/*
  Copyright 2020 David Robillard <d@drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

/*
  Tests that update events are received and than redisplays they trigger happen
  immediately in the same event loop iteration.
*/

#undef NDEBUG

#include "test_utils.h"

#include "pugl/pugl.h"
#include "pugl/stub.h"

#include <assert.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

#ifdef __APPLE__
static const double timeout = 1 / 60.0;
#else
static const double timeout = -1.0;
#endif

// Windows SetTimer has a maximum resolution of 10ms
static const double tolerance = 0.012;

static const uintptr_t timerId     = 1u;
static const double    timerPeriod = 1 / 60.0;

typedef enum {
  START,
  EXPOSED,
} State;

typedef struct {
  PuglWorld*      world;
  PuglView*       view;
  PuglTestOptions opts;
  size_t          numAlarms;
  double          firstAlarmTime;
  double          lastAlarmTime;
  State           state;
} PuglTest;

static void
onTimer(PuglView* const view, const PuglTimerEvent* const event)
{
  PuglTest* const test = (PuglTest*)puglGetHandle(view);
  const double    time = puglGetTime(puglGetWorld(view));

  assert(event->id == timerId);

  if (test->numAlarms++ == 0) {
    test->firstAlarmTime = time;
  }

  test->lastAlarmTime = time;
}

static PuglStatus
onEvent(PuglView* const view, const PuglEvent* const event)
{
  PuglTest* test = (PuglTest*)puglGetHandle(view);

  if (test->opts.verbose) {
    printEvent(event, "Event: ", true);
  }

  switch (event->type) {
  case PUGL_EXPOSE:
    test->state = EXPOSED;
    break;

  case PUGL_TIMER:
    onTimer(view, &event->timer);
    break;

  default:
    break;
  }

  return PUGL_SUCCESS;
}

static double
roundPeriod(const double period)
{
  return floor(period * 1000.0) / 1000.0; // Round down to milliseconds
}

int
main(int argc, char** argv)
{
  PuglTest test = {puglNewWorld(PUGL_PROGRAM, 0),
                   NULL,
                   puglParseTestOptions(&argc, &argv),
                   0,
                   0.0,
                   0.0,
                   START};

  // Set up view
  test.view = puglNewView(test.world);
  puglSetClassName(test.world, "Pugl Test");
  puglSetWindowTitle(test.view, "Pugl Timer Test");
  puglSetBackend(test.view, puglStubBackend());
  puglSetHandle(test.view, &test);
  puglSetEventFunc(test.view, onEvent);
  puglSetDefaultSize(test.view, 512, 512);

  // Create and show window
  assert(!puglRealize(test.view));
  assert(!puglShow(test.view));
  while (test.state != EXPOSED) {
    assert(!puglUpdate(test.world, timeout));
  }

  // Register a timer with a longer period first
  assert(!puglStartTimer(test.view, timerId, timerPeriod * 2.0));

  // Replace it with the one we want (to ensure timers are replaced)
  assert(!puglStartTimer(test.view, timerId, timerPeriod));

  puglUpdate(test.world, timerPeriod * 90.0);
  assert(test.numAlarms > 0);

  // Calculate the actual period of the timer
  const double duration = test.lastAlarmTime - test.firstAlarmTime;
  const double expected = roundPeriod(timerPeriod);
  const double actual   = roundPeriod(duration / (double)(test.numAlarms - 1));
  const double difference = fabs(actual - expected);

  if (difference > tolerance) {
    fprintf(stderr, "error: Period not within %f of %f\n", tolerance, expected);
    fprintf(stderr, "note: Actual period %f\n", actual);
  }

  assert(difference <= tolerance);

  // Deregister timer and tick once to synchronize
  assert(!puglStopTimer(test.view, timerId));
  puglUpdate(test.world, 0.0);

  // Update for a half second and check that we receive no more alarms
  test.numAlarms = 0;
  puglUpdate(test.world, 0.5);
  assert(test.numAlarms == 0);

  puglFreeView(test.view);
  puglFreeWorld(test.world);

  return 0;
}