#include <stdio.h>
#include <stdlib.h>

int mainmenu(int y)

{
    int c;
    char username1[50], password1[50];
    FILE*database;

    struct user
    {
        char student_ID[50], course[50], email[50], sem[50],name[50];
        int age;
    };
    struct user s;
    if(y==1)
    {


    database=fopen("database.dat","a");
    system("cls");
    printf("\t\t\t\t==============\n");
    printf("\t\t\t\tTHERMO COMPANY\n");
    printf("\t\t\t\t==============\n");

    printf("\n\n\t\tPlease complete the registration form neatly. Thanks!\n");

    printf("\n\n\tUsername: ");
    gets(username1);
    fgets(username1,50,stdin);
    fprintf(database,"\nUsername:\t%s", username1);

    printf("\n\tPassword: ");
    fgets(password1,50,stdin);
    fprintf(database,"Password:\t%s", password1);

    printf("\n\tName: ");
    fgets(s.name,50,stdin);
    fprintf(database,"Name:\t%s", s.name);

    printf("\n\tAge: ");
    scanf("%d", &s.age);
    fprintf(database,"Age:\t%d", s.age);

    gets(s.student_ID);
    printf("\n\tStudent ID: ");
    fgets(s.student_ID,50,stdin);
    fprintf(database,"Studen ID:\t%s", s.student_ID);

    printf("\n\tCourse: ");
    fgets(s.course,50,stdin);
    fprintf(database,"Course:\t%s", s.course);

    printf("\n\tSemester: ");
    fgets(s.sem,50,stdin);
    fprintf(database,"Semester:\t%s", s.sem);

    printf("\n\tE-Mail: ");
    fgets(s.email,50,stdin);
    fprintf(database,"E-Mail:\t%s", s.email);

    fclose(database);
    printf("\n\n\tYou have succesfully register.");
    printf("\n\n\tPress any key to continue login...");
    getch();
    goto login;


    }
    else if(y==2)
    {
        char username[50], password[50],attempt, attempt1;
        login:
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\t\t\tEnter your username and password:\n");
        printf("\n\t\t\tUsername:\t");
        scanf("%s", &username);
        printf("\n\t\t\tPassword:\t");
        scanf("%s", &password);

        attempt=strcmp(password,password1);
        attempt1=strcmp(username,username1);

        if(attempt==0&&attempt1==0)
        {
            system("cls");
            printf("\t\t\t\t==============\n");
            printf("\t\t\t\tTHERMO COMPANY\n");
            printf("\t\t\t\t==============\n");
            printf("\t\t\t\tLogin Successfully!\n");
            printf("\t\t\t\tPress enter to continue...");
            getch();
            homepage();

        }
        else
        {
            system("cls");
            printf("\t\t\t\t==============\n");
            printf("\t\t\t\tTHERMO COMPANY\n");
            printf("\t\t\t\t==============\n");

            printf("\n\n\tEither your name or your login id is wrong.\n\n\tIf you did not register yet please do it so at the main menu.");
            printf("\n\n\tPress 1 to try again and 2 to go back to the main menu.");
            printf("\n\n\tElse to exit.");
            scanf("%d", &c);

            if(c==1)
            {
                system("cls");
                goto login;
            }
            if(c==2)
            {
                system("cls");
                main();
            }

            else
            {
                return 0;
            }

        }
    }
    else if(y==3)
    {
        exit:
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\a\n\t\t\tThanks for using this programme.\n\n\n\n\n\n\n\n");
        return 0;
    }
    else if(y==4)
    {
        homepage();    }
    else
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\t\t\t\tInvalid input.");
        printf("\n\n\t\tPress 1 to go back and others key to close: ");
        scanf("%d", &y);

        if(y==1)
        {
            main();
        }
        else
        {
            goto exit;
        }
        return 0;
}
        return 0;

}

int homepage()
{
    FILE*registration;
    char ch,opt3;
    int i,opt=0;
    int option, options,x,z;
    float HE, R, HP, CHE, CR, CHP, work, Qin, Qout, Thigh, Tlow;
    homepage:
    system("cls");
    printf("\t\t\t\t==============\n");
    printf("\t\t\t\tTHERMO COMPANY\n");
    printf("\t\t\t\t==============\n\n\n");

    printf("\t_____________________________________________________\n");
    printf("\n\tA. Second Law of Thermodynamics\t\tE. My Profile \n");
    printf("\n\tB. General Energy Analysisis\t\tF. Log Out\n");
    printf("\n\tC. Properties of Pure Substance\t\tG. About Us\n");
    printf("\n\tD. Energy Analysis of Control Volume\tH. Exit\n");
    printf("\n\tEnter Your Selection: ");

    fflush(stdin);
    scanf("%c", &opt3);

    switch(opt3)
    {
        aiman:
        case 'a':case 'A':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\n\t--------Welcome to The Second Law of Thermodynamics--------\n\n");
    printf("\tPlease choose the following options below\n");
    printf("\t1.  Heat Engine\n");
    printf("\t2.  Refrigerators\n");
    printf("\t3.  Heat Pumps\n");
    printf("\t4.  Carnot Heat Engine\n");
    printf("\t5.  Carnot Refrigerators\n");
    printf("\t6.  Carnot Heat Pump\n");
    printf("\t7.  Main Menu.\n\n");
    printf("\tEnter Selection : ");
    scanf("%d", &option);

    if(option == 1)
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\n\tThis program will calculate the thermal efficiency of Heat Engine\n");
        printf("\n\tPlease choose which formula you will use:\n\n");
        printf("1.   First Formula(use when value of Work and Heat Enter are given in system)\n");
        printf("2.   Second Formula(use when value of Heat Enter and Heat Out are given in\n     system)\n");
        printf("\n\tSelection:  ");
        scanf("%d", &options);

        if(options == 1)
        {
            printf("\n\tPlease enter the value of Work : ");
            scanf("%f", &work);
            printf("\n\tPlease enter the value of Heat Enter : ");
            scanf("%f", &Qin);

            HE = work/Qin;

            printf("\n\tThe value of your Thermal Efficiency is %.4f\n", HE);
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;
        }

        else if(options == 2)
        {
            printf("\n\tPlease enter the value of Heat Enter :");
            scanf("%f", &Qin);
            printf("\n\tPlease enter the value of Heat Out :");
            scanf("%f", &Qout);

            HE = 1 - (Qout/Qin);

            printf("\n\tThe value of Thermal Efficiency is %.4f\n", HE);
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;
        }
        else
        {
            system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;
        }
    }

    else if(option == 2)
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\t     This program will calculate the Coefficient of Perfomance\n\t\t\t\tof Refrigerators\n");
        printf("\n\tPlease choose which formula you will use\n\n");
        printf("1.   First Formula(use when value of Work and Heat Out are given in system)\n");
        printf("2.   Second Formula(use when value of Heat Enter and Heat Out are given in\n     system)\n");
        printf("\n\tSelection: ");
        scanf("%d", &options);

        if(options == 1)
        {
            printf("\n\n\tPlease enter the value of Work : ");
            scanf("%f", &work);
            printf("\n\tPlease enter the value of Heat Enter : ");
            scanf("%f", &Qout);

            R = Qout/work;

            printf("\n\tThe value of the Coefficient of Perfomance is %.4f\n", R);
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

        }

        else if(options == 2)
        {
            printf("\n\n\tPlease enter the value of Heat Enter : ");
            scanf("%f", &Qin);
            printf("\n\tPlease enter the value of Heat Out : ");
            scanf("%f", &Qout);

            R = Qout/( Qin - Qout);

            printf("\n\tThe value of the Coefficient of Perfomance is %.4f\n", R);
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

        }

        else
        {
            system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

        }
    }

    else if(option == 3)
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\n\n\t\tThis program will calculate the Coefficient\n\t\t\tof Perfomance of Heat Pumps\n");
        printf("\n\tPlease choose which formula you will use\n");
        printf("\n1.   First Formula(use when value of Work and Heat Enter are given in system)\n");
        printf("2.   Second Formula(use when value of Heat Enter and Heat Out are given in\n     system)\n");
        printf("\n\n\tSelection: ");
        scanf("%d", &options);

        if(options == 1)
        {
            printf("\n\tPlease enter the value of Work :");
            scanf("%f", &work);
            printf("\n\tPlease enter the value of Heat Enter :");
            scanf("%f", &Qin);

            HP = Qin/work;

            printf("\n\tThe value of the Coefficient of Perfomance is %.4f\n", HP);
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

        }

        else if(options == 2)
        {
            printf("\n\tPlease enter the value of Heat Enter :");
            scanf("%f", &Qin);
            printf("\n\tPlease enter the value of Heat Out :");
            scanf("%f", &Qout);

            HP = Qin/( Qin - Qout);

            printf("\n\tThe value of the Coefficient of Perfomance is %.4f\n", HP);
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;


        }

        else
        {
            system("cls");
            printf("\t\t\t\t==============\n");
            printf("\t\t\t\tTHERMO COMPANY\n");
            printf("\t\t\t\t==============\n");



            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

        }
    }

    else if(option == 4)
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\t\tThis program will calculate the Thermal Efficiency\n\t\t\t     of Carnot Heat Engine\n");
        printf("\n\tPlease enter the value of High Temperature :");
        scanf("%f", &Thigh);
        printf("\n\tPlease enter the value of Low Temperature :");
        scanf("%f", &Tlow);

        CHE = 1 - ( Tlow / Thigh);

        printf("\n\n\tThe value of Thermal Efficiency is %.4f\n", CHE);
        printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;
    }

    else if(option == 5)
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\n\n\t\tThis program will calculate the Coefficient\n\t\t  of Perfomance of Carnot Refrigerators\n");
        printf("\n\tPlease enter the value of High Temperature : ");
        scanf("%f", &Thigh);
        printf("\n\tPlease enter the value of Low Temperature : ");
        scanf("%f", &Tlow);

        CR = Tlow / (Thigh - Tlow);

        printf("\n\n\tThe value of Coefficient of Perfomance is %.4f\n", CR);
        printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

    }

    else if(option == 6)
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\n\n\tThis program will calculate the Coefficient of Perfomance of Heat Pumps\n");
        printf("\nPlease enter the value of High Temperature :\n");
        scanf("%f", &Thigh);
        printf("\nPlease enter the value of Low Temperature :\n");
        scanf("%f", &Tlow);

        CHP = Thigh / (Thigh - Tlow);

        printf("The value of Thermal Efficiency is %.4f\n", CHP);
        getch();
        goto aiman;
    }

    if(option==7)
    {
        goto homepage;
    }

    else
    {
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");


            printf("\n\n\tInvalid input...");
            printf("\n\n\tPress Enter to continue...");
            getch();
            goto aiman;

    }


        break;

        case 'b':case 'B':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\n\t\t\tENERGY TRANSFER OF CLOSED SYSTEM");
        printf("\n\t\t\t________________________________");

    while(opt!=4)
    {
        printf("\n\n\tPlease select:\n");
        printf("\n\t1. Potential Energy");
        printf("\n\t2. Kinetic Energy");
        printf("\n\t3. Energy Trasfer");
        printf("\n\t4. Quit\n\t:");
        scanf("%d", &opt);

        if(opt==1)
        {
            potential_energy();
        }
        else if(opt==2)
        {
            kinetic_energy();
        }
        else if(opt==3)
        {
            energy_transfer();
        }
        else{goto homepage;}

    }
return 0;
        break;

        case 'c': case 'C':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\n\t\t\tENERGY ANALYSIS OF CONTROL VOLUME");
        printf("\n\t\t\t________________________________");

    while(opt!=3)
    {
        printf("\n\n\tPlease select:\n");
        printf("\n\t1. Quality");
        printf("\n\t2. Ideal Gas EoS");
        printf("\n\t3. Quit\n\t:");
        scanf("%d", &opt);

        if(opt==1)
        {
            quality();
        }
        else if(opt==2)
        {
            ideal_gas();
        }

        else
        {goto homepage;}
    }
return 0;

        break;

        case 'd': case 'D':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\n\t\t\t\t    ENTROPY");
        printf("\n\t\t\t\t    _______");

        break;

        case 'e': case 'E':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        registration=fopen( "database.dat","r");

        if(registration==NULL)
        {
            puts("\n\n\t\t     The database cannot read your profile.\n\t\tEither it is corrupted or you are not registered.");
            puts("\n\n\t\tThe system will now close for safety measurements.");
            break;
        }
        else
        {
            while (1)
        {
            ch=fgetc(registration);
            if(ch==EOF)
            break ;
            printf ( "%c", ch);
        }
            fclose(registration);

        }
            printf("\n\nPress Enter to continue...");
            getch();
            goto homepage;

            break;

        case 'f': case 'F':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\n\t\t\t\t>>>>Logout<<<<");
        getch();
        main();
        break;

        case 'g': case 'G':
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n\n\n");
        printf("\n\n\tThe mission of Thermo Company is to develop and supply");
        printf("\n\tsuperior software, databases and services for technical  ");
        printf("\n\tcalculations involving thermodynamics or thermal calculations.\n");
        printf("\n\tThermo Company continuously develops our software and");
        printf("\n\tdatabases in order to create new and better tools for\n\tsuch calculations.");
        printf("\n\n\tPress 1 to exit, else to go back: ");
        scanf("%d", &z);
        switch(z)
        {
            case 1: goto exit;
                    break;

            default:
                    goto homepage;
                    break;
        }
        break;


        case 'h': case 'H':
        system("cls");
        exit:
        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");

        printf("\a\n\t\t\tThanks for using this programme.\n\n\n\n\n\n\n\n");
        break;

        default:

        system("cls");
        printf("\t\t\t\t==============\n");
        printf("\t\t\t\tTHERMO COMPANY\n");
        printf("\t\t\t\t==============\n");
        printf("\n\t\t\t\tInvalid input.");
        printf("\n\n\t\tPress 1 to go back and others key to close: ");
        scanf("%d", &x);

        if(x==1)
        {
            goto homepage;
        }
        else
        {
            goto exit;
        }
        break;
    }
}
energy_transfer()
{
    float energy_transfer,heat_transfer, work_transfer, mass_flow;
    printf("\nEnter heat transfer :");
    scanf("%f", &heat_transfer);
    printf("\nEnter work transfer :");
    scanf("%f", &work_transfer);
    printf("\nEnter mass flow :");
    scanf("%f", &mass_flow);
    energy_transfer = heat_transfer + work_transfer + mass_flow;
    printf("\nEnergy transfer : %.2f", energy_transfer);
}

kinetic_energy()
{
    float kinetic_energy,mass,gravity,height;
    printf("\nEnter mass (kg):");
    scanf("%f", &mass);
    printf("\nEnter Gravity ");
    scanf("%f", &gravity);
    printf("\nEnter height (m)");
    scanf("%f", &height);
    kinetic_energy = mass*gravity*height;
    printf("\nKinetic Energy : %.2f", kinetic_energy);
}

potential_energy()
{
    float potential_energy,mass,velocity;
    printf("\nEnter mass (kg):");
    scanf("%f", &mass);
    printf("\nEnter velocity (m\s) :");
    scanf("%f", &velocity);
    potential_energy = (mass*velocity*velocity)/2;
    printf("\nPotential Energy : %.2f", potential_energy);
}

ideal_gas ()
{
    float ideal_gas, pressure, volume, mass, gas_constant,temperature;
    printf("Enter pressure :");
    scanf("%f", &pressure);
    printf("Enter volume :");
    scanf("%f", &volume);
    printf("Enter mass :");
    scanf("%f", &mass);
    printf("Enter gas constant :");
    scanf("%f", &gas_constant);
    printf("Enter temperature :");
    scanf("%f", &temperature);
    ideal_gas = (gas_constant*mass*temperature)/(pressure*volume);
    printf("Ideal gas EoS : %.2f", ideal_gas);
}

quality ()
{
    float quality,v_f, v_average, v_fg;
    printf("Enter v or v average :\n");
    scanf("%f", &v_average);
    printf("Enter vf :\n");
    scanf("%f", &v_f);
    printf("Enter vfg :");
    scanf("%f", &v_fg);
    quality = (v_f*v_average)/v_fg;
    printf("Quality : %.2f", quality);

}


int main()
{
    int opt1,y;
    main:
    system("cls");
    printf("\t\t\t\t==============\n");
    printf("\t\t\t\tTHERMO COMPANY\n");
    printf("\t\t\t\t==============\n");
    printf("\n\t\t\t\tWelcome Guest!\n");
    printf("\n\t\t\t\t______________\n");
    printf("\n\t\t\t\t1. REGISTER");
    printf("\n\t\t\t\t2. LOGIN\n");
    printf("\t\t\t\t3. EXIT\n");
    printf("\t\t\t\t______________\n");

    printf("\n\n\t\t\t\tEnter: ");

    scanf("%d", &opt1);
    mainmenu(opt1);
}