import hashlib
import json
import logging
import os
import pty
import shlex
import subprocess
import sys
import time
from datetime import datetime, date
from select import epoll, EPOLLIN, EPOLLHUP
from typing import Union

from .exceptions import *
from .output import log


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.")


class JsonEncoder:
	def _encode(obj):
		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] == '!':
					copy[JsonEncoder._encode(key)] = '******'
				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)):
			r = []
			for item in obj:
				r.append(json.loads(json.dumps(item, cls=JSON)))
			return r
		else:
			return obj


class JSON(json.JSONEncoder, json.JSONDecoder):
	def _encode(self, obj):
		return JsonEncoder._encode(obj)

	def encode(self, obj):
		return super(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

			output = output.strip('\r\n ')
			if len(output) <= 0:
				return False

			from .user_interaction import get_terminal_width

			# Move back to the beginning of the terminal
			sys.stdout.flush()
			sys.stdout.write("\033[%dG" % 0)
			sys.stdout.flush()

			# Clear the line
			sys.stdout.write(" " * get_terminal_width())
			sys.stdout.flush()

			# Move back to the beginning again
			sys.stdout.flush()
			sys.stdout.write("\033[%dG" % 0)
			sys.stdout.flush()

			# And print the new output we're peaking on:
			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 as err:
				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:
		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:
				os.execve(self.cmd[0], self.cmd, {**os.environ, **self.environment_vars})
			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 __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

		try:
			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()

		except SysCallError:
			return False

		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():
	o = b''.join(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