/************************************************************************************
 *** FILE: PQueue.cpp
 *** DATE: 04/27/2006
 *** GOAL: This file illustrates how to create a simple Priority Queue in MS
 ***       Managd Extension. The most important class here is PQueue which is
 ***       derived from System::Collections::ArrayList class.
 ***       As you can see we only overwrote method Add(), which now not only adds
 ***       a new Robot to the list, but also sorts the list. Note, that in order to
 ***       sort the list we need to define a Comparer class RobotComparer.
 ***       We also added a couple of methods:
 ***        - push (alias for Add)
 ***        - pop  that returns the top element of the queue and removes it from
 ***               the queue
 ***        - and a property Elem, which behaves symilar to standard property Item
 ***          but returns Robot* instead of generic Object*.
 *** BUILD: in order to compile this program use
 ***        c:> cl /clr PQueue.cpp
 ***        command
 ************************************************************************************/


#using <mscorlib.dll>

using namespace System;
using namespace System::Collections;

__gc class Robot : public Object {
private:
   static int lastID = 1;
   static Random *rand = new Random;
   int robotHP;
   int robotID;
public:
   Robot() { robotID=lastID++;  robotHP=rand->Next(100);  };
   String* ToString() { return String::Concat(S"Robot #", robotID.ToString(), S"  HP:", robotHP.ToString());  };
   __property int get_HP() { return robotHP; };
   __property void set_HP(int newHP) { if(newHP>=0) robotHP=newHP;  };
   __property int get_ID() { return robotID; };
   __gc struct RobotComparer : Collections::IComparer {
      int Compare(Object *a, Object *b)
      {
         Robot *left  = dynamic_cast<Robot*>(a);
         Robot *right = dynamic_cast<Robot*>(b);
         return right->HP - left->HP;
      }
   };
};



__gc class PQueue : public ArrayList {
public:
   __property Robot* get_Elem(int index) { return dynamic_cast<Robot*>(Item[index]); };
   void Add(Robot *r) { __super::Add(r);  Sort(new Robot::RobotComparer); };
   void push(Robot *r) { Add(r); };
   Robot* pop() { Robot *r = Elem[0];  RemoveAt(0);  return r; };
};

int main()
{
    // TODO: Please replace the sample code below with your own.
   Console::WriteLine(S"Testing managed robot queue:");
   int i;
   Robot *r;
   PQueue *queue = new PQueue;

   for(i=0;i<10;i++){
      r = new Robot;
      Console::WriteLine("{0} created and added to the queue", r);
      queue->Add(r);
   }
   Console::WriteLine(S"Initill robot queue is:");
   for(i=0;i<queue->Count;i++)
      Console::WriteLine("{0}: {1}", i.ToString(), queue->Elem[i]);

   Console::WriteLine(S"\nLet's remove the last added element and a couple of top elements:");
   queue->Remove(r);
   Console::WriteLine(S" - {0} removed", r);
   Console::WriteLine(S" - {0} removed", queue->pop());
   Console::WriteLine(S" - {0} removed", queue->pop());
   Console::WriteLine(S"Robot queue now is:");
   for(i=0;i<queue->Count;i++)
      Console::WriteLine("{0}: {1}", i.ToString(), queue->Elem[i]);

   Console::WriteLine(S"\nLet's kill some robots ...");
   dynamic_cast<Robot*>(queue->Item[1])->HP = 0;
   dynamic_cast<Robot*>(queue->Item[4])->HP = 0;
   Console::WriteLine(S"Robot queue now is:");
   for(i=0;i<queue->Count;i++)
      Console::WriteLine("{0}: {1}", i.ToString(), queue->Elem[i]);

   Console::WriteLine(S"\n...and remove the dead robot from the queue:");
   for(i=0;i<queue->Count;)
      if( queue->Elem[i]->HP == 0 ) queue->RemoveAt(i);
      else i++;
   Console::WriteLine(S"Robot queue now is:");
   for(i=0;i<queue->Count;i++)
      Console::WriteLine("{0}: {1}", i.ToString(), queue->Elem[i]);

   return 0;
}