#include <stddef.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
#include <linux/input.h>
#include "scode.h"
#include "config.h"
#include "log.h"
#include "msg_queue.h"
#include "gpio.h"
#include "time_func.h"

#define INPUT_EVENT_BATCH 16

PMSG_QUEUE Sys_Queue = NULL;

static pthread_t ithread;
static volatile sig_atomic_t running = 1;
static int ts_fd = 0;

static UINT32 last_bstate = 0;
static TIMESTAMP button_event_ok[GPIO_BUTTON_COUNT];

static UINT_PTR touch_x = 0;
static UINT_PTR touch_y = 0;
static UINT32 touch_nextmsg = WM_TOUCHMOVE;

static void poll_buttons(void)
{
  UINT32 st, down, up, mask;
  UINT_PTR attr;
  TIMESTAMP now;

  /* poll hardware buttons */
  st = Gpio_read_buttons();
  if (st != last_bstate)
  {
    now = Time_since_start();
    up = last_bstate & ~st;
    down = st & ~last_bstate;
    for (attr = 1, mask = GRB_STATE_BUTTON1; attr <= GPIO_BUTTON_COUNT; attr++, mask <<= 1)
    {
      if (now < button_event_ok[attr - 1])
	continue;
      if (up & mask)
      {
	button_event_ok[attr - 1] = now + Gconfig.button_debounce;
	Mq_post1(Sys_Queue, 0, WM_HWBUTTONUP, attr);
      }
      else if (down & mask)
	Mq_post1(Sys_Queue, 0, WM_HWBUTTONDOWN, attr);
    }
    last_bstate = st;
  }
}

static void poll_touchscreen(void)
{
  int nb, nev, xerrno, i;
  struct input_event buffer[INPUT_EVENT_BATCH];

  nb = read(ts_fd, buffer, INPUT_EVENT_BATCH * sizeof(struct input_event));
  if (nb == -1)
  {
    xerrno = errno;
    if ((xerrno != EAGAIN) && (xerrno != EWOULDBLOCK))
      Log(LERROR, "Error reading from touchscreen device (%d)", xerrno);
    return;
  }
  else if (nb == 0)
  {
    Log(LERROR, "Unexpected end of file reading from touchscreen device");
    return;
  }
  nev = nb / sizeof(struct input_event);
  xerrno = nev * sizeof(struct input_event);
  if (nb > xerrno)
    Log(LERROR, "read %d bytes from touchscreen but we can only use %d", nb, xerrno);
  for (i=0; i<nev; i++)
  {
    switch (buffer[i].type)
    {
      case EV_SYN:
	if (buffer[i].code == SYN_REPORT)
	{
	  Mq_post2(Sys_Queue, 0, touch_nextmsg, touch_x, touch_y);
	  touch_nextmsg = WM_TOUCHMOVE;
	}
	break;
	
      case EV_ABS:
	if (buffer[i].code == ABS_X)
	  touch_x = buffer[i].value;
	else if (buffer[i].code == ABS_Y)
	  touch_y = buffer[i].value;
	break;
	
      case EV_KEY:
	if (buffer[i].code == BTN_TOUCH)
	  touch_nextmsg = (buffer[i].value ? WM_TOUCHDOWN : WM_TOUCHUP);
	break;
	
      default:
	break;
    }
  }
}

static void *input_thread(void *arg)
{
  last_bstate = 0;
  memset(button_event_ok, 0, GPIO_BUTTON_COUNT * sizeof(TIMESTAMP));
  touch_x = touch_y = 0;
  touch_nextmsg = WM_TOUCHMOVE;
  
  while (running)
  {
    poll_buttons();
    poll_touchscreen();
  }
  return NULL;
}

static void do_disable_input(void)
{
  running = 0;
  pthread_join(ithread, NULL);
  close(ts_fd);
  ts_fd = -1;
  Mq_destroy(Sys_Queue);
  Sys_Queue = NULL;
}

HRESULT Sys_enable_input(void)
{
  HRESULT rc = S_OK;
  int threadrc;
  
  Sys_Queue = Mq_alloc(Gconfig.sys_mq_length);
  if (!Sys_Queue)
  {
    Log(LFATAL, "Unable to allocate system message queue.");
    return E_OUTOFMEMORY;
  }

  ts_fd = open(Gconfig.touchscreen_device, O_RDONLY|O_NONBLOCK);
  if (ts_fd < 0)
  {
    rc = ERRNO_AS_SCODE;
    Mq_destroy(Sys_Queue);
    Log(LFATAL, "Unable to open touchscreen device (%08X).", rc);
    return rc;
  }
  
  running = 1;
  threadrc = pthread_create(&ithread, NULL, input_thread, NULL);
  if (threadrc != 0)
  {
    rc = SCODE_FROM_ERRNO(threadrc);
    close(ts_fd);
    ts_fd = -1;
    Mq_destroy(Sys_Queue);
    Log(LFATAL, "Unable to start system input thread (%08X).", rc);
  }
  if (SUCCEEDED(rc))
  {
    rc = Config_exitfunc(do_disable_input);
    if (FAILED(rc))
      do_disable_input();
  }
  return rc;
}