/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/
#ifndef hsQueue_Defined
#define hsQueue_Defined

#include "hsTypes.h"

template <class T> class hsQueue {
private:
    
    int         fArraySize;
    T           *fArray;
    int         fHead;      // Index of first element in the queue
    int         fTail;      // Index of next free spot in the queue 
    int         fLook;      // Index of look pointer
    hsBool      fFull;      // Is queue full?
    hsBool      fEmpty;     // Is queue empty?
    
    void        Inc(int *index);
    int         Inc(int index);

    void        Dec(int *index);
    int         Dec(int index);
    
public:
                            hsQueue( int size );
                            ~hsQueue();
    hsBool                  Append(const T &newTail);   // Add to end of line
    hsBool                  Remove(const T &someElement);   // Find and remove element in the line
    hsBool                  Pop(T *headElement);            // Remove and return the head of the line
    hsBool                  StartLook(T *headElement);      // Return the head of the line w/out removing it
    hsBool                  NextLook(T *nextElement);       // Return the head of the line w/out removing it
    hsBool                  IsEmpty(void) { return fEmpty; }
    hsBool                  IsFull(void) { return fFull; }
};

//
// Constructor
// Allocate array, init head/tail indices
//
template <class T> hsQueue<T>::hsQueue( int size )
{
    fArraySize = size;
    fArray = TRACKED_NEW T[ size ];
    fHead = -1;
    fTail = -1;
    fLook = -1;
    fEmpty = true;
    fFull = false;
}

//
// Destructor.  free array
//
template <class T> hsQueue<T>::~hsQueue()
{
    delete [] fArray;
}

//
// Wrap index on increment
//
template <class T> void hsQueue<T>::Inc( int *index )
{
    (*index) ++;
    if ((*index) == fArraySize) {
        *index = 0;
    }
}

//
// Wrap index on increment
//
template <class T> int hsQueue<T>::Inc( int index )
{
    (index) ++;
    if ((index) == fArraySize) {
        index = 0;
    }
    return index;
}

//
// Wrap index on decrement
//
template <class T> void hsQueue<T>::Dec( int *index )
{
    (*index) --;
    if ((*index) < 0) {
        *index = fArraySize-1;
    }
}

//
// Wrap index on decrement
//
template <class T> int hsQueue<T>::Dec( int index )
{
    (index) --;
    if ((index) < 0) {
        index = fArraySize-1;
    }
    return index;
}

//
// Add copy of item to the array.
//
template <class T> hsBool hsQueue<T>::Append(const T &thing)
{
    if (fHead == -1 && fTail == -1) {
        // init case
        fHead = 0;
        fTail = 0;
    }

    if (fFull) {
        // Queue is full
        return false;
    }
    
    if ( (fHead<0 || fHead>=fArraySize) ) {
        hsIfDebugMessage( (fHead<0 || fHead>=fArraySize), "Append: Illegal head pointer", fHead);               
    }
    
    hsIfDebugMessage( (fTail<0 || fTail>=fArraySize), "Append: Illegal tail pointer", fTail);

    // Copy
    fArray[fTail] = thing;
    fEmpty = false;

    // increment tail pointer
    Inc(&fTail);
    if (fTail == fHead) {
        fFull = true;
    }
    
    return true;    
}

//
// Get a copy of the head of the array
//
template <class T> hsBool hsQueue<T>::Pop(T *thing)
{
    if (fEmpty) {
        return false;
    }
    
    hsIfDebugMessage( (fHead<0 || fHead>=fArraySize), "Pop: Illegal head pointer", fHead);
    hsIfDebugMessage( (fTail<0 || fTail>=fArraySize), "Pop: Illegal tail pointer", fTail);
            
    // Copy
    *thing = fArray[fHead];
    fFull = false;

    // Increment head pointer
    Inc(&fHead);
    if (fHead == fTail) {
        fEmpty = true;
    }       
    
    return true;
}

//
// Remove item from list
//
template <class T> hsBool hsQueue<T>::Remove(const T &thing)
{
    if (fEmpty) {
        return false;
    }
    
    hsIfDebugMessage( (fHead<0 || fHead>=fArraySize), "Remove: Illegal head pointer", fHead);
    hsIfDebugMessage( (fTail<0 || fTail>=fArraySize), "Remove: Illegal tail pointer", fTail);
    
    // loop through list, find item
    int i = fHead;
    do {
        if (fArray[i] == thing) {
            // Found it - now remove it by sliding everything down 1
            int j=Inc(i);
            while(j!= fTail) {
                if (fLook==j)
                    Dec(&fLook);
                fArray[Dec(j)] = fArray[j];
                Inc(&j);
            }
            if (fLook==fTail)
                Dec(&fLook);
            Dec(&fTail);
            if (fTail == fHead) {
                fEmpty = true;
            }
            return true;
        }

        Inc(&i);
        if (i==fTail) {
            return false;
        }

    } while(true);
}

//
// Return pointer to first item in list, without popping it.
// Return false if nothing there.
//
template <class T> hsBool hsQueue<T>::StartLook(T *thing)
{
    if (fEmpty) {
        return false;
    }
    
    hsIfDebugMessage( (fHead<0 || fHead>=fArraySize), "StartLook: Illegal head pointer", fHead);
    hsIfDebugMessage( (fTail<0 || fTail>=fArraySize), "StartLook: Illegal tail pointer", fTail);
    
    fLook = fHead;
    *thing = fArray[fLook];

    // inc look pointer 
    Inc(&fLook);
        
    // success
    return true;
}

//
// Return pointer to next item in list, without popping it.  Doesn't change head or tail.
// Should be called immediately after StartLook.
// Return false when at end of list.
//
template <class T> hsBool hsQueue<T>::NextLook(T *thing)
{
    if (fEmpty || fLook == fTail) {
        return false;
    }
    
    hsAssert(fLook != -1, "Must call StartLook first\n");
    hsIfDebugMessage( (fHead<0 || fHead>=fArraySize), "NextLook: Illegal head pointer", fHead);
    hsIfDebugMessage( (fTail<0 || fTail>=fArraySize), "NextLook: Illegal tail pointer", fTail);
    
    // Return copy of item without removing it
    *thing = fArray[fLook];     
    Inc(&fLook);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////
//
// Code for threaded message queues - move to another file
//
#ifdef MQUEUE

#include "hsThread.h"
#if HS_BUILD_FOR_UNIX
    #include <mqueue.h>
#endif

class hsListQue {
public:
    struct Elem {
        Elem*   fNext;
    };
private:
    Elem*   fHead;
    Elem*   fTail;
    int     fCount;
public:
                hsListQue();
    virtual     ~hsListQue();

    virtual int     Count();
    virtual void    Enqueue(Elem* newItem);
    virtual Elem*   Dequeue();
};

class hsMutexQueue : public hsListQue {
    hsMutex     fMutex;
public:
    hsMutexQueue() {}

    virtual int     Count();
    virtual void    Enqueue(Elem* newItem);
    virtual Elem*   Dequeue();  // will return nil if the queue is empty
};

class hsSemaphoreQueue : public hsMutexQueue {
    hsSemaphore fSema;
public:
    hsSemaphoreQueue() {}

    virtual void    Enqueue(Elem* newItem);
    virtual Elem*   Dequeue();  // never returns nil, it just waits
};

class hsMsgQueue {
    int fMaxSize;
#if HS_BUILD_FOR_UNIX
    mqd_t   fMQ;
#else
    class hsPrivateMQ*  fMQ;
    UInt32  fAccess;
#endif
public:
    enum {
        kRead   = 0x0001,
        kWrite  = 0x0002,
        kBlock  = 0x0004
    };

        hsMsgQueue();
    virtual ~hsMsgQueue();

    hsBool  Create(const char name[], int maxSize, UInt32 access);
    hsBool  Open(const char name[], UInt32 access);
    void    Close();

    int GetMaxSize() const { return fMaxSize; }
    hsBool  Send(const void* data, int size = 0);
    int Receive(void* data);    // returns actual size or 0

    static void Delete(const char name[]);
};
#endif // MQUEUE

#endif