// SYSC 2002 Winter 2011 Assignment #2
#include "stdstuff.h"

// global constants
const int MAXOPT=7, MAXCUST=100; 
   // Hint: make MAXCUST much smaller to test filling the database

// "customer" is the struct containing the customer information
// it is made up of id (an integer) and total (a double)
struct customer{
   int id;
   double total;
};

// Complete the functions here.  Note that the students can be stored in any order.

// add a new customer to the database; returns true if successful, false otherwise
// (database full or customer already exists)
bool addCustomer(int id, double total, customer db[], int &num) {
   
   if(num==MAXCUST) return false; // database is full
   
   for(int i=0;i<num;i++) {       
      if(db[i].id==id) return false; // Customer already in database
   }
   
   // insert Customer at end
   db[num].id = id;
   db[num].total = total;
   num++; // we've added a Customer
   return true; // success
}

// remove a Customer from the database; returns true if successful, false otherwise (Customer
// does not exist)
bool removeCustomer(int id, customer db[], int &num) {
   
   for(int i=0;i<num;i++) {
      if(db[i].id==id) { // found it 
         num--;
         db[i] = db[num]; // decrement number of customers and move last one into ith pos'n
         return true; // Customer removed
      }
   }
   
   return false; // Customer does not exist in database
}

// prints the full Customer database (or a note if the database is empty)
// Customers are printed one per line, with 2 decimals for the total.
void printCustomerDatabase(const customer db[], int num) {
     
   cout << setiosflags(ios::fixed|ios::showpoint); 
   cout << setprecision(2); // to get 2 decimal places for total
   
   if(num==0) { // empty database
      cout << "Customer database is empty.\n";
      return;
   }
   
   // otherwise print each Customer (one per line)
   for(int i=0;i<num;i++) {
      cout << "Customer id: " << db[i].id;
      cout << "  Customer total: " << db[i].total << endl;
   }
}

// change the Customer id of an existing Customer; returns true if successful, 
// false otherwise (Customer does not exist, or new Customer id in use)
bool changeCustomerID(int id, int nid, customer db[], int num) {

   for(int i=0;i<num;i++) { // check that new id not being used
      if(db[i].id==nid) return false; // new id already in use
   }
     
   for(int i=0;i<num;i++) {
      if(db[i].id==id) { // found the one we want to change
         db[i].id = nid; // change the id
         return true; // Customer information updated
      }
   }
   
   return false; // Customer does not exist in database
}


// change the Customer total of an existing Customer; returns true if successful, 
// false otherwise (Customer does not exist)
bool changeCustomerTotal(int id, double ntotal, customer db[], int num) {
     
   for(int i=0;i<num;i++) {
      if(db[i].id==id) { // found the one we want to change so update total
         db[i].total = ntotal;
         return true; // Customer information updated
      }
   }
   
   return false; // Customer does not exist in database
}

// returns the highest total of all Customers 
// (returns -1 if there are no Customers in the database)
double getBestCustomerTotal(const customer db[], int num) {
   double maxtotal;
       
   if(num==0) return -1; // return -1 if database empty
   
   maxtotal = db[0].total; // assume first total is largest and then check the rest
   
   for(int i=1;i<num;i++) {
      if(db[i].total>maxtotal)
         maxtotal=db[i].total;
   }
   
   return maxtotal;
}


// mainMenu returns an integer representing the menu option chosen
// Valid values are from 1 to "MAXOPT" (global constant).
int mainMenu(){
   int returnVal;
   for(;;){
      cout << endl;
      cout << "1: Add New Customer" << endl;
      cout << "2: Remove Existing Customer" << endl;
      cout << "3: Print Database Information" << endl;
      cout << "4: Change Existing Customer ID" << endl;
      cout << "5: Change Existing Customer Total" << endl;
      cout << "6: Find Best Customer Total" << endl;
      cout << "7: End Program\n\n"; // always use "max" for ending program
      cout << "Please enter the desired operation [1-" << MAXOPT << "]: ";
      cin >> returnVal;
      //return if valid option, otherwise output error message
      if(returnVal>=1&&returnVal<=MAXOPT)
         return returnVal;
      cout << "Please enter a valid integer option!" << endl;    ;
   }
}


// main program calls the functions most of which you need to write
int main(){
 
   int option, numCusts=0;
   int id, newid;
   double total, newtotal, maxtotal;
   
   // the Customer database (with numCusts customers in it)
   customer customerinfo[MAXCUST];

   for(;;){
      option=mainMenu();
        
      if(option==MAXOPT) break; // end of program
        
      switch(option) {
         case 1: // add new customer
            cout << "Enter customer id and total: ";
            cin >> id >> total;
            if(addCustomer(id,total,customerinfo,numCusts))
               cout << "Customer added.  There are now: " << numCusts << " customers in database.\n";
            else
               cout << "Customer could not be added: already in database or database full.\n";
            break;
              
         case 2: // remove existing Customer
            cout << "Enter customer id: ";
            cin >> id;
            if(removeCustomer(id,customerinfo,numCusts))
               cout << "Customer removed.  There are now: " << numCusts << " Customers in database.\n";
            else
               cout << "Customer could not be removed: did not exist in database.\n";
            break;
              
         case 3: // print database information, one customer per line, with total to 2
                 // decimal places
            printCustomerDatabase(customerinfo,numCusts); 
            break;
              
         case 4: // change customer id
            cout << "Enter existing customer id, and new customer id: ";
            cin >> id >> newid;
            if(changeCustomerID(id,newid,customerinfo,numCusts))
               cout << "customer id successfully updated.\n";
            else
               cout << "Customer could not be updated: did not exist in database or new id in use.\n";
            break;
              
         case 5: // change Customer total
            cout << "Enter customer id, and new Customer total: ";
            cin >> id >> newtotal;
            if(changeCustomerTotal(id,newtotal,customerinfo,numCusts))
               cout << "Customer total successfully updated.\n";
            else
               cout << "Customer could not be updated: did not exist in database.\n";
            break;
              
         case 6: // find best customer total
            maxtotal = getBestCustomerTotal(customerinfo,numCusts);
            if(maxtotal==-1)
               cout << "No customers: database is empty.\n";
            else
               cout << "Best customer total is: " << maxtotal << ".\n";
            break;
              
         default: // should never get here
            break;
      }
        
   } 
       
   pause();
   return 0;
}