# Copyright (c) 2010-2011 Chortos-2 <chortos@inbox.lv>

# TODO: copy the ansfile if not options.erase even if no validator is used

from __future__ import division, with_statement

from .compat import *
from .exceptions import *
from . import files, config
from __main__ import options

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

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

class DummySignalIgnorer(object):
	def __enter__(self): pass
	def __exit__(self, exc_type, exc_value, traceback): pass
signal_ignorer = DummySignalIgnorer()

try:
	from .win32 import *
except Exception:
	from .unix import *

__all__ = ('TestCase', 'SkippedTestCase', 'ValidatedTestCase', 'BatchTestCase',
           'OutputOnlyTestCase')



# 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',
	             'realinname', 'realoutname', 'maxcputime', 'maxwalltime',
	             'maxmemory', 'has_called_back', 'files_to_delete',
	             'cpu_time_limit_string', 'wall_time_limit_string',
	             'time_limit_string')
	has_ansfile = has_iofiles = False
	needs_realinname = True
	
	if ABCMeta:
		__metaclass__ = ABCMeta
	
	def __init__(case, prob, id, isdummy, points):
		case.problem = prob
		case.id = id
		case.isdummy = isdummy
		case.points = points
		case.maxcputime = case.problem.config.maxcputime
		case.maxwalltime = case.problem.config.maxwalltime
		case.maxmemory = case.problem.config.maxmemory
		if case.maxcputime:
			case.cpu_time_limit_string = '/%.3f' % case.maxcputime
		else:
			case.cpu_time_limit_string = ''
		if case.maxwalltime:
			case.wall_time_limit_string = '/%.3f' % case.maxwalltime
		else:
			case.wall_time_limit_string = ''
		if not isdummy:
			if case.needs_realinname:
				case.realinname = case.problem.config.testcaseinname
			case.realoutname = case.problem.config.testcaseoutname
		else:
			if case.needs_realinname:
				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 = []
		case.time_limit_string = case.wall_time_limit_string
		try:
			return case.test(callback)
		finally:
			now = clock()
			if getattr(case, 'time_started', None) is None:
				case.time_started = case.time_stopped = now
			elif getattr(case, 'time_stopped', None) is None:
				case.time_stopped = now
			if not case.has_called_back:
				callback()
			case.cleanup()
	
	def cleanup(case):
		# Note that native extensions clean up on their own
		# and never let this condition be satisfied
		if getattr(case, 'process', None) and case.process.returncode is None:
			kill(case.process)
		for name in case.files_to_delete:
			try:
				os.remove(name)
			except OSError:
				# 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 SkippedTestCase(TestCase):
	__slots__ = ()
	
	def test(case, callback):
		raise TestCaseSkipped


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
			buffer = refbuffer = crlfhalf = refcrlfhalf = ''.encode()
			crlf = '\r\n'.encode('ascii')
			case.open_outfile()
			with case.outfile.open() as refoutput:
				while True:
					data = output.read(4096 - len(buffer))
					refdata = refoutput.read(4096 - len(refbuffer))
					if not case.problem.config.binary:
						data, refdata = crlfhalf + data, refcrlfhalf + refdata
						size, refsize = len(data), len(refdata)
						if data and data != crlfhalf and data[-1] == crlf[0]:
							size -= 1
							crlfhalf = data[-1:]
						else:
							crlfhalf = ''.encode()
						if refdata and refdata != refcrlfhalf and refdata[-1] == crlf[0]:
							refsize -= 1
							refcrlfhalf = refdata[-1:]
						else:
							refcrlfhalf = ''.encode()
						data = data[:size].replace(crlf, crlf[1:])
						data = data.replace(crlf[:1], crlf[1:])
						refdata = refdata[:refsize].replace(crlf, crlf[1:])
						refdata = refdata.replace(crlf[:1], crlf[1:])
					buffer += data
					refbuffer += refdata
					if not (buffer or refbuffer or crlfhalf or refcrlfhalf):
						break
					elif not buffer and not crlfhalf or not refbuffer and not refcrlfhalf:
						raise WrongAnswer
					size = min(len(buffer), len(refbuffer))
					if buffer[:size] != refbuffer[:size]:
						raise WrongAnswer
					buffer, refbuffer = buffer[size:], refbuffer[size:]
			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])
			with signal_ignorer:
				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, True, comment
			else:
				if case.problem.config.okexitcodeflag:
					correct = bool(case.process.returncode & case.problem.config.okexitcodeflag)
					case.process.returncode &= ~case.problem.config.okexitcodeflag
				else:
					correct = case.process.returncode >= case.problem.config.maxexitcode
				if not correct and not case.process.returncode:
					raise WrongAnswer(comment)
				return case.process.returncode / case.problem.config.maxexitcode, correct, comment


class BatchTestCase(ValidatedTestCase):
	__slots__ = ()
	
	@property
	def has_iofiles(case):
		return (not case.problem.config.stdio or
		        case.validator and not callable(case.validator))
	
	@property
	def has_ansfile(case):
		return case.validator and not callable(case.validator)
	
	def test(case, callback):
		case.open_infile()
		if case.problem.config.stdio:
			if options.erase and not case.validator or not case.problem.config.inname:
				# 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:
				with tempfile.TemporaryFile('w+b') if options.erase and (not case.validator or callable(case.validator)) else open(case.problem.config.outname, 'w+b') as outfile:
					with open(inputdatafname) as infile:
						call(case.problem.config.path, case=case, stdin=infile, stdout=outfile, stderr=devnull)
					if case.problem.config.force_zero_exitcode and case.process.returncode or case.process.returncode < 0:
						raise NonZeroExitCode(case.process.returncode)
					case.has_called_back = True
					callback()
					outfile.seek(0)
					return case.validate(outfile)
		else:
			case.infile.copy(case.problem.config.inname)
			call(case.problem.config.path, case=case, stdin=devnull, stdout=devnull, stderr=devnull)
			if case.problem.config.force_zero_exitcode and case.process.returncode or case.process.returncode < 0:
				raise NonZeroExitCode(case.process.returncode)
			case.has_called_back = True
			callback()
			try:
				output = open(case.problem.config.outname, 'rb')
			except IOError:
				raise CannotReadOutputFile(sys.exc_info()[1])
			with output as output:
				return case.validate(output)


# This is the only test case type not executing any programs to be tested
class OutputOnlyTestCase(ValidatedTestCase):
	__slots__ = ()
	needs_realinname = False
	
	def cleanup(case):
		pass
	
	def test(case, callback):
		case.time_stopped = case.time_started = 0
		case.has_called_back = True
		callback()
		try:
			output = open(case.problem.config.outname.replace('$', case.id), 'rb')
		except IOError:
			raise CannotReadOutputFile(sys.exc_info()[1])
		with output as output:
			return case.validate(output)


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.