#include <cstdlib>
#include <fstream>
# include <iostream>
# include <filesystem>
# include <unordered_map>

#include <QObject>
#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>
#include <QString>
#include <QCoreApplication>
#include <QProcess>
#include <QFile>
#include <QTimer>
# include <QStandardPaths>
#include <sstream>
#include <type_traits>
# include <unistd.h>
#include <unordered_map>
# include <expected>

namespace globals {
  static std::filesystem::path config_path;

  std::expected<QJsonObject, bool> read_config() {
    if (std::filesystem::exists(globals::config_path)) {
      std::fstream file_input(globals::config_path, std::fstream::in);
      std::string data;
      std::string temp;
      while(std::getline(file_input, temp)) {
        data += temp;
      }
      file_input.close();
      return QJsonDocument::fromJson(QByteArray::fromStdString(data)).object();
    } else {
      return std::unexpected(false);
    }
  }

  void overwrite_config(QJsonObject& obj) {
    QJsonDocument doc;
    doc.setObject(obj);
    std::string data = doc.toJson().toStdString();
    std::fstream file_input(globals::config_path, std::fstream::out);
    file_input << data;
    file_input.flush();
    file_input.close();
  }

}

std::string get_current_time() {
  const auto now = std::chrono::system_clock::now();
  std::time_t ctime_now = std::chrono::system_clock::to_time_t(now);
  std::stringstream ss;
  ss << "[" << std::put_time(std::localtime(&ctime_now), "%d-%m-%y %H:%M:%S") << "] ";
  return ss.str();
}

int get_parent_id() {
  std::stringstream ss;
  int var;
  ss << getppid();
  ss >> var;
  return var;
}

void show_help() {
  std::stringstream ss;
  ss << "Usage: goto [OPTION|LINK_NAME]" << std::endl;
  ss << "Options:" << std::endl;
  ss << "    -h  --help        : Show this info" << std::endl;
  ss << "    -c  --create_link : Create a new link e.g: goto --create_link [LINK_NAME] [FROM_PATH]" << std::endl;
  ss << "    -l  --list        : List all the existing links" << std::endl;
  ss << "    -d  --delete_link : Delete an exisiting link e.g: goto -d [LINK_NAME]" << std::endl;
  ss << "    -rf --delete_file : Delete the existing link file completely." << std::endl;
  ss << "    [LINK_NAME]       : Goes to an exisiting link e.g: goto [LINK_NAME]" << std::endl;
  ss << "    [LINK_NAME]       : Rules for creating [LINK_NAME] name must be BASH variable and must not start with \"-\"" << std::endl;
  ss << "    [LINK_NAME]       : [LINK_NAME] cannot be \"last\"" << std::endl;
  std::cout << ss.str();
}

void show_invalid() {
  std::stringstream ss;
  ss << "[goto] Invalid arguments use -h or --help for help" << std::endl;
  std::cout << ss.str();
}


void print_links() {
  QJsonObject links = globals::read_config().or_else([](bool err){
    std::cout << "Could not read config file." << std::endl;
    exit(-1);
    return std::expected<QJsonObject, bool> {QJsonObject()};
  }).value();
  std::unordered_map<std::string, std::string> link_list;
  for(auto i = links.begin(); i != links.end(); i++) {
    link_list[i.key().toStdString()] = i.value().toString().toStdString();
  }
  int iter = 1;
  std::cout << "Links from file: " << globals::config_path << std::endl;
  for(auto &[key, value]: link_list) {
    if(key != "last")
      std::cout << iter++ << ". " <<  key << " --> " << value << std::endl;
  }
  if(link_list.find("last") != link_list.end()) {
    std::cout << iter << ". Last place --> " << link_list["last"] << std::endl;
  }
}

void delete_link(std::string link_name) {
  QJsonObject obj = globals::read_config().or_else([](bool err){
    std::cout << "Could not read config file." << std::endl;
    exit(-1);
    return std::expected<QJsonObject, bool> {QJsonObject()};
  }).value();
  obj.remove(QString::fromStdString(link_name));
  globals::overwrite_config(obj);
  std::cout << "Link: " << link_name << " deleted." << std::endl;
}

void create_link(std::string link_name, std::string dir) {
  if(dir == ".") {
    dir = std::filesystem::current_path().string();
  }
  if(std::filesystem::exists(globals::config_path)) {
    QJsonObject links = globals::read_config().or_else([](bool err){
      std::cout << "Could not read config file." << std::endl;
      exit(-1);
      return std::expected<QJsonObject, bool> {QJsonObject()};
    }).value();
    if(links.find(QString::fromStdString(link_name)) == links.end())
      links[QString::fromStdString(link_name)] = QString::fromStdString(dir);
    else {
      std::string char_in;
      std::cout << "Warning: Link name: " << link_name << " already exists. Do you want to overwrite it?";
      std::cout.flush();
      std::getline(std::cin, char_in);
      if(char_in.size() >= 1 && (char_in[0] == 'Y' || char_in[0] == 'y')) {
        std::string prev_value = links[QString::fromStdString(link_name)].toString().toStdString();
        links[QString::fromStdString(link_name)] = QString::fromStdString(dir);
        globals::overwrite_config(links);
        std::cout << "Overwritten link: " << link_name << " -> " << dir << " from: " << prev_value << " in: " << globals::config_path << std::endl;
        exit(0);
      }
      else {
        exit(-1);
      }
    }
    globals::overwrite_config(links);
    std::cout << "Written new link: " << link_name << " -> " << dir << " in: " << globals::config_path << std::endl;
    exit(0);
  }
  else {
    QJsonObject new_link;
    new_link[QString::fromStdString(link_name)] = QString::fromStdString(dir);
    globals::overwrite_config(new_link);
    std::cout << "Written new link: " << link_name << " -> " << dir << " in: " << globals::config_path << std::endl;
    exit(0);
  }
}

void goto_link(std::string link_name) {
  QJsonObject config = globals::read_config().or_else([](bool err){
    std::cout << "Could not read config file." << std::endl;
    exit(-1);
    return std::expected<QJsonObject, bool> {QJsonObject()};
  }).value();
  std::string place = config[QString::fromStdString(link_name)].toString("-_- Place Does not exist.").toStdString();
  if(place == "-_- Place Does not exist.") {
    std::cout << "Specified link: " << link_name << " does not exist in links file." << std::endl;
    exit(-1);
  }
  config["last"] = QString::fromStdString(place);
  globals::overwrite_config(config);
  // int parent_id = get_parent_id();
  // std::ostringstream std_out, std_err, std_log;
  //
  // auto prev_cout_buffer = std::cout.rdbuf();
  // auto prev_clog_buffer = std::clog.rdbuf();
  // auto prev_cerr_buffer = std::cerr.rdbuf();

  // std::cout.rdbuf(std_out.rdbuf());
  // std::cerr.rdbuf(std_err.rdbuf());
  // std::clog.rdbuf(std_log.rdbuf());

  std::cout << place << std::endl;
  // system(std::format("sh -c cd {}", place).c_str());
  // system(std::format("kill -9 {}", parent_id).c_str());
  // QProcess *proc = new QProcess();
  // proc->setProgram("/usr/bin/bash");
  // proc->setWorkingDirectory(QString::fromStdString(place));
  // proc->startDetached();

  // std::cout.rdbuf(prev_cout_buffer);
  // std::cerr.rdbuf(prev_cerr_buffer);
  // std::clog.rdbuf(prev_clog_buffer);
}

void delete_file() {
  std::string in;
  std::cout << "Are you sure you want to completely remove the links.json file?";
  std::cout.flush();
  std::getline(std::cin, in);
  if(in.size() >= 1 && (in[0] == 'y' || in[0] == 'Y')) {
    std::filesystem::remove(globals::config_path);
    std::cout << "Removed config file from: " <<globals::config_path << std::endl;
  } else {
    std::cout << "Not removing config file." << std::endl;
  }
}

int main(int argc, char *argv[]) {
  QCoreApplication app(argc, argv);
  QCoreApplication::setApplicationName("goto");
  QCoreApplication::setApplicationVersion("0.0.1");
  globals::config_path = QStandardPaths::writableLocation(QStandardPaths::ConfigLocation).toStdString();
  globals::config_path = globals::config_path / "goto";
  if(!std::filesystem::exists(globals::config_path)) {
    std::filesystem::create_directories(globals::config_path);
  }
  globals::config_path = globals::config_path / "links.json";

  std::unordered_map<std::string, int> command_list = {{"help", 1}, {"h", 1}, {"create_link", 2}, {"c", 2}, {"l", 3}, {"list", 3}, {"d", 4}, {"delete_link", 4}, {"rf", 5}, {"delete_file", 5}};


  int command_size = argc - 1;
  if(command_size == 0) {
    show_invalid();
    exit(0);
  } else {
    bool arg = false;
    if(std::string(argv[1]).starts_with("--") || std::string(argv[1]).starts_with("-")) {
      while(argv[1][0] == '-') {
        ++argv[1];
      }
      arg = true;
    }
    if(arg) {
      if(command_list.find(argv[1]) == command_list.end()) {
        show_invalid();
        exit(-1);
      }
      else {
        switch (command_list[argv[1]]) {
          case 1: {
            show_help();
            exit(0);
          }
          case 2: {
            if(command_size != 3) {
              show_invalid();
              exit(-1);
            }
            std::string link_name, directory;
            link_name = argv[2];
            directory = argv[3];
            create_link(link_name, directory);
            exit(0);
          }
          case 3: {
            if(command_size != 1) {
              show_invalid();
              exit(-1);
            }
            print_links();
            exit(0);
          }
          case 4: {
            if(command_size != 2) {
              show_invalid();
              exit(-1);
            }
            std::string link_name;
            link_name = argv[2];
            delete_link(link_name);
            exit(0);
          }
          case 5: {
            if(command_size != 1) {
              show_invalid();
              exit(-1);
            }
            delete_file();
            exit(0);
          }

        }
      }
    }
    else {
      std::string link_name = argv[1];
      goto_link(link_name);
      exit(0);
    }
    exit(0);
  }



  return app.exec();
}