//Include all the necessary libraries.
#include<stdio.h>
#include<iostream>
#include<fstream>
#include<string.h>

using namespace std;

int main(){
	//Considering the max length of data entered (name) to be 15.
	char data[15];
	int n = 0, option = 0, count_n = 0;
	//This is the initial mark alloted to a subject.
	string empty = "00";
	string proctor = "";
	//Name of the file in which DB is stored.
	ifstream f("Example.txt");
	string line;

	//The following for loop counts the total number of lines in the file.
	for (int i = 0; std::getline(f, line); ++i){
		count_n++;}

	while(option != 6){
//This prints out all the available options in the DB
	cout << "\nAvailable operations: \n1. Add New Students\n2."
		<< "Student Login\n3. Faculty Login\n4. Proctor Login\n5. Admin View\n"
		<< "6. Exit\nEnter option: ";
	cin >> option;

	if(option == 1){
	cout << "Enter the number of students: ";
	cin >> n;

	count_n = count_n + n;

	for (int i = 0;i < n;i++){
		ofstream outfile;
			outfile.open("Example.txt",ios::app);
		//The entire data of a single student is stored line-by-line.
		cout << "Enter your registration number: ";
		cin >> data;
		outfile << data << "\t";

		cout << "Enter your name: ";
		cin >> data;
		int len = strlen(data);

		while (len < 15){
			data[len] = ' ';
			len = len + 1;
		}
		outfile << data << "\t";
		//Inserting empty data initially into the file
		outfile << empty << "\t";
		outfile << empty << "\t";

		cout << "Enter your proctor ID: ";
		cin >> proctor;

		outfile << proctor << endl;
	}}

	else if (option == 2){
		char regno[9];
		cout << "Enter your registration number: ";
		cin >> regno;
		ifstream infile;
		int check = 0;
		infile.open("Example.txt",ios::in);

		//This loop prints out the data according to the registration number specified.
		while (infile >> data){
		if (strcmp(data,regno) == 0){
			cout << "\nRegistration Number: " << data << endl;
			infile >> data;
			cout << "Name: " << data << endl;

			infile >> data;
				cout << "CSE1001 mark: " << data << endl;

			infile>>data;
			cout<<"CSE1002 mark: "<<data<<endl;

			infile>>data;
			cout<<"Proctor ID: "<<data<<endl;

			infile.close();
			check = 1;}
		}

		if (check == 0){
			cout<<"No such registration number found!"<<endl;}

	}

	//This loop is used to view and add marks to the database of a student.
	else if (option == 3){
		char subcode[7];
		cout << "Enter your subject code: ";
		cin >> subcode;
		string code1 = "CSE1001", code2 = "CSE1002",mark = "";
		ifstream infile;
		int check = 0;

		cout << "\nAvailable operations: \n1. Add data about marks\n"
				<< "2. View data\nEnter option: ";
		cin >> option;

		if (option == 1){
			cout << "Warning! You would need to add mark"
					<< "details for all the students!" << endl;
			for(int i = 0;i < count_n;i++){
				fstream file("Example.txt");

								//The seek in file has been done according to the length
			//of the data being inserted. It needs to adjusted accordingly
			//for diffferent lengths of data.

			if(strcmp(subcode,code1.c_str()) == 0){
						file.seekp(26+37*i,std::ios_base::beg);
					cout << "Enter the mark of student#" << (i+1) << " : ";
				cin >> mark;
				file.write(mark.c_str(),2);}

			if(strcmp(subcode,code2.c_str()) == 0){
				file.seekp(29+37*i,std::ios_base::beg);
				cout << "Enter the mark of student#" << (i+1) << " : ";
				cin >> mark;
				file.write(mark.c_str(),2);}
			}

		}

		//This loop is used to view marks of a student.
		//The extra infile commands have been used to get a specific mark
		//only since the data has been seperated by a tabspace.

		else if(option == 2){
		infile.open("Example.txt",ios::in);
		if (strcmp(subcode,code1.c_str()) == 0){
			cout << "Registration number - Marks\n" << endl;
			while(infile >> data){
			cout << data;
			infile >> data;
				infile >> data;
			cout << " - " << data << endl;
			infile >> data;
			infile >> data;
			check = 1;
			}
		}

		infile.close();
		infile.open("Example.txt",ios::in);

		if(strcmp(subcode,code2.c_str()) == 0){
			cout << "Registration number - Marks\n" << endl;
				while(infile >> data){
			cout << data;
			infile >> data;
			infile >> data;
			infile >> data;
			cout << " - " << data << endl;
			infile >> data;
			check = 1;
			}
		}}

		infile.close();

		if (check == 0){
			cout << "No such subject code found!" << endl;
		}

	}

	//This loop displays all the details of students under the same proctor ID.

	else if (option == 4){
		char procid[7];
		cout << "Enter your proctor ID: ";
		cin >> procid;
			int check = 1;
		char temp1[100], temp2[100], temp3[100];
		char temp4[100], id[100];
		ifstream infile;
		infile.open("Example.txt",ios::in);

		while (infile >> temp1){
			infile >> temp2;
		infile >> temp3;
		infile >> temp4;
		infile >> id;

		if (strcmp(id,procid) == 0){
			cout << "\nRegistration Number: " << temp1 << endl;
			cout << "Name: " << temp2 << endl;
			cout << "CSE1001 Mark: " << temp3 << endl;
			cout << "CSE1002 Mark: " << temp4 << endl;
			check = 1;
		}
		}

		if (check == 0){
			cout << "No such proctor ID found!" << endl;
		}}

	//This loop acts as an admin view to see all the data in the file.

	else if(option == 5){
		char password[25];
		cout << "Enter the admin password: ";
		cin >> password;

		//This variable value can be changed according to your requirement
		//of the administrator password.

		string admin_pass = "admin";

		if (strcmp(password,admin_pass.c_str()) == 0){
			cout << "Reg No.	 \tName\tCSE1001\tCSE1002\tProctor ID" << endl;
			ifstream infile;
			infile.open("Example.txt",ios::in);
			char data[20];

			while(infile >> data){
				cout << data << "\t";
				infile >> data;
				cout << data << "\t";
				infile >> data;
				cout << data << "\t";
				infile >> data;
				cout << data << "\t";
				infile >> data;
				cout << data << endl;
			}
		}
	}
}}