#! /usr/bin/env python
# Copyright (c) 2010 Chortos-2 <chortos@inbox.lv>

from __future__ import division, with_statement

try:
	from compat import *
	import files, problem, config
except ImportError:
	import __main__
	__main__.import_error(sys.exc_info()[1])
else:
	from __main__ import clock, options

import glob, re, sys, tempfile, time
from subprocess import Popen, PIPE, STDOUT

import os
devnull = open(os.path.devnull, 'w+')

try:
	from signal import SIGTERM, SIGKILL
except ImportError:
	SIGTERM = 15
	SIGKILL = 9

try:
	from _subprocess import TerminateProcess
except ImportError:
	# CPython 2.5 does define _subprocess.TerminateProcess even though it is
	# not used in the subprocess module, but maybe something else does not
	try:
		import ctypes
		TerminateProcess = ctypes.windll.kernel32.TerminateProcess
	except (ImportError, AttributeError):
		TerminateProcess = None


# Do the hacky-wacky dark magic needed to catch presses of the Escape button.
# If only Python supported forcible termination of threads...
if not sys.stdin.isatty():
	canceled = init_canceled = lambda: False
	pause = None
else:
	try:
		# Windows has select() too, but it is not the select() we want
		import msvcrt
	except ImportError:
		try:
			import select, termios, tty, atexit
		except ImportError:
			# It cannot be helped!
			# Silently disable support for killing the program being tested
			canceled = init_canceled = lambda: False
			pause = None
		else:
			def cleanup(old=termios.tcgetattr(sys.stdin.fileno())):
				termios.tcsetattr(sys.stdin.fileno(), termios.TCSAFLUSH, old)
			atexit.register(cleanup)
			del cleanup
			tty.setcbreak(sys.stdin.fileno())
			def canceled(select=select.select, stdin=sys.stdin, read=sys.stdin.read):
				while select((stdin,), (), (), 0)[0]:
					if read(1) == '\33':
						return True
				return False
			def init_canceled():
				while select.select((sys.stdin,), (), (), 0)[0]:
					sys.stdin.read(1)
			def pause():
				sys.stdin.read(1)
	else:
		def canceled(kbhit=msvcrt.kbhit, getch=msvcrt.getch):
			while kbhit():
				c = getch()
				if c == '\33':
					return True
				elif c == '\0':
					# Let's hope no-one is fiddling with this
					getch()
			return False
		def init_canceled():
			while msvcrt.kbhit():
				msvcrt.getch()
		def pause():
			msvcrt.getch()


__all__ = ('TestCase', 'load_problem', 'TestCaseNotPassed',
           'TimeLimitExceeded', 'CanceledByUser', 'WrongAnswer',
           'NonZeroExitCode', 'CannotStartTestee',
           'CannotStartValidator', 'CannotReadOutputFile',
           'CannotReadInputFile', 'CannotReadAnswerFile')



# Exceptions

class TestCaseNotPassed(Exception): __slots__ = ()
class TimeLimitExceeded(TestCaseNotPassed): __slots__ = ()
class CanceledByUser(TestCaseNotPassed): __slots__ = ()

class WrongAnswer(TestCaseNotPassed):
	__slots__ = 'comment'
	def __init__(self, comment=''):
		self.comment = comment

class NonZeroExitCode(TestCaseNotPassed):
	__slots__ = 'exitcode'
	def __init__(self, exitcode):
		self.exitcode = exitcode

class ExceptionWrapper(TestCaseNotPassed):
	__slots__ = 'upstream'
	def __init__(self, upstream):
		self.upstream = upstream

class CannotStartTestee(ExceptionWrapper): __slots__ = ()
class CannotStartValidator(ExceptionWrapper): __slots__ = ()
class CannotReadOutputFile(ExceptionWrapper): __slots__ = ()
class CannotReadInputFile(ExceptionWrapper): __slots__ = ()
class CannotReadAnswerFile(ExceptionWrapper): __slots__ = ()



# Helper context managers

class CopyDeleting(object):
	__slots__ = 'case', 'file', 'name'
	
	def __init__(self, case, file, name):
		self.case = case
		self.file = file
		self.name = name
	
	def __enter__(self):
		if self.name:
			try:
				self.file.copy(self.name)
			except:
				try:
					self.__exit__(None, None, None)
				except:
					pass
				raise
	
	def __exit__(self, exc_type, exc_val, exc_tb):
		if self.name:
			self.case.files_to_delete.append(self.name)


class Copying(object):
	__slots__ = 'file', 'name'
	
	def __init__(self, file, name):
		self.file = file
		self.name = name
	
	def __enter__(self):
		if self.name:
			self.file.copy(self.name)
	
	def __exit__(self, exc_type, exc_val, exc_tb):
		pass



# Test case types

class TestCase(object):
	__slots__ = ('problem', 'id', 'isdummy', 'infile', 'outfile', 'points',
	             'process', 'time_started', 'time_stopped', 'time_limit_string',
	             'realinname', 'realoutname', 'maxtime', 'maxmemory',
	             'has_called_back', 'files_to_delete')
	
	if ABCMeta:
		__metaclass__ = ABCMeta
	
	def __init__(case, prob, id, isdummy, points):
		case.problem = prob
		case.id = id
		case.isdummy = isdummy
		case.points = points
		case.maxtime = case.problem.config.maxtime
		case.maxmemory = case.problem.config.maxmemory
		if case.maxtime:
			case.time_limit_string = '/%.3f' % case.maxtime
		else:
			case.time_limit_string = ''
		if not isdummy:
			case.realinname = case.problem.config.testcaseinname
			case.realoutname = case.problem.config.testcaseoutname
		else:
			case.realinname = case.problem.config.dummyinname
			case.realoutname = case.problem.config.dummyoutname
	
	@abstractmethod
	def test(case): raise NotImplementedError
	
	def __call__(case, callback):
		case.has_called_back = False
		case.files_to_delete = []
		try:
			return case.test(callback)
		finally:
			now = clock()
			if not getattr(case, 'time_started', None):
				case.time_started = case.time_stopped = now
			elif not getattr(case, 'time_stopped', None):
				case.time_stopped = now
			if not case.has_called_back:
				callback()
			case.cleanup()
	
	def cleanup(case):
		#if getattr(case, 'infile', None):
		#	case.infile.close()
		#if getattr(case, 'outfile', None):
		#	case.outfile.close()
		if getattr(case, 'process', None):
			# Try killing after three unsuccessful TERM attempts in a row
			# (except on Windows, where TERMing is killing)
			for i in range(3):
				try:
					try:
						case.process.terminate()
					except AttributeError:
						# Python 2.5
						if TerminateProcess and hasattr(proc, '_handle'):
							# Windows API
							TerminateProcess(proc._handle, 1)
						else:
							# POSIX
							os.kill(proc.pid, SIGTERM)
				except Exception:
					time.sleep(0)
					case.process.poll()
				else:
					case.process.wait()
					break
			else:
				# If killing the process is unsuccessful three times in a row,
				# just silently stop trying
				for i in range(3):
					try:
						try:
							case.process.kill()
						except AttributeError:
							# Python 2.5
							if TerminateProcess and hasattr(proc, '_handle'):
								# Windows API
								TerminateProcess(proc._handle, 1)
							else:
								# POSIX
								os.kill(proc.pid, SIGKILL)
					except Exception:
						time.sleep(0)
						case.process.poll()
					else:
						case.process.wait()
						break
		if case.files_to_delete:
			for name in case.files_to_delete:
				try:
					os.remove(name)
				except Exception:
					# It can't be helped
					pass
	
	def open_infile(case):
		try:
			case.infile = files.File('/'.join((case.problem.name, case.realinname.replace('$', case.id))))
		except IOError:
			e = sys.exc_info()[1]
			raise CannotReadInputFile(e)
	
	def open_outfile(case):
		try:
			case.outfile = files.File('/'.join((case.problem.name, case.realoutname.replace('$', case.id))))
		except IOError:
			e = sys.exc_info()[1]
			raise CannotReadAnswerFile(e)


class ValidatedTestCase(TestCase):
	__slots__ = 'validator'
	
	def __init__(case, *args):
		TestCase.__init__(case, *args)
		if not case.problem.config.tester:
			case.validator = None
		else:
			case.validator = case.problem.config.tester
	
	def validate(case, output):
		if not case.validator:
			# Compare the output with the reference output
			case.open_outfile()
			with case.outfile.open() as refoutput:
				for line, refline in zip_longest(output, refoutput):
					if refline is not None and not isinstance(refline, basestring):
						line = bytes(line, sys.getdefaultencoding())
					if line != refline:
						raise WrongAnswer
			return 1
		elif callable(case.validator):
			return case.validator(output)
		else:                 
			# Call the validator program
			output.close()
			if case.problem.config.ansname:
				case.open_outfile()
				case.outfile.copy(case.problem.config.ansname)
			try:
				case.process = Popen(case.validator, stdin=devnull, stdout=PIPE, stderr=STDOUT, universal_newlines=True, bufsize=-1)
			except OSError:
				raise CannotStartValidator(sys.exc_info()[1])
			comment = case.process.communicate()[0].strip()
			match = re.match(r'(?i)(ok|(?:correct|wrong)(?:(?:\s|_)*answer)?)(?:$|\s+|[.,!:]+\s*)', comment)
			if match:
				comment = comment[match.end():]
			if not case.problem.config.maxexitcode:
				if case.process.returncode:
					raise WrongAnswer(comment)
				else:
					return 1, comment
			else:
				return case.process.returncode / case.problem.config.maxexitcode, comment


class BatchTestCase(ValidatedTestCase):
	__slots__ = ()
	
	def test(case, callback):
		init_canceled()
		if sys.platform == 'win32' or not case.maxmemory:
			preexec_fn = None
		else:
			def preexec_fn():
				try:
					import resource
					maxmemory = int(case.maxmemory * 1048576)
					resource.setrlimit(resource.RLIMIT_AS, (maxmemory, maxmemory))
					# I would also set a CPU time limit but I do not want the time
					# that passes between the calls to fork and exec to be counted in
				except MemoryError:
					# We do not have enough memory for ourselves;
					# let the parent know about this
					raise
				except Exception:
					# Well, at least we tried
					pass
		case.open_infile()
		case.time_started = None
		if case.problem.config.stdio:
			if options.erase and not case.validator:
				# TODO: re-use the same file name if possible
				# FIXME: 2.5 lacks the delete parameter
				with tempfile.NamedTemporaryFile(delete=False) as f:
					inputdatafname = f.name
				contextmgr = CopyDeleting(case, case.infile, inputdatafname)
			else:
				inputdatafname = case.problem.config.inname
				contextmgr = Copying(case.infile, inputdatafname)
			with contextmgr:
				# FIXME: this U doesn't do anything good for the child process, does it?
				with open(inputdatafname, 'rU') as infile:
					with tempfile.TemporaryFile('w+') if options.erase and not case.validator else open(case.problem.config.outname, 'w+') as outfile:
						# TODO: make sure outfile.file is passed to Popen if needed
						try:
							try:
								case.process = Popen(case.problem.config.path, stdin=infile, stdout=outfile, stderr=devnull, universal_newlines=True, bufsize=-1, preexec_fn=preexec_fn)
							except MemoryError:
								# If there is not enough memory for the forked test.py,
								# opt for silent dropping of the limit
								# TODO: show a warning somewhere
								case.process = Popen(case.problem.config.path, stdin=infile, stdout=outfile, stderr=devnull, universal_newlines=True, bufsize=-1)
						except OSError:
							raise CannotStartTestee(sys.exc_info()[1])
						case.time_started = clock()
						time_next_check = case.time_started + .15
						if not case.maxtime:
							while True:
								exitcode, now = case.process.poll(), clock()
								if exitcode is not None:
									case.time_stopped = now
									break
								# For some reason (probably Microsoft's fault),
								# msvcrt.kbhit() is slow as hell
								else:
									if now >= time_next_check:
										if canceled():
											raise CanceledByUser
										else:
											time_next_check = now + .15
								 	time.sleep(0)
						else:
							time_end = case.time_started + case.maxtime
							while True:
								exitcode, now = case.process.poll(), clock()
								if exitcode is not None:
									case.time_stopped = now
									break
								elif now >= time_end:
									raise TimeLimitExceeded
								else:
									if now >= time_next_check:
										if canceled():
											raise CanceledByUser
										else:
											time_next_check = now + .15
								 	time.sleep(0)
						if config.globalconf.force_zero_exitcode and case.process.returncode:
							raise NonZeroExitCode(case.process.returncode)
						callback()
						case.has_called_back = True
						outfile.seek(0)
						return case.validate(outfile)
		else:
			case.infile.copy(case.problem.config.inname)
			try:
				try:
					case.process = Popen(case.problem.config.path, stdin=devnull, stdout=devnull, stderr=STDOUT, preexec_fn=preexec_fn)
				except MemoryError:
					# If there is not enough memory for the forked test.py,
					# opt for silent dropping of the limit
					# TODO: show a warning somewhere
					case.process = Popen(case.problem.config.path, stdin=devnull, stdout=devnull, stderr=STDOUT)
			except OSError:
				raise CannotStartTestee(sys.exc_info()[1])
			case.time_started = clock()
			time_next_check = case.time_started + .15
			if not case.maxtime:
				while True:
					exitcode, now = case.process.poll(), clock()
					if exitcode is not None:
						case.time_stopped = now
						break
					else:
						if now >= time_next_check:
							if canceled():
								raise CanceledByUser
							else:
								time_next_check = now + .15
					 	time.sleep(0)
			else:
				time_end = case.time_started + case.maxtime
				while True:
					exitcode, now = case.process.poll(), clock()
					if exitcode is not None:
						case.time_stopped = now
						break
					elif now >= time_end:
						raise TimeLimitExceeded
					else:
						if now >= time_next_check:
							if canceled():
								raise CanceledByUser
							else:
								time_next_check = now + .15
					 	time.sleep(0)
			if config.globalconf.force_zero_exitcode and case.process.returncode:
				raise NonZeroExitCode(case.process.returncode)
			callback()
			case.has_called_back = True
			with open(case.problem.config.outname, 'rU') as output:
				return case.validate(output)


# This is the only test case type not executing any programs to be tested
class OutputOnlyTestCase(ValidatedTestCase):
	__slots__ = ()
	def cleanup(case): pass

class BestOutputTestCase(ValidatedTestCase):
	__slots__ = ()

# This is the only test case type executing two programs simultaneously
class ReactiveTestCase(TestCase):
	__slots__ = ()
	# The basic idea is to launch the program to be tested and the grader
	# and to pipe their standard I/O from and to each other,
	# and then to capture the grader's exit code and use it
	# like the exit code of an output validator is used.


def load_problem(prob, _types={'batch'   : BatchTestCase,
                               'outonly' : OutputOnlyTestCase,
                               'bestout' : BestOutputTestCase,
                               'reactive': ReactiveTestCase}):
	if options.legacy:
		prob.config.usegroups = False
		prob.config.tests = list(prob.config.tests)
		for i, name in enumerate(prob.config.tests):
			try:
				if len(name) > 1:
					prob.config.usegroups = True
					break
				elif len(name):
					prob.config.tests[i] = name[0]
			except Exception:
				try:
					# Try to retrieve the first two test case ID's and cache them on success
					prob.config.tests[i] = name = iter(name)
				except TypeError:
					continue
				try:
					try:
						first = next(name)
					except NameError:
						# Python 2.5 lacks the next() built-in
						first = name.next()
				except StopIteration:
					prob.config.tests[i] = ()
				else:
					try:
						try:
							second = next(name)
						except NameError:
							second = name.next()
					except StopIteration:
						prob.config.tests[i] = first
					else:
						prob.config.tests[i] = itertools.chain((first, second), name)
						prob.config.usegroups = True
						break
	if prob.config.usegroups:
		# FIXME: test groups should again be supported!
		pass
	else:
		# We will need to iterate over these configuration variables twice
		try:
			len(prob.config.dummies)
		except Exception:
			prob.config.dummies = tuple(prob.config.dummies)
		try:
			len(prob.config.tests)
		except Exception:
			prob.config.tests = tuple(prob.config.tests)
		# First get prob.cache.padoutput right
		for i in prob.config.dummies:
			s = 'sample ' + str(i).zfill(prob.config.paddummies)
			prob.cache.padoutput = max(prob.cache.padoutput, len(s))
		for i in prob.config.tests:
			s = str(i).zfill(prob.config.padtests)
			prob.cache.padoutput = max(prob.cache.padoutput, len(s))
		# Now yield the actual test cases
		for i in prob.config.dummies:
			s = str(i).zfill(prob.config.paddummies)
			yield _types[prob.config.kind](prob, s, True, 0)
		for i in prob.config.tests:
			s = str(i).zfill(prob.config.padtests)
			yield _types[prob.config.kind](prob, s, False, prob.config.pointmap.get(i, prob.config.pointmap.get(None, prob.config.maxexitcode if prob.config.maxexitcode else 1)))