#include <string>
#include <vector>
#include <iostream>
#include <fstream>
#include <cctype> 
#include <random>

using namespace std;

// ============================= UTILS ================================= //

vector<string> split(string s, const string& delimiter) {
    vector<string> tokens;
    size_t pos = 0;
    while ((pos = s.find(delimiter)) != string::npos) {
        tokens.push_back(s.substr(0, pos));
        s.erase(0, pos + delimiter.length());
    }
    tokens.push_back(s);
    return tokens;
}

void string_tolower(string& str) {
for (char& chr : str) {
    chr = tolower(chr);
  }
}

int random_number(int max) {

    // Define range
    int min = 0;

    // Initialize a random number generator
    random_device rd;
    mt19937 gen(rd());
    uniform_int_distribution<> distrib(min, max);

    // Generate random number in the range [min, max]
    int randomValue = distrib(gen);

    return randomValue;
}

// -------------------------- file utils -------------------------------- //

string read_file(const string& filename) {
    ifstream file(filename);
    if (!file.is_open()) {
        cerr << "Error: Could not open " << filename << endl;
        return "";
    }
    string line, content;
    while (getline(file, line)) content += line + "\n";
    return content;
}

void append_file(const string& filename, const string& text){
    ofstream of;

    of.open(filename, ios::app);
    if (!of)
        cout << "No such file found";
    else {
        of << text << endl;
        of.close();
    }
}

// ============================ LOGIC ============================ //

vector<vector<string>> create_question_vector(const string& fileText) {
    vector<vector<string>> questionVector;
    vector<string> lines = split(fileText, "\n"); //split on line break
    for (string& line : lines) {
        if (!line.empty()) questionVector.push_back(split(line, ";")); //create new vector per line and split on ;
    }
    return questionVector;
}

vector<vector<string>> get_questions(const string& fileName) {
    string fileText = read_file(fileName);
    vector<vector<string>> questionVector = create_question_vector(fileText); //create vector out of plain text

    return questionVector;
}

int ask_questions(vector<vector<string>>& questionVector) {
    unsigned int score= 0, index = 1;

    for (vector<string>& question : questionVector) {
        string answer;
        cout << index << ".  ";
        cout << question[0] << endl << "    "; // ask question
        getline(cin, answer); // get answer
        
        string_tolower(answer);         // make case irellevant
        string_tolower(question[1]);
        if (answer == question[1]) {
            score++;
            cout << "    Richtig! ";
        } else {
            cout << "    Falsch!  ";
        }
        cout << "[" << score << "/" << questionVector.size() << "]\n\n"; // display score/highest reachable score

        index++; // count up in question number
    }

    return score;
}


void randomize_questions(vector<vector<string>>& questionVector) {
    for (vector<string>& question : questionVector) { // traverse vector and swap element with random index
        swap(question, questionVector[random_number(questionVector.size()-1)]);
    }
}

string enter_username() {
    string username;
    cout << "Gib deinen Nutzernamen an:\n";
    getline(cin, username);
    
    return username;
}

void write_score_list(const string& filename, const vector<vector<string>>& scoreList) {
    string text;
    for (const vector<string>& score : scoreList) {
        text += score[0] + ";" + score[1] + "\n";
    }

    ofstream file(filename);
    file << text;
    file.close();
}

vector<vector<string>> add_to_scoreboard(const string& username, const int& score) {
    // --------------------- read --------------------- //
    string filename = "scores.txt";
    vector<vector<string>> scoreList = get_questions(filename); // read existing scores from file
    vector<string> newScore = {username, to_string(score)}; // create new score from this run

    // if no file existed yet/it's empty
    if (scoreList.empty()) {
        cout << "Ignore previous error" << endl;
        scoreList.push_back(newScore);
        append_file("scores.txt", newScore[0] + ";" + newScore[1]);
        return scoreList;
    }
    
    //if file already existed
    for (vector<string>& score : scoreList) {
        if (newScore[0] == score[0]) { //if name already exists
            if (stoi(newScore[1]) > stoi(score[1])) { //and new score is higher
                score = newScore;
                write_score_list(filename, scoreList);
                return scoreList;
            }
        } 
    }
    
    scoreList.push_back(newScore);
    append_file(filename, newScore[0] + ";" + newScore[1]);

    return scoreList;
}

void show_leaderboard(const vector<vector<string>>& scoreList) {
    if (scoreList.empty()) {
        cout << "wtF";
    }
    cout << "#==================================#" << endl;
    for (vector<string> score : scoreList) {
        cout << score[0] << ": " << score[1] << endl;
    }
    cout << "#==================================#";
}

int main() {
    cout << "Willkommen im Knusprigen Quiz" << endl;

    vector<vector<string>> questionVector = get_questions("fragen.txt"); //load questions into vector
    randomize_questions(questionVector);
    int score = ask_questions(questionVector);
    string username = enter_username();
    vector<vector<string>> newScoreList = add_to_scoreboard(username, score);
    show_leaderboard(newScoreList);

    return 0;
}