handling . and .. files
      filename = full_file_name;
    }
    else {
      filename = full_file_name.substr(0, dotPos); //file name is everything going before the last dot in full file name
    }
  }
  else {
    filename = full_file_name; //if full file name contains no dots then it has no extension
  }

  return filename;
}

//Returns the file extension separated from it's name
string get_extension(string full_file_name) {
  string extension = "";

  int dotPos = full_file_name.find_last_of(".");
  if (dotPos > 0) {
    if (full_file_name != "." && full_file_name != "..") { //avoiding files . and .. 'cause they have no extension
      extension = full_file_name.substr(dotPos + 1);
    }
  }

  return extension;
}

//Removes file from filesystem.
//Arguments:
//  * full_file_name - full name of the file to remove (name and extension)
//  * path_to_file - path to the file to remove (without file name and extension)
//  * show_errors - if set to true, then function will output all the errors occured while removing files
void remove_file(string full_file_name, string path_to_file, bool show_errors) {
  string full_path = path_to_file + "/" + full_file_name;

  const char* temp = full_path.c_str();
  if (remove(temp) != 0 && show_errors == true) {
    cout << "Can't remove " << full_path << ": " << strerror(errno) << endl;
  }
}

int main (int argc, char* argv[]) {
  if (argc == 2 && string(argv[1]) == "--help" || string(argv[1]) == "-h") {
    cout << "Usage: ./task19 DIRECTORY... EXTENSION..." << endl;
    cout << "Removes from the DIRECTORY all the files with equal filenames except those which extension is EXTENSION." << endl;
    return 0;
  }

  if (argc < 3) {
    cout << "Missing some arguments. Try './task19 --help' for more information." << endl;
    return 0;
  }

  string dir_path = argv[1];
  string extension = argv[2];
  bool show_errors = false;

  if (argc > 3 && string(argv[3]) == "-er") {
    show_errors = true;
  }

  vector<string> filelist;

  DIR* dir_pointer = NULL;
  dir_pointer = opendir(dir_path.c_str());
  struct dirent* pent = NULL;

  //saving list of files in the directory to vector
  while (pent = readdir (dir_pointer)) {
    filelist.push_back(pent->d_name);
  }

  closedir(dir_pointer);

  for (int i = 0; i < filelist.size(); ++i) {
    string xname = get_filename(filelist[i]);
    string xext = get_extension(filelist[i]);

    for (int j = 0; j < filelist.size(); ++j) {
      string yname = get_filename(filelist[j]);
      string yext = get_extension(filelist[j]);

      if (xname == yname && filelist[i] != filelist[j]) {
        if (xext != extension) {
          remove_file(filelist[i], dir_path, show_errors);
        }
        if (yext != extension) {
          remove_file(filelist[j], dir_path, show_errors);
        }
      }
    }
  }

  return 0;
}