#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <vector>

using namespace std;

struct MarksRecord {
    string name;
    int maths_marks, chinese_marks, english_marks;
    string grade;
};

vector<MarksRecord> records;

string functionGetGrade(int maths_marks, int chinese_marks, int english_marks){
    string grade;
    int marks_sum;
    float marks_avg;

    marks_sum = 1;
    marks_sum = (maths_marks + chinese_marks + english_marks);
    marks_avg = marks_sum / 3;

    if (marks_avg > 90)  return "A";
    if (marks_avg > 80)  return "B";
    if (marks_avg > 70)  return "C";
    return "D";
}

void print_menu() {
    cout << "\n";
    cout << "Mark Record System\n";
    cout << "\n";
    cout << "------------------------------------------\n";
    cout << "1. Add marks record                       \n";
    cout << "2. Delete marks record                    \n";
    cout << "3. Edit marks record                      \n";
    cout << "4. Print current marks record in system   \n";
    cout << "5. import records from file               \n";
    cout << "6. export records to file                 \n";
    cout << "------------------------------------------\n";
    cout << "E. Exit\n";
    cout << "Enter your choice: ";
}

void functionAdd() {
    string temp;
    bool name_pass;
    name_pass = false;

    MarksRecord record;

    while (!name_pass){
        bool error;
        error = false;

        cout << "Enter name: ";
        cin >> temp;

        for (size_t i = 0; i < records.size(); i++) {
            if (records[i].name == temp) {
                error = true;
                cout << "ERROR: duplicated student name found"<<"\n";
            }
        }

        // check if name entered is empty
        if (temp == string()){
            error = true;
        }

        if (!error) {
            record.name = temp;
            name_pass = true;
        }
    }

    cout << "Enter maths marks: ";
    cin >> record.maths_marks;
    cout << "Enter chinese marks: ";
    cin >> record.chinese_marks;
    cout << "Enter english marks: ";
    cin >> record.english_marks;

    records.push_back(record);
    cout << "1 record added.";
}

void functionDelete() {
    string name;
    bool user_found;
    user_found = false;

    cout << "Enter name to delete: ";
    cin >> name;
    for (size_t i = 0; i < records.size(); i++) {
        if (records[i].name == name) {
            records.erase(records.begin() + i);
            user_found = true;
            break;
        }
    }

    if (!user_found){
        cout << "ERROR: student record not found";
    }else{
        cout << "1 record deleted.";
    }
}

void functionEdit() {
    string name;
    string temp;
    bool user_found;

    cout << "Enter name to edit: ";
    cin >> name;
    for (size_t i = 0; i < records.size(); i++) {
        if (records[i].name == name) {
            user_found = true;
            cout << "Enter new maths marks [- to skip]: ";
            cin >> temp;
            if (temp != "-") {
                records[i].maths_marks = stoi(temp);
            }

            cout << "Enter new chinese marks [- to skip]: ";
            cin >> temp;
            if (temp != "-") {
                records[i].chinese_marks = stoi(temp);
            }

            cout << "Enter new english marks [- to skip]: ";
            cin >> temp;
            if (temp != "-") {
                records[i].english_marks = stoi(temp);
            }

            break;
        }
    }

    if (!user_found){
        cout << "sorry but no user found to update record";
    }else{
        cout << "1 record updated.";
    }
}


void functionPrint() {
    cout << endl;
    cout
        << setw(10) << setfill(' ') << left << "Name" << setw(10)
        << setw(10) << setfill(' ') << left << "Maths" << setw(10)
        << setw(10) << setfill(' ') << left << "Chinese" << setw(10)
        << setw(10) << setfill(' ') << left << "English" << setw(10)
        << setw(10) << setfill(' ') << left << "Grade" << setw(10);

    cout << "" << setw(50) << setfill('-') << "\n";
    cout << "\n";

    for (const auto& record : records) {
        string calc_grade;
        calc_grade = functionGetGrade(record.maths_marks, record.chinese_marks, record.english_marks);

        cout
            << setw(10) << setfill(' ') << left << record.name
            << setw(10) << setfill(' ') << left << record.maths_marks
            << setw(10) << setfill(' ') << left << record.chinese_marks
            << setw(10) << setfill(' ') << left << record.english_marks

            // append 2 chars on the left
            << setw(2) << setfill(' ') << left << " "
            << setw(10) << setfill(' ') << left << calc_grade  << "\n";
    }
    cout << "\n";
}


void functionImport(){
    ifstream inFile;
    ofstream outFile;
    string student_name, maths_mark, chinese_mark, english_mark, grade;
    int record_added;
    record_added = 0;

    string filename;

    cout << "Please enter a file with list of student: ";
    cin >> filename;

    inFile.open(filename);
    if (!inFile) {
        cout << "Cannot open the input file." << endl;
        // << "The program terminates." << endl;
        // return 1;
    }else{
        while (true){
            inFile >> student_name;

            if (student_name == "END") {
                break;
            }else{
                inFile >> maths_mark >> chinese_mark >> english_mark;
                MarksRecord record;
                record.name = student_name;
                record.maths_marks = stoi(maths_mark);
                record.chinese_marks = stoi(chinese_mark);
                record.english_marks = stoi(english_mark);

                records.push_back(record);

                record_added = record_added + 1;
            }

        }

        cout << "record imported : " << record_added << "\n";
        cout << "\n";


        inFile.close();
    }

}

void functionExport(){
    ofstream outFile;
    string filename;

    cout << "Please enter a file to export: ";
    cin >> filename;

    outFile.open(filename);

    outFile << setw(10) << setfill(' ') << ""
        << "~ STUDENT RECORDS ~";
    outFile << "\n";
    outFile << "\n";

    outFile
        << setw(10) << setfill(' ') << left << "Name" << setw(10)
        << setw(10) << setfill(' ') << left << "Maths" << setw(10)
        << setw(10) << setfill(' ') << left << "Chinese" << setw(10)
        << setw(10) << setfill(' ') << left << "English" << setw(10)
        << setw(10) << setfill(' ') << left << "Grade" << setw(10);

    outFile << "" << setw(50) << setfill('-') << "\n";
    outFile << "\n";

    for (const auto& record : records) {
        string calc_grade;
        calc_grade = functionGetGrade(record.maths_marks, record.chinese_marks, record.english_marks);

        outFile
            << setw(10) << setfill(' ') << left << record.name
            << setw(10) << setfill(' ') << left << record.maths_marks
            << setw(10) << setfill(' ') << left << record.chinese_marks
            << setw(10) << setfill(' ') << left << record.english_marks

            // append 2 chars on the left
            << setw(2) << setfill(' ') << left << " "
            << setw(10) << setfill(' ') << left << calc_grade  << "\n";
    }
    outFile << "\n";
    cout << "export done !" << "\n";
}

int main() {
    char choice;
    while (true) {
        print_menu();
        cin >> choice;

        switch (choice) {
            case '1': functionAdd(); break;
            case '2': functionDelete(); break;
            case '3': functionEdit(); break;
            case '4': functionPrint(); break;
            case '5': functionImport(); break;
            case '6': functionExport(); break;

            // exit handler
            case 'E':
            case 'e':
                return 0;

            // exception handler
            default:
                cout << "Invalid choice. Please try again.\n";
        }
    }

    return 0;
}