#include <typeinfo>
#include <iostream>
#include <cassert>
#include "HList.h"

using namespace std;

// -------------------------------------------------------------------
// HNode Implementation
// -------------------------------------------------------------------

HNode::HNode() : next(NULL) {
   // do nothing else
}

HNode::~HNode() {
#ifndef NDEBUG
   cerr << "   HNode destructor\n" ;
#endif
   // do nothing
}

void HNode::print(ostream& os) const {
   os << "<no data>" ;
}

HNode *HNode::clone() const {
#ifndef NDEBUG
   cerr << "   HNode clone\n" ;
#endif

   return new HNode ;
}

bool HNode::operator == (const HNode& rhs_ref) const {  // virtual
   return typeid(rhs_ref) == typeid(HNode) ;
}

// All derived classes should have != opposite of ==, so there's
// no need to make != virtual. Note that the non-virtual != invokes
// the virtual == and this is actually what we want.
//
bool HNode::operator != (const HNode& rhs_ref) const {   // not virtual
   return ! operator==(rhs_ref) ;   // calls virtual ==
}


// -------------------------------------------------------------------
// HList Implementation
// -------------------------------------------------------------------


// Default constructor
//
HList::HList() : tail_ptr(&header), m_size(0) { 
   // do nothing else
}


// Copy constructor
//
HList::HList(const HList &L) {
#ifndef NDEBUG
   cerr << "HList copy constructor:\n" ;
#endif

   duplicate(L) ; 
}


// Destructor
//
HList::~HList() {
#ifndef NDEBUG
   cerr << "HList Destructor:\n" ;
#endif

   clear();
}


// Assignment operator
//
const HList& HList::operator=(const HList &rhs) {

   // check for self-assignment
   if(this == &rhs) return *this;

   clear(); // delete our old stuff
   duplicate(rhs) ;

   return *this ;
} 


// Make a copy of the linked list.
// The tail_ptr and m_size members set too.
// Note the use of the virtual clone function.
//
void HList::duplicate(const HList& L) {
   HNode *previous = &header ;
   HNode *ptr = L.header.next ;

   while (ptr !=NULL) {
      previous->next = ptr->clone() ;  // copy using virtual clone()
      previous = previous->next ;
      ptr = ptr->next ;
   }

   tail_ptr = previous ;
   m_size = L.m_size ;
}


// Empty the list.
// Make sure that tail_ptr and size are put in a good state.
// Note the use of the virtual destructor.
//
void HList::clear() {

   HNode *previous ;
   HNode *current = header.next;

   header.next = NULL;
   tail_ptr = &header ;
   m_size = 0 ;

   while(current != NULL) {
      previous = current ;
      current = current->next ;
      delete previous;    // virtual destructor called
   }
}


// Add node to the front of the linked list.
// Memory for the node pointed by ptr must be dynamically allocated.

void HList::push_front(HNode *ptr) {
   if (ptr == NULL) {
      cerr << "Inserting unallocated HNode!\n" ;
      exit(1) ;
   }

   ptr->next = header.next ;
   header.next = ptr ;

   // fix tail_ptr, if list was empty
   if (tail_ptr == &header) {
      tail_ptr = ptr ;
   }
   m_size++ ;
}


// Add node to the back of the linked list.
// Memory for the node pointed by ptr must be dynamically allocated.

void HList::push_back(HNode *ptr) {
   if (ptr == NULL) {
      cerr << "Inserting unallocated HNode!\n" ;
      exit(1) ;
   }

   tail_ptr->next = ptr ; ;
   tail_ptr = ptr ;
   m_size++ ;
}


// Return pointer to first node.
// Note: client can't access next to mess up the linking.
// Returns NULL if list is empty.
HNode *HList::front() {
   return header.next ;
}

// Return pointer to last node.
// Note: client can't access next to mess up the linking.
// Returns NULL if list is empty.
HNode *HList::back() {

   if (tail_ptr == &header) return NULL ;
   return tail_ptr ;
}



// Remove first node, no return value
// note the use of the virtual destructor
//
void HList::pop_front() {
   HNode *ptr = header.next ;

   // empty list, do nothing
   if (ptr == NULL) return ;

   header.next = ptr->next ;  // de-link

   // deleting last node?
   if (tail_ptr == ptr) tail_ptr = &header ;

   delete ptr ;   // Calls virtual destructor

   m_size-- ;
}


// Look for the node with "value" equal to X and return pointer
// to found node or NULL if none found.
// Note: client can't access next to mess up the linking.
// Note that != is not virtual, but calls the virtual ==
//
HNode *HList::find(const HNode& X) const {
   HNode* current = header.next ;
    
   while (current != NULL && *current != X) {
      current = current->next ;
   }

   return current ;
}


// Remove first node with "value" equal to X
// if none found, return false.
//
bool HList::remove(const HNode& X) {

   HNode* previous = &header;
   HNode* ptr ;

   while (previous->next != NULL) {
      if ( *(previous->next) == X ) {  // virtual ==
         ptr = previous->next ; 
         previous->next = ptr->next ;

         // fix tail_ptr if deleting last guy
         if (tail_ptr == ptr) {
            tail_ptr = previous ;
         }

         delete ptr ;   // calls virtual destructor
         m_size-- ;
         return true ;
      }

      previous = previous->next ;
   }

   return false;
}


// Print entire linked list using virtual HNode::print()

void HList::print(ostream& os /*=cout*/) const {
   HNode* current = header.next ;

   while(current != NULL) {
      current->print(os) ;
      os << " " ;
      current = current->next;
   }
}


unsigned int HList::size() const {
   return m_size;
}


// Overloaded << 
//
ostream& operator<< (ostream& os, const HList& L) {
   L.print(os) ;
   return os ;
}