import os
import fcntl
import ctypes
from functools import cache

def gpio_init(pin: int, output: bool) -> None:
  try:
    with open(f"/sys/class/gpio/gpio{pin}/direction", 'wb') as f:
      f.write(b"out" if output else b"in")
  except Exception as e:
    print(f"Failed to set gpio {pin} direction: {e}")

def gpio_set(pin: int, high: bool) -> None:
  try:
    with open(f"/sys/class/gpio/gpio{pin}/value", 'wb') as f:
      f.write(b"1" if high else b"0")
  except Exception as e:
    print(f"Failed to set gpio {pin} value: {e}")

def gpio_read(pin: int) -> bool | None:
  val = None
  try:
    with open(f"/sys/class/gpio/gpio{pin}/value", 'rb') as f:
      val = bool(int(f.read().strip()))
  except Exception as e:
    print(f"Failed to set gpio {pin} value: {e}")

  return val

def gpio_export(pin: int) -> None:
  if os.path.isdir(f"/sys/class/gpio/gpio{pin}"):
    return

  try:
    with open("/sys/class/gpio/export", 'w') as f:
      f.write(str(pin))
  except Exception:
    print(f"Failed to export gpio {pin}")

@cache
def get_irq_action(irq: int) -> list[str]:
  try:
    with open(f"/sys/kernel/irq/{irq}/actions") as f:
      actions = f.read().strip().split(',')
      return actions
  except FileNotFoundError:
    return []

def get_irqs_for_action(action: str) -> list[str]:
  ret = []
  with open("/proc/interrupts") as f:
    for l in f.readlines():
      irq = l.split(':')[0].strip()
      if irq.isdigit() and action in get_irq_action(irq):
        ret.append(irq)
  return ret

# *** gpiochip ***

class gpioevent_data(ctypes.Structure):
  _fields_ = [
    ("timestamp", ctypes.c_uint64),
    ("id", ctypes.c_uint32),
  ]

class gpioevent_request(ctypes.Structure):
  _fields_ = [
    ("lineoffset", ctypes.c_uint32),
    ("handleflags", ctypes.c_uint32),
    ("eventflags", ctypes.c_uint32),
    ("label", ctypes.c_char * 32),
    ("fd", ctypes.c_int)
  ]

def gpiochip_get_ro_value_fd(label: str, gpiochip_id: int, pin: int) -> int:
  GPIOEVENT_REQUEST_BOTH_EDGES = 0x3
  GPIOHANDLE_REQUEST_INPUT = 0x1
  GPIO_GET_LINEEVENT_IOCTL = 0xc030b404

  rq = gpioevent_request()
  rq.lineoffset = pin
  rq.handleflags = GPIOHANDLE_REQUEST_INPUT
  rq.eventflags = GPIOEVENT_REQUEST_BOTH_EDGES
  rq.label = label.encode('utf-8')[:31] + b'\0'

  fd = os.open(f"/dev/gpiochip{gpiochip_id}", os.O_RDONLY)
  fcntl.ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, rq)
  os.close(fd)
  return int(rq.fd)