#include<iostream>
#include<fstream>
#include<string>

using namespace std;

struct emp{
	int eno;
	char name[50],address[50];
	float basic,allowence,deduction;
};

void addEmp(); //adds new record to data file
void disEmp(); //displays all records from file
void delEmp(); //asks empNo and removes that record from file
void updEmp(); //asks empno and lets you reenter that data
void cls(); //just clear screen

int main(){
	string dummy;
	int choice;

	cout<<"===== Main Menu ====="<<endl;
	cout<<endl<<endl;
	cout<<"1 -> Add Record "<<endl;
	cout<<"2 -> Display Record"<<endl;
	cout<<"3 -> Delete Record"<<endl;
	cout<<"4 -> Update Record"<<endl;
	cout<<endl;
	cout<<"0 -> Exit"<<endl;
	cout<<endl<<endl<<"Selection ";
	cin>>choice;
	if(choice<0 || choice>4){
		cls();
		main();
	}
	switch(choice){
		case 0:	break;
		case 1:	addEmp();	break;
		case 2:	disEmp();	break;
		case 3:	delEmp();	break;
		case 4:	updEmp();	break;
	}
}

void addEmp(){
	fstream data; 
	string dummy;
	emp e;
	int choice;

	do{
		cls();
		cout<<"===== Enter New Record ====="<<endl;
		cout<<endl<<endl;
		cout<<"Eno :\t\t"; cin>>e.eno;
		getline(cin,dummy); //just to clear input buffer
		cout<<"\nName :\t\t"; gets_s(e.name,50);
		cout<<"\nAddress :\t"; gets_s(e.address,50);
		cout<<"\nBasic Salary :\t";cin>>e.basic;
		cout<<"\nAllowence :\t";cin>>e.allowence;
		cout<<"\nDeductions :\t";cin>>e.deduction;
		cout<<endl<<endl;
		cout<<"1 -> Save  | 2 -> Cancel"<<endl;
		cin>>choice;
	}while(!(choice==1 || choice==2));
		
	if(choice==1){
		data.open("data.dat",ios::out|ios::app);
		data.write((char*)&e,sizeof(e));
		data.close();
		cout<<"\nRecord Saved "<<endl<<endl;
	}else{
		cout<<"\n\nRecord Cancelled"<<endl<<endl;
	}
	cout<<"Enter another record?"<<endl;
	cout<<"1 -> Yes  | 2 -> No"<<endl;
	cin>>choice;
	if(choice==1)
		addEmp();
	else
		return;	
	main();
}

void disEmp(){
	fstream data;
	emp e;
	data.open("data.dat",ios::in);
	cls();
	while(data.read((char*) &e, sizeof(e))){
		cout<<"\n\n-----Displaying record for ENO " <<e.eno<<endl;
		cout<<"\nName :\t\t"<<e.name;
		cout<<"\nAddress :\t"<<e.address;
		cout<<"\nBasic Salary :\t"<<e.basic;
		cout<<"\nAllowence :\t"<<e.allowence;
		cout<<"\nDeductions :\t"<<e.deduction<<endl;
		cout<<endl<<"\nTotal Salary :\t"<<e.basic+e.allowence;
		cout<<"\nNet Paid :\t"<<e.basic+e.allowence-e.deduction;
		cout<<endl;
	}
	data.close();
	main();
}

void delEmp(){
	fstream data, temp;
	emp e;
	int eno;

	cls();
	cout<<"===== Delete Record ====="<<endl;
	cout<<endl<<endl<<endl;
	cout<<"Enter ENO to delete record ";cin>>eno;

	rename("data.dat","temp.dat");

	data.open("data.dat",ios::app);
	temp.open("temp.dat",ios::in);

	temp.seekg(0,ios::beg);

	while(temp.read((char*)&e,sizeof(e))){
		if(!(e.eno==eno)){
			cout<<"Record to delete "<<e.eno;
			data.write((char*) &e,sizeof(e));
		}
	}
	data.close();
	temp.close();

	system("Del temp.dat");

	main();
}

void updEmp(){
	fstream data, temp;
	emp e;
	string dummy;
	int eno;

	cls();
	cout<<"===== Update Record ====="<<endl;
	cout<<endl<<endl<<endl;
	cout<<"Enter ENO :_";cin>>eno;

	rename("data.dat","temp.dat");

	data.open("data.dat",ios::app);
	temp.open("temp.dat",ios::in);

	temp.seekg(0,ios::beg);

	while(temp.read((char*)&e,sizeof(e))){
		if(e.eno==eno){
			cout<<"-----Current data for ENO: "<<e.eno;
			cout<<"\nName :\t\t"<<e.name;
			cout<<"\nAddress :\t"<<e.address;
			cout<<"\nBasic Salary :\t"<<e.basic;
			cout<<"\nAllowence :\t"<<e.allowence;
			cout<<"\nDeductions :\t"<<e.deduction<<endl;
			cout<<endl<<"\nTotal Salary :\t"<<e.basic+e.allowence;
			cout<<"\nNet Paid :\t"<<e.basic+e.allowence-e.deduction;
			cout<<endl<<endl;
			
			cout<<"-----Enter New Values-----"<<endl;
			cout<<"\nEno :\t\t"; cin>>e.eno;
			getline(cin,dummy); //just to clear input buffer
			cout<<"\nName :\t\t"; gets_s(e.name,50);
			cout<<"\nAddress :\t"; gets_s(e.address,50);
			cout<<"\nBasic Salary :\t";cin>>e.basic;
			cout<<"\nAllowence :\t";cin>>e.allowence;
			cout<<"\nDeductions :\t";cin>>e.deduction;	
		}
		data.write((char*) &e,sizeof(e));
	}
	data.close();
	temp.close();

	system("Del temp.dat");

	main();
}
void cls(){
	for (int i=0;i<50;i++)
		cout<<"\n";
}