/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * Timer implementation

 *

 * Copyright 2025 Armin Novak <anovak@thincast.com>

 * Copyright 2025 Thincast Technologies GmbH

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <winpr/thread.h>

#include <winpr/collections.h>

#include <freerdp/timer.h>

#include <freerdp/log.h>

#include "rdp.h"

#include "utils.h"

#include "timer.h"

#if !defined(EMSCRIPTEN)

#define FREERDP_TIMER_SUPPORTED

#else

#define TAG FREERDP_TAG("timer")

#endif

typedef ALIGN64 struct

{

  FreeRDP_TimerID id;

  uint64_t intervallNS;

  uint64_t nextRunTimeNS;

  FreeRDP_TimerCallback cb;

  void* userdata;

  rdpContext* context;

  bool mainloop;

} timer_entry_t;

struct ALIGN64 freerdp_timer_s

{

  rdpRdp* rdp;

  wArrayList* entries;

  HANDLE thread;

  HANDLE event;

  HANDLE mainevent;

  size_t maxIdx;

  bool running;

};

FreeRDP_TimerID freerdp_timer_add(rdpContext* context, uint64_t intervalNS,

                                  FreeRDP_TimerCallback callback, void* userdata, bool mainloop)

{

  WINPR_ASSERT(context);

  WINPR_ASSERT(context->rdp);

#if !defined(FREERDP_TIMER_SUPPORTED)

  WINPR_UNUSED(context);

  WINPR_UNUSED(intervalNS);

  WINPR_UNUSED(callback);

  WINPR_UNUSED(userdata);

  WINPR_UNUSED(mainloop);

  WLog_WARN(TAG, "Platform does not support freerdp_timer_* API");

  return 0;

#else

  FreeRDPTimer* timer = context->rdp->timer;

  WINPR_ASSERT(timer);

  if ((intervalNS == 0) || !callback)

    return false;

  const uint64_t cur = winpr_GetTickCount64NS();

  const timer_entry_t entry = { .id = ++timer->maxIdx,

                              .intervallNS = intervalNS,

                              .nextRunTimeNS = cur + intervalNS,

                              .cb = callback,

                              .userdata = userdata,

                              .context = context,

                              .mainloop = mainloop };

  if (!ArrayList_Append(timer->entries, &entry))

    return 0;

  (void)SetEvent(timer->event);

  return entry.id;

#endif

}

static BOOL foreach_entry(void* data, WINPR_ATTR_UNUSED size_t index, va_list ap)

{

  timer_entry_t* entry = data;

  WINPR_ASSERT(entry);

  FreeRDP_TimerID id = va_arg(ap, FreeRDP_TimerID);

  if (entry->id == id)

  {

    /* Mark the timer to be disabled.

     * It will be removed on next rescheduling event

     */

    entry->intervallNS = 0;

    return FALSE;

  }

  return TRUE;

}

bool freerdp_timer_remove(rdpContext* context, FreeRDP_TimerID id)

{

  WINPR_ASSERT(context);

  WINPR_ASSERT(context->rdp);

  FreeRDPTimer* timer = context->rdp->timer;

  WINPR_ASSERT(timer);

  return !ArrayList_ForEach(timer->entries, foreach_entry, id);

}

static BOOL runTimerEvent(timer_entry_t* entry, uint64_t* now)

{

  WINPR_ASSERT(entry);

  entry->intervallNS =

      entry->cb(entry->context, entry->userdata, entry->id, *now, entry->intervallNS);

  *now = winpr_GetTickCount64NS();

  entry->nextRunTimeNS = *now + entry->intervallNS;

  return TRUE;

}

static BOOL runExpiredTimer(void* data, WINPR_ATTR_UNUSED size_t index,

                            WINPR_ATTR_UNUSED va_list ap)

{

  timer_entry_t* entry = data;

  WINPR_ASSERT(entry);

  WINPR_ASSERT(entry->cb);

  /* Skip all timers that have been deactivated. */

  if (entry->intervallNS == 0)

    return TRUE;

  uint64_t* now = va_arg(ap, uint64_t*);

  WINPR_ASSERT(now);

  bool* mainloop = va_arg(ap, bool*);

  WINPR_ASSERT(mainloop);

  if (entry->nextRunTimeNS > *now)

    return TRUE;

  if (entry->mainloop)

    *mainloop = true;

  else

    runTimerEvent(entry, now);

  return TRUE;

}

#if defined(FREERDP_TIMER_SUPPORTED)

static uint64_t expire_and_reschedule(FreeRDPTimer* timer)

{

  WINPR_ASSERT(timer);

  bool mainloop = false;

  uint64_t next = UINT64_MAX;

  uint64_t now = winpr_GetTickCount64NS();

  ArrayList_Lock(timer->entries);

  ArrayList_ForEach(timer->entries, runExpiredTimer, &now, &mainloop);

  if (mainloop)

    (void)SetEvent(timer->mainevent);

  size_t pos = 0;

  while (pos < ArrayList_Count(timer->entries))

  {

    timer_entry_t* entry = ArrayList_GetItem(timer->entries, pos);

    WINPR_ASSERT(entry);

    if (entry->intervallNS == 0)

    {

      ArrayList_RemoveAt(timer->entries, pos);

      continue;

    }

    if (next > entry->nextRunTimeNS)

      next = entry->nextRunTimeNS;

    pos++;

  }

  ArrayList_Unlock(timer->entries);

  return next;

}

static DWORD WINAPI timer_thread(LPVOID arg)

{

  FreeRDPTimer* timer = arg;

  WINPR_ASSERT(timer);

  // TODO: Currently we only support ms granularity, look for ways to improve

  DWORD timeout = INFINITE;

  HANDLE handles[2] = { utils_get_abort_event(timer->rdp), timer->event };

  while (timer->running &&

         (WaitForMultipleObjects(ARRAYSIZE(handles), handles, FALSE, timeout) != WAIT_OBJECT_0))

  {

    (void)ResetEvent(timer->event);

    const uint64_t next = expire_and_reschedule(timer);

    const uint64_t now = winpr_GetTickCount64NS();

    if (next == UINT64_MAX)

    {

      timeout = INFINITE;

      continue;

    }

    if (next <= now)

    {

      timeout = 0;

      continue;

    }

    const uint64_t diff = next - now;

    const uint64_t diffMS = diff / 1000000ull;

    timeout = INFINITE;

    if (diffMS < INFINITE)

      timeout = (uint32_t)diffMS;

  }

  return 0;

}

#endif

void freerdp_timer_free(FreeRDPTimer* timer)

{

  if (!timer)

    return;

  timer->running = false;

  if (timer->event)

    (void)SetEvent(timer->event);

  if (timer->thread)

  {

    (void)WaitForSingleObject(timer->thread, INFINITE);

    CloseHandle(timer->thread);

  }

  if (timer->mainevent)

    CloseHandle(timer->mainevent);

  if (timer->event)

    CloseHandle(timer->event);

  ArrayList_Free(timer->entries);

  free(timer);

}

static void* entry_new(const void* val)

{

  const timer_entry_t* entry = val;

  if (!entry)

    return NULL;

  timer_entry_t* copy = calloc(1, sizeof(timer_entry_t));

  if (!copy)

    return NULL;

  *copy = *entry;

  return copy;

}

FreeRDPTimer* freerdp_timer_new(rdpRdp* rdp)

{

  WINPR_ASSERT(rdp);

  FreeRDPTimer* timer = calloc(1, sizeof(FreeRDPTimer));

  if (!timer)

    return NULL;

  timer->rdp = rdp;

  timer->entries = ArrayList_New(TRUE);

  if (!timer->entries)

    goto fail;

  wObject* obj = ArrayList_Object(timer->entries);

  WINPR_ASSERT(obj);

  obj->fnObjectNew = entry_new;

  obj->fnObjectFree = free;

  timer->event = CreateEventA(NULL, TRUE, FALSE, NULL);

  if (!timer->event)

    goto fail;

  timer->mainevent = CreateEventA(NULL, TRUE, FALSE, NULL);

  if (!timer->mainevent)

    goto fail;

#if defined(FREERDP_TIMER_SUPPORTED)

  timer->running = true;

  timer->thread = CreateThread(NULL, 0, timer_thread, timer, 0, NULL);

  if (!timer->thread)

    goto fail;

#endif

  return timer;

fail:

  freerdp_timer_free(timer);

  return NULL;

}

static BOOL runExpiredTimerOnMainloop(void* data, WINPR_ATTR_UNUSED size_t index,

                                      WINPR_ATTR_UNUSED va_list ap)

{

  timer_entry_t* entry = data;

  WINPR_ASSERT(entry);

  WINPR_ASSERT(entry->cb);

  /* Skip events not on mainloop */

  if (!entry->mainloop)

    return TRUE;

  /* Skip all timers that have been deactivated. */

  if (entry->intervallNS == 0)

    return TRUE;

  uint64_t* now = va_arg(ap, uint64_t*);

  WINPR_ASSERT(now);

  if (entry->nextRunTimeNS > *now)

    return TRUE;

  runTimerEvent(entry, now);

  return TRUE;

}

bool freerdp_timer_poll(FreeRDPTimer* timer)

{

  WINPR_ASSERT(timer);

  if (WaitForSingleObject(timer->mainevent, 0) != WAIT_OBJECT_0)

    return true;

  ArrayList_Lock(timer->entries);

  (void)ResetEvent(timer->mainevent);

  uint64_t now = winpr_GetTickCount64NS();

  ArrayList_ForEach(timer->entries, runExpiredTimerOnMainloop, &now);

  (void)SetEvent(timer->event); // Trigger a wakeup of timer thread to reschedule

  ArrayList_Unlock(timer->entries);

  return true;

}

HANDLE freerdp_timer_get_event(FreeRDPTimer* timer)

{

  WINPR_ASSERT(timer);

  return timer->mainevent;

}