// Program to main Employee database and allow all common operations.
// Assignment-35
// empdbapp.cpp, Author - Krishna Kumar Khatri.

// Uncomment ONLY the following line if you are using Turbo/Borland compiler.
// #define TC
#ifdef TC
	#include <iostream.h>
	#include <fstream.h>
	#include <string.h>
	#include <iomanip.h>
#else
	#include <iostream>
	#include <fstream>
	#include <cstring>
	#include <iomanip>
	using namespace std;
#endif
#include <conio.h>  // For getch.
#include <stdlib.h>	// For system.
#include <stdio.h>	// For remove and rename.
const int MAXLEN = 30;

class Employee
{
		int empid;
		char empname[MAXLEN];
		char designation[MAXLEN / 2];
		char qualification[MAXLEN / 2];
		double salary;
	public:
		void getdata();
		void putdata();
		void repdata();		// Tabular report.
		int getempid();		// Accessor.
		char* getempname();	// Accessor.
};

void Employee::getdata()
{
	cout << "Enter Employee ID: "; cin >> empid;
	cout << "Name: "; cin >> empname;
	cout << "Designation: "; cin >> designation;
	cout << "Qualification: "; cin >> qualification;
	cout << "Salary: "; cin >> salary;
}

void Employee::putdata()
{
	cout << "Emp ID - " << empid << endl;
	cout << "Name   - " << empname << endl;
	cout << "Dsgnt. - " << designation << endl;
	cout << "Qualf. - " << qualification << endl;
	cout << "Salary - " << salary;
}

void Employee::repdata()
{
	cout << setw(4) << empid << " "
		 << setw(12) << setiosflags(ios::left) << empname << " "
		 << setw(12) << designation << " "
		 << setw(12) << qualification << " "
		 << "$" << setw(12) << salary;
}

int Employee::getempid()
	{ return empid; }

char* Employee::getempname()
	{ return empname; }

long filesize(char* filename)
{
	fstream fn;
	long b, e;
	int reccnt;
	fn.open(filename, ios::in);

	fn.seekg(0, ios::beg); b = fn.tellg();
	fn.seekg(0, ios::end); e = fn.tellg();

	reccnt = e / sizeof(Employee);
	cout << endl;
	reccnt == 0 ? cout << "Empty database." :
				  cout << setw(3) << reccnt << " record(s)";

	return (e - b);
}

int main()
{
	#ifdef TC
		clrscr();
	#endif
	char* filename = "Empdb.txt";
	char* newfilnm = "Tmpdb.txt";
	ofstream ofs;
	ifstream ifs;
	ofstream tmpf;
	char choice;
	Employee emp;
	int empid;
	int flag = 'f';
	char empname[MAXLEN];

	do {
		cout << "------------------------------" << endl;
		cout << " Employee Database Management " << endl;
		cout << "------------------------------" << endl;
		cout << "[a] Add new record." << endl;
		cout << "[u] Update existing record." << endl;
		cout << "[q] Query the database." << endl;
		cout << "[s] Display all records." << endl;
		cout << "[d] Delete the record." << endl;
		cout << "[x] Exit." << endl << endl;
		cout << "Your choice: ["; choice = getche(); cout << ']';

		switch (choice) {
			case 'a':
				cout << endl << endl << "Record details for employee,"
					 << endl;
				emp.getdata();
				ofs.open(filename, ios::app);	// Append mode.
				ofs.write((char*)&emp, sizeof(emp));
				ofs.close();
				cout << "Record written.";
				break;
			case 'u':
				cout << endl << endl << "Updating record." << endl;
				cout << "Enter Emp ID (reference): ";
				cin >> empid;

				ifs.open(filename);
				tmpf.open(newfilnm);
				flag = 'f';

				ifs.read((char*)&emp, sizeof(emp));
				while (ifs) {
					if (emp.getempid() == empid) {
						cout << endl << "Entries for matching record are," << endl;
						emp.putdata();
						cout << endl << endl << "Enter new data," << endl;
						emp.getdata();
						flag = 't';
					}
					tmpf.write((char*)&emp, sizeof(emp));
					ifs.read((char*)&emp, sizeof(emp));
				}
				ifs.close();
				tmpf.close();

				remove(filename);
				rename(newfilnm, filename);

				if (flag == 't')
					cout << endl << "Record updated.";
				else
					cout << endl << "Matching record not found!";
				break;
			case 'q':
				cout << endl << endl << "Querying for records."
					 << endl << endl;
				cout << "Query for," << endl;
				do {
					cout << "[i] Employee ID." << endl;
					cout << "[n] Employee name." << endl << endl;
					cout << "Your choice (i/n): ["; choice = getche();
					cout << ']';
				} while (choice != 'i' && choice != 'n');

				ifs.open(filename);

				switch (choice) {
					case 'i':
						cout << endl << "Enter Emp ID (reference): ";
						cin >> empid;
						while (ifs) {
							ifs.read((char*)&emp, sizeof(emp));
							if (emp.getempid() == empid) {
								cout << endl << "Record found." << endl;
								emp.putdata();
								break;
							}
						}
						break;
					case 'n':
						cout << endl << "Enter Emp name (reference): ";
						cin >> empname;
						while (ifs) {
							ifs.read((char*)&emp, sizeof(emp));
							if (strcmp(emp.getempname(), empname) == 0) {
								cout << endl << "Record found." << endl;
								emp.putdata();
								break;
							}
						}
						break;
					default:
						cout << "Invalid choice.";
						break;
				}
				if (!ifs)
					cout << endl << "Matching record not found!";
				ifs.close();
				break;
			case 's':
				if (filesize(filename) == 0L)
					break;
				cout << " affected." << endl;
				cout << "------------------------" << endl;
				cout << " ID  NAME         DSGNT   ";
				cout << "     QUALF        SALARY       " << endl;
				cout << "---- ------------ --------";
				cout << "---- ------------ -------------" << endl;
				ifs.open(filename);
				ifs.read((char*)&emp, sizeof(emp));
				while (!ifs.eof()) {
					emp.repdata();
					cout << endl;
					ifs.read((char*)&emp, sizeof(emp));
				}
				ifs.close();
				break;
			case 'd':
				cout << endl << endl << "Deleting record." << endl;
				cout << "Enter Emp ID (reference): ";
				cin >> empid;

				ifs.open(filename);
				tmpf.open(newfilnm);
				flag = 'f';

				ifs.read((char*)&emp, sizeof(emp));
				while (ifs) {
					if (emp.getempid() == empid) {
						cout << endl << "Entries for matching record are," << endl;
						emp.putdata();
						cout << endl << endl
							 << "Permanently delete this record (y/n): ";
						choice = getche();
						if (choice != 'y')
							tmpf.write((char*)&emp, sizeof(emp));
						flag = 't';
					} else
						tmpf.write((char*)&emp, sizeof(emp));
					ifs.read((char*)&emp, sizeof(emp));
				}
				ifs.close();
				tmpf.close();

				remove(filename);
				rename(newfilnm, filename);

				if (flag == 't') {
					if (choice == 'y')
						cout << endl << "Record deleted.";
					else
						cout << endl << "Record not deleted.";
				}
				else
					cout << endl << "Matching record not found!";
				break;
			case 'x':
				// Do nothing.
				break;
			default:
				cout << endl << endl << "Invalid choice.";
				break;
		}

		if (choice != 'x') {
			cout << endl << endl << "Press any key to continue...";
			getch();
		}
		cout << endl << endl;
	} while (choice != 'x');

	cout << endl << "Program over. Press any key to exit...";
	getch();
	return 0; // Successful termination.
}