import hashlib
import json
import logging
import os
import shlex
import subprocess
import sys
import time
from datetime import datetime, date
from typing import Union
try:
	from select import epoll, EPOLLIN, EPOLLHUP
except:
	import select
	EPOLLIN = 0
	EPOLLHUP = 0

	class epoll():
		""" #!if windows
		Create a epoll() implementation that simulates the epoll() behavior.
		This so that the rest of the code doesn't need to worry weither we're using select() or epoll().
		"""
		def __init__(self):
			self.sockets = {}
			self.monitoring = {}

		def unregister(self, fileno, *args, **kwargs):
			try:
				del(self.monitoring[fileno])
			except:
				pass

		def register(self, fileno, *args, **kwargs):
			self.monitoring[fileno] = True

		def poll(self, timeout=0.05, *args, **kwargs):
			try:
				return [[fileno, 1] for fileno in select.select(list(self.monitoring.keys()), [], [], timeout)[0]]
			except OSError:
				return []

from .exceptions import RequirementError, SysCallError
from .output import log
from .storage import storage

def gen_uid(entropy_length=256):
	return hashlib.sha512(os.urandom(entropy_length)).hexdigest()


def multisplit(s, splitters):
	s = [s, ]
	for key in splitters:
		ns = []
		for obj in s:
			x = obj.split(key)
			for index, part in enumerate(x):
				if len(part):
					ns.append(part)
				if index < len(x) - 1:
					ns.append(key)
		s = ns
	return s


def locate_binary(name):
	for PATH in os.environ['PATH'].split(':'):
		for root, folders, files in os.walk(PATH):
			for file in files:
				if file == name:
					return os.path.join(root, file)
			break  # Don't recurse

	raise RequirementError(f"Binary {name} does not exist.")

def json_dumps(*args, **kwargs):
	return json.dumps(*args, **{**kwargs, 'cls': JSON})

class JsonEncoder:
	def _encode(obj):
		"""
		This JSON encoder function will try it's best to convert
		any archinstall data structures, instances or variables into
		something that's understandable by the json.parse()/json.loads() lib.

		_encode() will skip any dictionary key starting with an exclamation mark (!)
		"""
		if isinstance(obj, dict):
			# We'll need to iterate not just the value that default() usually gets passed
			# But also iterate manually over each key: value pair in order to trap the keys.

			copy = {}
			for key, val in list(obj.items()):
				if isinstance(val, dict):
					# This, is a EXTREMELY ugly hack.. but it's the only quick way I can think of to trigger a encoding of sub-dictionaries.
					val = json.loads(json.dumps(val, cls=JSON))
				else:
					val = JsonEncoder._encode(val)

				if type(key) == str and key[0] == '!':
					pass
				else:
					copy[JsonEncoder._encode(key)] = val
			return copy
		elif hasattr(obj, 'json'):
			return obj.json()
		elif hasattr(obj, '__dump__'):
			return obj.__dump__()
		elif isinstance(obj, (datetime, date)):
			return obj.isoformat()
		elif isinstance(obj, (list, set, tuple)):
			return [json.loads(json.dumps(item, cls=JSON)) for item in obj]
		else:
			return obj

	def _unsafe_encode(obj):
		"""
		Same as _encode() but it keeps dictionary keys starting with !
		"""
		if isinstance(obj, dict):
			copy = {}
			for key, val in list(obj.items()):
				if isinstance(val, dict):
					# This, is a EXTREMELY ugly hack.. but it's the only quick way I can think of to trigger a encoding of sub-dictionaries.
					val = json.loads(json.dumps(val, cls=UNSAFE_JSON))
				else:
					val = JsonEncoder._unsafe_encode(val)

				copy[JsonEncoder._unsafe_encode(key)] = val
			return copy
		else:
			return JsonEncoder._encode(obj)

class JSON(json.JSONEncoder, json.JSONDecoder):
	"""
	A safe JSON encoder that will omit private information in dicts (starting with !)
	"""
	def _encode(self, obj):
		return JsonEncoder._encode(obj)

	def encode(self, obj):
		return super(JSON, self).encode(self._encode(obj))

class UNSAFE_JSON(json.JSONEncoder, json.JSONDecoder):
	"""
	UNSAFE_JSON will call/encode and keep private information in dicts (starting with !)
	"""
	def _encode(self, obj):
		return JsonEncoder._unsafe_encode(obj)

	def encode(self, obj):
		return super(UNSAFE_JSON, self).encode(self._encode(obj))

class SysCommandWorker:
	def __init__(self, cmd, callbacks=None, peak_output=False, environment_vars=None, logfile=None, working_directory='./'):
		if not callbacks:
			callbacks = {}
		if not environment_vars:
			environment_vars = {}

		if type(cmd) is str:
			cmd = shlex.split(cmd)

		if cmd[0][0] != '/' and cmd[0][:2] != './':
			# "which" doesn't work as it's a builtin to bash.
			# It used to work, but for whatever reason it doesn't anymore.
			# We there for fall back on manual lookup in os.PATH
			cmd[0] = locate_binary(cmd[0])

		self.cmd = cmd
		self.callbacks = callbacks
		self.peak_output = peak_output
		self.environment_vars = environment_vars
		self.logfile = logfile
		self.working_directory = working_directory

		self.exit_code = None
		self._trace_log = b''
		self._trace_log_pos = 0
		self.poll_object = epoll()
		self.child_fd = None
		self.started = None
		self.ended = None

	def __contains__(self, key: bytes):
		"""
		Contains will also move the current buffert position forward.
		This is to avoid re-checking the same data when looking for output.
		"""
		assert type(key) == bytes

		if (contains := key in self._trace_log[self._trace_log_pos:]):
			self._trace_log_pos += self._trace_log[self._trace_log_pos:].find(key) + len(key)

		return contains

	def __iter__(self, *args, **kwargs):
		for line in self._trace_log[self._trace_log_pos:self._trace_log.rfind(b'\n')].split(b'\n'):
			if line:
				yield line + b'\n'

		self._trace_log_pos = self._trace_log.rfind(b'\n')

	def __repr__(self):
		self.make_sure_we_are_executing()
		return str(self._trace_log)

	def __enter__(self):
		return self

	def __exit__(self, *args):
		# b''.join(sys_command('sync')) # No need to, since the underlying fs() object will call sync.
		# TODO: https://stackoverflow.com/questions/28157929/how-to-safely-handle-an-exception-inside-a-context-manager

		if self.child_fd:
			try:
				os.close(self.child_fd)
			except:
				pass

		if self.peak_output:
			# To make sure any peaked output didn't leave us hanging
			# on the same line we were on.
			sys.stdout.write("\n")
			sys.stdout.flush()

		if len(args) >= 2 and args[1]:
			log(args[1], level=logging.ERROR, fg='red')

		if self.exit_code != 0:
			raise SysCallError(f"{self.cmd} exited with abnormal exit code: {self.exit_code}")

	def is_alive(self):
		self.poll()

		if self.started and self.ended is None:
			return True

		return False

	def write(self, data: bytes, line_ending=True):
		assert type(data) == bytes  # TODO: Maybe we can support str as well and encode it

		self.make_sure_we_are_executing()

		os.write(self.child_fd, data + (b'\n' if line_ending else b''))

	def make_sure_we_are_executing(self):
		if not self.started:
			return self.execute()

	def tell(self) -> int:
		self.make_sure_we_are_executing()
		return self._trace_log_pos

	def seek(self, pos):
		self.make_sure_we_are_executing()
		# Safety check to ensure 0 < pos < len(tracelog)
		self._trace_log_pos = min(max(0, pos), len(self._trace_log))

	def peak(self, output: Union[str, bytes]) -> bool:
		if self.peak_output:
			if type(output) == bytes:
				try:
					output = output.decode('UTF-8')
				except UnicodeDecodeError:
					return False

			sys.stdout.write(output)
			sys.stdout.flush()
		return True

	def poll(self):
		self.make_sure_we_are_executing()

		got_output = False
		for fileno, event in self.poll_object.poll(0.1):
			try:
				output = os.read(self.child_fd, 8192)
				got_output = True
				self.peak(output)
				self._trace_log += output
			except OSError:
				self.ended = time.time()
				break

		if self.ended or (got_output is False and pid_exists(self.pid) is False):
			self.ended = time.time()
			try:
				self.exit_code = os.waitpid(self.pid, 0)[1]
			except ChildProcessError:
				try:
					self.exit_code = os.waitpid(self.child_fd, 0)[1]
				except ChildProcessError:
					self.exit_code = 1

	def execute(self) -> bool:
		import pty

		if (old_dir := os.getcwd()) != self.working_directory:
			os.chdir(self.working_directory)

		# Note: If for any reason, we get a Python exception between here
		#   and until os.close(), the traceback will get locked inside
		#   stdout of the child_fd object. `os.read(self.child_fd, 8192)` is the
		#   only way to get the traceback without loosing it.
		self.pid, self.child_fd = pty.fork()
		os.chdir(old_dir)

		if not self.pid:
			try:
				try:
					with open(f"{storage['LOG_PATH']}/cmd_history.txt", "a") as cmd_log:
						cmd_log.write(f"{' '.join(self.cmd)}\n")
				except PermissionError:
					pass

				os.execve(self.cmd[0], self.cmd, {**os.environ, **self.environment_vars})
				if storage['arguments'].get('debug'):
					log(f"Executing: {self.cmd}", level=logging.DEBUG)

			except FileNotFoundError:
				log(f"{self.cmd[0]} does not exist.", level=logging.ERROR, fg="red")
				self.exit_code = 1
				return False

		self.started = time.time()
		self.poll_object.register(self.child_fd, EPOLLIN | EPOLLHUP)

		return True

	def decode(self, encoding='UTF-8'):
		return self._trace_log.decode(encoding)


class SysCommand:
	def __init__(self, cmd, callback=None, start_callback=None, peak_output=False, environment_vars=None, working_directory='./'):
		_callbacks = {}
		if callback:
			_callbacks['on_end'] = callback
		if start_callback:
			_callbacks['on_start'] = start_callback

		self.cmd = cmd
		self._callbacks = _callbacks
		self.peak_output = peak_output
		self.environment_vars = environment_vars
		self.working_directory = working_directory

		self.session = None
		self.create_session()

	def __enter__(self):
		return self.session

	def __exit__(self, *args, **kwargs):
		# b''.join(sys_command('sync')) # No need to, since the underlying fs() object will call sync.
		# TODO: https://stackoverflow.com/questions/28157929/how-to-safely-handle-an-exception-inside-a-context-manager

		if len(args) >= 2 and args[1]:
			log(args[1], level=logging.ERROR, fg='red')

	def __iter__(self, *args, **kwargs):

		for line in self.session:
			yield line

	def __getitem__(self, key):
		if type(key) is slice:
			start = key.start if key.start else 0
			end = key.stop if key.stop else len(self.session._trace_log)

			return self.session._trace_log[start:end]
		else:
			raise ValueError("SysCommand() doesn't have key & value pairs, only slices, SysCommand('ls')[:10] as an example.")

	def __repr__(self, *args, **kwargs):
		return self.session._trace_log.decode('UTF-8')

	def __json__(self):
		return {
			'cmd': self.cmd,
			'callbacks': self._callbacks,
			'peak': self.peak_output,
			'environment_vars': self.environment_vars,
			'session': True if self.session else False
		}

	def create_session(self):
		if self.session:
			return True

		self.session = SysCommandWorker(self.cmd, callbacks=self._callbacks, peak_output=self.peak_output, environment_vars=self.environment_vars)

		while self.session.ended is None:
			self.session.poll()

		if self.peak_output:
			sys.stdout.write('\n')
			sys.stdout.flush()

		return True

	def decode(self, fmt='UTF-8'):
		return self.session._trace_log.decode(fmt)

	@property
	def exit_code(self):
		return self.session.exit_code

	@property
	def trace_log(self):
		return self.session._trace_log


def prerequisite_check():
	if not os.path.isdir("/sys/firmware/efi"):
		raise RequirementError("Archinstall only supports machines in UEFI mode.")

	return True


def reboot():
	SysCommand("/usr/bin/reboot")

def pid_exists(pid: int):
	try:
		return any(subprocess.check_output(['/usr/bin/ps', '--no-headers', '-o', 'pid', '-p', str(pid)]).strip())
	except subprocess.CalledProcessError:
		return False


def run_custom_user_commands(commands, installation):
	for index, command in enumerate(commands):
		log(f'Executing custom command "{command}" ...', fg='yellow')
		with open(f"{installation.target}/var/tmp/user-command.{index}.sh", "w") as temp_script:
			temp_script.write(command)
		execution_output = SysCommand(f"arch-chroot {installation.target} bash /var/tmp/user-command.{index}.sh")
		log(execution_output)
		os.unlink(f"{installation.target}/var/tmp/user-command.{index}.sh")