/*
 * Timer functions
 *
 * Copyright 1993 Alexandre Julliard
 */

static char Copyright[] = "Copyright  Alexandre Julliard, 1993";

#include "windows.h"
#include "message.h"


typedef struct tagTIMER
{
    HWND             hwnd;
    WORD             msg;  /* WM_TIMER or WM_SYSTIMER */
    WORD             id;
    WORD             timeout;
    struct tagTIMER *next;
    DWORD            expires;
    FARPROC          proc;
} TIMER;

#define NB_TIMERS            34
#define NB_RESERVED_TIMERS    2  /* for SetSystemTimer */

static TIMER TimersArray[NB_TIMERS];

static TIMER * pNextTimer = NULL;  /* Next timer to expire */

  /* Duration from 'time' until expiration of the timer */
#define EXPIRE_TIME(pTimer,time) \
          (((pTimer)->expires <= (time)) ? 0 : (pTimer)->expires - (time))


/***********************************************************************
 *           TIMER_InsertTimer
 *
 * Insert the timer at its place in the chain.
 */
static void TIMER_InsertTimer( TIMER * pTimer )
{
    if (!pNextTimer || (pTimer->expires < pNextTimer->expires))
    {
	pTimer->next = pNextTimer;
	pNextTimer = pTimer;
    }
    else
    {
        TIMER * ptr = pNextTimer;	
	while (ptr->next && (pTimer->expires >= ptr->next->expires))
	    ptr = ptr->next;
	pTimer->next = ptr->next;
	ptr->next = pTimer;
    }
}


/***********************************************************************
 *           TIMER_RemoveTimer
 *
 * Remove the timer from the chain.
 */
static void TIMER_RemoveTimer( TIMER * pTimer )
{
    if (pTimer == pNextTimer) pNextTimer = pTimer->next;
    else
    {
	TIMER * ptr = pNextTimer;
	while (ptr && (ptr->next != pTimer)) ptr = ptr->next;
	if (ptr) ptr->next = pTimer->next;
    }
    pTimer->next = NULL;
}


/***********************************************************************
 *           TIMER_RestartTimers
 *
 * Restart an expired timer.
 */
static void TIMER_RestartTimer( TIMER * pTimer, DWORD curTime )
{
    TIMER_RemoveTimer( pTimer );
    pTimer->expires = curTime + pTimer->timeout;
    TIMER_InsertTimer( pTimer );
}

			       
/***********************************************************************
 *           TIMER_CheckTimer
 *
 * Check whether a timer has expired, and create a message if necessary.
 * Otherwise, return time until next timer expiration in 'next'.
 * If 'hwnd' is not NULL, only consider timers for this window.
 * If 'remove' is TRUE, remove all expired timers up to the returned one.
 */
BOOL TIMER_CheckTimer( LONG *next, MSG *msg, HWND hwnd, BOOL remove )
{
    TIMER * pTimer = pNextTimer;
    DWORD curTime = GetTickCount();

    if (hwnd)  /* Find first timer for this window */
	while (pTimer && (pTimer->hwnd != hwnd)) pTimer = pTimer->next;

    if (!pTimer) *next = -1;
    else *next = EXPIRE_TIME( pTimer, curTime );
    if (*next != 0) return FALSE;  /* No timer expired */

    if (remove)	/* Restart all timers before pTimer, and then pTimer itself */
    {
	while (pNextTimer != pTimer) TIMER_RestartTimer( pNextTimer, curTime );
	TIMER_RestartTimer( pTimer, curTime );
    }

      /* Build the message */
    msg->hwnd    = pTimer->hwnd;
    msg->message = pTimer->msg;
    msg->wParam  = pTimer->id;
    msg->lParam  = (LONG)pTimer->proc;
    msg->time    = curTime;
    return TRUE;
}


/***********************************************************************
 *           TIMER_SetTimer
 */
static WORD TIMER_SetTimer( HWND hwnd, WORD id, WORD timeout,
			    FARPROC proc, BOOL sys )
{
    int i;
    TIMER * pTimer;

    if (!timeout) return 0;
    if (!hwnd && !proc) return 0;

      /* Check if there's already a timer with the same hwnd and id */

    if (hwnd)
    {
	for (i = 0, pTimer = TimersArray; i < NB_TIMERS; i++, pTimer++)
	    if ((pTimer->hwnd == hwnd) && (pTimer->id == id) &&
		(pTimer->timeout != 0))
	    {
		  /* Got one: set new values and return */
		pTimer->timeout = timeout;
		pTimer->expires = GetTickCount() + timeout;
		pTimer->proc    = proc;
		TIMER_RemoveTimer( pTimer );
		TIMER_InsertTimer( pTimer );
		return id;
	    }
    }

      /* Find a free timer */
    
    for (i = 0, pTimer = TimersArray; i < NB_TIMERS; i++, pTimer++)
	if (!pTimer->timeout) break;

    if (i >= NB_TIMERS) return 0;
    if (!sys && (i >= NB_TIMERS-NB_RESERVED_TIMERS)) return 0;
    if (!hwnd) id = i + 1;
    
      /* Add the timer */

    pTimer->hwnd    = hwnd;
    pTimer->msg     = sys ? WM_SYSTIMER : WM_TIMER;
    pTimer->id      = id;
    pTimer->timeout = timeout;
    pTimer->expires = GetTickCount() + timeout;
    pTimer->proc    = proc;
    TIMER_InsertTimer( pTimer );
    MSG_IncTimerCount( GetTaskQueue(0) );
    if (!id)
	return TRUE;
    else
	return id;
}


/***********************************************************************
 *           TIMER_KillTimer
 */
static BOOL TIMER_KillTimer( HWND hwnd, WORD id, BOOL sys )
{
    int i;
    TIMER * pTimer;
    
      /* Find the timer */
    
    for (i = 0, pTimer = TimersArray; i < NB_TIMERS; i++, pTimer++)
	if ((pTimer->hwnd == hwnd) && (pTimer->id == id) &&
	    (pTimer->timeout != 0)) break;
    if (i >= NB_TIMERS) return FALSE;
    if (!sys && (i >= NB_TIMERS-NB_RESERVED_TIMERS)) return FALSE;
    if (!sys && (pTimer->msg != WM_TIMER)) return FALSE;
    else if (sys && (pTimer->msg != WM_SYSTIMER)) return FALSE;    

      /* Delete the timer */

    pTimer->hwnd    = 0;
    pTimer->msg     = 0;
    pTimer->id      = 0;
    pTimer->timeout = 0;
    pTimer->proc    = 0;
    TIMER_RemoveTimer( pTimer );
    MSG_DecTimerCount( GetTaskQueue(0) );
    return TRUE;
}


/***********************************************************************
 *           SetTimer   (USER.10)
 */
WORD SetTimer( HWND hwnd, WORD id, WORD timeout, FARPROC proc )
{
#ifdef DEBUG_TIMER    
    printf( "SetTimer: %d %d %d %p\n", hwnd, id, timeout, proc );
#endif
    return TIMER_SetTimer( hwnd, id, timeout, proc, FALSE );
}


/***********************************************************************
 *           SetSystemTimer   (USER.11)
 */
WORD SetSystemTimer( HWND hwnd, WORD id, WORD timeout, FARPROC proc )
{
#ifdef DEBUG_TIMER    
    printf( "SetSystemTimer: %d %d %d %p\n", hwnd, id, timeout, proc );
#endif
    return TIMER_SetTimer( hwnd, id, timeout, proc, TRUE );
}


/***********************************************************************
 *           KillTimer   (USER.12)
 */
BOOL KillTimer( HWND hwnd, WORD id )
{
#ifdef DEBUG_TIMER
    printf( "KillTimer: %d %d\n", hwnd, id );
#endif
    return TIMER_KillTimer( hwnd, id, FALSE );
}


/***********************************************************************
 *           KillSystemTimer   (USER.182)
 */
BOOL KillSystemTimer( HWND hwnd, WORD id )
{
#ifdef DEBUG_TIMER
    printf( "KillSystemTimer: %d %d\n", hwnd, id );
#endif
    return TIMER_KillTimer( hwnd, id, TRUE );
}